US20050052755A1 - Dual-band lens - Google Patents

Abstract

A single lens or optical system is used to image two different optical bands, for example visible and infrared, with the same possible adjustments in zoom and/or focus. A dual band singlet is formed of a first, larger, optical element, suitable for operating on light of a first optical band, with an aperture cut out of it. A smaller element, suitable for operating on light of a second optical band, is secured in, or on either side of, the aperture cut through the larger optical element, thus forming a dual band singlet that can operate on two different wavelength bands. Combinations of dual band lenses, lens elements, and lenses with cut-out apertures are used to form dual-band optical systems, including systems with dual-band focus and zoom.

Description

FIELD OF THE INVENTION
• 1. Field
• Embodiments relate to the field of optics and in particular to imaging lenses.
• 2. Related Art
• Different cameras, sensitive to different optical wavelength bands, are commercially available for a variety of applications. For example, visible cameras and infrared cameras are used in industrial, security, and rescue applications. Infrared and Ultraviolet cameras are used in fire detection. It can be advantageous to have two different cameras, sensitive to two different wavelength bands, observe the same scene. For example, a visible camera could be combined with an infrared camera. The visible camera would show a typical image of a scene, so that an operator could see normally. Meanwhile, the infrared camera would show the operator where there were hot-spots.
• One approach to providing dual waveband viewing is to mount two separate cameras on a common base. Another approach is to use a shared reflective optical system, because reflective systems can typically process light of many different wavelengths. After passing through the reflective system, the light from each band is separated and directed to its own imaging device. However, there are problems with both approaches.
• When two separate cameras are mounted on a common base, they do not view objects along the same optical axis. Therefore, there is parallax between the two cameras; objects don't line up identically in the two cameras at all field distances. An exception is the case where there is a common aperture, and a beam-splitter is used to direct light of each wavelength band to each camera. However, as aperture increases, a larger and larger beam-splitter is required. As beam-splitter size increases, so does cost and difficulty of manufacture.
• Further, if the two cameras have adjustable focus or zoom, matching focus or zoom changes between the two separate systems can be difficult. Typical zoom or focus settings on cameras are not precisely metered or calibrated. Therefore, it is likely that the two cameras might focus at different object distances or have different magnification (different image size for the same object). This could make it difficult to recombine the images on a single display, or perform data fusion or other image processing. Two separate systems also have more mass and take up more space than a single camera.
• When a reflective lens is used, multiple wavelengths can be imaged simultaneously through the same reflective optics. However, reflective systems are difficult to focus by element motion, typically take up more space than refractive systems, and are difficult to design with zoom features.
• Therefore, what is needed is a refractive lens system which can image scenes in two differing wavelength bands, through the same aperture, and which can provide focus and zoom capability for both wavelength bands with the same adjustments.
SUMMARY OF THE INVENTION
• Embodiments include a lens formed of two lens elements: a smaller lens element fixed within an aperture cut through a larger lens element. In some embodiments, a lens is formed of an infrared lens element and a visible lens element. Embodiments include optical systems that contain dual wavelength lenses, so that a single optical system can image the same scene in two different optical wavelength bands through the same aperture. Embodiments include systems with common zoom and focus groups, capable of imaging in dual wavelength bands (for example visible and infrared, visible and UV, UV and infrared, two infrared bands) simultaneously.
BRIEF DESCRIPTION OF THE ILLUSTRATIONS
• FIG. 1A andFIG. 1B are plan and axial views of a single dual-band lens, according to the present invention.
• FIG. 2 is a plan view of a complex dual-band lens, according to the present invention.
• FIG. 3 is a plan view of a dual band lens with a focus group, according to the present invention.
• FIG. 4A is a plan view of a dual band zoom lens, according to the present invention.
• FIG. 4B-FIG. 4I are diagrams that illustrate the motions of infrared and visible subsystems in a dual band lens, according to the present invention.
• FIG. 5 is a plan view of a dual wavelength camera, according to the present invention.
DESCRIPTION
• FIG. 1A andFIG. 1B are plan and axial views of a single dual-band lens, according to the present invention. The dual bands may be any optical bands (e.g., near-infrared, mid-infrared, long-infrared, very-long-infrared, visible, ultraviolet). Dual-band lens110 is formed offirst lens element120, which is constructed of a refractive optical material. In some embodiments, for example, where infrared light is to be imaged,lens element120 is formed of a suitable infrared lens material (e.g., Ge, Si, ZnSe, CaF2) that transmits and refracts infrared light. In some embodiments,lens element120 is formed of a suitable visible lens material (e.g., BK7, F2) that transmits and refracts visible light, or another wavelength-appropriate material, depending on the wavelength band for which imaging is to be performed.
