CN115268042A - Light-small medium wave infrared continuous zooming optical system with large zoom ratio - Google Patents
Light-small medium wave infrared continuous zooming optical system with large zoom ratio Download PDFInfo
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- 230000003287 optical effect Effects 0.000 title claims abstract description 102
- 230000005499 meniscus Effects 0.000 claims description 88
- 239000000463 material Substances 0.000 claims description 28
- 239000013078 crystal Substances 0.000 claims description 16
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 15
- 239000005387 chalcogenide glass Substances 0.000 claims description 15
- 229910052710 silicon Inorganic materials 0.000 claims description 15
- 239000010703 silicon Substances 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 11
- PFNQVRZLDWYSCW-UHFFFAOYSA-N (fluoren-9-ylideneamino) n-naphthalen-1-ylcarbamate Chemical compound C12=CC=CC=C2C2=CC=CC=C2C1=NOC(=O)NC1=CC=CC2=CC=CC=C12 PFNQVRZLDWYSCW-UHFFFAOYSA-N 0.000 claims description 9
- 229910052732 germanium Inorganic materials 0.000 claims description 6
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 6
- 239000005355 lead glass Substances 0.000 claims description 5
- 239000005083 Zinc sulfide Substances 0.000 claims description 3
- 230000008030 elimination Effects 0.000 claims description 3
- 238000003379 elimination reaction Methods 0.000 claims description 3
- 230000000007 visual effect Effects 0.000 claims description 3
- 229910052984 zinc sulfide Inorganic materials 0.000 claims description 3
- DRDVZXDWVBGGMH-UHFFFAOYSA-N zinc;sulfide Chemical compound [S-2].[Zn+2] DRDVZXDWVBGGMH-UHFFFAOYSA-N 0.000 claims description 3
- 238000012634 optical imaging Methods 0.000 abstract description 3
- 238000005057 refrigeration Methods 0.000 description 24
- 238000005516 engineering process Methods 0.000 description 15
- 238000012546 transfer Methods 0.000 description 12
- 238000003384 imaging method Methods 0.000 description 11
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- G02B15/146—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having more than five groups
- G02B15/1461—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having more than five groups the first group being positive
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- G—PHYSICS
- G02—OPTICS
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Abstract
The invention relates to a light-small medium wave infrared continuous zooming optical system with a large zoom ratio, and belongs to the technical field of optical imaging. The system comprises: <xnotran> , , , , , , , . </xnotran> The optical system has the characteristics of large zoom range, small size envelope, light system weight and the like, and has wide application prospect in the fields of security protection such as navigation, search, tracking, warning, reconnaissance and the like.
Description
Technical Field
The invention belongs to the technical field of optical imaging, relates to a light-small medium wave infrared continuous zooming optical system with a large zoom ratio, and particularly relates to a refrigeration type medium wave infrared continuous zooming optical system mainly used for the aspects of large-scale search reconnaissance, remote tracking identification, handheld thermal infrared imagers, vehicle-mounted thermal infrared imagers, airborne thermal infrared imagers and the like.
Background
The infrared thermal imager has the advantages of good environmental adaptability, capability of working in all weather, difficulty in interference and the like, and is widely applied to the aspects of security protection, industrial monitoring, military warning and the like. Along with the performance improvement of infrared detection devices in recent years, refrigeration detectors are rapidly developed towards the directions of small size, light weight and low power consumption, and the medium wave infrared detectors of the type integrating small refrigerators or split linear refrigerators are widely applied to space-limited infrared photoelectric systems such as weapon thermo-sighting lenses, portable handheld thermal imagers, small unmanned aerial vehicles, unmanned vehicles, remote control snipers, remote control weapon stations, missile guide heads and the like due to the characteristics of small size, light weight, high reliability and the like. The miniaturization of the refrigeration detector promotes the infrared continuous zooming optical system to be continuously developed towards the direction of higher magnification, smaller size envelope and lighter weight so as to meet the use requirements of various light and small photoelectric devices for security protection, warning, reconnaissance, search, tracking and the like, so that the light, small and large zooming ratio infrared continuous zooming optical system has wide application requirements.
