Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide an optical projection lens which is matched with a self-luminous chip and has better projection brightness and projection uniformity and a corresponding AR equipment solution.
In order to solve the above technical problems, the present invention provides an optical projection lens, which includes: the method comprises the following steps of: a first lens, a second lens, a third lens, and a fourth lens; wherein the first lens has positive focal power, the second lens has negative focal power, the third lens has positive focal power, and the fourth lens has negative focal power; wherein the focal length f of the optical projection lens, the focal length f1 of the first lens, the focal length f2 of the second lens, the focal length f3 of the third lens, and the focal length f4 of the fourth lens satisfy the following relationship: 0.8< f3/f <1.3; |f1+f2+f3+ f4|/f >0.15;0.5< (f1+f2+f3)/f <1.5.
The thickness CT1 of the first lens on the optical axis, the spacing distance AT3 between the third lens and the fourth lens on the optical axis, and the focal length f of the optical projection lens satisfy the following relation: 0.25< (CT2+AT3)/f <0.45.
The surface of the projection side of the third lens is a convex surface, and the surface of the chip side of the third lens is a concave surface.
The surface of the first lens on the projection side is a convex surface, and the surface of the first lens on the chip side is a concave surface; the surface of the projection side of the second lens is a convex surface, and the surface of the chip side of the second lens is a concave surface; and both side surfaces of the fourth lens are concave surfaces.
The distance ST between the diaphragm and the first lens on the optical axis satisfies the following relation: ST is more than or equal to 1mm.
Wherein, the radius of curvature R21 of the projection side of the second lens and the radius of curvature R22 of the chip side thereof satisfy the following relation: 1.5< R21/R22<2.5.
Wherein, the radius of curvature R31 of the projection side of the third lens and the radius of curvature R42 of the chip side of the fourth lens satisfy the following relation: 0.15< R31/R42<1.5.
Wherein, the thickness CT1 of the first lens on the optical axis and the thickness CT3 of the third lens on the optical axis satisfy the following relation: CT1/CT3<1.1.
The optical surfaces of the first lens, the second lens, the third lens and the fourth lens are all aspheric surfaces.
Any two adjacent lenses in the first lens, the second lens, the third lens and the fourth lens have a distance different from zero on the optical axis.
According to another aspect of the present application, there is also provided an AR projection apparatus including: the optical projection lens of any one of the preceding claims; a self-luminous chip for projecting an optical information image to the optical projection lens; and a waveguide device including a coupling-in region provided at a front end of the first lens, the front end being an output end of the optical projection lens.
The waveguide device is a waveguide sheet, and the waveguide sheet is provided with the coupling-in area and the coupling-out area.
The waveguide sheet is provided with a first surface and a second surface, wherein the first surface is provided with a microstructure forming the coupling-in area, and the second surface is arranged between the first surface and the first lens.
The diaphragm of the optical projection lens is arranged on the first surface.
The optical projection lens further comprises a lens barrel, and the first lens, the second lens, the third lens and the fourth lens are arranged on the lens barrel and are assembled into a lens group through the lens barrel; the second surface is a plane, and the second surface is supported against an end face of the lens barrel.
Compared with the prior art, the application has at least one of the following technical effects:
1. The optical projection lens can improve the projection brightness and the projection uniformity.
2. In some embodiments of the application, the third lens provides the primary diopter and is configured with a first lens having a positive diopter and second and fourth lenses having a weaker diopter, which allows for a greater degree of acceptance into the beam angle of the light emitted by the image source device and a reduction in the exit angle of the image source device corresponding to the central light of the lens to increase the luminous flux of the light passing through the projection system.
3. In some embodiments of the application, the second lens may act as a beam expander throughout the optical system to ensure that the incoming beam fills the coupling-in area of the entire waveguide sheet without vignetting.
4. In some embodiments of the present application, the interval between the thickness of the second lens and the fourth lens of the optical projection lens may be used to adjust and improve the temperature drift performance of the optical system, so that the positive and negative focal powers of the lens can be ensured to compensate each other during the temperature change process, and the good image quality can be maintained in both high and low temperature environments.
