US20040181950A1 - Alignment of microkeratome blade to blade handle - Google Patents

Abstract

A cutting tool (20) for a microkeratome (4) is disclosed. This cutting tool (20) includes a blade handle (24) and a separate cutting blade (56). Both the blade handle (24) and cutting blade (56) include features to register or align a cutting edge (80) of the cutting blade (56) with a microkeratome registration surface (28) of the blade handle (24). This microkeratome registration surface (28) of the blade handle (24) interfaces with a cutting tool registration surface (14) of a head assembly (10) of the microkeratome (4) on which the cutting tool (20) is installed. Therefore, the cutting edge (80) of the cutting blade (56) is registered or aligned relative to the cutting tool registration surface (14) of the head assembly (10) of the microkeratome (4).

Description

FIELD OF THE INVENTION
• The present invention generally relates to cutting blades and, more particularly, to including one or more features in the structure of the cutting blade to facilitate the registration or alignment of the blade's cutting edge.[0001]
BACKGROUND OF THE INVENTION
• Many types of blades exist for many types of applications. Blades are used for cutting biological materials of various types and for various applications. One application that is becoming quite prevalent is the cutting of human eye tissue in relation to a LASIK eye procedure. Here the blade is used in an automated instrument that is commonly referred to as microkeratome or the like. The blade is used to cut a thin protective layer of comeal tissue from the patient's eye. Typically the cut is made such that this tissue remains attached to the patient's eye, and thus it is commonly referred to as a “flap.” Positioning the flap away from the underlying area (e.g., by a pivotal-like motion about the remaining interconnection with the patient's eye) exposes the desired portion of the patient's cornea. A laser is then used to remove tissue from the patient's cornea or to otherwise “shape” the cornea to address associated refractive errors. Thereafter the flap is placed back in its original position. Within a few minutes the flap reattaches to the patient's eye, without the use of sutures.[0002]
• Conventional microkeratome blades are stainless steel. There are a number of issues with these types of blades. One is that the blade edge is typically examined under a microscope before being used in a LASIK procedure in an attempt to identify deficiencies in the blade edge. Various discontinuities (e.g., burrs) may exist along the blade edge based upon the way in which the blade edge is formed (e.g., mechanical grinding, polishing) and the material from which the blade is formed, as well as because of the vulnerability of the cutting edge after being formed. Certain deficiencies associated with the blade edge may adversely affect the performance of the blade in cutting the eye flap for a LASIK procedure. Another is that the blade edge of conventional stainless steel microkeratome blades will typically degrade after cutting a single eye flap. Nonetheless, a common practice is to use the same microkeratome blade to cut a flap on both of the patient's eyes in a single office visit where the LASIK procedure is performed on each eye.[0003]
• Most microkeratome blades are mounted on a blade handle, that is in turn mounted on a head assembly of the microkeratome. How the microkeratome blade is aligned to the blade handle can have a significant impact on the blade's cutting performance when installed on the microkeratome. Certain conventional stainless steel microkeratome blades have a mark on a surface thereof where the blade handle must be optically aligned therewith. Other conventional stainless steel microkeratome blades have holes that extend through the body of the blade. The corresponding blade handle has pins that are disposed within these holes. How these alignment marks or holes are formed on the cutting blade may have an impact on the accuracy with which the cutting edge of the blade is disposed relative to a reference surface of the blade handle. This in turn will affect the accuracy of the positioning of the blade's cutting edge when installed in the microkeratome.[0004]
• Other types of microkeratome blades have been proposed. One is diamond in which a crystal is typically cleaved to define a cutting edge. Another is silicon. Both isotropic and anisotropic etches have been suggested as options for fabricating a cutting edge for a microkeratome blade or the like from a silicon wafer. Notwithstanding the recognition of these various types of options in the art, stainless steel microkeratome blades still dominate the market. In fact, the inventors associated with the subject patent application do not have knowledge of any silicon microkeratome blade that is commercially available.[0005]
• There are of course many other types of applications where a blade is used to cut biological tissue (e.g., hand-held surgical instruments, scalpels), as well as many other types of non-biological cutting applications. One or more of these cutting applications may benefit from the ability to effectively fabricate cutting blades in a batch-type process using an anisotropic etch. Certain cutting applications may benefit from the ability to more accurately align the blade's cutting edge to an alignment surface on a blade handle to which the blade is mounted. Still other cutting applications may benefit from the ease with which a blade angle may be selected for the desired application and then fabricated using an anisotropic etch.[0006]
BRIEF SUMMARY OF THE INVENTION
• A first aspect of the present invention is generally directed to a cutting tool that includes a blade mounted to a blade handle. The blade includes a first cutting edge surface, a second cutting edge surface, a cutting edge that is defined by the intersection of the first and second cutting edge surfaces, and a first registration surface. This first registration surface is spaced from the cutting edge and is parallel with the first cutting edge surface. The blade handle includes a first registrant. Both the first registration surface of the blade and the first registrant of the blade handle contribute to accurately disposing the cutting edge in a desired alignment.[0007]
• Various refinements exist of the features noted in relation to the first aspect of the present invention. Further features may also be incorporated in the first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. The cutting tool of the first aspect may be used for any appropriate application, including biological applications. In one embodiment, this cutting tool is used by a microkeratome for cutting flaps of human eye tissue for LASIK procedures. The cutting edge of the blade may be accurately aligned to a reference surface of the blade handle using the first registration surface of the blade and the first registrant of the blade handle. This in turn allows the cutting edge to be accurately positioned on a microkeratome.[0008]
• Semiconductor processing techniques may be used to fabricate the cutting blade of the first aspect from a wafer. This wafer may have top and bottom major surfaces that are defined by a set of 3 Miller indices, where at least one Miller index of the set of 3 Miller indices has an absolute value greater than 3 (and thereby including both the positive and negative intercepts). This increases the likelihood of being able to fabricate the cutting edge at a particular blade angle (the angle between the first and second cutting edge surfaces). A variety of blade angles may be utilized in relation to the first aspect. It should be appreciated that at least certain blade angles may be realized in accordance with the first aspect without the requirement that at least one individual Miller index in the set of 3 Miller indices that define the top and bottom surface of the blade have an absolute value greater than 3.[0009]
• In one embodiment of the first aspect, a wafer is subjected to an anisotropic etch to simultaneously define the first cutting edge surface and the first registration surface. As such, the first cutting edge surface and the first registration surface should “respond” the same to the etch process (e.g., to an under etch; to an over etch). Both the first cutting edge surface and the first registration surface may correspond with a particular crystal plane that defines a desired blade angle relative to the second cutting edge surface, and that in effect acts as an etch stop for the anisotropic etch. In one embodiment, both the first cutting edge surface and the first registration surface of the blade are parallel with the same crystal plane within the {111} family of crystal planes (including both the positive and negative intercepts).[0010]
• The cutting edge associated with the blade of the first aspect may be defined in a variety of manners. In one embodiment, the blade includes top and bottom surfaces that are planar and disposed parallel to each other. The first cutting edge surface may be disposed at an angle relative to and intersect with the top surface, while the second cutting edge surface may be defined by the bottom surface of the blade. This may be characterized as a single-beveled configuration for the cutting blade and is the preferred configuration in the case of the first aspect. Another option is to use a double-beveled configuration for the blade. Here the blade again may include top and bottom surfaces that are planar and disposed parallel to each other. In the double-beveled case, however, the second cutting edge surface is disposed an angle relative to and intersects with the bottom surface.[0011]
• Multiple registration surfaces may be formed on the blade of the cutting tool of the first aspect. In one embodiment, at least two registration surfaces are disposed within a common reference plane (e.g., coplanar). This common reference plane may be parallel with the cutting edge. Each registration surface utilized by the blade may be defined by a registration cavity that is formed in an upper surface of the blade. Any such registration cavity may extend through the entire thickness of the blade. In this case, the first cutting edge surface would extend between the cutting edge and a first edge at the top or upper surface of the blade, while the first registration surface would extend between a second edge at the top or upper surface of the blade and a third edge at the bottom or lower surface of the blade. The first edge associated with the first cutting edge surface and the second edge associated with the first registration cavity may be disposed within a first reference plane that is parallel with a second reference plane that contains the cutting edge associated with the first cutting edge surface and the third edge associated with the first registration cavity.[0012]
• A first registration cavity that defines the first registration surface of the blade of the first aspect may be characterized as being concave or accessible through a top or upper surface of the blade. This first registration cavity would be spaced from the cutting edge and include first and second ends, with the first end being disposed or located between the cutting edge and the second end. The second end of the first registration cavity may include the first registration surface, and will more typically be defined entirely by the first registration surface. This first registration cavity may extend partially within the cutting blade (i.e., extend from a top surface of the blade toward, but not to, a bottom surface of the blade), or may extend all the way through the body of the blade as noted above. The first end of the first registration cavity may be disposed in any appropriate orientation relative to a planar top surface of the blade, while the first registration surface may be disposed at an angle other than perpendicular relative to this planar top surface.[0013]
• The first registrant of the blade handle in the case of the first aspect may extend at least within the above-noted first registration cavity. Multiple options exist for registering the first registrant of the blade handle with the blade. When registering with the blade, the first registrant of the blade handle may be spaced from the first end of the first registration cavity (e.g., by a distance of at least about[0014]1 millimeter in one embodiment). Registration may be provided along and limited to a line contact between the first registrant of the blade handle and the blade. Consider the case where the first registration surface extends from a first edge at the intersection of the first registration surface at a top surface of the blade, to a second edge. In one embodiment, the first registrant interfaces with the first registration surface closer to the second edge than to the first edge. The second edge may be located at the intersection of the first registration surface with a bottom or lower surface of the blade. In another embodiment, the first registrant interfaces with the first registration surface at its second edge. In yet another embodiment, the first registrant interfaces with the first registration surface at an intermediate location between its first and second edges.
• A second aspect of the present invention is generally directed to a cutting tool that includes a blade mounted to a blade handle. The blade includes a first cutting edge surface, a second cutting edge surface, a cutting edge that is defined by the intersection of the first and second cutting edge surfaces, and a first registration cavity. This first registration cavity is spaced from the cutting edge and includes first and second ends. The first end is disposed or located between the cutting edge and the second end. The blade handle includes a first registrant that at least extends within the first registration cavity. Both the first registration cavity of the blade and the first registrant of the blade handle contribute to accurately disposing the cutting edge in a desired alignment.[0015]
• Various refinements exist of the features noted in relation to the second aspect of the present invention. Further features may also be incorporated in the second aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. The cutting tool of the second aspect may be used for any appropriate application, including biological applications. In one embodiment, this cutting tool is used by a microkeratome for cutting flaps of human eye tissue for LASIK procedures. The cutting edge of the blade may be accurately aligned to a reference surface of the blade handle using the first registration cavity of the blade and the first registrant of the blade handle. This in turn allows the cutting edge to be accurately positioned on a microkeratome.[0016]
• The first registration cavity of the second aspect may be characterized as being concave in that it is accessible through a top or upper surface of the blade. This first registration cavity may extend partially within the cutting blade (i.e., extend from a top surface of the blade toward, but not to, a bottom surface of the blade), or may extend all the way through the body of the blade. The first end of the first registration cavity may be disposed in any appropriate orientation relative to a planar top surface of the blade, while the second end may be disposed at an angle other than perpendicular relative to this planar top surface. In one embodiment, no portion of the first registrant contacts the first end of the first registration cavity when the blade and blade handle are registered utilizing the first registration cavity and the first registrant.[0017]
• Multiple concave registration cavities may be formed on the blade of the cutting tool of the second aspect. In one embodiment, the blade includes a concave second registration cavity that is spaced from the cutting edge and that includes third and fourth ends. The third end is disposed or located between the cutting edge and the fourth end. The blade handle includes a second registrant that at least extends within the second registration cavity. Both the second registration cavity of the blade and the second registrant of the blade handle further contribute to accurately disposing the cutting edge in a desired alignment.[0018]
• The above-noted second registrant of the blade handle associated with the second aspect may be positioned such that the first and second registrants are disposed along a line that is parallel with the cutting edge of the blade. Another way to characterize the position of the second registrant relative to the first registrant is that they are equidistantly disposed from the cutting edge of the blade. In any case, the second end of the first registration cavity and the fourth end of the second registration cavity may be planar surfaces that are parallel with the first cutting edge surface. The first and second registration surfaces may be coplanar or located within a common reference plane. These first and second registration surfaces may be utilized by the first and second registrants to properly register the blade (more specifically its cutting edge) relative to the blade handle (more specifically a registration surface or structure associated therewith).[0019]
