CN115327752A - Large-view-field small-distortion long-wave infrared optical imaging system with external entrance pupil - Google Patents
Large-view-field small-distortion long-wave infrared optical imaging system with external entrance pupil Download PDFInfo
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- CN115327752A CN115327752A CN202211030095.2A CN202211030095A CN115327752A CN 115327752 A CN115327752 A CN 115327752A CN 202211030095 A CN202211030095 A CN 202211030095A CN 115327752 A CN115327752 A CN 115327752A
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- 210000001747 pupil Anatomy 0.000 title claims abstract description 31
- 238000012634 optical imaging Methods 0.000 title claims abstract description 25
- 238000003384 imaging method Methods 0.000 claims abstract description 34
- 230000003287 optical effect Effects 0.000 claims abstract description 31
- 230000004075 alteration Effects 0.000 claims description 10
- 238000011156 evaluation Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 230000000007 visual effect Effects 0.000 claims description 4
- 238000012546 transfer Methods 0.000 description 12
- 238000010586 diagram Methods 0.000 description 11
- 238000013461 design Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 3
- 238000002834 transmittance Methods 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000005387 chalcogenide glass Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007516 diamond turning Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 238000003331 infrared imaging Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/14—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
- G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
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- Optics & Photonics (AREA)
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- Lenses (AREA)
Abstract
The invention discloses a large-view-field small-distortion long-wavelength infrared optical imaging system with an external entrance pupil, which relates to the field of optical systems and comprises an imaging system, wherein the imaging system is provided with a plurality of lenses, the lenses are a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens in sequence, and the rear surfaces of the first lens, the third lens and the fourth lens are high-order aspheric surfaces; the entrance pupil of the optical system is arranged at the front end 28mm of the optical system through the system, so that a plane mirror is arranged at the entrance pupil, the infrared target imaging within a 180-degree half-space range is realized by the minimum mirror size through scanning of the plane mirror, the working waveband of the system is 8-12 micrometers, the focal length is 8.8mm, the F # is 1, the full field of view is 82 degrees, the distortion is less than 5 percent, and the infrared target imaging within the 180-degree field of view can be realized as long as the size of the scanning mirror is greater than 60 mm.
Description
Technical Field
The invention relates to the optical system technology, in particular to a large-view-field small-distortion long-wave infrared optical imaging system with an external entrance pupil.
Background
In order to realize imaging of an infrared target in a 180-degree half-space range, the field of view of an infrared optical imaging system needs to be enlarged, and a scanning plane reflecting mirror needs to be added at the front end of the infrared optical imaging system. Because the entrance pupils of the traditional large-field infrared optical imaging system are all positioned in the optical system, the size of a scanning plane reflector at the front end of the optical system is huge (generally 3-5 times of the maximum aperture of the optical imaging), and the miniaturization of the whole system cannot be realized.
When the existing infrared optical imaging system is used, the entrance pupil of the large-field infrared imaging system is arranged at the front end of the optical system, so that the size of the scanning plane reflector can be greatly reduced, the design difficulty of the optical imaging system is increased, and the optical imaging system is especially challenging in the aspect of aberration control such as chromatic aberration, distortion and the like.
Disclosure of Invention
The invention aims to provide a large-view-field small-distortion long-wave infrared optical imaging system with an external entrance pupil, so as to solve the defects in the prior art.
In order to achieve the above purpose, the invention provides the following technical scheme: the utility model provides an infrared optical imaging system of external big visual field small distortion long wave of entrance pupil, includes imaging system, its characterized in that, imaging system is provided with the multi-disc lens, the multi-disc the lens is first lens, second lens, third lens, fourth lens, fifth lens and sixth lens in proper order, the rear surface of first lens, the rear surface of third lens and the rear surface of fourth lens are high order aspheric surface, the rear surface of sixth lens is the diffraction face of stack on the aspheric surface.
Furthermore, the imaging system comprises a diffraction element, wherein 180 grating periods are arranged in the range of the clear aperture of the diffraction element, the minimum grating period of the grating periods is 180 μm, and the step depth of the grating periods is 3.333 μm.
Further, the imaging system further comprises a large-field-of-view infrared optical system for controlling system distortion, and the large-field-of-view infrared optical system comprises an imaging lens group and a subsequent imaging lens group.