Through research and research on related documents, domestic refrigeration type medium-wave infrared continuous zooming optical systems have achieved more research results. For example: 3238 Zxft 3238, a design result of a 30-time F # 4 focal length 23mm-701mm and a system size 345mm × 176mm × 224mm is realized by adopting a two-element positive group compensation technology by using a medium wave refrigeration detector with 640 × 512@15 μm and U-shaped folding of 10 lenses and two reflectors (infrared and laser engineering 2013,42 (2)). 3238 Zxft 3238, 8 lenses and two reflectors are folded in a U shape, a medium wave refrigeration detector of 640 x 512@15 μm is adapted, and a two-component positive group compensation technology is adopted to realize a design result of 35 times F # 4 focal length 15mm-550mm and system size 390mm x 137.5mm x 110mm (infrared and laser engineering 2013,42 (10)). The design result that the focal length of F # 2 is 30 times and the total length of the optical system is 460mm is realized by using 8 lenses and adapting a medium wave detector with the wavelength of 640 multiplied by 512@15 mu m and adopting three groups of linkage technologies in the development of a continuous zooming infrared optical system with large zoom ratio and large relative aperture in ocean (the academic newspaper of infrared and millimeter waves 2019,38 (1)). 3238 Zxft 3238, a compact medium-wave infrared continuous zooming optical system with large zoom ratio is designed, 10 lenses are used, a medium-wave detector with a wavelength of 640 x 512@15 mu m is adapted, and a design result of 30 times F # 4 focal length of 18mm-550mm of the total length of the optical system of 350mm is realized by adopting a two-component positive group compensation technology (application optics 2019,40 (1)). 3238 Zxft 3238, 6 lenses are used, a medium wave detector with the wavelength of 640 x 512@15 mu m is matched, and a design result that the focal length of F #4.0 is 12 times, the focal length is 25mm-300mm, the system size is 200mm x 140mm x 110mm is realized by adopting a two-component positive group compensation technology (laser and infrared 3262 Zxft 3262 (1)).
Chinese patent CN102213822A discloses a medium wave infrared continuous zoom lens, which adopts a two-component positive group compensation technology, uses 7 lenses and two plane reflectors, can be applied to a 640 x 512 medium wave detector, and realizes a design result of 10 times F #4.0 focal length of 50mm-500 mm. Chinese patent CN102590990B discloses a three-group linkage medium wave infrared continuous zooming optical structure, which adopts three groups of lenses to realize continuous zooming in a nonlinear movement mode, uses 10 lenses to be matched with a medium wave detector with the wavelength of 640 multiplied by 512@15 mu m, and realizes the design result of 30 times F # 4 focal length of 25mm-750 mm.
The design results of the above documents and patents use a large number of lenses or a plurality of binary diffraction surfaces, thereby increasing the use cost of the system; or the envelope size of the system is large, so that the light and small use requirements are difficult to meet; currently, vehicle-mounted thermal infrared imagers and airborne thermal infrared imagers develop towards the trend of light weight, small size, high performance and low cost, and have higher requirements on the imaging quality, the overall length and the system volume of an infrared continuous zooming optical system. Therefore, how to overcome the defects of the prior art is a problem to be solved in the technical field of optical imaging at present.
Disclosure of Invention
The invention aims to solve the defects of the prior art and provide a light and small medium-wave infrared continuous zooming optical system with large zoom ratio, and the light and small infrared continuous zooming optical system adopting three groups of linkage technologies can achieve the aims of reducing the volume of the system, shortening the total length, reducing the weight and reducing the number of lenses, so that the light and small infrared continuous zooming optical system is widely applied to the fields of military warning and civil security, such as navigation, search, tracking, reconnaissance and the like.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the medium wave infrared continuous zooming optical system with light weight, small size and large zoom ratio comprises:
<xnotran> , , , , , , , , ; </xnotran>
The concave surface of the positive focal power meniscus lens of the front fixed group faces the image space;
the concave surface of the positive focal power meniscus lens as the rear fixed group faces the image space;
the concave surface of the negative power meniscus lens as a relay group faces the image side;
the normal of the first plane reflector and the normal of the second plane reflector form an angle of 45 degrees relative to the optical axis, and the light path is U-shaped and turned by 180 degrees.
Further, it is preferable that the positive power meniscus lens material as the front fixed group is a silicon single crystal;
the negative focal power biconcave lens material as the variable power group is a germanium single crystal or a chalcogenide glass material;
the positive focal power biconvex lens material as the compensation group is silicon single crystal;
the negative focal power biconcave lens material used as the second compensation group is germanium single crystal, silicon single crystal or chalcogenide glass material;
the positive focal power meniscus lens material as the rear fixed group is silicon single crystal, chalcogenide glass material or zinc selenide;
the positive focal power biconvex lens material as the relay group is a silicon single crystal, a chalcogenide glass material or zinc selenide;
the negative power meniscus lens material as the relay group is a chalcogenide glass material, zinc sulfide or zinc selenide.
Further, it is preferable that the positive power meniscus lens as the front fixed group is an aspherical positive power meniscus lens;
the negative focal power biconcave lens as the variable power group is an aspheric negative focal power biconcave lens;
the positive focal power biconvex lens as the compensation group is an aspheric positive focal power biconvex lens;
the negative focal power biconcave lens as the second compensation group is an aspheric negative focal power biconcave lens;
the positive focal power meniscus lens as the rear fixed group is a spherical positive focal power meniscus lens;
the positive focal power biconvex lens as the relay group is a positive focal power aspheric diffraction lens;
the negative power meniscus lens as the relay group is a spherical negative power meniscus lens.