• In one embodiment of the second aspect, the second end of the first registration cavity includes a first registration surface that is parallel with the first cutting edge surface. The first registrant of the blade handle in the case of the second aspect may extend at least within the above-noted first registration cavity. Multiple options exist for registering the first registrant of the blade handle with the blade. When registering with the blade, the first registrant of the blade handle may be spaced from the first end of the first registration cavity (e.g., by a distance of at least about 1 millimeter in one embodiment). Registration may be provided along and limited to a line contact between the first registrant of the blade handle and the blade. Consider the case where the first registration surface extends from a first edge at the intersection of the first registration surface at a top surface of the blade, to a second edge. In one embodiment, the first registrant interfaces with the first registration surface closer to the second edge than to the first edge. The second edge may be located at the intersection of the first registration surface with a bottom or lower surface of the blade. In another embodiment, the first registrant interfaces with the first registration surface at its second edge. In yet another embodiment, the first registrant interfaces with the first registration surface at an intermediate location between its first and second edges.[0020]
• Semiconductor processing techniques may be used to fabricate the cutting blade of the second aspect from a wafer. This wafer may have top and bottom major surfaces that are defined by a set of Miller indices, where at least one Miller index of the set of 3 Miller indices has an absolute value greater than 3 (including both the positive and negative intercepts). This increases the likelihood of being able to fabricate the cutting edge at a particular blade angle (the angle between the first and second cutting edge surfaces). A variety of blade angles may be utilized in relation to the second aspect. It should be appreciated that at least certain blade angles may be realized in accordance with the second aspect without the requirement that at least one individual Miller index in the set of 3 Miller indices that define the top and bottom surface of the blade have an absolute value greater than 3.[0021]
• In one embodiment of the second aspect, a wafer is subjected to an anisotropic etch to simultaneously define the first cutting edge surface and the first registration cavity. Both the first cutting edge surface and the second end of the first registration cavity may correspond with a particular crystal plane that defines a desired blade angle relative to the second cutting edge surface, and that in effect acts as an etch stop for the anisotropic etch. In one embodiment, both the first cutting edge surface and the second end of the first registration cavity of the blade are parallel with the same crystal plane within the {111} family of crystal planes (including both the positive and negative intercepts).[0022]
• The cutting edge associated with the blade of the second aspect may be defined in a variety of manners. In one embodiment, the blade includes top and bottom surfaces that are planar and disposed parallel to each other. The first cutting edge surface may be disposed at an angle relative to and intersect with the top surface, while the second cutting edge surface may be defined by the bottom surface of the blade. This may be characterized as a single-beveled configuration for the cutting blade and is the preferred configuration. Another option is to use a double-beveled configuration for the blade. Here the blade again may include top and bottom surfaces that are planar and disposed parallel to each other. In the double-beveled case, however, the second cutting edge surface is disposed an angle relative to and intersects with the bottom surface.[0023]
• A third aspect of the present invention is generally directed to a cutting tool that includes a blade. The blade includes a first cutting edge surface, a second cutting edge surface, a cutting edge that is defined by the intersection of the first and second cutting edge surfaces, and a first registration surface. This first registration surface is spaced from the cutting edge and is parallel with the first cutting edge surface.[0024]
• Various refinements exist of the features noted in relation to the third aspect of the present invention. Further features may also be incorporated in the third aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. The cutting tool of the third aspect may be used for any appropriate application, including biological applications. In one embodiment, this cutting tool is used by a microkeratome for cutting flaps of human eye tissue for LASIK procedures. The cutting edge of the blade may be accurately aligned relative to the microkeratome utilizing at least the first registration surface.[0025]
• Semiconductor processing techniques may be used to fabricate the cutting blade of the third aspect from a wafer. This wafer may have top and bottom major surfaces that are defined by a set of 3 Miller indices, where at least one Miller index of the set of 3 Miller indices has an absolute value greater than 3 (including both the positive and negative intercepts). This increases the likelihood of being able to fabricate the cutting edge at a particular blade angle (the angle between the first and second cutting edge surfaces). A variety of blade angles may be utilized in relation to the third aspect. It should be appreciated that at least certain blade angles may be realized in accordance with the third aspect without the requirement that at least one individual Miller index in the set of 3 Miller indices that define the top and bottom surface of the wafer have an absolute value greater than 3.[0026]
• In one embodiment of the third aspect, a wafer is subjected to an anisotropic etch to simultaneously define the first cutting edge surface and the first registration surface. Both the first cutting edge surface and the first registration surface may correspond with a particular crystal plane that defines a desired blade angle relative to the second cutting edge surface, and that in effect acts as an etch stop for the anisotropic etch. In one embodiment, both the first cutting edge surface and the first registration surface of the blade are parallel with the same crystal plane within the {111} family of crystal planes (including both the positive and negative intercepts).[0027]
• The cutting edge associated with the blade of the third aspect may be defined in a variety of manners. In one embodiment, the blade includes top and bottom surfaces that are planar and disposed parallel to each other. The first cutting edge surface may be disposed at an angle relative to and intersect with the top surface, while the second cutting edge surface may be defined by the bottom surface of the blade. This may be characterized as a single-beveled configuration for the cutting blade and is the preferred configuration. Another option is to use a double-beveled configuration for the blade. Here the blade again may include top and bottom surfaces that are planar and disposed parallel to each other. In the double-beveled case, however, the second cutting edge surface is disposed an angle relative to and intersects with the bottom surface.[0028]
• Multiple registration surfaces may be formed on the blade of the cutting tool of the third aspect. In one embodiment, at least two registration surfaces are disposed within a common reference plane. This common reference plane may be parallel with the cutting edge. Each registration surface utilized by the blade may be defined by a registration cavity that is formed in an upper surface of the blade. Any such registration cavity may extend through the entire thickness of the blade. In this case, the first cutting edge surface would extend between the cutting edge and a first edge at the top or upper surface of the blade, while the first registration surface would extend between a second edge at the top or upper surface of the blade and a third edge at the bottom or lower surface of the blade. The first edge associated with the first cutting edge surface and the second edge associated with the first registration cavity may be disposed within a first reference plane that is parallel with a second reference plane that contains the cutting edge associated with the first cutting edge surface and the third edge associated with the first registration cavity.[0029]
• A first registration cavity that defines the first registration surface of the blade of the third aspect may be characterized as being concave or accessible through a top or upper surface of the blade. This first registration cavity would be spaced from the cutting edge and include first and second ends, with the first end being disposed or located between the cutting edge and the second end. The second end of the first registration cavity may be defined by the first registration surface. This first registration cavity may extend partially within the cutting blade (i.e., extend from a top surface of the blade toward, but not to, a bottom surface of the blade), or may extend all the way through the body of the blade as noted above. The first end of the first registration cavity may be disposed in any appropriate orientation relative to a planar top surface of the blade, while the first registration surface may be disposed at an angle other than perpendicular relative to this planar top surface.[0030]
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
• FIG. 1 is a side view of one embodiment of a microkeratome.[0031]
• FIG. 2A is a top-based perspective view of a cutting blade of the cutting tool utilized by the microkeratome of FIG. 1.[0032]
• FIG. 2B is a top view of the cutting blade of the cutting tool utilized by the microkeratome of FIG. 1.[0033]
• FIG. 2C is a plan view of a modified registration cavity that may be used by the cutting blade of FIGS.[0034]2A-B.
• FIG. 3A is a cross-sectional view of the cutting blade of FIG. 2B take along line[0035]3-3.
• FIG. 3B is a cross-sectional view of an alternative embodiment of a cutting blade, namely in relation to the definition of its cutting edge in relation to that illustrated in FIG. 3A.[0036]
• FIG. 4 is a side-based perspective view of the cutting tool utilized by the microkeratome of FIG. 1.[0037]
• FIG. 5 is a top-based perspective view of the cutting tool utilized by the microkeratome of FIG. 1.[0038]
• FIG. 6 is a bottom-based perspective view of the cutting tool utilized by the microkeratome of FIG. 1.[0039]
• FIG. 7 is an exploded, perspective view of the cutting tool utilized by the microkeratome of FIG. 1.[0040]
• FIG. 8A is a cutaway, bottom view illustrating one registrant of the blade handle of the cutting tool utilized by the microkeratome of FIG. 1, while engaging a registration surface of the cutting blade.[0041]
• FIG. 8B is a cutaway, side view illustrating a registrant of a blade handle of the cutting tool utilized by the microkeratome of FIG. 1, while engaging a registration surface of the cutting blade.[0042]
• FIG. 8C is a cutaway, side view illustrating an alternative embodiment of a registrant of the blade handle of the cutting tool utilized by the microkeratome of FIG. 1, while engaging the registration surface of the cutting blade.[0043]
• FIG. 8D is a cutaway, side view illustrating yet another alternative embodiment of a registrant of the blade handle of the cutting tool utilized by the microkeratome of FIG. 1, while engaging the registration surface of the cutting blade.[0044]
• FIG. 9A is a cross-sectional view of a pair of masking layers formed on opposing surfaces of a substrate or wafer.[0045]
• FIG. 9B is a cross-sectional view after a cutting blade mask has been transferred onto one of the masking layers of FIG. 9A, along with the resulting openings in the masking layer.[0046]
• FIG. 9C is a top plan view of the openings in the masking layer illustrated in FIG. 9B[0047]
• FIG. 9D is a cross-sectional view after the substrate/wafer has been etched to define the cutting blade of the cutting tool utilized by the microkeratome of FIG. 1.[0048]
• FIG. 10 is a flowchart illustrating one method of fabricating multiple blades from a wafer, including steps that correspond with FIGS.[0049]9A-D.
• FIG. 11 is a plan view of a wafer with alignment slots etched therein for aligning a blade mask relative to the wafer.[0050]
• FIG. 12 is a plan view of a wafer having a plurality of cutting blades fabricated therefrom in accordance with the protocol of FIG. 10.[0051]
• FIG. 13A is an enlarged, plan view of the interconnection between a single cutting blade and the wafer from FIG. 12.[0052]
• FIG. 13B is an enlarged, cutaway view of one embodiment of a blade separation score that is only schematically illustrated in FIG. 13A and which is used to separate the cutting blade from a corresponding blade support tab of the wafer.[0053]
• FIG. 13C is an enlarged, plan view of a portion of the rear of the cutting blade of FIG. 13A after its separation from the wafer along the score of FIG. 13B.[0054]
• FIG. 13D is a plan view of a blade mask perimeter profile and one embodiment of an actual perimeter profile produced when anisotropically etching a wafer based upon this blade mask perimeter profile.[0055]
• FIG. 14 is a perspective view of one embodiment of a fixture and base plate for installing blade handles on the cutting blades from the wafer of FIG. 12.[0056]
• FIG. 15 is an exploded, perspective view of the blade handle mounting fixture and base plate of FIG. 14.[0057]
• FIG. 16 is a perspective view of an upper surface of the blade handle mounting fixture of FIG. 14.[0058]
• FIG. 17 is a perspective view of a lower surface of the blade handle mounting fixture of FIG. 14.[0059]
• FIG. 18 is an enlarged, perspective view of a portion of the upper surface of the blade handle mounting fixture of FIG. 14 that would interface with one of the cutting blades.[0060]
• FIG. 19 is an enlarged, perspective view of a portion of the upper surface of the blade handle mounting fixture of FIG. 14 when supporting one of the cutting blades.[0061]
• FIG. 20 is a perspective view of one embodiment of a blade separation fixture for separating blades from the wafer of FIG. 12.[0062]
• FIG. 21 is an exploded perspective view of the blade separation fixture of FIG. 20.[0063]
• FIG. 22 is an enlarged perspective view of a portion of one of the cutting edge cavities and one of the registrant/pivot cavities used by the blade separation fixture of FIG. 20.[0064]
• FIG. 23 is an enlarged perspective view of one of the cutting tools from the wafer of FIG. 12 being positioned over the cutting edge cavity and registrant/pivot cavity illustrated in FIG. 22.[0065]
DETAILED DESCRIPTION OF THE INVENTION
• The present invention will now be described in relation to the accompanying drawings which at least assist in illustrating its various pertinent features. A schematic of one embodiment of a[0066]microkeratome4 that may be used to perform a LASIK procedure on a patient's eye (not shown) is illustrated in FIG. 1. Themicrokeratome4 generally includes ahead assembly10 having apresser6, a cut flap receiver8, and acutting tool receiver12 with acutting tool20 disposed therein. Generally, thepresser6 pushes down on the front of the patient's eye while thecutting tool20 is brought into engagement with and cuts a flap from the patient's eye. Cutting operations generally entail moving thecutting tool20 in an appropriate manner relative to the patient's eye (e.g., by oscillation of thecutting tool20 relative to thehead assembly10 in a direction that is parallel with acutting edge80 associated with the cutting tool20 (in and out of the page in the view presented in FIG. 1), as well as by a movement of thehead assembly10 in the direction of the arrow A). In any case, the resulting eye flap (with a portion typically still remaining attached to the patient) is then directed into the cut flap receiver8 formed in thehead assembly10 of themicrokeratome4.
• There are two primary components of the[0067]cutting tool20, namely ablade handle24 and acutting blade56. Thecutting blade56 includes the above-notedcutting edge80. Thiscutting edge80 is formed on its forward end. The blade handle24 interfaces with thecutting blade56 so as to desirably align or register the position of thecutting edge80 of theblade56 with amicrokeratome registration surface28 of the blade handle24 with enhanced accuracy. Thismicrokeratome registration surface28 in turn interfaces with a cuttingtool registration surface14 associated with thehead assembly10 of themicrokeratome4. More specifically, the cuttingtool20 is disposed within acutting tool receiver12 formed within thehead assembly10. A pair of support surfaces13 of thehead assembly10 engage corresponding portions of abottom surface64 of thecutting blade54 to “vertically” support the cutting blade54 (shown in slightly vertically spaced relation in FIG. 1 for clarity), while other portions of thisbottom surface64 of thecutting blade54 are disposed and maintained in spaced relation to the underlying portion of thehead assembly10. Moreover, themicrokeratome registration surface28 of the blade handle24 engages the cuttingtool registration surface14 of thehead assembly10 of themicrokeratome4. Because the position of thecutting edge80 is registered relative to themicrokeratome registration surface28 of theblade handle24, and because the position of themicrokeratome registration surface28 of the blade handle24 is registered relative to the cuttingtool registration surface14 of thehead assembly10 of themicrokeratome4, the position of thecutting edge80 of theblade56 is likewise registered relative to this cuttingtool registration surface14. Enhancing the accuracy of the positioning of thecutting edge80 for a LASIK procedure is of course very desirable.