• Lens element120 is formed withsub-aperture122 cut out.Sub-aperture122 may be formed during casting of the lens, drilled out of the substrate, or any other process. In some embodiments,sub-aperture122 is circular and concentric withlens element120. In some embodiments, undesired light is excluded by coating123 onlens element120, by the spectral transmittance properties of the material of whichlens element120 is formed, or other means, such as a filter placed in front oflens element120.
• Wavelengths of light for whichlens element120 is designed, travel along paths represented byray path124, through aperture-portion125. The light is refracted (focused) bylens element120 and proceeds alongray path126 to focuspoint128, which may be an image.
• Lens element130 is shown fixed insub-aperture122. However,lens element130 could also be disposed on either side ofsub-aperture122.Lens element130 is formed of a refractive optical material, appropriate for a second optical wavelength band. Undesired wavelengths of light can be excluded by appropriate wavelength-selective coating133, the material oflens element130, a filter earlier in the optical path, or any other method.
• Light suitable to refraction bylens element130 travels alongray path134 and is focused alongray path136 towardsfocus138. In some embodiments,lens element130 andlens element120 have the same focal length so thatfocus138 is at the same point asfocus128 onoptical axis140. Thus,portion125 of the aperture ofdual lens110 is occupied bylens element120 and another aperture-portion, defined bysub-aperture122, is occupied bylens element130.
• In some embodiments,dual lens110 may be attached to focusmechanism150, which can movelens110 alongdirection152, in order to movepositions128 and138 alongoptical axis140, adjusting the focus.
• FIG. 1B is an axial view oflens110, includinglens element120, sub-aperture122,lens element130, andoptical axis140. In some embodiments,lens elements120 and130 are circular and concentric. In some embodiments, sub-apertures such assub-aperture122 are not circular (e.g., rectangular, oval), and are not necessarily concentric with lens elements such aslens element120.
• FIG. 2 is a plan view of complex dual-band lens200.Dual band lens200 includesoptical subsystem210 andoptical subsystem220.Optical subsystem210 is a doublet, formed oflens element211 andlens element212.Sub-aperture213 is cut-throughoptical system210. Incoming light travels alongray path214, is refracted byoptical subsystem210, and converges along paths represented byray path216, to focus218. Of course,optical sub-systems210 and220 could be of any optical system forms, including systems with several lenses.Optical subsystems210 and220 could have finite objects, be afocal, or have any desired optical functions.
• Optical subsystem220 includeslens elements221,222, and223.Optical subsystem220 fits substantially withinsub-aperture213. Light travels alongray path224, and converges alongray path226 to focus228. Ifoptical systems210 and220 have the same focal length, then focus218 and focus228 are at the same point alongoptical axis240. However, in some embodiments, optical subsystems have different focal lengths, are shapes other than circular (e.g. square, oval), or may be eccentric (rather than concentric).
• Optical subsystem210 andoptical subsystem220 are designed to accept and operate on light of different wavelengths, so thatimages218 and228 are formed of light from different wavelength bands.
• FIG. 3 is a plan view of a dual band lens, according to the present invention. Inlens300,lens elements310,312,314, and316, formoptical subsystem317, suitable for imaging light of one wavelength band, for example an infrared band. Light enters alongray path320 and converges to image322 onoptical axis360.Image recording device318, for example a focal plane or film, receivesimage318.Lens elements310 and312 have cut-outsub-apertures311 and313.
• Lens elements330,332,334, and336 formoptical subsystem337, suitable for imaging light a second wavelength band, for example a visible band.Lens element330 is fixed inside the sub-aperture oflens element310 andlens elements334 and336 are fixed in the sub-aperture of lens element312. Light travels alongray path342, is brought out fromoptical axis360 by fold element338 (e.g., mirror, prism), and focuses atimage344.Image recording device340 is placed to receiveimage344.
• In some embodiments, other configurations are used to reachimage344. In some embodiments,image344 is formed onoptical axis360, andimaging device340 is placed onoptical axis360, similar to the elements ofoptical system337. In some embodiments, one imaging device records both optical bands. Many different fold configurations can be used todirect image344 orimage322 to different paths or locations.
• It can be seen thatlens elements314 and316 are not cut-out. Also, it can be seen thatelement332 is not secured within a sub-aperture. Thus, many different element types or elements placed in different locations can be used to form a dual band system, according to the present invention.
• Lens elements310 and330form focusing element346. Focusingmechanism348, which can be any of a number of electronic or mechanical devices (e.g., motor, cam, screw), moveselement346 alongpath350 to adjust the focus of bothimages322 and344 at the same time. Because one motion focuses light along bothpaths320 and342 at the same time and by the same amount, changes in object distance can be corrected for bothoptical subsystems317 and337. Becausesubsystems317 and337 are coaxial, there is no parallax.
• TABLE1A through TABLE1B contain a prescription (performed on the ZEMAX lens design software of Focus Software of Tucson, Ariz.) for an embodiment of a dual infrared and visible optical system, according to the present invention.Optical subsystem317, having the larger aperture, is the infrared subsystem, described in TABLE1A and TABLE1B. Making the infraredoptical subsystem317 with the larger portion of the aperture can help with diffraction blur, which is worse in the longer wavelengths of the infrared. Of course, this effect also depends on the diameter ofsubsystem337. The visible elements are described in TABLE1C. TABLE1D describes possible focus positions from infinity to near-focus.