Further, it is preferable that focal lengths of the positive power meniscus lens as the front fixed group, the negative power biconcave lens as the variable power group, the positive power biconvex lens as the compensation group, and the negative power biconcave lens as the second compensation group should satisfy the following conditions:
3.2<|fL/f1|<5.6；
16.8<|fL/f2|<28.8；
10.4<|fL/f3|<20.8；
8.2<|fL/f4|<18.2；
where fL is a focal length of the telephoto end of the optical system, f1 is a focal length of the positive power meniscus lens as the front fixed group, f2 is a focal length of the negative power biconcave lens as the variable power group, f3 is a focal length of the positive power biconvex lens as the compensation group, and f4 is a focal length of the negative power biconcave lens as the second compensation group.
Further, it is preferable that the positive power biconvex lens as the compensation group and the negative power biconcave lens as the second compensation group move in the same direction along the optical axis during zooming, so as to realize the continuous zoom compensation function.
Further, it is preferable that the negative power biconcave lens as the variable power group moves back and forth in the optical axis direction to realize the focus adjustment of the visual range and the high and low temperature athermal difference.
The system is arranged so that infrared radiation rays of a target scenery pass through a positive focal power meniscus lens serving as a front fixed group in front, a negative focal power biconcave lens serving as a variable power group, a positive focal power biconvex lens serving as a compensation group, a negative focal power biconcave lens serving as a second compensation group, a positive focal power meniscus lens serving as a rear fixed group, a first plane reflector, a second plane reflector, a positive focal power biconvex lens serving as a relay group and a negative focal power meniscus lens serving as a relay group, are converged to a medium wave refrigeration detector window and are imaged on a focal plane of a medium wave refrigeration detector.
The negative focal power biconcave lens as the zoom group, the positive focal power biconvex lens as the compensation group and the negative focal power biconcave lens as the second compensation group can move axially to realize continuous zooming, namely: when the negative focal power biconcave lens as the variable power group moves from the position close to the positive focal power meniscus lens as the front fixed group to the direction of the positive focal power meniscus lens as the rear fixed group, the positive focal power biconvex lens as the compensation group and the negative focal power biconcave lens as the second compensation group move nonlinearly from the position close to the positive focal power meniscus lens as the rear fixed group to the direction of the positive focal power meniscus lens as the front fixed group according to the compensation curve, and the system focal length continuously increases from short focus to long focus in the corresponding zooming process; the system is in a short focus position when the negative power biconcave lens as the variable power group is close to the positive power meniscus lens as the front fixed group, and in a long focus position when the negative power biconcave lens as the variable power group is close to the positive power biconvex lens as the compensation group.
The negative focal power biconcave lens serving as the zoom group has a focusing function of moving back and forth along the optical axis direction, and can compensate the defocusing of a system in high and low temperature environments through focusing.
The system adopts three groups of linkage zooming technologies to compress the total length of the 30 times of the medium wave infrared continuous zooming optical system and adopts two plane reflectors U-shaped folding light paths to compress the longitudinal length of the system again, thereby realizing the miniaturization of the system.
In the present invention, the positive focal power meniscus lens as the front fixed group, the negative focal power biconcave lens as the variable power group, the positive focal power biconvex lens as the compensation group, the negative focal power biconcave lens as the second compensation group, the positive focal power meniscus lens as the rear fixed group, the positive focal power biconvex lens as the relay group, and the negative focal power meniscus lens as the relay group have optical structural layouts of positive, negative, positive, and negative, respectively.
The system zoom range is 14.8mm-460mm, the system F number application range is 3.5-5.5, the system volume envelope is less than or equal to 208mm (length) x 136mm (width) x 120mm (height), and the total system weight is less than or equal to 236g.
The refrigerating medium wave infrared focal plane detector adaptive to the system of the invention can be applicable to the following specifications: 384 multiplied by 288/25 μm, 640 multiplied by 512/15 μm, 640 multiplied by 512/17 μm, 1024 multiplied by 768/10 μm and other refrigeration type medium wave infrared focal plane detectors; the applicable wavelength range is as follows: medium wave 3.7-4.8 μm, medium wave 3.2-4.3 μm, and medium wave 3.0-5.0 μm.
The refrigeration type medium wave infrared optical system realizes the 30-time continuous zooming function of the refrigeration type medium wave infrared optical system with seven lenses by adopting the three-group linkage zooming technology; the aperture of the front fixed group is restricted by adopting a secondary imaging technology, and the 100% cold shielding efficiency of the system is realized; two plane reflectors are adopted to compress the longitudinal length to realize system miniaturization; the imaging of the continuous zooming optical system is clear under the conditions of high temperature and low temperature through the active focusing compensation heat difference elimination technology.
The key points of the invention are as follows:
the optical system of the invention adopts three groups of linkage continuous zooming technology to reduce the number of lenses and the total length of a compression system, and totally seven lenses, thereby realizing the 30-time light and small refrigeration medium wave infrared continuous zooming function.