5. In some embodiments of the application, the diaphragm may be disposed in the coupling-in region of the waveguide plate. The design can reduce the influence of vignetting of the coupling-in area of the waveguide sheet on the image information to the greatest extent, thereby improving the contrast, brightness and uniformity of the picture.
Detailed Description
For a better understanding of the application, various aspects of the application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the application and is not intended to limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.
It should be noted that in this specification, the expressions first, second, etc. are only used to distinguish one feature from another feature, and do not represent any limitation of the feature. Accordingly, a first body discussed below may also be referred to as a second body without departing from the teachings of the present application.
In the drawings, the thickness, size and shape of the object have been slightly exaggerated for convenience of explanation. The figures are merely examples and are not drawn to scale.
It will be further understood that the terms "comprises," "comprising," "includes," "including," "having," "containing," and/or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Furthermore, when a statement such as "at least one of the following" appears after a list of features that are listed, the entire listed feature is modified instead of modifying a separate element in the list. Furthermore, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.
As used herein, the terms "substantially," "about," and the like are used as terms of a table approximation, not as terms of a table level, and are intended to illustrate inherent deviations in measured or calculated values that would be recognized by one of ordinary skill in the art.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other.
The application provides an optical projection lens based on a self-luminous chip design, which comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an optical information projection end to an image source device end. The lens with diopter is four non-adhesive aspheric lenses, namely, the non-adhesive lens is formed by arranging a space between any two adjacent lenses of the first lens, the second lens, the third lens and the fourth lens of the optical projection lens, and the design can effectively avoid the problem caused by the adhesive lens. In particular, a cemented surface is formed between adjacent lenses, the surface shape of which is often difficult to determine (e.g., the cemented surface may deform due to heat), thereby introducing additional errors; the cemented lens may also suffer from de-bonding problems due to heat; furthermore, the difficulty of lens coating is increased by assembling the lens group by adopting a gluing technology. In the application, any two adjacent lenses of the first lens, the second lens, the third lens and the fourth lens of the optical projection lens are provided with a space, namely, the lens group is assembled by adopting the non-adhesive lens, so that the problems can be effectively avoided.
In a series of embodiments of the present application, the first lens having positive optical power (i.e., having positive refractive power) in the optical projection lens has a convex surface on a side close to the light information projection end (may be simply referred to as a projection side) and a concave surface on a side close to the image source device (in this embodiment, the image source device is typically implemented by a self-luminous image chip, and thus the side close to the image source device may be simply referred to as a chip side). In the present application, the optical power characterizes the refractive power of the optical system to an incident parallel beam in diopters (Dioptre). The first lens plays a role of adjusting the light ray direction in the system and is suitable for projecting the light ray to the coupling-in area of the waveguide sheet. Wherein the coupling-in region of the waveguide sheet is suitable for being arranged at the emergent end of the first lens. The third lens provides a primary diopter and configures a first lens having a positive diopter, and second and fourth lenses having a weaker diopter. This design allows for greater acceptance of the beam angle of light emitted by the image source device (e.g., self-illuminating image chip) and for a reduction in the exit angle of the image source device corresponding to the central light of the lens to increase the luminous flux of light passing through the projection system.
Further, in some embodiments of the present application, the optical projection lens has a positive power second lens, the projection side of which is convex, and the surface of the chip side of which is concave. The second lens may act as a beam expander in the overall optical system to ensure that the incoupling beam fills the coupling-in area of the entire waveguide without vignetting. The interval between the thickness of the second lens and the interval between the thickness of the fourth lens of the optical projection lens can be used for adjusting and improving the temperature drift performance of an optical system, and the positive and negative focal power lenses of the lens can be mutually compensated in the temperature change process within the range, so that the good image quality can be kept in both high and low temperature environments.