• Additional views of the[0068]cutting blade56 are presented in FIGS.2A-B and3A. Thecutting blade56 includes a top wall orsurface60 and a bottom wall orsurface64. A pair of side walls or surfaces68 of thecutting blade56 are laterally spaced from a central,longitudinal reference axis58 associated with thecutting blade56. Herein, the term “laterally” spaced, extending, or the like means being at least generally in or along a direction that is perpendicular to the central,longitudinal reference axis58 of theblade56. Longitudinally spaced from thecutting edge80 of thecutting blade56 is a rear wall orsurface106. Herein, the term “longitudinally” spaced, extending, or the like means being at least generally in or along a direction that is collinear with or parallel to the central,longitudinal reference axis58 of theblade56. Both the side surfaces68 and therear surface106 extend between and interconnect thetop surface60 andbottom surface64 of theblade56. The distance between thetop surface60 and thebottom surface64 thereby defines a thickness of thecutting blade56. In one embodiment, the thickness of thecutting blade56 is within a range of about 230 microns to about 250 microns.
• The[0069]rear surface106 of theblade56 includes a notch orrecess100 that is centrally disposed relative to the central,longitudinal reference access58. In this regard, therear surface106 includes what may be characterized as a pair offirst sections112, asecond section114 that is longitudinally spaced from thefirst section112 in the direction of thecutting edge80, and a pair of laterally spacedthird sections116 that interconnect thesecond section114 with one of thefirst sections112. Generally, the configuration of therear surface106 facilitates the removal of thecutting blade56 from a wafer from which a plurality of cuttingblades56 may be fabricated in a batch process. This will be discussed in more detail below.
• In the illustrated embodiment of the cutting blade[0070]56: 1) eachside surface68 includes afirst section69 that extends rearwardly from thecutting edge80 perpendicularly thereto, as well as asecond section70 that extends rearwardly from its correspondingfirst section69 and at least generally toward the central,longitudinal reference axis58; 2) the pair offirst sections112 and thesecond section114 associated with thenotch110 on therear surface106 are all parallel with thecutting edge80; and 3) the pair of laterally spaced (relative to the central, longitudinal reference axis58)third sections116 associated with thenotch110 are parallel with the central,longitudinal reference axis58. Other configurations for thecutting blade56 may be appropriate depending upon the application, as well as other configuration/orientations for the various parts thereof unless otherwise noted herein as being required.
• A planar first[0071]cutting edge surface72 is disposed at an angle relative to thetop surface60 of theblade56 and intersects with thistop surface60 at anupper edge76. The firstcutting edge surface72 extends between thisupper edge76 and thecutting edge80 of thecutting blade56. In the illustrated embodiment, the firstcutting edge surface72 also intersects with thebottom surface64 of thecutting blade56. As such, that portion of thebottom surface64 of thecutting blade56 that is adjacent to thecutting edge80 and intersects with the firstcutting edge surface72 may be characterized as a secondcutting edge surface66 for thecutting blade56. The firstcutting edge surface72 is disposed at an angle θ (FIG. 3A) relative to the secondcutting edge surface66, and this may be characterized as the blade angle θ. Any appropriate blade angle θ may be utilized by thecutting blade56 and which may depend upon the application in which theblade56 is to be used. In one embodiment for the case of biological applications (e.g., cutting tissue, such as a human eye), the blade angle θ is preferably within a range of about 15° to about 25° .
• Other options exist for defining the[0072]cutting edge80 and the blade angle θ of thecutting blade56. One example is presented in FIG. 3B where thecutting edge80′ is defined by a secondcutting edge surface66′ that is disposed at an angle relative to thebottom surface64 of theblade56′ and that intersects with the firstcutting edge surface72′. This of course disposes thecutting edge80′ at what may be characterized as an “intermediate elevation” between the elevation of thetop surface60 and the elevation of thebottom surface64 of thecutting blade56′.
• Features are incorporated into the structure of the[0073]cutting blade56 for purposes of registering or aligning thecutting edge80 to a particular position when installed on themicrokeratome4. These same features are incorporated in eachcutting blade56 so that thecutting edge80 of each cuttingtool20 that is installed in themicrokeratome4 is registered or aligned to the same position, preferably within a tolerance of 25 microns. That is, the variance of the position of thecutting edge80 relative to the desired position is no more than about 25 microns in any dimension for each cuttingtool20 that may be installed in themicrokeratome4. This variation principally relates to the geometry of theblade handle24 and the adhesion of the blade handle24 to thecutting blade56.
• The[0074]cutting blade56 includes a pair ofregistration cavities84 that interface or cooperate with the blade handle24 in a manner so as to register or align thecutting edge80 to the desired position when installed in themicrokeratome4. Any appropriate number ofregistration cavities84 may be utilized and disposed in any appropriate position on thecutting blade56. However, utilizing a pair ofregistration cavities84 in the position of the illustrated embodiment provides a number of advantages, including facilitating parallel orientation of the blade handle24 relative to thecutting edge80 of theblade56.
• Both[0075]registration cavities84 of thecutting blade56 are identical. Only oneregistration cavity84 then need be described herein. Theregistration cavity84 extends through the entire thickness of thecutting blade56 in the illustrated embodiment, although such may not be required for all applications that may utilize theblade56 or cuttingtool20. For instance, theregistration cavity84 could be formed on thetop surface60 of theblade56 and extend down toward, but not to, thebottom surface64. However, preferably the “bottom” of the registration cavity84 (more specifically alower edge102 of a registration wall orsurface94 associated with the registration cavity84) and thecutting edge80 are disposed at the same elevation or distance from the top surface60 (measured perpendicularly to the top surface60). In any case, theregistration cavity84 may be characterized as being at least generally concave or “upwardly open” in relation to thetop surface60 of the cutting blade56 (e.g., accessible through thetop surface60 of the blade56).
• Each[0076]registration cavity84 includes afront wall92, a rear wall orregistration surface94 that is longitudinally spaced from thefront wall92, and a pair of laterally spacedside walls88 that extend between and interconnect thefront wall92 with theregistration surface94. Generally, thefront wall92 andside walls88 of theregistration cavity84 may be of any appropriate shape/configuration/orientation, as it is theregistration surface94 that provides the desired registration in relation to thecutting edge80. How far theregistration surface94 and the correspondingfront wall92 should be longitudinally spaced (represented by distance “S” in FIG. 8B) is at least by a distance that would allow the blade handle24 to first be installed on thecutting blade56, and then moved parallel with thetop surface60 of thecutting blade56 to register or align the blade handle24 relative to thecutting blade56 using the registration surface(s)94. The spacing between theside walls88 of theregistration cavities84 may provide a “lateral” registration feature for the blade handle24 relative to thecutting blade56 as will be discussed in more detail below.
• Registration or alignment of the[0077]cutting edge80 relative to themicrokeratome registration surface28 of theblade handle24, and thereby relative to the cuttingtool registration surface14 of thehead assembly10 of themicrokeratome4, is provided in the case of thecutting blade56 by having theregistration surface94 be a planar surface that is parallel with the planar firstcutting edge surface72. That is, theregistration surface94 of eachregistration cavity84 utilized by thecutting blade56 is a planar surface that extends from an upper edge98 (at the intersection with thetop surface60 in the illustrated embodiment) to a lower edge102 (at the intersection with thebottom surface64 in the illustrated embodiment) in the same orientation that the planar firstcutting edge surface72 extends from itsupper edge76 to thecutting edge80. Thelower edge102 of eachregistration cavity84 is parallel with thecutting edge80. In the illustrated embodiment, theupper edge76 of the firstcutting edge surface72 and theupper edge98 of eachregistration surface94 are disposed within a first reference plane that is parallel with a second reference plane, that in turn contains thecutting edge80 associated with the firstcutting edge surface72 and thelower edge102 of each registration surface94 (and parallel with thetop surface60 andbottom surface64 of theblade56 for that matter). Moreover, the pair of registration surfaces94 of theregistration cavities84 are disposed within a common reference plane. As such, theregistration cavities84 are disposed equidistantly from thecutting edge80, as are their corresponding registration surfaces94.
• One preferable way to fabricate the[0078]cutting blade56 is by using an anisotropic etch, at least for purposes of defining the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84. Preferably theentire cutting blade56 is defined by a single anisotropic etch. This allows the various structures to be very precisely positioned. For instance, theregistration cavities84 may be very precisely positioned relative to thecutting edge80. The maximum variation in the location of thecutting edge80 relative to thelower edge102 of each registration cavity is about6 microns. This variation may be influenced by a number of factors. Referring to FIG. 2A, theupper edge76 of the firstcutting edge surface72 and theupper edge98 of eachregistration cavity84 are formed to within a tolerance of1 micron or better. This is due to the fact that they may be defined using the same photolithographic mask as will be discussed in more detail below in relation to FIGS.9A-D and FIG. 10. FIGS.9A-D and FIG. 10 are specifically directed to the fabrication of thecutting blade56. Any variation in the location of the firstcutting edge surface72 relative to theregistration surface94 of eachregistration cavity84 would be due to errors in the position of one or more of theupper edge76 of the firstcutting edge surface72 and theupper edge98 of eachregistration cavity84, coupled with errors associated with the etch process. However, any variation in the location of the firstcutting edge surface72 relative to theregistration surface94 of eachregistration cavity84 should be no more than about2 microns. This in turn will then influence the location of thecutting edge80 relative to thelower edge102 of eachregistration cavity84, as will the geometry of the planes that intersect to form theedges80,76,98, and102. Once again, the maximum variation between the location of thecutting edge80 relative to thelower edge102 of eachregistration cavity84 should be no more than about 6 microns for a blade angle θ of 19 degrees that will be discussed in more detail below (e.g., 2 microns, divided by the sine of 19 degrees).
• It should be appreciated that the structure of the[0079]blade56 set forth herein is “idealized” in accordance with its corresponding blade mask as noted above, and therefore that the resulting shape of the various components of theblade56 may not conform exactly to the illustrations provided herein. For instance, FIGS.2A-B illustrate the shape of theregistration cavities84 in accordance with the blade mask. The anisotropic etch may actually produce a profile that is illustrated in FIG. 2C, where a “single prime” designation again is used to identify an alternative configuration for theregistration cavity84′ (along with its correspondingupper edge98′,registration surface94′,lower edge102′,side walls88′, andfront wall92′).
• There are a number of features of the[0080]cutting blade56 that accommodate or relate in at least some manner to using an anisotropic etch fabrication technique for theblade56. One that is key in relation to the above-described registration feature is that the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84 should be coplanar or parallel with a common crystal plane that the selected anisotropic etchant will etch to, but not through. In one embodiment where the anisotropic etchant is KOH and where thecutting blade56 is etched from single crystal silicon, the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84 are coplanar or parallel with a plane in the {111} family of planes (which includes both the positive and negative intercepts). That is, a plane within the {111} family of planes in effect is an etch stop for the anisotropic etch. Other crystal planes could be selected for the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84. However, an appropriate anisotropic etchant must of course be selected for the material being etched and the crystal plane that is to be used to define the orientation of the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84 in the described manner.
• Both the[0081]top surface60 and thebottom surface64 of thecutting blade56 should be planar surfaces, including for purposes of accommodating using an anisotropic etchant to define the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84.
• Flexibility in relation to the definition of the[0082]cutting edge80, more specifically in relation to its associated blade angle θ (FIG. 3A), may be realized by forming thetop surface60 andbottom surface64 of thecutting blade56 in a certain manner. At least one Miller index of the set of three Miller indices that define thetop surface60 and thebottom surface64 of thecutting blade56 should have an absolute value greater than “3” and be within the family of planes defined by the set of three Miller indices {ABC}, where “A”, “B”, and “C” each represent one Miller index, where at least one of the three indexes has an absolute value greater than “3”, and where “A”, “B”, and “C” each include both the positive and negative intercepts.
• Each of the side surfaces[0083]68 of thecutting blade56, thefront wall92 and pair ofside walls88 of eachregistration cavity84, and therear surface106 of thecutting blade56 may be of any orientation relative to thetop surface60 andbottom surface64 of theblade56. In one embodiment and for the case where thecutting blade56 is fabricated from single crystal silicon: thefront wall92 of eachregistration cavity84 and therear surface106 of thecutting blade56 are both perpendicular to thetop surface60 andbottom surface64 of theblade56, and further are coplanar with or parallel with a crystal plane in the {111} family of planes (including both the positive and negative intercepts); and the side surfaces68 of thecutting blade56 and theside walls88 of eachregistration cavity84 are not perpendicular to thetop surface60 andbottom surface64 of theblade56, and are not necessarily coplanar with a crystal plane in the {111} family of planes (including both the positive and negative intercepts).
• Cooperation between the cutting[0084]blade56 and the blade handle24 of thecutting tool20 is at least one component of registering or aligning thecutting blade56 in a desired position relative to a patient when installed in themicrokeratome4, more specifically itscutting edge80. Various features of the blade handle24 are presented in FIGS. 4-7 for the case of the configuration of thehead assembly10 utilized by themicrokeratome4 of FIG. 1. It should be appreciated that other configurations for the blade handle24 may be required for different applications of thecutting blade56, different types ofmicrokeratomes4, or different head assemblies. Moreover, not all applications of thecutting blade56 will necessarily require an “intermediate” blade handle.
• The blade handle[0085]24 is attached or anchored to thecutting blade56 so that there is no substantial movement therebetween. Stated another way, theblade handle24 and thecutting blade56 function as a single unit and move together during operation of themicrokeratome4. Any appropriate way of maintaining the blade handle24 in a fixed relative positional relationship with thecutting blade56 may be used, including any appropriate adhesive (e.g., an epoxy; a UV curable epoxy; an epoxy with spacing spheres), or by deforming some portion of thehandle24 by melting or heat-staking.