The invention adopts the compensation technology that two compensation groups move in the same direction along the optical axis direction, realizes the continuous zooming compensation function, and simplifies the cam design technology or the servo control technology.
The optical system of the invention achieves clear imaging by actively focusing through the negative focal power biconcave lens of the zoom group at the low temperature of minus 45 ℃ and the high temperature of plus 70 ℃.
The optical system of the invention restrains the diameter of the front fixed group of positive focal power meniscus lens by adopting optical twice focusing imaging, reduces the size of optical parts and realizes 100 percent cold screen efficiency.
The optical system of the invention adopts two plane reflectors to fold the light path in a U shape, compresses the longitudinal length, and limits the longitudinal length of the 30-time light small refrigeration medium wave infrared continuous zooming optical system within the range of 208 mm.
Compared with the prior art, the invention has the beneficial effects that:
by adopting the light and small medium-wave infrared continuous zooming optical system with large zoom ratio, the 30-time continuous zooming function of the infrared optical system can be realized only by seven lenses. The diameter of the front fixed group of positive focal power meniscus lens is constrained by optical twice focusing imaging, so that the size of an optical part is reduced, the 100% cold screen efficiency is realized, and the imaging quality is improved; the system keeps better imaging quality within the range of minus 45 ℃ to 70 ℃ by actively focusing and removing heat through the zoom group.
The zoom range of the system is 14.8mm-460mm, the envelope of the system is less than or equal to 208mm (length) and less than or equal to 136mm (width) and less than or equal to 120mm (height), and the total weight of the system is less than or equal to 236g, so that the zoom optical system with large zoom ratio is light and small. The whole system has the advantages of small lens quantity, short axial size, light weight, small volume, low cost, high transmittance and the like.
Drawings
FIG. 1 is a schematic view of the zooming process of the system of the present invention.
FIG. 2 is a diagram of a 460mm focal length optical system with a small field of view according to an embodiment of the present invention.
FIG. 3 is a 275mm focal length optical system diagram of a medium and small field of view in accordance with one embodiment of the present invention.
FIG. 4 is a diagram of an optical system with a 109mm focal length field according to an embodiment of the present invention.
FIG. 5 is a diagram of a 14.8mm focal length optical system with a large field of view according to an embodiment of the present invention.
FIG. 6 is a diagram of a 460mm focal length modulation transfer function for a small field of view according to an embodiment of the present invention.
FIG. 7 is a 275mm focal length modulation transfer function plot for a medium and small field of view, in accordance with an embodiment of the present invention.
FIG. 8 is a diagram of a 109mm field of view focal length modulation transfer function according to an embodiment of the present invention.
FIG. 9 is a diagram of a 14.8mm wide field of view focal length modulation transfer function according to an embodiment of the present invention.
FIG. 10 is a diagram of the modulation transfer function of 460mm focal length at a small field of view at a temperature of two to 45 ℃ in accordance with an embodiment of the present invention.
FIG. 11 is a diagram of the modulation transfer function of 460mm focal length in a small field of view at two +70 ℃ according to an embodiment of the present invention.
FIG. 12 is a cam graph illustrating the zooming process of the first compensation group, the second compensation group and the zoom group according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples.
It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The materials or equipment used are not indicated by manufacturers, and all are conventional products available by purchase.
Example 1
As shown in fig. 2 to 5, the light, small, large magnification ratio medium wave infrared continuous zoom optical system is characterized by comprising:
a positive focal power meniscus lens 1 as a front fixed group, a negative focal power biconcave lens 2 as a variable power group, a positive focal power biconvex lens 3 as a compensation group, a negative focal power biconcave lens 4 as a second compensation group, a positive focal power meniscus lens 5 as a rear fixed group, a first plane mirror 6, a second plane mirror 7, a positive focal power biconvex lens 8-2 as a relay group and a negative focal power meniscus lens 8-1 as a relay group are sequentially arranged along the optical axis direction;
the concave surface of the positive focal power meniscus lens 1 of the front fixed group faces the image space;
the concave surface of the positive power meniscus lens 5 as the rear fixed group faces the image side;
the concave surface of a negative-power meniscus lens 8-1 as a relay group faces the image side;
the normal of the first plane reflector 6 and the normal of the second plane reflector 7 form an angle of 45 degrees relative to the optical axis, and the light path is U-shaped and turned by 180 degrees.
Example 2
As shown in fig. 2 to 5, the light, small and large zoom ratio medium wave infrared continuous zoom optical system includes:
a positive focal power meniscus lens 1 as a front fixed group, a negative focal power biconcave lens 2 as a zoom group, a positive focal power biconvex lens 3 as a compensation group, a negative focal power biconcave lens 4 as a second compensation group, a positive focal power meniscus lens 5 as a rear fixed group, a first plane mirror 6, a second plane mirror 7, a positive focal power biconvex lens 8-2 as a relay group and a negative focal power meniscus lens 8-1 as a relay group are sequentially arranged along the optical axis direction;
the concave surface of the positive focal power meniscus lens 1 of the front fixed group faces the image space;
the concave surface of the positive power meniscus lens 5 as the rear fixed group faces the image side;
the concave surface of a negative-power meniscus lens 8-1 as a relay group faces the image side;
the normal of the first plane reflector 6 and the normal of the second plane reflector 7 form an angle of 45 degrees relative to the optical axis, and the light path is U-shaped and turned by 180 degrees.