  TABLE 1A
  IR
  SURFACE
  DATA
  Surf	Type	Radius (mm)	Thick (mm)	Glass	Dia (mm)	Conic

  OBJ	STD	Infinity	Infinity		0	0
  1	STD	Infinity	50		61.16146	0
  2	STD	63.42498	6	AMTIR4	50.90581	−0.7739041
  3	STD	750.2383	10		50.1996	0
  4	STD	−49.07076	4.5	AMTIR4	41.75451	0
  STO	BIN_2	−86.2833	27.60546		42.75661	6.517522
  6	STD	21.78942	5	AMTIR4	21.75929	0
  7	STD	23.31248	11.76972		18.13065	1.586647
  8	STD	Infinity		1	GE_LONG	11.01212	0
  9	STD	Infinity	0		10.84075	0
  IMA	STD	Infinity	10.84075		0

• 	TABLE 1B
  	SURFACE DATA DETAIL

  	Surface STO:	BINARY_2
  	Diffract Order:	1
  	Coeff on r 2:	0
  	Coeff on r 4:	−2.9405054e−006
  	Coeff on r 6:	2.0090442e−009
  	Coeff on r 8:	6.3599093e−014
  	Coeff on r 10:	1.9619292e−015
  	Maximum term:	4
  	Maximum rad ap:	28
  	Term on P to 2:	−71.430552
  	Term on P to 4:	−194.74879
  	Term on P to 6:	744.14389
  	Term on P to 8:	−685.68238

• TABLE 1C
  Visible
  SURFACE DATA
  Surf	Type	Radius (mm)	Thick (mm)	Glass	Dia (mm)	Conic
  OBJ	STD	Infinity	6.8e+009		1.4959e+9	0
  1	STD	36.79642	1.36	F2	12	0
  2	STD	388.6092	8.5		12	0
  STO	STD	−17.34062	0.68	FK5	9	0
  4	STD	16.56215	6.084034		9	0
  5	STD	−933.3208	3.4	SK5	12	0
  6	STD	−8.625559	3.4	SF11	12	0
  7	STD	−17.53535	0.1		12	0
  8	STD	47.34954	3	BK7	12	0
  9	STD	−22.6334	1		12	0
  10	STD	Infinity	6.35	BK7	12.7	0
  11	CDBRK	—		0	—	—
  12	STD	Infinity	0	MIRROR	17.96051	0
  13	CBRK	—	−6.35		—	—
  14	STD	Infinity	−23.55		12.7	0
  IMA	STD	Infinity			5.814062	0

• 	TABLE 1D
  	MULTI-CONFIGURATION
  	DATA:

  	Configuration 1:
  	1 Thickness 0:	1e+010
  	2 Thickness 3:	10
  	Configuration 2:
  	1 Thickness 0:	3000
  	2 Thickness 3:	10.58457 Variable
  	Configuration 3:
  	1 Thickness 0:	1000
  	2 Thickness 3:	11.80299 Variable

• FIG. 4A is a plan view of a dual band zoom lens, according to the present invention. A zoom lens typically consists of a focus group, a zoom group, a variator group, and a fixed group. Dualwavelength zoom lens400 includesfocus group410,variator group420,compensator group430, and fixedlenses442,444, and445.
• In some embodiments,lens400 images visible and infrared light. In such an embodiment,focus group410 is made up ofinfrared element412 and a visible doublet formed ofelements414 and415;variator group420 is made up ofinfrared element422 and a visible doublet formed ofelements424 and425;compensator group430 is made up ofinfrared element432 and a visible doublet formed ofelements434 and435. In some embodiments,reflective element440 is used to bend the visible optical path away from originaloptical axis402, thus providing physical access to the visible optical path, separate from the infrared optical path.Element442 is a fixed group for the infrared channel andelements444 and445 form a visible doublet fixed group for the visible channel. Thus, motion ofgroup410 controls focus, motion ofgroup420 controls focal length, motion ofgroup430 compensates for motion ofgroup420, andfixed elements442,444, and445 complete the imaging sub-systems. Motions of the focus, variator, and compensator groups in a zoom lens are typically accomplished by rotating cams or individual motors.
• Infrared light travels along an infrared optical path, through an optical subsystem formed ofelements412,422,432, and442, coming to a focus atpoint443. Visible light travels along a visible optical path, through an optical subsystem formed ofelements414,415,424,425,434,435,444, and445, and comes to a focus atpoint446. A portion of the infrared lens elements,elements412,422, and432, have central apertures, near to which a portion of thevisible elements414,415,424,425,434, and435 have been fixed. Those skilled in the art will recognize thatFIG. 4A is illustrative of many possible designs, and that additional fixed or moving lens elements can be added to, or elements can be modified in, either or both the infrared or visible channel, to adjust the optical properties oflens400.
• TABLE 2A is a prescription for the infrared subsystem of an embodiment oflens400, as described by the ZEMAX optical design software of Focus Software of Tucson, Ariz. TABLE 2B is a prescription for the visible subsystem of an embodiment oflens400.