Furthermore, the imaging system further comprises an entrance pupil and an optical system, the distance between the entrance pupil and the front surface of the optical system is 28mm, the distance between the entrance pupil position and the outer end face of the lens structure is 25mm, and the aperture at the entrance pupil position is 17mm.
Furthermore, the first lens, the second lens, the fourth lens and the fifth lens are made of the same material.
Furthermore, the imaging system also comprises a refraction and diffraction mixed optical imaging system and an evaluation function, wherein the refraction and diffraction mixed optical imaging system is used for correcting and correcting chromatic aberration and thermal aberration, a diffraction surface is arranged in the refraction and diffraction mixed optical imaging system, and the diffraction surface phase expression coefficient of the diffraction surface is controlled through the evaluation function.
Compared with the prior art, the large-view-field small-distortion long-wavelength infrared optical imaging system with the external entrance pupil has the advantages that the entrance pupil of the optical system is arranged at the front end 28mm of the optical system, the plane mirror is arranged at the entrance pupil, infrared target imaging in a 180-degree half-space range is realized through the scanning of the plane mirror by the smallest mirror size, the working waveband of the system is 8-12 microns, the focal length is 8.8mm, the F # is 1, the full view field is 82 degrees, the distortion is less than 5 percent, and the infrared target imaging in the 180-degree view field range can be realized as long as the size of the scanning mirror is larger than 60 mm.
Drawings
In order to more clearly illustrate the embodiments of the present application or technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings can be obtained by those skilled in the art according to these drawings.
FIG. 1 is a light path diagram of a large field of view long wavelength infrared optical system provided by the present invention;
FIG. 2 is a schematic diagram of the transfer function at 20 ℃ provided by the present invention;
FIG. 3 is a schematic diagram of a transfer function at-40 ℃ according to the present invention;
FIG. 4 is a schematic diagram of the transfer function at-20 ℃ provided by the present invention;
FIG. 5 is a schematic diagram of the transfer function at 0 ℃ provided by the present invention;
FIG. 6 is a schematic diagram of a transfer function at 30 ℃ according to the present invention;
FIG. 7 is a schematic diagram of a transfer function at 50 ℃ according to the present invention;
FIG. 8 is a schematic diagram of a transfer function at 70 ℃ provided by the present invention;
FIG. 9 is a schematic diagram of a transfer function at 20 ℃ provided by the present invention;
FIG. 10 is a schematic illustration of the distortion provided by the present invention;
FIG. 11 is a schematic diagram of relative illumination of an optical system according to the present invention;
fig. 12 is a schematic diagram showing a design result of the diffractive optical element according to the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, those skilled in the art will now describe the present invention in further detail with reference to the accompanying drawings.
Referring to fig. 1-12, a large field of view small distortion long wavelength infrared optical imaging system with an external entrance pupil is shown in fig. 1. The system consists of 6 lenses in total. The distance between the entrance pupil and the front surface of the optical system is 28mm, and the distance between the position of the entrance pupil and the outer end surface of the lens structure is 25mm. The aperture size at the entrance pupil was 17mm. The 6 lens materials are IG6 (chalcogenide glass), IG6, znS, IG6, IG6 and Ge. The rear surfaces of the first lens, the third lens and the fourth lens are high-order aspheric surfaces (the highest order is 6). The back surface of the sixth lens is a diffraction surface superimposed on an aspherical surface, the diffraction surface has a grating period number of 20, and the minimum grating period is 180 μm. The distance of an alignment object is set to be infinite during design, the spectral range is set to be 8-14 μm, the designed half field of view is 41 degrees, the focal length is 8.8mm, the entrance pupil is 8.8mm (equivalent to F # is 1), and the maximum clear aperture size of the lens is 56mm. The on-chip lens transmittance was 97%, the transmittance was 83.3%, and the total transmittance of the system was estimated to be 75% considering the diffraction efficiency of the diffraction element of 90%. The overall system length was 142mm (from the front surface of the first lens to the detector face) and the back working distance was 12.59mm (from the apex of the back surface of the last lens to the detector target face).