The positive focal power meniscus lens 1 as the front fixed group is made of silicon single crystal;
the negative focal power biconcave lens 2 as the zoom group is made of germanium single crystal or chalcogenide glass material;
the positive focal power biconvex lens 3 as the compensation group is made of silicon single crystal;
the negative focal power biconcave lens 4 as the second compensation group is made of germanium single crystal, silicon single crystal or chalcogenide glass material;
the positive focal power meniscus lens 5 as the rear fixed group is made of silicon single crystal, chalcogenide glass material or zinc selenide;
the positive focal power biconvex lens 8-2 material as the relay group is silicon single crystal, chalcogenide glass material or zinc selenide;
the negative-power meniscus lens 8-1 as the relay group is made of chalcogenide glass material, zinc sulfide or zinc selenide.
The positive focal power meniscus lens 1 as the front fixed group is an aspheric positive focal power meniscus lens;
the negative focal power biconcave lens 2 as the variable power group is an aspheric negative focal power biconcave lens;
the positive focal power biconvex lens 3 as a compensation group is an aspheric positive focal power biconvex lens;
the negative focal power biconcave lens 4 as the second compensation group is an aspheric negative focal power biconcave lens;
the positive focal power meniscus lens 5 as the rear fixed group is a spherical positive focal power meniscus lens;
the positive focal power biconvex lens 8-2 as a relay group is a positive focal power aspheric diffraction lens;
the negative power meniscus lens 8-1 as the relay group is a spherical negative power meniscus lens.
The focal lengths of the positive power meniscus lens 1 as the front fixed group, the negative power biconcave lens 2 as the variable power group, the positive power biconvex lens 3 as the compensation group, and the negative power biconcave lens 4 as the second compensation group are required to satisfy the following conditions:
3.2<|fL/f1|<5.6；
16.8<|fL/f2|<28.8；
10.4<|fL/f3|<20.8；
8.2<|fL/f4|<18.2；
where fL is a focal length of the telephoto end of the optical system, f1 is a focal length of the positive-power meniscus lens 1 as the front fixed group, f2 is a focal length of the negative-power biconcave lens 2 as the variable power group, f3 is a focal length of the positive-power biconvex lens 3 as the compensation group, and f4 is a focal length of the negative-power biconcave lens 4 as the second compensation group.
The positive focal power biconvex lens 3 as a compensation group and the negative focal power biconcave lens 4 as a second compensation group move along the same direction of the optical axis in the zooming process, thereby realizing the continuous zoom compensation function.
The negative focal power biconcave lens 2 as a zoom group moves back and forth along the optical axis direction to realize the focusing of the visual range and the heat difference elimination of high and low temperature.
Application example 1
The invention provides a light, small and medium-wave infrared continuous zooming optical system with large zoom ratio, as shown in figure 2, in the optical axis direction determined on the medium-wave infrared ray path radiated by the scenery target, the optical system is sequentially arranged from the object direction to the image direction: the system comprises a positive focal power meniscus lens 1 as a front fixed group, a negative focal power biconcave lens 2 as a variable power group, a positive focal power biconvex lens 3 as a compensation group, a negative focal power biconcave lens 4 as a second compensation group, a positive focal power meniscus lens 5 as a rear fixed group, a first plane mirror 6, a second plane mirror 7, a positive focal power biconvex lens 8-2 as a relay group, a negative focal power meniscus lens 8-1 as a relay group, a medium wave refrigeration detector window 9 and a medium wave refrigeration detector focal plane 10 imaged; so that the infrared radiation light of the target scenery is converged to a medium wave refrigeration detector window 9 through a positive focal power meniscus lens 1 serving as a front fixed group, a negative focal power biconcave lens 2 serving as a variable power group, a positive focal power biconvex lens 3 serving as a compensation group, a negative focal power biconcave lens 4 serving as a second compensation group, a positive focal power meniscus lens 5 serving as a rear fixed group, a first plane reflector 6, a second plane reflector 7, a positive focal power biconvex lens 8-2 serving as a relay group and a negative focal power meniscus lens 8-1 serving as a relay group, and is imaged on a medium wave refrigeration detector focal plane 10.
The optical system specific parameters are shown in table 1.