  TABLE 2A
  Surf	Type	Radius	Thick	Glass	Dia (mm)	Conic

  OBJ	STANDARD	Infinity	Infinity
  1	STANDARD	72.68131	6	AMTIR4	52	1.081439
  2	BINARY_2	2847.093	1		52
  3	STANDARD	Infinity	1.893045		28.30202
  4	STANDARD	−46.08221	2.4	AMTIR4	30	−6.43137
  5	BINARY_2	53.02568	17.95646		30	−1.562856
  6	STANDARD	45.52305	5	AMTIR4	42	−4.07756
  7	BINARY_2	214.604	8.951938		42	−2.800258
  STO	STANDARD	Infinity	19.3061		36.48307
  9	EVENASPH	50.59115	4	AMTIR4	37	−1.510571
  10	BINARY_2	669.0731	25.14		37
  11	STANDARD	Infinity		1	GE_LONG	11.75859
  12	STANDARD	Infinity	0.5		11.5516
  IMA	STANDARD	Infinity			11.09906

• TABLE 2B
  Surf	Type	Radius (in)	Thickness (in)	Glass	Diameter (in)	Conic
  OBJ	STD	Infinity	3.937008e+8		2.16443e+8	0
  1	STD	0.9536221	0.03937008	F2	0.6299213	0
  2	STD	0.4923513	0.1968504	BK7	0.6299213	0
  3	STD	−3.961359	0.03937008		0.6299213	0
  4	STD	Infinity	0.07452756		0	0
  5	STD	−0.7321447	0.05511811	SF6	0.4724409	0
  6	STD	−0.3410998	0.03937008	LAKN12	0.4724409	0
  7	STD	0.6637404	0.7069472		0.4724409	0
  STO	STD	0.9835458	0.03937008	LAF2	0.3937008	0
  9	STD	0.3407645	0.1574803	SK4	0.3937008	0
  10	STD	−2.749945	0.1949031		0.3937008	0
  11	STD	Infinity	0		0	0
  12	STD	1.683481	0.07874016	SF57	0.4724409	0
  13	STD	0.5892404	0.04897531		0.4724409	0
  14	STD	0.7205954	0.1574803	LAKN12	0.4724409	0
  15	STD	−0.7043201	0.1574803		0.4724409	0
  16	CBRK	—	0	—	—	—
  17	STD	Infinity	0	MIRROR	0.5497474	0
  18	CBRK	—	−0.8267717	—	—	—
  IMA	STD	Infinity			0.3287124	0

• 	TABLE 3
  	Aperture:	Circular Aperture
  	Minimum Radius:	0
  	Maximum Radius:	25.2 mm
  	Surface 2:	BINARY_2
  	Diffract Order:	1
  	Coeff on r 2:	0
  	Coeff on r 4:	8.6438078e−007
  	Coeff on r 6:	−1.1018959e−010
  	Maximum term:	1
  	Maximum rad ap:	26 mm
  	Term on P to 2:	−47.916994
  	Aperture:	Floating Aperture
  	Maximum Radius:	26 mm
  	Aperture:	Circular Aperture
  	Minimum Radius:	0
  	Maximum Radius:	14.2 mm
  	Surface 5:	BINARY_2
  	Diffract Order:	1
  	Coeff on r 2:	0
  	Coeff on r 4:	−2.0200256e−006
  	Coeff on r 6:	6.5985686e−010
  	Maximum term:	1
  	Maximum rad ap:	15
  	Term on P to 2:	39.46
  	Aperture:	Floating Aperture
  	Maximum Radius:	15
  	Surface 7:	BINARY_2
  	Diffract Order:	1
  	Coeff on r 2:	0
  	Coeff on r 4:	−2.0632414e−006
  	Coeff on r 6:	1.8567942e−009
  	Maximum term:	1
  	Maximum rad ap:	21
  	Term on P to 2:	−34.195207
  	Aperture:	Floating Aperture
  	Maximum Radius:	21
  	Surface 9:	EVENASPH
  	Coeff on r 2:	0
  	Coeff on r 4:	−7.3770432e−006
  	Coeff on r 6:	−1.3774416e−008
  	Aperture:	Circular Aperture
  	Minimum Radius:	0
  	Maximum Radius:	17.6
  	Surface 10:	BINARY_2
  	Diffract Order:	1
  	Coeff on r 2:	0
  	Coeff on r 4:	−7.4626349e−006
  	Coeff on r 6:	−8.4132712e−009
  	Coeff on r 8:	0
  	Maximum term:	1
  	Maximum rad ap:	18.5
  	Term on P to 2:	−30.9673
  	Aperture:	Floating Aperture
  	Maximum Radius:	18.5

• FIG. 4B-FIG. 4E illustrate the motion ofinfrared subsystem elements412,422, and432, relative to fixedelement442, through zoom. TABLE 4A describes the zoom motions of the infrared subsystem withinlens400, as shown inFIG. 4B-FIG. 4E.Configurations 1 through 4 in TABLE 4A correspond toFIG. 4B throughFIG. 4E.