In order to accurately evaluate the image quality of the large-view-field optical system under different view fields, the normalized view field of 0.854 is added besides the normalized view fields of 0, 0.5,0.7 and 1 at the view field sampling points in the optimized design. The transfer functions of the system at 20 deg.C, -40 deg.C, -20 deg.C, 0 deg.C, 30 deg.C, 50 deg.C, and 70 deg.C are shown in FIGS. 2, 3, 4, 5, 6, 7, and 8, respectively (the structural material is aluminum, and the expansion coefficient is set to 23.5X 10-6/K). The field-of-view transfer function 0 is greater than 0.5,0.7 at 30lp/mm and greater than 0.45,1 at 30lp/mm and greater than 0.4. The distortion of the system is shown in fig. 9, with a relative distortion of less than 5%. At an imaging distance of 2m, the transfer function of the system at normal temperature is shown in FIG. 10, and the transfer function of each field of view is greater than 0.6 at 8 lp/mm. The system luminance is shown in fig. 11, and the relative luminance in the full field of view is greater than 78%.
The profile of the diffraction element is as shown in fig. 12, the total number of the grating periods is 180 in the range of the clear aperture, the minimum grating period is 180 μm, the step depth is 3.333 μm, and the current diamond turning process can complete the processing of the diffraction element. The diffraction efficiency of the diffraction optical element can reach 90%, and the energy of other diffraction orders does not exceed 10%. Because the focal power borne by the diffraction element is not large, the focal plane of the 0-order and + 2-order imaging is about 1.2mm away from the focal plane of the + 1-order imaging through simulation analysis, and therefore the multi-order diffraction order has little influence on imaging.
By utilizing a secondary imaging mode, the system distortion is effectively controlled in the design of the large-field-of-view infrared optical system. The large-field-of-view infrared optical system can be divided into a primary imaging lens group and a subsequent imaging lens group. Firstly, a target is imaged on an intermediate image surface through a primary imaging lens group, and then the intermediate image surface is imaged to a final image surface through a subsequent imaging lens group. Distortion must exist during primary imaging of a large visual field, generally positive distortion exists, negative distortion can be introduced into a subsequent lens group, so that the distortion of the primary imaging lens group and the distortion of the subsequent lens group are mutually offset, and the design of the infrared optical system with small distortion and the large visual field is realized.
The traditional refraction-diffraction mixed optical imaging system can effectively correct chromatic aberration and thermal aberration. The invention provides a refraction-diffraction mixed cooperative optimization method for controlling chromatic aberration, thermal aberration and distortion. The method is characterized in that a diffraction surface is introduced into an optical system, and an evaluation function is set to control a phase expression coefficient of the diffraction surface, so that the focal power of the diffraction surface meets the requirements of correcting chromatic aberration and thermal difference of the system, the heights of principal rays of different fields of view reaching an image surface are effectively controlled, and the design of an infrared refraction and diffraction mixed optical system with small distortion is realized.
The working principle is as follows: when the system is used, the entrance pupil of the optical system is placed at 28mm of the front end of the optical system, so that the plane reflector is placed at the entrance pupil, infrared target imaging in a 180-degree half-space range is realized by the smallest reflector size through scanning of the plane reflector, the working waveband of the system is 8-12 microns, the focal length is 8.8mm, the F # is 1, the full field of view is 82 degrees, the distortion is less than 5 percent, and infrared target imaging in a 180-degree field of view can be realized as long as the size of the scanning reflector is greater than 60 mm.
While certain exemplary embodiments of the present invention have been described above by way of illustration only, it will be apparent to those of ordinary skill in the art that the described embodiments may be modified in various different ways without departing from the spirit and scope of the invention. Accordingly, the drawings and description are illustrative in nature and should not be construed as limiting the scope of the invention.
Claims (6)
1. The utility model provides an infrared optical imaging system of external big visual field small distortion long wave of entrance pupil, includes imaging system, its characterized in that, imaging system is provided with the multi-disc lens, the multi-disc the lens is first lens, second lens, third lens, fourth lens, fifth lens and sixth lens in proper order, the rear surface of first lens, the rear surface of third lens and the rear surface of fourth lens are high order aspheric surface, the rear surface of sixth lens is the diffraction face of stack on the aspheric surface.
2. The external entrance pupil imaging system with the large field of view and the small distortion long-wavelength infrared optical system according to claim 1, wherein the imaging system comprises a diffractive element, a total of 180 grating periods are arranged in the range of the clear aperture of the diffractive element, the minimum grating period of the grating periods is 180 μm, and the step depth of the grating periods is 3.333 μm.