• Features may be incorporated into the structure of the blade handle[0086]24 for interfacing with thehead assembly10 of themicrokeratome4 or otherwise. The blade handle24 includes a pair of laterally spacedguide rails52 in the illustrated embodiment that are disposed along a portion of the side surfaces68 of the cutting blade56 (more specifically the second sections70) when the blade handle24 is mounted on thecutting blade56. In one embodiment, thesurface54 of each of theguide rail52 that projects toward the corresponding portion of theside surface68 of thecutting blade56 is planar and disposed in parallel relation with the corresponding portion of theside surface68 of thecutting blade56. Other profiles may be appropriate. There may be a space between at least a portion of thissurface54 of the guide rails52 and theircorresponding side surface68 when the blade handle24 is registered or aligned with thecutting blade56.
• Registration or alignment of the[0087]cutting edge80 of thecutting blade56 in the desired position in themicrokeratome4 utilizes themicrokeratome registration surface28 of theblade handle24. Thismicrokeratome registration surface28 again interfaces with the cuttingtool registration surface14 on thehead assembly10 of themicrokeratome4. Although the cuttingtool registration surface14 is disposed on the “foreword” end of theblade handle24, it may be disposed in any appropriate position so as to cooperate with a corresponding registration surface on thehead assembly10 of themicrokeratome4.
• Multiple features of the blade handle[0088]24 relate in at least some manner to the accurate positioning of thecutting edge80 of thecutting blade56 relative to theblade handle24, more specifically itsmicrokeratome registration surface28. One is aplanar bottom surface48 of the blade handle24 that interfaces with the planartop surface60 of thecutting blade56. This provides what may be characterized as a “vertical” registration feature between theblade handle24 and cuttingblade56. Both a lateral and a longitudinal or “fore/aft” registration feature between theblade handle24 and thecutting blade56 may be provided by the blade handle24 including at least oneregistrant32. Eachregistrant32 extends or projects at least generally downwardly from theplanar bottom surface48 of theblade handle24. A pair ofregistrants32 are utilized by the blade handle24 in the illustrated embodiment, one for eachregistration cavity84 of thecutting blade56. Theseregistrants32 are disposed along a common line that is parallel with thecutting edge80 of theblade56 when theblade56 is properly registered to theblade handle24.
• Each[0089]registrant32 includes aperipheral wall36 that intersects with abottom wall40. Four side walls orsurfaces37a-d(FIGS.8A-B) define theperipheral wall36 in the illustrated embodiment, with theside walls37aand37cbeing parallel with each other, and with theside walls37band37dbeing parallel with each other. In the illustrated embodiment, thebottom wall40 is rectangular. These fourside walls37a-dof theperipheral wall36 of eachregistrant32 are disposed perpendicular to thebottom surface48 of the blade handle24 in the illustrated embodiment. Lateral registration of the blade handle24 relative to thecutting blade56 may be provided by the having theside walls37band37dof eachregistrant32 be spaced apart the same distance as theside walls88 of thecorresponding registration cavity84 in which theregistrant32 is disposed. This will then dispose theside walls37b,37dof a givenregistrant32 in interfacing or at least closely spaced relation with thecorresponding side wall88 of thecorresponding registration cavity84. Other configurations/orientations of theperipheral wall36 for eachregistrant32 may be appropriate and provide at least a degree of lateral registration. Longitudinal registration of the blade handle24 to thecutting blade56 is provided by cooperation between eachregistrant32 and itscorresponding registration surface94, namely that which is associated with theregistration cavity84 in which theregistrant32 is disposed.
• Mounting the blade handle[0090]24 on thecutting blade56 may generally entail disposing an appropriate adhesive on at least one of thetop surface60 of thecutting blade56 and thebottom surface48 of theblade handle24. A light curable epoxy is a particularly desirable way to attach the blade handle24 to thecutting blade56. Eachregistrant32 on thebottom surface48 of the blade handle24 is then disposed within itscorresponding registration cavity84 on thecutting blade56. Although only relative movement is required, in one embodiment the blade handle24 is advanced toward astationary cutting blade56. In any case, preferably theregistrants32 are initially disposed within thecorresponding registration cavity84 so as to not contact its rear wall orregistration surface94. This may be utilized to seat theplanar bottom surface48 of the blade handle24 on the planartop surface60 of thecutting blade56. Thecutting blade56 is now supporting the blade handle24 by itself. The blade handle24 may then be moved relative to thecutting blade56 so as to increase the spacing between themicrokeratome registration surface28 of theblade handle24 and thecutting edge80 of thecutting blade56, or stated another way so as to increase the spacing “S” between theregistrant32 of theblade handle24 and thefront wall92 of itscorresponding registration cavity84 on theblade56. Preferably, thebottom surface48 of the blade handle24 is maintained in interfacing relation with thetop surface60 of thecutting blade56 during this movement. Stated another way, the noted relative movement between theblade handle24 and cuttingblade56 is in a direction that is at least generally parallel with thetop surface60 of thecutting blade56 and thebottom surface48 of theblade handle24. The blade handle24 is moved relative to thecutting blade56 in this manner until eachregistrant32 cooperates with itscorresponding registration surface94, more typically a portion thereof. This then registers or aligns thecutting edge80 of thecutting blade56 relative to themicrokeratome registration surface28 of theblade handle24, which in turn registers or aligns thecutting edge80 of thecutting blade56 in a desired position within themicrokeratome4. In one embodiment, eachregistrant32 is separated from its correspondingfront wall92 by a distance of at least about 1 millimeter when theregistrant32 is interfacing with itscorresponding registration surface94.
• The blade handle[0091]24 is fixed to thecutting blade56 when in the above-noted registered position. This emphasizes the desirability of using a light curable epoxy, including a UV curable epoxy. That is, a light curable epoxy allows the blade handle24 to be mounted on theblade56 in the above-noted manner so as to register the position of the blade handle24 relative to thecutting blade56 before the light curable epoxy sets. An appropriate light source (e.g., UV) may then be directed at the light curable epoxy to cure the same (in less than10 seconds in the case of at least certain UV curable epoxies) and thereby fix the position of theblade holder24 relative to thecutting blade56. Having the position of thecutting edge80 of theblade56 registered relative to themicrokeratome registration surface28 of the blade handle24 registers the position of thecutting edge80 when installed in themicrokeratome4. Once again, themicrokeratome registration28 of the blade handle24 is registered or aligned relative to the cuttingtool registration surface14 of thehead assembly10 of themicrokeratome4.
• Any appropriate cooperation between a given[0092]registrant32 of theblade handle24 and itscorresponding registration surface94 of thecutting blade56 may be utilized that provides the desired registration or alignment of thecutting edge80 of thecutting blade56 relative to themicrokeratome registration surface28 of the blade handle24 in the longitudinal or fore-aft dimension. In one embodiment, the contact between aregistrant32 and itscorresponding registration surface94 is limited to being at least generally along a line. Stated another way, the interface between a givenregistrant32 and itscorresponding registration surface94 is limited to a “line contact” in one embodiment. This may be provided in any number of manners. Three options are illustrated in FIGS.8B-D. FIG. 8B illustrates that theregistrant32 actually extends below thebottom surface64 of thecutting blade56, such that thelower edge102 of theregistration surface94 engages a portion of theperipheral wall36 of theregistrant32, namely theside wall37c. FIG. 8C illustrates that thelower edge102 of theregistration surface94 engages aregistrant32′ of the blade handle24′ at least generally at the intersection between theperipheral wall36 and thebottom wall40 of theregistrant32. FIG. 8D illustrates that the intersection between theperipheral wall36 and thebottom wall40 of theregistrant32 engages itscorresponding registration surface94 somewhere between thelower edge102 of theregistration surface94 and theupper edge98 of thisregistration surface94. Preferably, theregistrant32 interfaces with itscorresponding registration surface94 closer to thelower edge102 than itsupper edge98, and including at the intersection between thebottom surface64 of theblade56 and thecorresponding registration surface94.
• Standard semiconductor processing techniques may be utilized to fabricate the[0093]cutting blade56 of thecutting tool20. One significant advantage of using this technique is the accuracy with which thecutting blade56 may be fabricated, particularly the accuracy of the position of thecutting edge80 relative to the position of theregistration surface94 of eachregistration cavity84 of thecutting blade56. FIGS.9A-D illustrate a number of steps in one method by which thecutting blade56 may be fabricated using standard semiconductor processing techniques. Initially, a suitable material is selected for the fabrication of thecutting blade56. Suitable materials for fabrication of thecutting blade56 using the process described herein include without limitation single crystal silicon, single crystal quartz, and potentially other single crystal material having suitable crystal-plane selective etchants. Those materials that are suitable for fabrication of thecutting blade56 generally are those that may be etched so that the etch will stop at a predetermined place/position within the material (e.g., at a particular crystal plane within the same material, that in effect acts as an etch stop), and further where the same etch behavior exists regardless of the location of the opening in the mask being utilized for the etch. Regarding the latter characterization, the material must be such that a particular etchant will behave the same anywhere within the material that is to be etched. It is really the combination of the material and the selected etchant that allows the etchant to anisotropically etch the material in the desired manner to define thecutting blade56.
• The material from which the[0094]cutting blade56 is fabricated in accordance with FIGS.9A-D generally may be characterized as asubstrate130, and will more typically be in the form of awafer130. It should be appreciated that wafers that are “commonly available” for the fabrication of semiconductor devices (e.g., silicon wafers having top and bottom surfaces parallel with either the (110) and (100) crystal planes) may not be suitable in relation to defining the desired blade angle θ for one or more applications of thecutting blade56. In any case, maskinglayers118,126 are defined on anupper surface134 and alower surface138, respectively, of thewafer130 using conventional semiconductor processing techniques. This is illustrated in FIG. 9A. The masking layers118,126 may be formed on thecorresponding surface134,138 of thewafer130 in any appropriate manner (e.g., chemical vapor deposition, physical vapor deposition, or thermal growth in the case of silicon dioxide on silicon). Any material that may be patterned for a subsequent selective etching of thewafer130 may be utilized by the masking layers118,126 (e.g., silicon nitride, silicon oxide).
• What may be characterized as a blade mask is transferred onto the[0095]upper masking layer118 in a manner known in the art for purposes of defining thecutting blade56 and as illustrated in FIGS.9B-C. Multiple masking layer openings or apertures122a-care formed on theupper masking layer118 to define eachcutting blade56 that is to be fabricated from thewafer130. These masking layer apertures122a-cextend entirely through theupper masking layer118 to expose desired, selective portions of theupper surface134 of thewafer130. Any appropriate technique may be utilized for transferring the blade mask onto theupper masking layer118, including photomasking, masking, photolithography, microlithography, which is then followed by a suitable technique of etching the pattern into theupper masking layer118 by means of wet chemical etching, plasma etching, reactive ion etching, or ion beam milling. The creation of the hard mask can also be accomplished using a dual step process of using the photoresist to define the pattern into an intermediate layer of silicon dioxide. Once the photoresist is stripped, the silicon dioxide is then used as an etch mask layer to define the silicon nitride by means of hot phosphoric acid.
• The[0096]masking layer aperture122ais sized and configured to define the firstcutting edge surface72 of thecutting blade56 and the perimeter of the cutting blade56 (thecutting edge80, side surfaces68, and rear surface106). Eachmasking layer aperture122bis “interiorly” disposed (inwardly of what will ultimately be the perimeter of the cutting blade56) and is sized and configured to define aregistration cavity84 for thecutting blade56. A masking layer aperture122cis also formed through theupper masking layer118 to define a score or score line within thewafer130 to facilitate the removal of thecutting blade56 from thewafer130 after theblade56 has been fabricated by an anisotropic etch (identified byreference numeral132 in FIGS. 12 and 13A). This score need not, but may, pass through the entire vertical extent of thewafer130.
• No portion of the[0097]lower surface138 of thewafer130 needs to be patterned to fabricate thecutting blade56 from thewafer130. As such, no portion of thelower surface138 needs to be exposed to an etchant for the fabrication of thecutting blade56. However, a masking layer opening or aperture would be formed in thelower masking layer126 in order to define the secondcutting edge surface66′ of thecutting blade56′ of FIG. 3B.
• After the upper masking layer[0098]118 (andlower masking layer126 if required by the desired cutting edge configuration) has been processed to define the desired configuration for thecutting blade56 and the various individual surfaces thereof, thewafer130 is exposed to a suitable etchant. One way to execute the desired etching operation is to dispose thewafer130 in an etchant bath. In any case, those portions of theupper surface134 of thewafer130 that are exposed to the etchant will have material removed to define the configuration illustrated in FIG. 9D, which corresponds with thecutting blade56. The etchant simultaneously defines the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84 utilized by theblade56, and also defines the perimeter of thecutting blade56. A small portion of thecutting blade56 remains attached to thewafer130 in the form of a blade support tab at this time (see FIG. 12 to be discussed below, where this blade support tab is identified by reference numeral131). This blade support tab is disposed under the portion of theupper mask118 identified byreference numeral119 in FIG. 9C. The etchant also etches are least partially through thewafer130 through the mask aperture122c to define a score (see FIG. 12 to be discussed below, where this score is identified by reference numeral132). Generally, thecutting blade56 is thereafter separated from the remainder of thewafer130 by fracturing or breaking thewafer130 along this score.
• As noted above, an anisotropic etchant is utilized to fabricate the[0099]cutting blade56. The anisotropic etchant simultaneously forms the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84 as planar, parallel surfaces. This is done by selecting an anisotropic etchant that will in effect stop etching when reaching a certain crystal plane that defines the desired orientation for the firstcutting edge surface72 relative to thetop surface60 of thecutting blade56. Generally, the material defining thewafer130 and the selected etchant must be such that the behavior of the etchant is the same, regardless of the location of any mask aperture in the upper masking layer118 (or thelower masking layer126 for that matter). For the case of thewafer130 being single crystal silicon and the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84 being parallel with a {111} crystal plane, an appropriate anisotropic etchant for simultaneously defining the firstcutting edge surface72 and eachregistration surface94 is KOH. That is, the KOH etchant will etch to, but not through, the first (111) crystal plane that is disposed under the edge of the upper masking layer118 (corresponding with theupper edge76 and the upper edge98).