  TABLE 4A
  MULTI-CONFIGURATION
  DATA:

  Configuration 1:
  1 Stop Surf:	8
  2 Aperture (mm):	25
  3 Thickness (mm):	1.176e+010
  4 Field vdy 2:	−0.01516838
  5 Field vcy 2:	0.01517066
  6 Field vdy 3:	−0.007223461
  7 Field vcy 3:	0.07068578
  8 Y-field 2:	10.76
  9 Y-field 3:	15.37
  10 Thickness 2:	1
  11 Thickness 3:	1.893045 Variable
  12 Thickness 5:	17.95646 Variable
  13 Thi So P2 7:	36.20144 Variable
  Configuration 2:
  1 Stop Surf:	8
  2 Aperture:	42
  3 Thickness 0:	1.176e+010
  4 Field vdy 2:	0.02730892
  5 Field vcy 2:	0.06378812
  6 Field vdy 3:	0.04207523
  7 Field vcy 3:	0.1277079
  8 Y-field 2:	6.251
  9 Y-field 3:	8.93
  10 Thickness 2:	1 Pick up from configuration 1,
  	operand 10, scale 1, offset 0
  11 Thickness 3:	12.15629 Variable
  12 Thickness 5:	11.89784 Variable
  13 Thi So P2 7:	36.20144 Pick up from configuration 1,
  	operand 13, scale 1, offset 0
  Configuration 3:	1 Stop Surf: 1
  2 Aperture:	50
  3 Thickness 0:	1.176e+010
  4 Field vdy 2:	−0.05037608
  5 Field vcy 2:	0.05038193
  6 Field vdy 3:	−0.06996329
  7 Field vcy 3:	0.0699695
  8 Y-field 2:	3.666
  9 Y-field 3:	5.237
  10 Thickness 2:	1 Pick up from configuration 1,
  	operand 10, scale 1, offset 0
  11 Thickness 3:	17.84855 Variable
  12 Thickness 5:	2
  13 Thi So P2 7:	36.20144 Pick up from configuration 1,
  	operand 13, scale 1, offset 0
  Configuration 4:
  1 Stop Surf:	1
  2 Aperture:	50
  3 Thickness 0:	600
  4 Field vdy 2:	−0.0212013
  5 Field vcy 2:	0.02120325
  6 Field vdy 3:	−0.04582351
  7 Field vcy 3:	0.04582863
  8 Y-field 2:	3.666
  9 Y-field 3:	5.237
  10 Thickness 2:	4.592189 Variable
  11 Thickness 3:	17.84855 Pick up from configuration 3,
  	operand 11, scale 1, offset 0
  12 Thickness 5:	2 Pick up from configuration 3,
  	operand 12, scale 1, offset 0
  13 Thi So P2 7:	36.20144 Pick up from configuration 1,
  	operand 13, scale 1, offset 0

• FIG. 4F-FIG. 4I illustrate the motions ofvisible subsystem elements414,415,424,425,434, and435, relative tofixed elements444 and445, indual band lens400. TABLE 4B describes the zoom motions of the infrared subsystem withinlens400.Configurations 1 through 4 in TABLE 4B correspond toFIG. 4F throughFIG. 41. In some embodiments, the motions of the corresponding visible and infrared elements will be the same, in order to provide the same zoom and focus changes to both the visible and infrared channels.

  	TABLE 4B
  	Configuration 1:
  	1 Stop Surf:	8
  	2 Aperture:	0.1968504
  	3 Thickness 0:	3.937008e+008
  	4 Field vdy 2:	−0.02025824
  	5 Field vdy 3:	−0.002123443
  	6 Field vcy 2:	0.02025998
  	7 Field vcy 3:	0.1714582
  	8 Y-field 2:	10.76
  	9 Y-field 3:	15.37
  	10 Thickness 3:	0.03937008
  	11 Thickness 4:	0.07452756
  	12 Thickness 7:	0.7069472
  	Configuration 2:
  	1 Stop Surf:	8
  	2 Aperture:	0.3228346
  	3 Thickness 0:	3.937008e+008
  	4 Field vdy 2:	0.1880455
  	5 Field vdy 3:	0.4631203
  	6 Field vcy 2:	0.1880653
  	7 Field vcy 3:	0.4897827
  	8 Y-field 2:	6.251
  	9 Y-field 3:	8.93
  	10 Thickness 3:	0.03937008
  	11 Thickness 4:	0.4785941
  	12 Thickness 7:	0.4684189
  	Configuration 3:
  	1 Stop Surf:	5
  	2 Aperture:	0.4724409
  	3 Thickness 0:	3.937008e+008
  	4 Field vdy 2:	0.0624353
  	5 Field vdy 3:	0.04725005
  	6 Field vcy 2:	0.06244235
  	7 Field vcy 3:	0.2760152
  	8 Y-field 2:	3.66
  	9 Y-field 3:	5.237
  	10 Thickness 3:	0.03937008
  	11 Thickness 4:	0.7026988
  	12 Thickness 7:	0.07874016
  	Configuration 4:
  	1 Stop Surf:	5
  	2 Aperture:	0.5905512
  	3 Thickness 0:	23.62205
  	4 Field vdy 2:	0.1297347
  	5 Field vdy 3:	0.09582019
  	6 Field vcy 2:	0.2561988
  	7 Field vcy 3:	0.5318
  	8 Y-field 2:	3.66
  	9 Y-field 3:	5.237
  	10 Thickness 3:	0.1807949
  	11 Thickness 4:	0.7026988
  	12 Thickness 7:	0.07874016