3. The external entrance pupil large field of view small distortion long wavelength infrared optical imaging system of claim 1, further comprising a large field of view infrared optical system for controlling system distortion, said large field of view infrared optical system comprising an imaging lens group and a subsequent imaging lens group.
4. The infrared optical imaging system with large field of view and small distortion of claim 1, further comprising an entrance pupil and an optical system, wherein the entrance pupil is located at a distance of 28mm from the front surface of the optical system, the entrance pupil is located at a distance of 25mm from the outer end surface of the lens structure, and the aperture of the entrance pupil is 17mm.
5. The system of claim 1, wherein the first, second, fourth and fifth lenses are made of the same material.
6. The external-entrance-pupil long-wavelength infrared optical imaging system with large field of view and small distortion as claimed in claim 1, further comprising a hybrid diffractive optical imaging system for correcting chromatic and thermal aberrations, wherein a diffractive surface is disposed in the hybrid diffractive optical imaging system, and the phase expression coefficients of the diffractive surface are controlled by the evaluation function.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211030095.2A CN115327752A (en) | 2022-08-26 | 2022-08-26 | Large-view-field small-distortion long-wave infrared optical imaging system with external entrance pupil |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211030095.2A CN115327752A (en) | 2022-08-26 | 2022-08-26 | Large-view-field small-distortion long-wave infrared optical imaging system with external entrance pupil |
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| CN115327752A true CN115327752A (en) | 2022-11-11 |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1766690A (en) * | 2004-10-28 | 2006-05-03 | 清华大学 | Micro Camera Lens System |
| CN1844958A (en) * | 2006-04-29 | 2006-10-11 | 杭州照相机械研究所 | Aspherical diffraction optical lens |
| CN202794679U (en) * | 2012-04-24 | 2013-03-13 | 中国电子科技集团公司第十一研究所 | Infrared double waveband confocal optical system and confocal plane infrared double waveband detector |
| CN104297898A (en) * | 2013-11-28 | 2015-01-21 | 中国航空工业集团公司洛阳电光设备研究所 | Large-field double-wave harmonic diffractive infrared optical system |
| CN109343201A (en) * | 2018-11-07 | 2019-02-15 | 中国航空工业集团公司洛阳电光设备研究所 | The low distortion wide-angle long wave uncooled ir optical system of PASSIVE OPTICAL athermal |
| CN113433677A (en) * | 2021-05-25 | 2021-09-24 | 中国科学院西安光学精密机械研究所 | Refrigeration type double-view-field infrared optical system with external entrance pupil |
| CN216696831U (en) * | 2022-01-12 | 2022-06-07 | 云南北方光电仪器有限公司 | Optical passive athermal optical system for uncooled long-wave infrared imaging |
-
2022
- 2022-08-26 CN CN202211030095.2A patent/CN115327752A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1766690A (en) * | 2004-10-28 | 2006-05-03 | 清华大学 | Micro Camera Lens System |
| CN1844958A (en) * | 2006-04-29 | 2006-10-11 | 杭州照相机械研究所 | Aspherical diffraction optical lens |
| CN202794679U (en) * | 2012-04-24 | 2013-03-13 | 中国电子科技集团公司第十一研究所 | Infrared double waveband confocal optical system and confocal plane infrared double waveband detector |
| CN104297898A (en) * | 2013-11-28 | 2015-01-21 | 中国航空工业集团公司洛阳电光设备研究所 | Large-field double-wave harmonic diffractive infrared optical system |
| CN109343201A (en) * | 2018-11-07 | 2019-02-15 | 中国航空工业集团公司洛阳电光设备研究所 | The low distortion wide-angle long wave uncooled ir optical system of PASSIVE OPTICAL athermal |
| CN113433677A (en) * | 2021-05-25 | 2021-09-24 | 中国科学院西安光学精密机械研究所 | Refrigeration type double-view-field infrared optical system with external entrance pupil |
| CN216696831U (en) * | 2022-01-12 | 2022-06-07 | 云南北方光电仪器有限公司 | Optical passive athermal optical system for uncooled long-wave infrared imaging |
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