• Fabricating the[0100]cutting blade56 in the above-noted manner provides a number of advantages. Initially, the position of thecutting edge80 relative to the position of eachregistration surface94 can be done with a very high degree of accuracy due to the high degree of accuracy with which mask apertures can be formed in a mask in accordance with the foregoing. Moreover, the firstcutting edge surface72 is simultaneously formed with theregistration surface94 of eachregistration cavity84, and this is done so that the cuttingedge surface72 and theregistration surface94 of eachregistration cavity84 are disposed in parallel relation to a high degree of accuracy. As noted above, the anisotropic etch will proceed to the same exact crystal plane when defining each of the firstcutting edge surface72 and theregistration surface94 of eachregistration cavity84. The etch will then have the same effect on both the firstcutting edge surface76 and theregistration surface94 of eachregistration cavity84. Each of these factors contributes to being able to enhance the precision with which thecutting edge80 of theblade56 is disposed relative to a particular structure.
• FIG. 10 depicts one embodiment of a[0101]protocol140 for fabricating one ormore cutting blades56 from thewafer130. Thisprotocol140 utilizes the basic steps/results that are illustrated in FIGS.9A-D. Step142 of theprotocol140 is directed to forming a masking layer on a wafer (e.g., wafer130). In the illustrated embodiment, what is commonly referred to in the art as a “hard mask” will ultimately be formed from this particular masking layer. Silicon nitride is used for the masking layer bystep142, although other materials may be appropriate. Any appropriate way of forming the silicon nitride masking layer on the wafer may be utilized bystep142.
• A first photoresist layer is formed on the silicon nitride masking layer in accordance with[0102]step146 of theprotocol140. Either a positive-acting or negative-acting photoresist material may be used bystep146. Any appropriate way of forming the first photoresist layer on the silicon nitride masking layer may be utilized bystep146. What may be characterized as an alignment slot mask is then transferred onto the first photoresist layer through execution ofstep150. Generally, this alignment slot mask is used to define certain structures on the wafer to thereafter align what may be characterized as a “blade mask” to the wafer in a certain manner, more specifically to align the blade mask to a certain crystal orientation associated with the wafer. This “blade mask” is that which has a layout of masking layer openings extending therethrough such that selected portions of the wafer will be etched in a manner so as to simultaneously fabricate/define a plurality of cuttingblades56.
• [0103]Step154 of theprotocol140 indicates that the first photoresist layer is developed in accordance with the alignment slot mask to create a plurality of openings that extend completely through the first photoresist layer in a layout that will be discussed in more detail below in relation to FIG. 11. “Developing” the first photoresist layer includes both exposing portions of the first photoresist layer to an appropriate type of light (either that portion of the first photoresist material that is to be removed in the case of a positive-acting photoresist material, or that portion of the first photoresist layer that is to remain in the case of a negative-acting photoresist material), and thereafter exposing the “light treated” first photoresist layer to an appropriate developer to remove portions of the first photoresist layer in accordance with the alignment slot mask. Openings in accordance with the desired/required layout are formed through the entire vertical extent of the first photoresist layer to expose the underlying silicon nitride masking layer.
• Appropriate openings are next etched through the entire vertical extent of the silicon nitride masking layer in accordance with[0104]step158 of theprotocol140. The layout of these openings is in accordance with the openings in the first photoresist layer, and thereby in accordance with the alignment slot mask. In one embodiment, a reactive ion etch is used to define the openings in the silicon nitride masking layer in the layout required by the alignment slot mask. Other types of etches may be appropriate. In any case, this then exposes selected portions of the upper surface of the underlying wafer. The first photoresist layer is then stripped (step162) from the now patterned silicon nitride masking layer, and another etch is initiated to form alignment slots that extend within, but typically not through, the wafer. In one embodiment, the etch fromstep166 of theprotocol140 is a KOH etch. Other etches may be appropriate. The etch fromstep166 reaches the wafer through the openings in the silicon nitride masking layer associated withstep158 of theprotocol140, and thereby in accordance with the alignment slot mask ofstep150.
• The alignment slots on the wafer formed in accordance with steps[0105]146-166 of theprotocol140 are analyzed to determine which alignment slot(s) is suitably aligned with a particular crystal orientation associated with the wafer. This is represented bystep170 of theprotocol140 of FIG. 10. The alignment slot(s) that are aligned with a particular crystal orientation associated with the wafer are then identified (step174 of the protocol140) for subsequent use in aligning/orienting the blade mask to the wafer.
• FIG. 11 illustrates one way in which the alignment slots referred to by the[0106]protocol140 of FIG. 10 may be formed on thewafer130 to orient the blade mask relative to thewafer130. Thewafer130 includes a flat206 that is disposed at the 6:00 o'clock position. Areference axis218 extends from the 3:00 o'clock position to the 9:00 o'clock position, through acenter212 of thewafer130. Generally, a plurality ofalignment slots210a-kare formed on one side of thewafer130, while a plurality of alignment slots214a-kare formed on an opposite side of thewafer130. Any number ofalignment slots210a-k,214a-kmay be utilized. The alignment slot210acorresponds with thealignment slot214a, the alignment slot210bcorresponds with the alignment slot214b, and so forth.Corresponding alignment slots210a-k/214a-kare disposed along a common axis that extends through thecenter212 of thewafer130. That is, thealignment slots210a,214aare positioned along a common axis that extends through thecenter212 of thewafer130, the alignment slots210b,214bare positioned along a common axis that extends through thecenter212 of thewafer130, and so forth. The axes along which correspondingslots210a-k,214a-kare disposed are preferably equally spaced about thecenter212 of thewafer130. That is, the axis along which the alignment slots210b,214bare disposed is rotated counterclockwise a predetermined amount from the axis along which theslots210a,214aare disposed, the axis along which the alignment slots210c,214care disposed is rotated counterclockwise this same predetermined amount from the axis along which the slots210b,212bare disposed, and so forth.
• The[0107]alignment slots210a-k, the alignment slots214a-k, or both may be analyzed to identify which corresponding pair of alignment slots (e.g., (210a,214a); (210b,214b); (210c;214c), etc) may be used to align the blade mask to thewafer130 for purposes ofstep182 of theprotocol140 of FIG. 10. This analysis may be done in any appropriate manner, including optically. This analysis is undertaken pursuant to step170 of theprotocol140 of FIG. 10 that was discussed above. Generally, thealignment slot210a-kthat is narrowest or of the smallest width (“width” being the dimension that is perpendicular to its length dimension, which is along a radius extending from thecenter212 of the wafer130) is that which is most closely aligned with a predetermined crystal plane of the wafer. The same is true for the alignment slots214a-k.
• Once a corresponding pair of[0108]alignment slots210,214 has been identified as being suitably aligned with a predetermined crystal plane of the wafer (if onealignment slot210 is identified, its corresponding alignment slot214 will also be of the narrowest width from the group of alignment slots214a-k, and vice versa), this pair ofalignment slots210,214 is “selected” as noted bystep174 of theprotocol140 of FIG. 10. That is, the location of this particular pair ofalignment slots210,214 is noted such that alignment marks on the blade mask may be aligned thereto in accordance withstep182 of theprotocol140. More specifically, a second photoresist layer is formed on the silicon nitride masking layer in accordance withstep178 of theprotocol140 and in any appropriate manner. Either a positive-acting or negative-acting photoresist again began may be utilized. In any case, the blade mask is aligned with the selected alignment slots in accordance withstep182 of theprotocol140, and the blade mask is thereafter transferred onto the second photoresist layer in accordance withstep186. The blade mask is such that thealignment slots210a-k,214a-kwill not interfere with the fabrication of the individual cutting blades56 (e.g., thealignment slots210a-k,214a-kare disposed beyond the region of the wafer on whichcutting blades56 are fabricated).
• [0109]Step190 of theprotocol140 indicates that the second photoresist layer is developed in accordance with the blade mask to create openings that extend completely through the second photoresist layer. “Developing” the second photoresist layer includes both exposing portions of the second photoresist layer to an appropriate type of light (either that portion of the second photoresist material that is to be removed in the case of a positive-acting photoresist material, or that portion of the second photoresist layer that is to remain in the case of a negative-acting photoresist material), and thereafter exposing the “light treated” second photoresist layer to an appropriate developer to remove the desired portions of the second photoresist layer. Openings in accordance with the desired/required layout are formed through the entire vertical extent of the second photoresist layer to expose the underlying silicon nitride masking layer.
• Appropriate openings in accordance with the blade pattern are next etched through the entire vertical extent of the silicon nitride masking layer pursuant to step[0110]194 of theprotocol140. The layout of these openings is in accordance with the openings in the second photoresist layer, and thereby in accordance with the blade mask. In one embodiment, a reactive ion etch is used to define these openings in the silicon nitride masking layer required by the blade mask. Other types of etches may be appropriate. In any case, this then exposes selected portions of the upper surface of the underlying wafer. The second photoresist layer is then stripped (step198) from the now patterned silicon nitride masking layer, and another etch is initiated throughstep202 of theprotocol140. This particular etch defines thevarious blades56 that are included in the blade mask associated withstep186 of theprotocol140, and the result of which corresponds with FIG. 9D. In one embodiment, the etch ofstep202 is a KOH etch. Other etches may be appropriate.
• Any number of[0111]blades56 may be simultaneously fabricated in accordance with theprotocol140 of FIG. 10, depending of course on the size of theblades56 and the size of thewafer130 from which theblades56 are fabricated. One blade pattern that may be utilized by theprotocol140 results in the layout illustrated in FIG. 12. Here, a number of rows and columns ofblades56 have been fabricated on thewafer130 utilizing theprotocol140 of FIG. 10. Eachblade56 remains attached to thewafer130 by ablade support tab131 of thewafer130 at this point in time. This is the only “interconnection” between eachblade56 and thewafer130 at this time, and which is the result of the etch ofstep202 of theprotocol140. All portions of thewafer130 other than theblades56 and their correspondingblade support tabs131 may be characterized as a frame orskeleton128 of the wafer130 (e.g., a remainder). As such, ablade56 may be characterized as being attached to itsblade support tab131, that in turn is attached to theframe128.
• Referring now to FIGS. 12 and 13A-B and as previously noted, a[0112]score132 is formed on eachblade support tab131 to facilitate the removal of thecorresponding blade56 from the remainder of thewafer130 in a manner that will be discussed in more detail below. Eachscore132 may, but preferably does not, extend through the entire vertical extent of thewafer130. In one embodiment, the depth of eachscore132 is within a range of about 2% to about 75% of the thickness of thewafer130. In another embodiment, the depth of eachscore132 is on the order of about 10-30 microns, where the thickness of thewafer130 is about 240 microns.
• A pair of planar score surfaces[0113]133a,133bintersect at a location identified by reference numeral133cin FIG. 13B (hereafter “intersection133”) to define thecorresponding score132 in the illustrated embodiment (e.g., a V-shaped configuration). The planar score surfaces133a,133bmay each be disposed in any appropriate angular orientation. In the illustrated embodiment, the planar score surface133ais parallel with the cuttingedge surface72, while the planar score surface133bis perpendicular to thetop surface60 andbottom surface64 of theblade56. Other configurations may be appropriate for thescore132 and yet still facilitate separation of thecutting blade56 from thewafer130 in a desired manner.
• It should be noted that the[0114]score132 associated with eachblade56 preferably does not extend across the entire lateral extent of its correspondingblade support tab131. That is, each score132 preferably does not extend up to and intersect with that portion of thesecond section114 of thenotch110 that is defined by the etch associated withstep202 of thefabrication protocol140 of FIG. 10. One benefit of this preferred configuration is that it enhances the structural integrity of theblade support tabs131. Stated another way, having each score132 extend all the way across its correspondingblade support tab131 could possibly weaken the interconnection between theblade support tab131 and itscorresponding blade56. That is, in a situation where thescore132 did extend across the entire lateral extent of the blade support tab131 (not shown), the etch associated withstep202 of thefabrication protocol140 of FIG. 10 may further reduce the lateral extent of that end of theblade support tab131 that interfaces with its correspondingblade56. This could weaken the “joint” between theblade support tab131 and itscorresponding blade56 to the point of being susceptible to premature separation of thecorresponding cutting blade56 from the remainder of thewafer130. The depth of thescore132 may also of course have an effect on the structural integrity of theblade support tab131, or stated another way on the ability for theblade56 to remain attached to thewafer130, including while mounting ablade handle24 thereon. In one embodiment, a portion of theblade support tab131 is disposed beyond each end of thescore132 such that thescore132 does not extend across the entire width or lateral extent of theblade support tab131, and thescore132 is about 2%-5% of the thickness of theblade56. This provides sufficient structural integrity for theblade56 to remain attached to thewafer130 during handling and while mounting thehandle24 on theblade56, and yet still facilitates separation of theblade56 from thewafer130 at least substantially along thescore132 at the desired time.
• There are a number of other characteristics of note in relation to the[0115]scores132. Initially, eachscore132 is preferably aligned with a crystallographic plane such that the separation of theblades56 occurs at least substantially along a crystallographic plane, and in one embodiment the intersection133cof the planar score surfaces133a,133bof a givenscore132 is aligned with a crystallographic plane. Moreover, preferably eachscore132 is parallel with itscorresponding cutting edge80. Another is that thescores132 are longitudinally offset from their correspondingfirst sections112 of therear surface106 of thecorresponding blade56. That is, thescores132 are “longitudinally recessed” relative to the rear edge of thecorresponding cutting blade56. Other configurations of therear surface106 of theblade56 may be utilized and still provide this “longitudinally recessed” feature. That is, what is of importance is that thescore132 be positioned at a location that is longitudinally recessed from a most rearwardly disposed portion of therear surface106 of theblade56. Stated another way, thescore132 is preferably disposed closer to thecutting edge80 than the most rearwardly disposed portion of therear surface106 of the blade56 (both measured along/parallel to the central,longitudinal reference axis58 associated with the blade56). This may be of benefit if one or more sharp edges develops during the separation of theblade56 from thewafer130 at least generally along itscorresponding score132.
• Separation of the[0116]cutting blade56 from the remainder of thewafer130 utilizing thescore132 produces the configuration that is illustrated in FIG. 13C. Locations A and B correspond with the locations where theblade support tab131 had previously merged with thecutting blade56. It can be seen that the planar score surface133bof thescore132 has become part of thecutting blade56. This also illustrates the preferred approach where thescore132 and the portion of thesecond section114 of thenotch110 on the opposite sides thereof are both defined by an etch, and thereby are similarly shaded. In contrast, the region that is bounded by the pair of dashed lines, and further that does not include planar score surface133b, is defined by fracturing thewafer130.Reference numeral133d identifies this fracture region and utilizes a different shading than the surfaces defining the planar score surface133band thesecond section114. Thefracture region133dis longitudinally spaced from the rear-most portion of thecutting blade56. In one embodiment, thefracture region133dis coplanar with thesecond section114, and may be considered as part thereof. In another embodiment, thefracture region133dis parallel to, but longitudinally offset from, thesecond section114 of the blade56 (not illustrated). In this latter instance, thefracture regions133ddesirably still does not define the most rearwardly disposed portion of thecutting blade56.