• FIG. 5 is a plan view of an embodiment of a dual wavelength camera, according to the present invention.Lens elements502,504,506, and508 image light of a first wavelength band (e.g., thermal infrared), formingimage509 on imaging device510 (e.g., an infrared focal plane array). Embodiments can, of course, incorporate many optical forms. Signals fromimaging device510 are processed bycard512. Processing can also be accomplished by many other electronic configurations, or (for example) electronics built into the focal plane.
• Lens elements514,516, and518, and fold520 image light of a second wavelength band (e.g., visible), formingimage521 on imaging device522 (e.g., CMOS imager, CCD). Signals fromimaging device522 are processed bycard524. Processing can also be accomplished by many other electronic configurations, or (for example) electronics built into the focal plane
• Lens elements502 and514 are moved alongdirection526 byfocus drive528, operated byswitch530, to focus objects inscene532. A manual focus system could also be employed, or switch530 could represent an auto-focus control. An image ofscene532 in either or both optical wavelength bands is projected by display534 (e.g., LCD display, CRT) througheyepiece536 for viewing byoperator538.Camera500 is contained incase540.
• Mechanism528 focuses bothimages521 and509 at the same time and by the same amount. Thus, if bothimages509 and521 are displayed ondisplay534, they will remain the same size and quality as focus is adjusted. The same objects inscene532 will be in-focus in both optical wavelength bands. Whilelens300 ofFIG. 3 is shown inFIG. 5,lens400 fromFIG. 4, or any other configuration of dual band lens could be used incamera500.
• Thus, a single, refractive optical system can image two wavelength bands through the same aperture, compressing required space and avoiding parallax. Such an optical system can also focus or zoom images in two different wavelength bands the same amount at the same time. Thus, images in two wavelength bands can be kept at constant magnification and identical focus positions, facilitating common viewing, data processing such as data-fusion, recording, or other use of a scene, in both wavelength bands.
• While various embodiments of the invention have been described, it should be understood that they have been presented by way of example and not limitation. Those skilled in the art will understand that various changes in forms or details may be made without departing from the spirit of the invention. Thus, the above description does not limit the breadth and scope of the invention as set forth in the following claims.

Claims (26)

1-8. (Cancelled)

9. A dual optical system, comprising:

a first optical subsystem, comprising a first plurality of lenses, wherein, a portion of the first plurality of lenses comprise cut-out sub-apertures and remaining apertures; and

a second optical subsystem, comprising a second plurality of lenses; wherein, a portion of the second set of lenses are positioned within the cut-out sub-apertures of the first set of lenses,

wherein, the first optical subsystem transmits a first band of optical wavelengths through the remaining apertures, and the second optical subsystem transmits a second band of optical wavelengths not transmitted by the first optical subsystem.

10. The dual optical system ofclaim 9, wherein the first optical subsystem and the second optical subsystem are refractive.

11. The dual optical system ofclaim 10, wherein the first set of lenses, the second set of lenses, and the sub-apertures are circular.

12. The dual optical system ofclaim 11, wherein a portion of the first set of lenses and a portion of the second set of lenses are disposed along a common optical axis.

13. The dual optical system ofclaim 12, wherein the first optical subsystem is capable of producing a first image and the second optical subsystem is capable of producing a second image.

14. The dual optical system ofclaim 13, wherein the first optical subsystem comprises a first subsystem focus group, the second optical subsystem comprises a second subsystem focus group, and wherein the dual optical system further comprises a first focus mechanism, attached to and capable of moving the first and second sub-system focus groups.

15. The dual optical system ofclaim 14, wherein the first band of optical wavelengths is an infrared band, and the second band of optical wavelengths is a visible band.

16. The dual optical system ofclaim 10, wherein the first optical system comprises a first subsystem focus group, the second optical subsystem comprises a second subsystem focus group, and the dual optical system further comprises a first focus mechanism, attached to and capable of moving the first and second sub-system focus groups.

17. The dual optical system ofclaim 16, wherein the first band of optical wavelengths is an infrared band, and the second band of optical wavelengths is a visible band.

18. The dual optical system ofclaim 9, further comprising:

a focus element, the focus element comprising:

a first lens, capable of refracting light of a first band of optical wavelengths, and having an aperture cut through it; and

a second lens, capable of refracting light of a second band of optical wavelengths, fixed in the aperture of the first lens; and

a focus mechanism, attached to the focus element, capable of moving the focus element.

19. The dual optical system ofclaim 18, wherein the first optical subsystem is capable of producing a first image formed of light from the first optical wavelength band, and the second optical subsystem is capable of producing a second image from light of the second optical wavelength band, and wherein motion of the focus element adjusts the focus of both the first image and second image.

20. The dual optical system ofclaim 19, wherein the optical system is receptive of light along a common light path, and further comprising:

a first output light path;

a second output light path; and

a fold element, capable of directing a portion of light of the first optical band along a first output light path,

and wherein light of the second optical band exits along a second output light path.

21. The dual optical system ofclaim 20, wherein the first band of optical wavelengths is an infrared band, and the second band of optical wavelengths is a visible band.