Further, in some embodiments of the present application, the optical projection lens has a positive power third lens, a projection side surface of which is convex, and a chip side surface of which is concave. The third lens is matched with the first lens with positive diopter and the second lens with negative diopter to play a role of beam expansion and is matched with the fourth lens with negative diopter so as to provide more effective light for a large-size coupling-in area of the waveguide plate, and the luminous flux and the projection brightness of projection light information of the emergent end are increased. Fig. 31 is a schematic diagram showing a top view of a waveguide sheet of an AR device according to an embodiment of the present application. Referring to fig. 31, the waveguide sheet generally includes a coupling-in region 110 and a coupling-out region 120, and the light projected by the optical projection lens is coupled into the coupling-in region 110 of the waveguide sheet, and the coupled light is transmitted laterally in the waveguide sheet by one diffraction or multiple reflections, and then enters the coupling-out region 120, and after being coupled out of the waveguide sheet through the coupling-out region 120, the light can be received by human eyes. Generally, the area of the coupling-out region 120 is larger than the area of the coupling-in region 110 in a plan view. The coupling-in region 110 is typically a region having a specific optical function formed after the surface of the waveguide sheet is subjected to a microstructure processing. Only when the light beam projected by the optical projection lens enters the coupling-in region 110, the light beam can be transmitted to the coupling-out region through the waveguide plate and received by human eyes.
Further, in some embodiments of the present application, the optical projection lens has a fourth lens with negative focal power, whose two sides are concave surfaces, and the fourth lens is matched with the third lens with positive focal power, so that aberrations (including spherical aberration and coma aberration) other than chromatic aberration can be balanced better under a certain curvature radius ratio, thereby improving optical performance of the optical projection lens. Meanwhile, the fourth lens is matched with the third lens, so that the application range of the optical projection lens can be expanded, and the optical performance requirements of image source devices with different sizes can be met.
Further, in some embodiments of the application, the aperture of the optical system of the AR device may be placed outside the optical projection lens. Specifically, the first lens, the second lens, the third lens, and the fourth lens of the optical projection lens may be mounted in a barrel, and a diaphragm of an optical system of the optical projection lens may be disposed outside the barrel. In particular, the diaphragm may be arranged in the coupling-in region of the waveguide plate. The design can reduce the influence of vignetting of the coupling-in area of the waveguide sheet on the image information to the greatest extent, thereby improving the contrast, brightness and uniformity of the picture. In this embodiment, the AR device may include a waveguide sheet, an optical projection lens, and a self-luminous chip. The light rays forming the image information output by the self-luminous chip are projected to the coupling-in area of the waveguide sheet through the optical projection lens, and then are transversely transmitted to the coupling-out area of the waveguide sheet based on a diffraction or multiple reflection mechanism, and finally received by human eyes. In this embodiment, the two surfaces of the waveguide sheet may be a plane surface and a functional surface on which a microstructure is formed (the functional surface is sometimes referred to herein as a first surface, and the plane surface as a protective cover is referred to as a second surface). The plane can be supported on the end face of the lens barrel of the optical projection lens, and the functional surface is positioned on the surface deviating from the lens barrel. I.e. the second surface is located between the first surface and the first lens. In this embodiment, the diaphragm may be fabricated on a functional surface of the waveguide sheet, that is, on a surface of the waveguide sheet facing away from the lens barrel. In this embodiment, the coupling-in area of the first surface is formed by a specific microstructure manufactured on the surface of the waveguide sheet, and the area other than the microstructure cannot couple in the projection light, so that the boundary of the coupling-in area formed by the microstructure can be regarded as the light-transmitting hole of the diaphragm. In this embodiment, no aperture is required to be additionally disposed on the optical projection lens itself, for example, the end face of the lens barrel of the optical projection lens may not be disposed with an aperture, so that more light can be coupled into the waveguide sheet, thereby improving the brightness of the projected image.
Further, in some embodiments of the present application, to achieve the above-mentioned beneficial effects, the following relationships are satisfied by a plurality of parameters of the optical element of the optical projection lens: assuming that the focal length of the optical projection lens is f, wherein the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the thickness of the first lens on the optical axis is CT1, the thickness of the second lens on the optical axis is CT2, the distance between the diaphragm and the first lens on the optical axis is ST, the distance between the third lens and the fourth lens on the optical axis is AT3, which satisfies the following conditions: 0.8< f3/f <1.3, |f1+f2+f3+f4|/f >0.15, ST.gtoreq.1 mm, 0.5< (f1+f2+f3)/f <1.5. More preferably, in some preferred embodiments, the following conditions may be further satisfied: 0.25< (CT2+AT3)/f <0.45.