• As noted above, there may be some variation between the blade mask and the resulting configuration of the[0117]blade56 when etched from thewafer130. For instance, FIG. 13D includes a reference numeral57athat represents the blade mask perimeter profile for theblade56. The entire blade mask perimeter profile57afor ablade56 is illustrated in FIG. 13D, as well as a portion of its correspondingblade support tab131.Reference numeral57bin FIG. 13D represents an actual perimeter profile of ablade56 when fabricated from thewafer130 by an anisotropic etch. That is, theactual perimeter profile57bis that which is actually achieved when using an anisotropic etch from a blade mask have the blade mask perimeter profile57a. Only a portion of theactual perimeter profile57bis illustrated in FIG. 13D for convenience.
• [0118]Blades56 are separated from the remainder of thewafer130 generally by first mounting ablade handle24 on anindividual cutting blade56 in the above-noted manner so as to properly register the blade handle24 to thecutting blade56. Once the adhesive has cured an appropriate amount or once the blade handle24 is otherwise sufficiently fixed to anindividual blade56, the blade handle24 is moved (e.g., manually) relative to thewafer130 so as to cause thewafer130 to fracture along itscorresponding score132. In the illustrated embodiment, blade handles24 are attached to each of theindividual blades56 on awafer130 while in a blade handle mounting fixture224 (FIGS. 14-19). Thewafer130 with the blade handles24 mounted on itsvarious blades54 is then transferred to ablade separation fixture300 where theindividual blades56, with ablade handle24 mounted thereon, are separated from the remainder of the wafer130 (FIGS. 20-23).
• FIGS. 14-19 illustrate a desirable configuration for allowing blade handles[0119]24 to be mounted onindividual cutting blades56 while still attached to and thereby part of thewafer130. Abase plate220 is appropriately attached to abottom surface278 of a bladehandle mounting fixture224. One or more appropriate fasteners (not shown) are directed through mountingholes222 in thebase plate220 and into mountingholes296 formed on thebottom surface278 of the bladehandle mounting fixture224. Any appropriate way of interconnecting thebase plate220 with the bladehandle mounting fixture224 may be utilized.
• The[0120]base plate220 generally cooperates with the bladehandle mounting fixture224 to define a vacuum chamber284 (FIG. 17). More specifically, anannular groove288 is defined on thebottom surface278 of the bladehandle mounting fixture224. Anannular seal ring292 is disposed within thisannular groove288 and seats against an annular portion of ainner surface223 of thebase plate220 that projects toward or faces thebottom surface278 of the bladehandle mounting fixture224. The perimeter of thevacuum chamber284 thereby corresponds with theannular seal ring292, while the top and bottom of thevacuum chamber284 are defined by thebottom surface278 of the bladehandle mounting fixture224 and theinner surface223 of thebase plate220, respectively.
• A vacuum is generated within the[0121]noted vacuum chamber284 by fluidly interconnecting a vacuum pump or the like (not shown) to a vacuum pull-down port276 associated with the bladehandle mounting fixture224. This vacuum pull-down port276 extends within the body of thefixture224 and intersects with avacuum linking port280. Thisvacuum linking port280 is disposed inwardly of theannular seal ring292 and intersects with thebottom surface278 of thefixture224 so as to be fluidly interconnected with thevacuum chamber284. A plurality of vacuum holes268 are also disposed inwardly of theannular seal ring292 so as to interface with thevacuum chamber284. These vacuum holes268 extend from thebottom surface278 of the bladehandle mounting fixture224 to anupper surface228 of thefixture224 on which thewafer130 is disposed.
• The[0122]upper surface228 of the bladehandle mounting fixture224 is configured to suitably support thewafer130 and maintain the same in a fixed position while installing the blade handles24 on theindividual blades56 when still part of thewafer130. Generally, less than the entirety of thelower surface138 of thewafer130 is in actual contact with theupper surface228 of thefixture224. Moreover, theupper surface228 of thefixture224 is configured so as to reduce the potential for damage to thecutting edge80 of eachblade56 while mounting the blade handles24 on theindividual blades56 thewafer130. Theupper surface228 of thefixture224 is also configured so as to allow thebottom surface48 of each blade handle24 to properly seat on thetop surface60 of its corresponding blade56 (e.g., so as to be in interfacing relation, or at least in closely spaced and parallel relation). When adhesives are used, there will of course be a bond line between theblade handle24 and theblade56. Finally, theblade56 itself is directly supported by the fixture224 (in one embodiment in coplanar relation with non-blade portions of thewafer130 and including at least part of the above-noted frame128), preferably in a manner such that the net moment about thecorresponding score132 is zero (i.e., no torque) when mounting ablade handle24 on thecutting blade56.
• The[0123]upper surface228 of the bladehandle mounting fixture224 includes arecess232 having a base236 that is vertically offset from anannular perimeter portion230 of theupper surface228. Thisbase236 includes a planarwafer supporting surface238, a plurality of cuttingedge cavities244, and a plurality ofregistrant cavities256. Anannular side wall240 of therecess232 extends from the lower elevationwafer supporting surface238 of thebase236 of therecess232 to the higher elevationannular perimeter portion230 of theupper surface228 of thefixture224. Thisannular side wall240 at least substantially approximates a perimeter of thewafer130. Preferably, theannular side wall240 and the perimeter of thewafer130 are disposed in closely spaced relation (e.g., such that there is no more than about a 1 millimeter gap between any portion of theannular side wall240 and a corresponding portion of the perimeter of the wafer130).
• At least one[0124]notch272 is formed on theupper surface228 of the bladehandle mounting fixture224. Eachnotch272 has a base274 that is vertically offset from thewafer supporting surface238 of thebase236 of therecess232. Thebase274 of eachnotch272 is disposed at a lower elevation than thewafer supporting surface238 of thebase236 of therecess232. There is thereby a space between thewafer130 and thebase274 of eachnotch272. This space facilitates installation of thewafer130 within therecess232 of the bladehandle mounting fixture224, as well as the removal of thewafer130 from the bladehandle mounting fixture224. Both manual (e.g., human operator) and a machine(s) are contemplated for one or both of the installation and removal of thewafer130 relative to the bladehandle mounting fixture224.
• Multiple features are incorporated in the configuration of the[0125]base236 of therecess232 that is formed on theupper surface228 of the bladehandle mounting fixture224 for receipt of thewafer130. One is that thevarious vacuum holes268 intersect with thebase236 of therecess232. Preferably these vacuum holes268 intersect with thewafer supporting surface238 of thebase236 of the recess232 (FIG. 16). Thewafer supporting surface238 interfaces with thelower surface138 of thewafer130 to vertically support thewafer130 while on thefixture224. When thewafer130 is disposed within therecess232, a vacuum is pulled through thevarious vacuum holes268 against the overlyingwafer130, through thevacuum chamber284, through thevacuum linking port280, and through the vacuum pull-down port276 by an appropriate source. Suction forces thereby retain thelower surface138 of thewafer130 against the planarwafer supporting surface238 of thebase236 of therecess232. Exactly how the suction or vacuum force is generated and transferred to thewafer130 to retain the same against thefixture224 is not of particular importance. Other configurations may be utilized to generate this type of retention force for thewafer130 on thefixture224.
• Another feature of the[0126]base236 of therecess232 formed on theupper surface228 of the bladehandle mounting fixture224 is that it includes multiplecutting edge cavities244. Eachcutting edge cavity244 is defined by a base248 that is vertically spaced from thewafer supporting surface238, and aside wall252 that extends from thelower elevation base248 to the higher elevation wafer supporting surface238 (e.g., FIG. 18). In the illustrated embodiment, at least part of theside wall252 of eachcutting edge cavity244 is disposed in perpendicular relation to the adjacent portion of thewafer supporting surface238 of thebase236 of therecess232. Any appropriate orientation of theside wall252 of the variouscutting edge cavities244 may be utilized.
• What is of principal importance in relation to each[0127]cutting edge cavity244 is that they be sized and oriented on theupper surface228 of thefixture224 such that thecutting edge80 of eachblade56 will be disposed over one of thecutting edge cavities244 when thewafer130 is disposed within therecess232 of thefixture224. That is, thecutting edge80 of eachblade56 is disposed in vertically spaced relation to the bladehandle mounting fixture224. Preferably, thecutting edge80 of eachblade56 never contacts thefixture224 while thewafer130 is positioned thereon. In the illustrated embodiment, a givencutting edge cavity244 accommodates thecutting edge80 formultiple blades56. More specifically, a plurality of thecutting edge cavities244 are disposed in equally spaced rows along thebase236 of therecess232. A givencutting edge cavity244 accommodates all of theblades56 in a corresponding row on the wafer130 (i.e., provides a space below thecutting edge80 of eachblade56 in a given row on the wafer130) in the illustrated embodiment. It should be appreciated that thebase236 of therecess232 could be configured such that thecutting edge80 of eachindividual blade56 has its own individual cutting edge cavity244 (not shown).
• [0128]Multiple registrant cavities256 are also formed on thebase236 of therecess232 of the bladehandle mounting fixture224. Generally, theseregistrant cavities256 are sized so that theregistrants32 on thebottom surface48 of the blade handle24 do not contact thefixture224 while mounting ablade handle24 on aparticular cutting blade56. Eachregistrant cavity256 is defined by a base260 that is vertically spaced fromwafer supporting surface238, and aside wall264 that extends from thelower elevation base260 to the higher elevation wafer supporting surface238 (e.g., FIG. 18). In the illustrated embodiment, at least part of theside wall264 of eachregistrant cavity256 is disposed in perpendicular relation to the adjacent portion of thewafer supporting surface238 of thebase236 of therecess232. Any appropriate orientation of theside wall264 of thevarious registrant cavities256 may be utilized.
• What is of principal importance in relation to each[0129]registrant cavity256 is that they be sized and oriented on theupper surface228 of the bladehandle mounting fixture224, such that eachregistration84 of eachblade56 will be disposed over one of theregistrant cavities256 when thewafer130 is disposed within therecess232 on thefixture224. More specifically, eachregistrant cavity256 should be sized and oriented on theupper surface228 of thefixture224 such that aregistrant cavity256 is disposed below eachregistrant32 of each blade handle24 to keep thebottom wall40 of eachregistrant32 of each blade handle24 in vertically spaced relation to the bladehandle mounting fixture224. In the illustrated embodiment, some registrant cavities256 (those on an end of a row of registrant cavities256) accommodate asingle registrant32 from asingle blade handle24, whileother registrant cavities256 accommodate aregistrant32 from a pair of blade handles24 mounted on adjacently disposedblades56 within a given row on thewafer130. Although a plurality of rows ofregistrant cavities256 could be utilized and spaced such that a givensingle registrant cavity256 accommodated theregistrant32 of each blade handle24 mounted on all of theblades56 within a given row on the wafer130 (not shown), the illustrated configuration is advantageous in relation to how thewafer130 is supported by thefixture224 for installation of the blade handles24.
• Appropriate support of the[0130]wafer130 is provided by the illustrated configuration of the bladehandle mounting fixture224 when installing the blade handles24 on theindividual blades56 that are still attached to and part of thewafer130. Portions of thewafer supporting surface238 that are disposed under, interface with, and support therepresentative blade56 illustrated in FIG. 19, are shown by the dashed lines in FIG. 19. In this regard, eachblade56 of thewafer130 is supported by theblade supporting surface238 of thefixture224 across the entire width of theblade56 over a region that is spaced back from itscutting edge80, which again is disposed over one of thecutting edge cavities244 so as to be spaced from thefixture224. Eachblade56 is also supported by theblade supporting surface238 of thefixture224 across the entire width of theblade56 at or toward the rear of the blade56 (e.g., proximate the rear surface106). Finally, theblade56 is also supported by theblade supporting surface238 of thefixture224 under its correspondingblade support tab131 and along a longitudinally extending region between theregistrant cavities84. Therefore, theblades56 do not tend to deflect downwardly a significant degree when installing blade handles24 on theblades56 at a time when theseblades56 are still attached to and part of thewafer130. As noted above, preferably theblade56 itself is directly supported by the fixture224 (in one embodiment in coplanar relation with non-blade portions of the wafer130), in a manner such that the net moment about thecorresponding score132 is zero (i.e., no torque) when mounting ablade handle24 on thecutting blade56.
• Summarizing the manner in which blade handles[0131]24 are mounted on theblades56, thewafer130 with theblades56 formed thereon is disposed within therecess232 of the bladehandle mounting fixture224 in the manner illustrated in FIG. 14. A vacuum is drawn so as to retain portions of thewafer130 against thewafer supporting surface238 associated with thefixture224. An appropriate adhesive may be applied on at least one of thetop surface60 of one or more of thecutting blades56 and thebottom surface48 of a corresponding number of blade handles24. Eachregistrant32 on thebottom surface48 of a particular blade handle24 is then disposed within acorresponding registration cavity84 on aparticular blade56 by moving the blade handle24 toward thefixture224. Preferably, theregistrants32 of this blade handle24 are initially disposed within thecorresponding registration cavity84 of theparticular blade24 so as to not contact its rear wall orregistration surface94. This may be utilized to seat theplanar bottom surface48 of the blade handle24 on the planartop surface60 of thecutting blade56. The blade handle24 may then be moved generally rearwardly until eachregistrant32 cooperates with itscorresponding registration surface94, more typically a portion thereof. This then registers or aligns thecutting edge80 of theparticular cutting blade56 relative to themicrokeratome registration surface28 of itscorresponding blade handle24, which in turn registers or aligns thecutting edge80 of thecutting blade56 in a desired position within themicrokeratome4. Once again, themicrokeratome registration28 of the blade handle24 is registered or aligned relative to the cuttingtool registration surface14 of thehead assembly10 of themicrokeratome4.
• [0132]Multiple cutting blades56 may be formed on thewafer130 prior to being positioned on the bladehandle mounting fixture224. A blade handle24 may be mounted on eachcutting blade56 in the above-described manner. Blade handles24 may be sequentially mounted on the variousindividual cutting blades56, multiple blade handles24 may be simultaneously mounted onmultiple cutting blades56, or blade handles24 may be simultaneously mounted on all cuttingblades56 formed on thewafer130. Regardless of how many cuttingblades56 are formed on thewafer130 and the sequence of installing any blade handle(s)24 thereon, thewafer130 may be removed from thefixture224 with ablade handle24 being mounted on at least onecutting blade56 and with the cutting blade(s)56 remaining part of thewafer130. That is, after ablade handle24 has been mounted on at least onecutting blade56, thewafer130 may be removed from thefixture224 and without having separated any such cutting blade56 (with ablade handle24 mounted thereon) from thewafer130. Thereafter, the variousindividual cutting blades56 with ablade handle24 mounted thereon may be separated from the remainder of thewafer130.