22. The dual optical system ofclaim 20, further comprising:

a first recording means, for recording the first image positioned in the first output path; and

a second recording means, for recording the second image positioned in the second output path.

23. The dual optical system ofclaim 22, further comprising display means, for displaying the first image and/or the second image to an operator.

24. (Currently amended) The dual optical system ofclaim 23, wherein the first band of optical wavelengths is an infrared band, and the second band of optical wavelengths is a visible band.

25. A dual optical system, comprising:

a first optical subsystem, comprising a first set of lenses, wherein, a portion of the first set of lenses comprise cut-out sub-apertures; and

a second optical subsystem, comprising a second set of lenses;

wherein, a portion of the second set of lenses are positioned within the sub-apertures of the first set of lenses, wherein

the first optical subsystem further comprises a first variator group and a first compensator group, and

wherein the second optical subsystem further comprises a second variator group in contact with the first variator group and a second compensator group in contact with the first compensator group, and

wherein the dual optical system further comprises a zoom mechanism, capable of moving the first and second variator groups and the first and second compensator groups.

26-27. (Cancelled)

28. A dual band optical system, comprising:

a first imaging means, receptive of light of a first wavelength band, for forming a first image, and having a first annular aperture;

a second imaging means, receptive of light of a second wavelength band, for forming a second image, and having a second aperture, wherein the second aperture is contained within the first aperture; and

a focusing means, for adjusting focus of the first image and the second image, simultaneously.

29. A dual band lens, having a visible optical path and an infrared optical path, comprising:

a dual-band focus group, comprising

an annular first infrared lens element having an inner radius, and

a circular first visible lens element, located within the inner radius of the annular infrared lens element;

a fixed infrared imaging group, comprising a plurality of fixed infrared lens elements; and

a fixed visible imaging group, comprising a plurality of fixed visible lens elements;

wherein, the dual band focus group and the fixed infrared imaging group are placed along the infrared optical path, and wherein the dual and focus group and the fixed visible imaging group are placed along the visible optical path.

30. The dual band lens ofclaim 29, wherein a portion of the plurality of fixed infrared lens elements comprise cut-out sub-apertures, and wherein a portion of the visible optical path passes through the cut out sub-apertures.

31. A dual band lens, having a visible optical path and an infrared optical path, comprising:

a dual-band focus group, comprising

an annular first infrared lens element having an inner radius, and

a circular first visible lens element, located within the inner radius of the annular infrared lens element:

a fixed infrared imaging group, comprising a plurality of fixed infrared lens elements: and a fixed visible imaging group, comprising a plurality of fixed visible lens elements:

wherein, the dual band focus group and the fixed infrared imaging group are placed along the infrared optical path, and wherein the dual and focus group and the fixed visible imaging group are placed alone the visible optical path,

wherein a portion of the plurality of fixed infrared lens elements comprise cut-out sub-apertures, and wherein a portion of the visible optical path passes through the cut out sub-apertures, further comprising:

a dual-band variator group, comprising an infrared variator element positioned along the infrared optical path and a visible variator element positioned along the visible optical path, in contact with the infrared variator element;

a dual-band compensator group, comprising an infrared compenstator element positioned along the infrared optical path and a visible compensator element positioned along the visible optical path, in contact with the infrared compensator element; and

a zoom mechanism, in contact with the dual band variator group and the dual band compensator group, capable of zooming the dual band lens.

32. The dual lens ofclaim 31, wherein,

the dual-band focus group first infrared lens element has a first radius of curvature of approximately 73 mm, a second radius of curvature of approximately 2847 mm, a thickness of approximately 6 mm, a diameter of approximately 52 mm, and is formed of AMTIR4;

the dual-band focus group first visible lens element is a cemented doublet, having a first radius of curvature of approximately 0.95 inches, a second radius of approximately 0.49 inches a first thickness of approximately 10.04 inches of F2, a second thickness of approximately 0.2 inches of BK7, and a diameter of approximately 0.63 inches;

the infrared variator element has a first radius of curvature of approximately −46 mm, a second radius of approximately 53 mm, a thickness of approximately 2.4 mm, a diameter of approximately 30 mm and is formed of AMTIR4;

the visible variator element is a cemented doublet, having a first radius of curvature of approximately −0.73 inches, a second radius of approximately 0.04 inches a first thickness of approximately 0.06 inches of SF6, a second thickness of approximately 0.04 inches of LAKN12, and a diameter of approximately 0.47 inches;

the infrared compensator element has a first radius of curvature of approximately 46 mm, a second radius of approximately 214 mm, a thickness of approximately 4 mm, a diameter of approximately 42 mm, and is formed of AMTIR4;

the visible compensator element is a cemented doublet, having a first radius of curvature of approximately 0.98 inches, a second radius of approximately 0.34 inches a first thickness of approximately 0.04 inches of LAF2, a second thickness of approximately 0.06 inches of SK4, and a diameter of approximately 0.39 inches;

the plurality of fixed infrared lens elements comprises:

a first lens, having a first radius of curvature of approximately 51 mm, a second radius of approximately 669 mm, a thickness of approximately 4 mm, a diameter of approximately 37 mm, formed of AMTIR4; and

a second lens, having a first radius of curvature of approximately infinity, a second radius of approximately infinity, a thickness of approximately 1 mm, a diameter of approximately 12 mm, formed of GE_LONG; and,

the plurality of fixed visible lens elements comprises:

a first lens, having a first radius of curvature of approximately 1.68 inches, a second radius of approximately 0.59 inches, a thickness of approximately 0.08 inches, a diameter of approximately 0.47 inches, formed of SF57; and

a second lens, having a first radius of curvature of approximately 0.72 inches, a second radius of approximately −0.7 inches, a thickness of approximately 0.16 inches, a diameter of approximately 0.47 inches, formed of LAKN12.