Further, in some embodiments, assuming that the radius of curvature of the surface on the exit side of the second lens is R21, the radius of curvature of the surface on the chip side is R22, the radius of curvature of the surface on the exit side of the third lens is R31, and the radius of curvature of the surface on the chip side of the fourth lens is R42. Which satisfies the following conditions: 1.5< R21/R22<2.5, 0.15< R31/R42<1.5. Further, in some preferred embodiments, the following conditions may be further satisfied: CT1/CT3<1.1.
In accordance with the above embodiments, specific examples are set forth below in conjunction with the drawings.
Wherein, the aspherical curve equation of each lens is expressed as follows:
Wherein:
X: a point on the aspheric surface that is Y from the optical axis, which is a relative distance tangential to the intersection plane on the aspheric surface optical axis;
Y: the perpendicular distance of the point on the aspherical curve from the optical axis;
r: radius of curvature;
k: conical surface coefficient;
Ai: the i-th order aspheric coefficient.
Example 1 ]
In the optical projection lens of embodiment 1, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which is as follows: f=5.78 mm; fno=1.66; fov=30 degrees.
Specific values of the conditions of the optical projection lens of example 1 are as follows:
f3/f＝0.89
|f1+f2+f3+f4|/f＝0.66
(f1+f2+f3)/f＝0.59
(CT2+AT3)/f＝0.36
R21/R22＝1.75
R31/R42＝1.02
CT1/CT3＝1.03
ST＝1mm
More specific optical parameters of the optical projection lens of embodiment 1 and the respective optical elements of the corresponding AR device (which includes a waveguide and an aperture) can be referred to the following table 1 and table 2. In the table, the diaphragm and the diaphragm, the surface 1 represents the diaphragm-provided surface of the waveguide sheet, and the surface 2 represents one surface of the waveguide sheet serving as a Cover Glass (CG for short). In AR devices, an image source device generally has an image source device protective Cover (here, a Cover Glass, abbreviated as CG) and a self-luminous chip. In the table, the surface 11 and the surface 12 represent two surfaces of the protective cover (i.e., glass cover plate) of the image source device, and the surface 13 represents the light emitting surface of the self-luminous chip, respectively. In other tables below, the meaning of each surface is identical to table 1, and will not be described again. In addition, the thickness column in table 1 actually means the distance on the optical axis from the current surface to the next surface. For example, the corresponding thickness of surface 1 refers to the distance between surface 1 and surface 2 on the optical axis. Wherein the optical axis refers to the optical axis of the optical projection lens. In other tables below, the actual meaning of the thickness column is identical to that of table 1, and will not be described again.
TABLE 1
TABLE 2
Table 1 is detailed structural data of example 1 of fig. 1, in which the radius of curvature, thickness and focal length are in mm, and surfaces 1-13 represent surfaces from the object side to the image side in order. Table 2 shows the aspherical data in example 1, wherein K represents the conic coefficient in the aspherical curve equation, and A4-A16 represent the 4 th-16 th order aspherical coefficients of each surface. Further, fig. 1,2,3,4 and 5 show the structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of the optical projection lens according to embodiment 1 of the present application in order. In fig. 1, E1 denotes a waveguide, E2 denotes a first lens, E3 denotes a second lens, E4 denotes a third lens, E5 denotes a fourth lens, E6 denotes an image source device protective cover, and E7 denotes a light emitting surface of a self-light emitting chip. Further, STO represents surfaces 1, S2-13 represent surfaces 2-13, respectively, in Table 1. Hereinafter, fig. 6,7,8, 9 and 10 show the structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of the optical projection lens according to embodiment 2 of the present application in order. The meaning of the reference numerals in fig. 6 may refer to fig. 1 corresponding to embodiment 1, and will not be described again. Further, fig. 11, 12, 13, 14 and 15 show the structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of the optical projection lens according to embodiment 3 of the present application in order; fig. 16, 17, 18, 19 and 20 show the structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of the optical projection lens according to embodiment 4 of the present application in order; fig. 21, 22, 23, 24 and 25 show the structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of the optical projection lens according to embodiment 5 of the present application in order; fig. 26, 27, 28, 29 and 30 show the structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of the optical projection lens according to embodiment 6 of the present application in this order. The meaning of the reference numerals in the above-mentioned optical projection lens structure diagrams may refer to the description of fig. 1, and will not be repeated.