• FIGS. 20-23 illustrate a desirable configuration for allowing[0133]blades54 and their corresponding blade handles24 to be separated from thewafer130. Various characteristics of one configuration of ablade separation fixture300 is disclosed by FIGS. 20-23. Initially, thewafer130 is retained on theblade separation fixture300 using a vacuum in the same manner discussed above in relation to the bladehandle mounting fixture224 of FIGS. 14-19. Therefore, the bottom surface of theblade separation fixture300 will similarly include an annular groove and an annular seal ring of the type used by the bladehandle mounting fixture224, so that thebase plate220 may be attached to thefixture300 in the same manner as theblade mounting fixture224 to define a vacuum chamber. Theblade separation fixture300 will then also include a vacuum pull-down port, a vacuum linking port, and vacuum holes (not shown) of the type used by theblade mounting fixture224 to draw a vacuum for retaining thewafer130 on thefixture300. Additional vacuum ports may be included on theupper surface304 of thefixture300 so as to retain thecutting tool20 against thefixture300 after itscorresponding blade56 has been separated from the remainder of the wafer130 (e.g., by including vacuum ports on ablade interface wall352 of the fixture300).
• An[0134]upper surface304 of theblade separation fixture300 is configured to suitably support thewafer130 and maintain the same in a fixed position while separatingblades56 from the remainder of thewafer130 using the blade handle24 previously mounted thereon (e.g., in accordance with FIGS. 14-19). Generally, less than the entirety of thelower surface138 of thewafer130 is in actual contact with theupper surface304 of thefixture300. Moreover, theupper surface304 of thefixture300 is configured so as to reduce the potential for damage to thecutting edge80 of eachblade56 while separatingblades56 from the remainder of thewafer130. Finally, theupper surface304 of thefixture300 is configured so as to allow thebottom surface48 of each blade handle24 to remain properly seated on thetop surface60 of itscorresponding blade56 and in spaced relation to the fixture300 (e.g., so as to be in interfacing relation, or at least in closely spaced and parallel relation).
• The[0135]upper surface304 of theblade separation fixture300 includes arecess312 having a base320 that is vertically offset from anannular perimeter portion308 of theupper surface304. Thisbase320 includes a planar wafer supporting surface324 (which includes a bladesupport tab section326 for interfacing with and supporting eachblade support tab131 of thewafer130, which again provides the interconnection between theblades56 and the remainder of the wafer130), a plurality of cuttingedge cavities328, and a plurality of registrant/pivot cavities340. An annular side wall316 of therecess312 extends from the lower elevationwafer supporting surface324 of thebase320 of therecess312 to the higher elevationannular perimeter portion308 of theupper surface304 of thefixture300. This annular side wall316 at least substantially approximates a perimeter of thewafer130. Preferably, the annular side wall316 and the perimeter of thewafer130 are disposed in closely spaced relation (e.g., such that there is no more than about a 1 millimeter gap between any portion of the annular side wall316 and a corresponding portion of the perimeter of the wafer130).
• At least one[0136]notch305 is formed on theupper surface304 of theblade separation fixture300. Eachnotch305 has a base306 that is vertically offset from thewafer supporting surface324 of thebase320 of therecess312. Thebase305 of eachnotch304 is disposed at a lower elevation than thewafer supporting surface324 of thebase320 of therecess312. There is a thereby a space between thewafer130 and thebase306 of eachnotch305. This space facilitates installation of thewafer130 within therecess312 of theblade separation fixture300, as well as the removal of thewafer130 from theblade separation fixture300. Both manual (e.g., human operator) and a machine(s) are contemplated for one or both of the installation and removal of thewafer130 relative to theblade separation fixture300.
• Multiple features are incorporated in the configuration of the[0137]base320 of therecess312 that is fonned on theupper surface304 of theblade separation fixture300 for receipt of thewafer130. One is that the various vacuum holes (not shown) intersect with thebase320 of therecess312. Preferably these vacuum holes intersect with thewafer supporting surface324 of thebase320 of therecess312. Thewafer supporting surface324 interfaces with thelower surface138 of thewafer130 to vertically support thewafer130 while on thefixture300. When thewafer130 is disposed within therecess312, a vacuum is pulled against thelower surface138 of thewafer130 through the various vacuum holes, through the vacuum chamber, through the vacuum linking port, and through the vacuum pull-down port by an appropriate source and in the same manner discussed above in relation to the bladehandle mounting fixture224. Suction forces thereby retain thelower surface138 of thewafer130 against the planarwafer supporting surface324 of thebase320 of therecess312. Exactly how the suction or vacuum force is generated and transferred to thewafer130 to retain the same against thefixture300 is not of particular importance. Other configurations may be utilized to generate this type of retention force for thewafer130 on thefixture300.
• Another feature of the[0138]base320 of therecess312 formed on theupper surface304 of theblade separation fixture300 is that it includes multiplecutting edge cavities328. Eachcutting edge cavity328 is defined by a base332 that is vertically spaced from thewafer supporting surface324, and aside wall336 that extends from thelower elevation base332 to the higher elevation wafer supporting surface328 (e.g., FIG. 22). In the illustrated embodiment, at least part of theside wall336 of eachcutting edge cavity328 is disposed in perpendicular relation to the adjacent portion of thewafer supporting surface324 of thebase320 of therecess312. Any appropriate orientation of theside wall336 of the variouscutting edge cavities328 may be utilized.
• What is of principal importance in relation to each[0139]cutting edge cavity328 is that they be sized and oriented on theupper surface304 of thefixture300 such that thecutting edge80 of eachblade56 will be disposed over one of thecutting edge cavities328 when thewafer130 is disposed within therecess312 on thefixture300. That is, thecutting edge80 of eachblade56 is disposed in vertically spaced relation to theblade separation fixture300. In the illustrated embodiment, a givencutting edge cavity328 accommodates thecutting edge80 formultiple blades56. More specifically, a plurality of thecutting edge cavities328 are disposed in equally spaced rows along thebase320 of therecess312. A givencutting edge cavity328 accommodates all of theblades56 in a corresponding row on the wafer130 (i.e., provides a space below thecutting edge80 of eachblade56 in a given row on the wafer130) in the illustrated embodiment. It should be appreciated that thebase320 of therecess312 could be configured such that thecutting edge80 of eachindividual blade56 had its own individual cutting edge cavity328 (not shown).
• Multiple registrant/[0140]pivot cavities340 are also formed on thebase320 of therecess312 of theblade separation fixture300. Each registrant/pivot cavity340 is defined by a base344 that is vertically spaced fromwafer supporting surface324, aside wall348 that extends from thelower elevation base344 to the higher elevation wafer supporting surface324 (e.g., FIG. 22), and ablade interface wall352. In the illustrated embodiment, at least part of theside wall348 of each registrant/pivot cavity340 is disposed in perpendicular relation to the adjacent portion of thewafer supporting surface324 of thebase320 of therecess312. Any appropriate orientation of theside wall348 of the various registrant/pivot cavities340 may be utilized. Theblade interface wall352 defines the forward boundary of the corresponding registrant/pivot cavity340 and is configured to interface with thebottom surface64 of ablade56 after being separated from thewafer130 in a manner that will be discussed in more detail below.
• What is of principal importance in relation to each registrant/[0141]pivot cavity340 is that they be sized and oriented on theupper surface304 of thefixture300 such that eachregistration cavity84 of eachblade56 will be disposed over one of the registrant/pivot cavities340 when thewafer130 is disposed within therecess312 on thefixture300. More specifically, each registrant/pivot cavity340 should be sized and oriented on theupper surface304 of thefixture300 such that the registrant/pivot cavity340 is disposed below eachregistrant32 of each blade handle24 to keep thebottom wall40 of eachregistrant32 of each blade handle24 in vertically spaced to theblade separation fixture300. In the illustrated embodiment, a given registrant/pivot cavity340 accommodates theregistrants32 ofmultiple cutting tools20. More specifically, a plurality of the registrant/pivot cavities340 are disposed in equally spaced rows along thebase320 of therecess312. A given registrant/pivot cavity340 accommodates all of theblades56 in a corresponding row on the wafer130 (i.e., provides a space below theregistrant cavities84 of eachblade56 in a given row on the wafer130) in the illustrated embodiment. It should be appreciated that thebase320 of therecess312 could be configured such that eachindividual blade56 had its own registrant/pivot cavity340 (not shown).
• The[0142]various blades56 of thewafer130 are suspended above theupper surface304 of theblade separation fixture300. That is, theblades56 are disposed in vertically spaced relation to theunderlying base320 of therecess312 of theblade separation fixture300. Those portions of thewafer130 that are disposed between the rows ofblades56, as well as the outer perimeter of the wafer130 (e.g., the above-noted frame128), interface with and are supported by thewafer supporting surface324 of thefixture300. Part of thewafer supporting surface324, namely structures in the form of a plurality of blade supportingtab sections326, interfaces with and supports the variousblade support tabs131 that interconnect each of theblades56 with the remainder of thewafer130. Each bladesupport tab section326 extends toward, but not beyond, thescore132 of the correspondingblade support tab131. Preferably, the distal end of each bladesupport tab section326 is vertically aligned with ascore132.
• A[0143]blade supporting surface356 is located under thevarious blades56 in a given row of thewafer130 at a location that is longitudinally between the correspondingcutting edge cavity328 and the corresponding registrant/pivot cavity340. Thisblade supporting surface356 is a planar surface, is parallel with thewafer supporting surface324, and is recessed relative to thewafer supporting surface324. That is, theblade supporting surface356 is disposed at a lower elevation than thewafer supporting surface324. Overlyingblades56 are thereby initially separated from the correspondingblade supporting surface356 by a space when thewafer130 is in thefixture300. The above-notedblade interface wall352 extends from theblade supporting surface356 down to thebase344 of the corresponding registrant/pivot cavity340. Thisblade interface wall352 is a planar surface and is disposed at an angle a (FIG. 22) that is preferably within a range of about15 degrees to about 30 degrees.
• Summarizing the manner in which[0144]blades56 are separated from the remainder of thewafer130, thewafer130 is disposed within therecess312 on theblade separation fixture300 and in the manner illustrated in FIG. 20. Blade handles24 typically will have been mounted to each of theblades56 of the wafer130 (utilizing the bladehandle mounting fixture224 discussed above in relation FIGS. 14-19) at this time, although any number ofblades56 may have ablade handle224 mounted thereon and still utilize theblade separation fixture300. A vacuum is drawn so as to retain portions of the wafer130 (e.g., its frame128) against thewafer supporting surface324 associated with thefixture300 by “pulling down” on portions of thewafer130.
• An at least generally downwardly directed force is then exerted on a particular blade handle[0145]24 to separate itscorresponding blade56 from thewafer130 in one embodiment. In another embodiment, this force is exerted directly on theblade56. In either case, this may be done manually (e.g., by hand) or by a machine(s) (e.g., manually activated or in an automated manner). In one embodiment, this force is directed so as to be least generally perpendicular to thetop surface60 of thecorresponding cutting blade56. In any case, this type of force will cause thecutting blade56 to deflect down toward the underlying blade supporting surface356 a sufficient degree to cause the blade56 (with its blade handle24 mounted thereon) to separate from the remainder of thewafer130 at least generally along itscorresponding score132. This separation preferably occurs before theblade56 contacts theupper surface304 of thefixture300. Thecutting edge80 moves toward, but does not contact, theunderlying fixture300 during this deflection. One benefit of the configuration of therear surface106 of thecutting blade56, namely by having thescore132 disposed within thenotch110 on theback surface106 of theblade56, is that even if the fracture does not occur exactly along thescore132, the wafer surface exposed by the fracture should still be longitudinally offset or spaced relative to thefirst sections112 of therear surface106 of theblade56.
• Once the[0146]blade56 has separated from thewafer130 in the above-noted manner, the now separatedblade56 will continue in a downward direction until it contacts the underlyingblade supporting surface356. Since the force is being exerted on theblade56 through itscorresponding blade handle24, thebottom surface64 of theblade56 will tend to move toward and most likely interface with an underlyingblade interface wall352. As noted above, suction forces or a vacuum may be used to retain thebottom surface64 of each cuttingblade56 against an underlyingblade interface wall352 after being separated from the remainder of thewafer130 in the above-noted manner. In any case, this of course moves itscorresponding cutting edge80 further away from the blade separation fixture300 (e.g., by a pivoting or pivotal-like motion) so as to further reduce the potential for thecutting edge80 being damaged during separation of theblade56 from thewafer130. A givencutting edge80 thereby first moves at least generally toward theunderlying fixture300, and then at least generally away from thefixture300.
• The[0147]blade56 again preferably moves into contact with thefixture300 only after separating from thewafer130. It initially does so by landing on theblade supporting surface356 of thefixture300. Thisblade supporting surface356 is in effect a laterally extending beam about which theblade56 pivots into contact with the inclinedblade interface wall352. Therefore, thecutting edge80 first moves toward, but not to, thefixture300 when theblade56 is being separated from thewafer130. When thecutting blade56 does contact thefixture300 after separation from the wafer130 (the noted blade supporting surface356), thecutting edge80 of theblade56 is still spaced from thefixture300 by being over/within acutting edge cavity328. Theblade56 then pivots in a direction to move thecutting edge80 away from thefixture300, and in turn move its rear edge toward the fixture300 (e.g., a teeter-totter-like action). Thebottom surface64 of theblade56 will then interface with the inclinedblade interface wall352 such that therear surface106 of the blade56 (or an associated edge) is disposed on thebase352 of the registrant/pivot cavity340 (e.g., projecting at least generally downward) and further such that itscutting edge80 is projecting at least generally upward and in spaced relation to thefixture300. Therefore, thecutting edge80 also preferably never contacts thefixture300.
• It is contemplated that each of the[0148]blades56 may be sequentially removed from the remainder of thewafer130 in the above-described manner (that is, one at a time), in one or more groups, or all simultaneously. In this regard,multiple cutting blades56 may be formed on thewafer130 prior to being positioned on theblade separation fixture300. A blade handle24 may be mounted on eachcutting blade56 as well before thewafer130 is positioned on thefixture300. Cuttingblades56 may be sequentially separated from the remainder of thewafer130 in the above-noted manner,multiple cutting blades56 may be simultaneously separated from the remainder of thewafer130 in the above-noted manner, or all cuttingblades56 formed on thewafer130 may be simultaneously separated from the remainder of thewafer130 in the above-noted manner. Regardless of how many cuttingblades56 are formed on thewafer130 and the sequence of separatingcutting blades56 from the remainder of thewafer130, thewafer130 may be removed from thefixture300 after at least onecutting blade56 has been separated from the remainder of thewafer130. Allcutting blades56 are preferably separated from thewafer130 prior to removing thewafer130 from thefixture300. However, anycutting blade56 that has been separated from the remainder of thewafer130 may be removed from thefixture300 prior to or after thewafer300 is removed from thefixture300.
• The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.[0149]