In table 1, the front surface and the back surface refer to that one surface of each optical element close to the scenery in the optical axis direction is the front surface, and the surface facing the focal plane of the refrigeration detector is the back surface; the radius of curvature refers to the radius of curvature of the front and rear surfaces of each optical lens; the center thickness refers to the center thickness of each optical lens; the distance refers to the distance between the center of the rear surface of each optical lens and the center of the front surface of the adjacent optical lens along the optical axis direction; the material is an optical material for an optical element; the aspheric parameters are even aspheric equation coefficients of the aspheric surface of the optical lens.
In table 1, a is a coefficient of the fourth power of the equation, B is a coefficient of the sixth power of the equation, and C is a coefficient of the eighth power of the equation, and the even aspheric surface equation is defined as follows:
wherein z is the lens rise of the aspheric surface along the optical axis direction; c0 is the curvature of the top point of the surface of the optical lens; k is a conic constant; y is a half aperture of the lens perpendicular to the optical axis direction; A. b, C, D is coefficient (D =0 in table 1);
TABLE 1 optical system parameter table (Unit: mm)
The diffraction coefficient is the diffraction surface equation coefficient of the aspheric diffraction surface of the optical lens;
the diffraction surface equation is: phi = H1Y2+H2Y4+H3Y6
Wherein phi is the phase of the diffraction surface; y is a half aperture of the lens perpendicular to the optical axis direction; h1, H2, and H3 are diffraction plane phase coefficients (H3 =0 in table 1).
The system zooming process schematic diagram is shown in fig. 1, when the system zooms from a large-field short-focus position to a small-field long-focus position, a negative-power biconcave lens 2 as a variable-power group moves from a position close to a positive-power meniscus lens 1 as a front fixed group to a direction of a positive-power biconvex lens 3 as a compensation group, the positive-power biconvex lens 3 as the compensation group moves from a position close to a positive-power meniscus lens 5 as a rear fixed group to a direction of the negative-power biconcave lens 2 as the variable-power group for compensation, the negative-power biconcave lens 4 as a second compensation group and the positive-power biconvex lens 3 as the compensation group move in the same direction at the same time, and the system focal length continuously increases in the corresponding zooming process; the system is in a short focus position when the negative power biconcave lens 2 as a variable power group is close to the positive power meniscus lens 1 as a front fixed group, and in a long focus position when the negative power biconcave lens 2 as a variable power group is close to the positive power biconvex lens 3 as a compensation group.
As shown in fig. 5, when the negative-power biconcave lens 2 as the variable power group is close to the position of the positive-power meniscus lens 1 as the front fixed group, a short-focal-length large-field optical path of the system 14.8mm is constituted, the positive-power meniscus lens 1 as the front fixed group is spaced 17.8mm from the negative-power biconcave lens 2 as the variable power group, the negative-power biconcave lens 2 as the variable power group is spaced 72.2mm from the positive-power biconvex lens 3 as the compensation group, the positive-power biconvex lens 3 as the compensation group is spaced 4.2mm from the negative-power biconcave lens 4 as the second compensation group, and the negative-power biconcave lens 4 as the second compensation group is spaced 4.5mm from the positive-power meniscus lens 5 as the rear fixed group.
When the negative-power biconcave lens 2 as the variable power group moves towards the positive-power biconvex lens 3 as the compensation group, and simultaneously the positive-power biconvex lens 3 as the compensation group and the negative-power biconcave lens 4 as the second compensation group move towards the negative-power biconcave lens 2 as the variable power group, the position of the lens moves as shown in fig. 4, then a field optical path in the focal length of 109mm of the system is formed, the positive-power meniscus lens 1 as the front fixed group is separated from the negative-power biconcave lens 2 as the variable power group by 63.9mm, the negative-power biconcave lens 2 as the variable power group is separated from the positive-power lens 3 as the compensation group by 52.8mm, the positive-power biconvex lens 3 as the compensation group is separated from the negative-power biconcave lens 4 as the second compensation group by 9.8mm, and the negative-power biconcave lens 4 as the second compensation group is separated from the positive-power meniscus lens 5 as the rear fixed group by 28.6mm.
When the negative-power biconcave lens 2 serving as the variable power group continues to move towards the positive-power biconvex lens 3 serving as the compensation group, and simultaneously the positive-power biconvex lens 3 serving as the compensation group and the negative-power biconcave lens 4 serving as the second compensation group continue to move towards the negative-power biconcave lens 2 serving as the variable power group, the position movement is as shown in fig. 3, at this time, a small field optical path with a focal length of 275mm in the system is formed, the positive-power meniscus lens 1 serving as the front fixed group is separated from the negative-power biconcave lens 2 serving as the variable power group by 68.5mm, the negative-power biconcave lens 2 serving as the variable power group is separated from the positive-power biconvex lens 3 serving as the compensation group by 19.2mm, the positive-power biconcave lens 3 serving as the compensation group is separated from the negative-power biconcave lens 4 serving as the second compensation group by 21.0mm, and the negative-power biconcave lens 4 serving as the second compensation group is separated from the positive-power biconvex lens 5 serving as the rear fixed group by 46.4mm.