33. The dual lens ofclaim 25, wherein,

the dual-band focus group first infrared lens element has a first radius of curvature of approximately 73 mm, a second radius of curvature of approximately 2847 mm, a thickness of approximately 6 mm, a diameter of approximately 52 mm, and is formed of AMTIR4;

the dual-band focus group first visible lens element is a cemented doublet, having a first radius of curvature of approximately 0.95 inches, a second radius of approximately 0.49 inches a first thickness of approximately 10.04 inches of F2, a second thickness of approximately 0.2 inches of BK7, and a diameter of approximately 0.63 inches;

the infrared variator element has a first radius of curvature of approximately −46 mm, a second radius of approximately 53 mm, a thickness of approximately 2.4 mm, a diameter of approximately 30 mm and is formed of AMTIR4;

the visible variator element is a cemented doublet, having a first radius of curvature of approximately −0.73 inches, a second radius of approximately 0.04 inches a first thickness of approximately 0.06 inches of SF6, a second thickness of approximately 0.04 inches of LAKN12, and a diameter of approximately 0.47 inches;

the infrared compensator element has a first radius of curvature of approximately 46 mm, a second radius of approximately 214 mm, a thickness of approximately 4 mm, a diameter of approximately 42 mm, and is formed of AMTIR4;

the visible compensator element is a cemented doublet, having a first radius of curvature of approximately 0.98 inches, a second radius of approximately 0.34 inches a first thickness of approximately 0.04 inches of LAF2, a second thickness of approximately 0.16 inches of SK4, and a diameter of approximately 0.39 inches;

the plurality of fixed infrared lens elements comprises:

a first lens, having a first radius of curvature of approximately 51 mm, a second radius of approximately 669 mm, a thickness of approximately 4 mm, a diameter of approximately 37 mm formed of AMTIR4; and

a second lens, having a first radius of curvature of approximately infinity, a second radius of approximately infinity, a thickness of approximately 1 mm, a diameter of approximately 12 mm, formed of GE_LONG;

the plurality of fixed visible lens elements comprises:

a first lens, having a first radius of curvature of approximately 1.68 inches, a second radius of approximately 0.59 inches, a thickness of approximately 0.08 inches, a diameter of approximately 0.47 inches, formed of SF57; and

a second lens, having a first radius of curvature of approximately 0.72 inches, a second radius of approximately −0.7 inches, a thickness of approximately 0.16 inches, a diameter of approximately 0.47 inches, formed of LAKN12.

34. The dual optical system ofclaim 21, wherein,

the first lens of the focus element has a first radius of curvature of approximately 63 mm, a second radius of curvature of approximately 750 mm, a thickness of approximately 6 mm, a diameter of approximately 51 mm, and is formed of AMTIR4;

the second lens of the focus group, has a first radius of curvature of approximately 37 mm, a second radius of approximately 389 mm a thickness of approximately 1.4, a diameter of approximately 12mm, and is formed of F2;

the first set of lenses comprises:

a first infrared imaging lens, having a first radius of curvature of approximately −49 mm, a second radius of approximately −86 mm, a thickness of approximately 4.5 mm, a diameter of approximately 42 mm, formed of AMTIR4; and

a second infrared imaging lens, having a first radius of curvature of approximately 22 mm, a second radius of approximately 23 mm, a thickness of approximately 5 mm, a diameter of approximately 22 mm, formed of AMTIR4; and,

a third infrared imaging lens, having a first radius of curvature of approximately infinity, a second radius of approximately infinity, a thickness of approximately 1 mm, a diameter of approximately 12mm, formed of GE_LONG;

the second set of lenses comprises:

a first visible imaging lens, having a first radius of curvature of approximately 37 mm, a second radius of approximately 389 mm inches, a thickness of approximately 0.7 mm, a diameter of approximately 9 mm, formed of FK5;

a second visible imaging lens, having a first radius of curvature of approximately 0.72 inches, a second radius of approximately −0.7 inches, a thickness of approximately 0.16 inches, a diameter of approximately 0.47 inches, formed of LAKN12;

a third visible imaging lens, being a cemented doublet, having a first radius of curvature of approximately −933 mm, a second radius of approximately −8.6 mm, a first thickness of approximately 3.4 m of SK5, a second thickness of approximately 3.4 mm of SF11, and a diameter of approximately 12mm; and,

a fourth visible imaging lens, having a first radius of curvature of approximately 47 mm, a second radius of approximately −22 mm, a thickness of approximately 3 mm, a diameter of approximately 12mm, formed of BK7.

Images