Claims (46)

What is claimed is:

1. A cutting tool, comprising:

a blade comprising first cutting edge surface, a second cutting edge surface, a cutting edge defined by an intersection of said first and second cutting edge surfaces, and a first registration surface spaced from said cutting edge and parallel with said first cutting edge surface; and

a blade handle interconnected with said blade and comprising a first registrant that interfaces with at least part of said first registration surface.

2. A cutting tool, as claimed inclaim 1, wherein:

said blade further comprises top and bottom surfaces that are planar and disposed in parallel relation, wherein said first cutting edge surface is disposed at an angle relative to and intersects with said top surface, and wherein said bottom surface comprises said second cutting edge surface.

3. A cutting tool, as claimed inclaim 1, wherein:

said blade further comprises top and bottom surfaces that are planar and disposed in parallel relation, wherein both said first cutting edge surface and said first registration surface are disposed at an angle relative to and intersect with said top surface, wherein said bottom surface comprises said second cutting edge surface, and wherein said first registration surface is disposed at an angle relative to and intersects with said bottom surface.

4. A cutting tool, as claimed inclaim 1, wherein:

said first cutting edge surface extends from a first edge to said cutting edge, wherein said first registration surface extends from a second edge to a third edge, wherein said first and second edges are disposed within a first reference plane, wherein said cutting edge and said third edge are disposed within a second reference plane, and wherein said first and second reference planes are parallel.

5. A cutting tool, as claimed inclaim 1, wherein:

said blade comprises a second registration surface spaced from said cutting edge and parallel with said first cutting edge surface; and

wherein said blade handle comprises a second registrant that interfaces with at least part of said second registration surface.

6. A cutting tool, as claimed inclaim 5, wherein:

said first and second registration surfaces are coplanar.

7. A cutting tool, as claimed inclaim 1, wherein:

said blade comprises a concave first registration cavity spaced from said cutting edge and comprising first and second ends with said first end being disposed between said cutting edge and said second end, wherein said second end comprises said first registration surface.

8. A cutting tool, as claimed inclaim 7, wherein:

said first registration cavity extends entirely through said blade.

9. A cutting tool, as claimed inclaim 7, wherein:

said blade comprises a planar top surface, wherein said first end of said first registration cavity is perpendicular to said planar top surface, and wherein said first registration surface is disposed at an angle other than perpendicular relative to said planar top surface.

10. A cutting tool, as claimed inclaim 7, wherein:

said first registrant is separated from said first end by a space.

11. A cutting tool, as claimed inclaim 7, wherein:

said blade further comprises a concave second registration cavity spaced from said cutting edge and comprising third and fourth ends with said third end being disposed between said cutting edge and said fourth end, wherein said fourth end comprises a second registration surface that is parallel with said first cutting edge surface and coplanar with said first registration surface; and

wherein said blade handle comprises a second registrant that interfaces with at least part of said second registration surface.

12. A cutting tool, as claimed inclaim 1, wherein:

an interface between said first registrant and said first registration surface is limited to being at least substantially along a line.

13. A cutting tool, as claimed inclaim 1, wherein:

said blade further comprises top and bottom surfaces, wherein an intersection between said first registration surface and said top surface defines a first edge, and wherein an intersection between said first registration surface and said bottom surface defines a second edge.

14. A cutting tool, as claimed inclaim 13, wherein:

said first registrant interfaces with said first registration surface closer to said second edge than said first edge.

15. A cutting tool, as claimed inclaim 13, wherein:

said first registrant interfaces with said first registration surface along said second edge.

16. A cutting tool, as claimed inclaim 13, wherein:

said first registrant extends below said second edge.

17. A cutting tool, as claimed inclaim 1, wherein:

said blade handle comprises a second registrant, wherein said second registrant disposes said blade handle in a predetermined position relative to a microkeratome when said cutting tool is installed on the microkeratome.

18. A cutting tool, comprising:

a blade comprising a first cutting edge surface, a second cutting edge surface, a cutting edge defined by an intersection of said first and second cutting edge surfaces, a concave first registration cavity spaced from said cutting edge and comprising first and second ends with said first end being disposed between said first cutting edge and said second end; and

a blade handle interconnected with said blade and comprising a first registrant that extends within said first registration cavity, wherein said first registrant interfaces with at least part of said second end of said first registration cavity and is spaced from said first end of said first registration cavity.

19. A cutting tool, as claimed inclaim 18, wherein:

said first registration cavity extends entirely through said blade.

20. A cutting tool, as claimed inclaim 18, wherein:

said blade comprises a planar top surface, wherein said first end of said first registration cavity is perpendicular to said planar top surface, and wherein said second end of said first registration cavity is disposed at an angle other than perpendicular relative to said planar top surface.

21. A cutting tool, as claimed inclaim 18, wherein:

said first registrant is separated from said first end of said first registration cavity by a distance of at least about 1 millimeter.

22. A cutting tool, as claimed inclaim 18, wherein:

said blade further comprises a concave second registration cavity spaced from said cutting edge and comprising third and fourth ends with said third end being disposed between said cutting edge and said fourth end; and

wherein said blade handle comprises a second registrant that interfaces with at least part of said fourth end and is spaced from said third end.

23. A cutting tool, as claimed inclaim 22, wherein:

said first and second registrants are positioned along a reference axis that is parallel with said cutting edge.

24. A cutting tool, as claimed inclaim 22, wherein:

said first and second registrants are equidistant from said cutting edge.

25. A cutting tool, as claimed inclaim 22, wherein:

said second end of said first registration cavity comprises a first registration surface that is spaced from said first cutting edge and parallel with said first cutting edge surface;

wherein said fourth end of said second registration cavity comprises a second registration surface that is spaced from said cutting edge and parallel with said first cutting edge surface; and

wherein said second registrant interfaces with at least part of said second registration surface.

26. A cutting tool, as claimed inclaim 25, wherein:

said first and second registration surfaces are coplanar.

27. A cutting, tool, as claimed inclaim 18, wherein:

said second end of said first registration cavity comprises a first registration surface that is spaced from said cutting edge and parallel with said first cutting edge surface, wherein said first registrant interfaces with at least part of said first registration surface.

28. A cutting tool, as claimed inclaim 27, wherein:

said blade further comprises top and bottom surfaces that are planar and disposed in parallel relation, wherein said first cutting edge surface is disposed at an angle relative to and intersects said top surface, and wherein said bottom surface comprises said second cutting edge surface.

29. A cutting tool, as claimed inclaim 27, wherein:

said blade further comprises top and bottom surfaces that are planar and disposed in parallel relation, wherein both said first cutting edge surface and said first registration surface are disposed at an angle relative to and intersects with said top surface, wherein said bottom surface comprises said second cutting edge surface, and wherein said first registration surface is disposed at an angle relative to and intersects with said bottom surface.

30. A cutting tool, as claimed inclaim 27, wherein:

said first cutting edge surface extends from a first edge to said cutting edge, wherein said first registration surface extends from a second edge to a third edge, wherein said first and second edges are disposed within a first reference plane, wherein said cutting edge and said third edge are disposed within a second reference plane, and wherein said first and second reference planes are parallel.

31. A cutting tool, as claimed inclaim 27, wherein:

an interface between said first registrant and said first registration surface is limited to being at least substantially along a line.

32. A cutting tool, as claimed inclaim 27, wherein:

said blade further comprises top and bottom surfaces, wherein an intersection between said first registration surface and said top surface defines a first edge, and wherein an intersection between said first registration surface and said bottom surface defines a second edge.

33. A cutting tool, as claimed inclaim 32, wherein:

said first registrant interfaces with said first registration surface closer to said second edge than said first edge.

34. A cutting tool, as claimed inclaim 32, wherein:

said first registrant interfaces with said first registration surface along said second edge.

35. A cutting tool, as claimed inclaim 32, wherein:

said first registrant extends below said second edge.

36. A cutting tool, as claimed inclaim 18, wherein:

said blade handle comprises a second registrant, wherein said second registrant disposes said blade handle in a predetermined position relative to a microkeratome when said cutting tool is installed on the microkeratome.

37. A cutting tool, comprising:

a blade comprising first cutting edge surface, a second cutting edge surface, a cutting edge defined by an intersection of said first and second cutting edge surfaces, and a first registration surface spaced from said cutting edge and parallel with said first cutting edge surface.

38. A cutting tool, as claimed inclaim 37, wherein:

said blade further comprises top and bottom surfaces that are planar and disposed in parallel relation, wherein said first cutting edge surface is disposed at an angle relative to and intersects with said top surface, and wherein said bottom surface comprises said second cutting edge surface.

39. A cutting tool, as claimed inclaim 37, wherein:

said blade further comprises top and bottom surfaces that are planar and disposed in parallel relation, wherein both said first cutting edge surface and said first registration surface are disposed at an angle relative to and intersect with said top surface, wherein said bottom surface comprises said second cutting edge surface, and wherein said first registration surface is disposed at an angle relative to and intersects with said bottom surface.

40. A cutting tool, as claimed inclaim 37, wherein:

said first cutting edge surface extends from a first edge to said cutting edge, wherein said first registration surface extends from a second edge to a third edge, wherein said first and second edges are disposed within a first reference plane, wherein said cutting edge and said third edge are disposed within a second reference plane, and wherein said first and second reference planes are parallel.

41. A cutting tool, as claimed inclaim 37, wherein:

said blade comprises a second registration surface spaced from said cutting edge and parallel with said first cutting edge surface.

42. A cutting tool, as claimed inclaim 41, wherein:

said first and second registration surfaces are coplanar.

43. A cutting tool, as claimed inclaim 37, wherein:

said blade comprises a concave first registration cavity spaced from said cutting edge and comprising first and second ends with said first end being disposed between said cutting edge and said second end, wherein said second end comprises said first registration surface.

44. A cutting tool, as claimed inclaim 43, wherein:

said first registration cavity extends entirely through said blade.

45. A cutting tool, as claimed inclaim 43, wherein:

said blade comprises a planar top surface, wherein said first end of said first registration cavity is perpendicular to said planar top surface, and wherein said first registration surface is disposed at an angle other than perpendicular relative to said planar top surface.

46. A cutting tool, as claimed inclaim 43, wherein:

said blade further comprises a concave second registration cavity spaced from said cutting edge and comprising third and fourth ends with said third end being disposed between said cutting edge and said fourth end, wherein said fourth end comprises a second registration surface that is parallel with said first cutting edge surface and coplanar with said first registration surface.

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