When the negative-power biconcave lens 2 serving as the variable power group continues to move towards the positive-power biconvex lens 3 serving as the compensation group, and simultaneously the positive-power biconvex lens 3 serving as the compensation group and the negative-power biconcave lens 4 serving as the second compensation group continue to move towards the negative-power biconcave lens 2 serving as the variable power group, the position movement is as shown in fig. 2, at this time, a 460mm focal length small field optical path of the system is formed, the positive-power meniscus lens 1 serving as the front fixed group is spaced from the negative-power biconcave lens 2 serving as the variable power group by 72.5mm, the negative-power biconcave lens 2 serving as the variable power group is spaced from the positive-power biconvex lens 3 serving as the compensation group by 5.0mm, the positive-power biconcave lens 3 serving as the second compensation group is spaced from the negative-power biconcave lens 4 serving as the second compensation group by 30.4mm, and the negative-power biconcave lens 4 serving as the second compensation group is spaced from the positive-power biconcave lens 5 serving as the rear fixed group by 47.2mm.
When the system is adaptive to 640 multiplied by 512/15 microns, and a refrigeration type medium wave infrared focal plane detector 10 with an F number of 4 is in a 14.8mm short-focus large field of view, the optical modulation transfer function of the system is shown in fig. 9, when the system is in a 109mm focal length medium field of view, the optical modulation transfer function of the system is shown in fig. 8, when the system is in a 275mm focal length medium field of view, the optical modulation transfer function of the system is shown in fig. 7, when the system is in a 460mm focal length small field of view, the optical modulation transfer function of the system is shown in fig. 6, the imaging quality of the whole zooming process is always kept good, and images are clear.
The moving cam curves of the negative-power biconcave lens 2 as the zoom group, the positive-power biconvex lens 3 as the compensation group and the negative-power biconcave lens 4 as the second compensation group in the zooming process are shown in fig. 12, the maximum stroke of the negative-power biconcave lens 2 as the zoom group is 54.7mm, the maximum stroke of the positive-power biconvex lens 3 as the compensation group is 72.5mm, and the maximum stroke of the negative-power biconcave lens 4 as the second compensation group is 42.7mm, so that the cam curves are smooth and easy to servo control.
Application example 2
The invention provides a light, small and medium-wave infrared continuous zooming optical system with large zoom ratio, as shown in figure 2, in the optical axis direction determined on the medium-wave infrared ray path radiated by the scenery target, the optical system is sequentially arranged from the object direction to the image direction: the system comprises a positive focal power meniscus lens 1 as a front fixed group, a negative focal power biconcave lens 2 as a variable power group, a positive focal power biconvex lens 3 as a compensation group, a negative focal power biconcave lens 4 as a second compensation group, a positive focal power meniscus lens 5 as a rear fixed group, a first plane mirror 6, a second plane mirror 7, a positive focal power biconvex lens 8-2 and a negative focal power meniscus lens 8-1 as a relay group, a medium wave refrigeration detector window 9 and a medium wave refrigeration detector focal plane 10, wherein the positive focal power meniscus lens 1 and the negative focal power biconcave lens are imaged on the medium wave refrigeration detector focal plane; so that the infrared radiation light of the target scenery is converged to a medium wave refrigeration detector window 9 through a positive focal power meniscus lens 1 serving as a front fixed group, a negative focal power biconcave lens 2 serving as a zoom group, a positive focal power biconvex lens 3 serving as a compensation group, a negative focal power biconcave lens 4 serving as a second compensation group, a positive focal power meniscus lens 5 serving as a rear fixed group, a first plane reflector 6, a second plane reflector 7, a positive focal power biconvex lens 8-2 serving as a relay group and a negative focal power meniscus lens 8-1, and is imaged on a medium wave refrigeration detector focal plane 10.
When the negative-power biconcave lens 2 as the variable power group is close to the positive-power biconvex lens 3 as the compensation group, and the positive-power biconvex lens 3 as the compensation group and the negative-power biconcave lens 4 as the second compensation group are close to the negative-power biconcave lens 2 as the variable power group, the positions are as shown in fig. 2, and then the system is formed with 460mm focal length small field optical path, the positive-power meniscus lens 1 as the front fixed group is spaced from the negative-power biconcave lens 2 as the variable power group by 72.5mm, the negative-power biconcave lens 2 as the variable power group is spaced from the positive-power biconcave lens 3 as the compensation group by 5.0mm, the positive-power biconvex lens 3 as the compensation group is spaced from the negative-power biconcave lens 4 as the second compensation group by 30.4mm, and the negative-power biconcave lens 4 as the second compensation group is spaced from the positive-power biconcave lens 5 as the rear fixed group by 47.2mm.
When the system is at a low temperature of-45 ℃, the negative focal power biconcave lens 2 serving as a zoom group moves backwards by 0.32mm along the optical axis direction for focusing compensation, the optical modulation transfer function of the system after focusing compensation is shown in fig. 10, and the system has clear imaging.