In addition, the definition of the data in each table of each embodiment is the same as that of table 1 and table 2 of embodiment 1, and the description thereof is omitted herein.
Example 2]
In the optical projection lens of embodiment 2, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which is as follows: f=5.84 mm; fno=1.66; fov=30 degrees.
Specific values of the conditions of the optical projection lens of example 2 are as follows:
f3/f＝1.23
|f1+f2+f3+f4|/f＝17.68
(f1+f2+f3)/f＝1.05
(CT2+AT3)/f＝0.28
R21/R22＝1.95
R31/R42＝0.36
CT1/CT3＝1.0
ST＝1mm
More specific optical parameters of the optical projection lens of example 2 and the respective optical elements of the corresponding AR device (which includes the waveguide and the aperture) can be referred to table 3 and table 4 below.
TABLE 3 Table 3
TABLE 4 Table 4
Example 3 ]
In the optical projection lens of embodiment 3, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which is as follows: f=6.0 mm; fno=1.66; fov=30 degrees.
Example 3 the conditional specific values of the optical projection lens are as follows:
f3/f＝0.87
|f1+f2+f3+f4|/f＝0.54
(f1+f2+f3)/f＝0.80
(CT2+AT3)/f＝0.37
R21/R22＝1.84
R31/R42＝0.3
CT1/CT3＝0.99
ST＝1mm
More specific optical parameters of the optical projection lens of example 3 and the respective optical elements of the corresponding AR device (which includes the waveguide and the aperture) can be referred to table 5 and table 6 below.
TABLE 5
TABLE 6
Example 4]
In the optical projection lens of example 4, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which is as follows: f=6.00 mm; fno=1.66; fov=30 degrees.
Example 4 the conditional specific values of the optical projection lens are as follows:
f3/f＝0.82
|f1+f2+f3+f4|/f＝0.28
(f1+f2+f3)/f＝0.79
(CT2+AT3)/f＝0.4
R21/R22＝1.81
R31/R42＝0.28
CT1/CT3＝0.92
ST＝1mm
More specific optical parameters of the optical projection lens of example 4 and the respective optical elements of the corresponding AR device (which includes the waveguide and the aperture) can be referred to table 7 below and table 8 below.
TABLE 7
TABLE 8
Example 5]
In the optical projection lens of embodiment 5, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which is as follows: f=6.08 mm; fno=1.8; fov=30 degrees.
Example 5 the conditional specific values of the optical projection lens are as follows:
f3/f＝0.89
|f1+f2+f3+f4|/f＝0.98
(f1+f2+f3)/f＝0.92
(CT2+AT3)/f＝0.33
R21/R22＝2.22
R31/R42＝0.19
CT1/CT3＝1.04
ST＝1mm
more specific optical parameters of the optical projection lens of example 5 and the respective optical elements of the corresponding AR device (which includes the waveguide and the aperture) can be referred to the following table 9 and table 10.
TABLE 9
Table 10
Example 6]
In the optical projection lens of example 6, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which is as follows: f=5.9 mm; fno=1.56; fov=30 degrees.
Example 6 the specific values of the conditions for the optical projection lens are as follows:
f3/f＝0.84
|f1+f2+f3+f4|/f＝0.18
(f1+f2+f3)/f＝0.76
(CT2+AT3)/f＝0.41
R21/R22＝1.79
R31/R42＝0.35
CT1/CT3＝1.0
ST＝1mm
More specific optical parameters of the optical projection lens of example 6 and the respective optical elements of the corresponding AR device (which includes the waveguide and the aperture) can be referred to the following table 11 and table 12.
TABLE 11
Table 12
Given the above specific examples of the optical designs of 6 specific optical lens shots and corresponding AR devices, table 13 below further shows the values of these 6 examples under various conditional expressions.
TABLE 13
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the appended claims.