When the system is at a high temperature of +70 ℃, focusing compensation is carried out by moving the negative focal power biconcave lens 2 serving as a zoom group forward by 0.28mm along the optical axis direction, the optical modulation transfer function of the system after focusing compensation is shown in fig. 11, and the system is clear in imaging.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are given by way of illustration of the principles of the present invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, and such changes and modifications are within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (6)
1. The infrared continuous zoom optical system of medium wave of big zoom ratio of light and small-size, its characterized in that includes:
a positive focal power meniscus lens (1) as a front fixed group, a negative focal power biconcave lens (2) as a variable power group, a positive focal power biconvex lens (3) as a compensation group, a negative focal power biconcave lens (4) as a second compensation group, a positive focal power meniscus lens (5) as a rear fixed group, a first plane reflector (6), a second plane reflector (7), a positive focal power biconvex lens (8-2) as a relay group and a negative focal power meniscus lens (8-1) as a relay group are sequentially arranged along the optical axis direction;
the normal of the first plane reflector (6) and the normal of the second plane reflector (7) form an angle of 45 degrees relative to the optical axis, and the U-shaped light path is folded by 180 degrees.
2. The small and light medium-wave infrared continuous zooming optical system with large zoom ratio according to claim 1, wherein:
the positive focal power meniscus lens (1) as the front fixed group is made of silicon single crystal;
the material of the negative focal power biconcave lens (2) as the variable power group is germanium single crystal or chalcogenide glass material;
the positive focal power biconvex lens (3) as the compensation group is made of silicon single crystal;
the negative focal power biconcave lens (4) used as the second compensation group is made of germanium single crystal, silicon single crystal or chalcogenide glass material;
the positive focal power meniscus lens (5) as the rear fixed group is made of silicon single crystal, chalcogenide glass material or zinc selenide;
the positive focal power biconvex lens (8-2) as the relay group is made of silicon single crystal, chalcogenide glass material or zinc selenide;
the material of the negative-power meniscus lens (8-1) as the relay group is a chalcogenide glass material, zinc sulfide or zinc selenide.
3. The small and light medium-wave infrared continuous zooming optical system with large zoom ratio according to claim 1, wherein:
the positive focal power meniscus lens (1) as the front fixed group is an aspheric positive focal power meniscus lens;
the negative focal power biconcave lens (2) as the variable power group is an aspheric negative focal power biconcave lens;
the positive focal power double-convex lens (3) as a compensation group is an aspheric positive focal power double-convex lens;
the negative focal power biconcave lens (4) as the second compensation group is an aspheric negative focal power biconcave lens;
the positive focal power meniscus lens (5) as the rear fixed group is a spherical positive focal power meniscus lens;
the positive focal power biconvex lens (8-2) as the relay group is a positive focal power aspheric diffraction lens;
the negative power meniscus lens (8-1) as the relay group is a spherical negative power meniscus lens.
4. The light, small and large zoom ratio medium wave infrared continuous zoom optical system according to claim 1, characterized in that:
the focal lengths of a positive-power meniscus lens (1) as a front fixed group, a negative-power biconcave lens (2) as a variable power group, a positive-power biconvex lens (3) as a compensation group and a negative-power biconcave lens (4) as a second compensation group are required to satisfy the following conditions:
3.2<|fL/f1|<5.6；
16.8<|fL/f2|<28.8；
10.4<|fL/f3|<20.8；
8.2<|fL/f4|<18.2；
wherein, fL is the focal length of the long focal end of the optical system, f1 is the focal length of the positive-power meniscus lens (1) as the front fixed group, f2 is the focal length of the negative-power biconcave lens (2) as the variable power group, f3 is the focal length of the positive-power biconvex lens (3) as the compensation group, and f4 is the focal length of the negative-power biconcave lens (4) as the second compensation group.
5. The light, small and large zoom ratio medium wave infrared continuous zoom optical system according to claim 1, characterized in that: the positive focal power biconvex lens (3) as a compensation group and the negative focal power biconcave lens (4) as a second compensation group move along the same direction of the optical axis in the zooming process, thereby realizing the continuous zoom compensation function.
6. The small and light medium-wave infrared continuous zooming optical system with large zoom ratio according to claim 1, wherein: the negative focal power biconcave lens (2) as a zoom group moves back and forth along the optical axis direction to realize the focusing of the visual range and the high-low temperature heat difference elimination.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116858504A (en) * | 2023-09-04 | 2023-10-10 | 武汉振光科技有限公司 | Optical axis monitoring system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116858504A (en) * | 2023-09-04 | 2023-10-10 | 武汉振光科技有限公司 | Optical axis monitoring system |
| CN116858504B (en) * | 2023-09-04 | 2023-12-08 | 武汉振光科技有限公司 | Optical axis monitoring system |
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