Medium-wave infrared pixel-level spectral polarization optical system

Abstract

The utility model discloses a medium-wave infrared pixel-level spectral polarization optical system, which belongs to the field of lenses and comprises a refraction lens group, a cold diaphragm, a super-structure micro-lens array and a medium-wave infrared quantum dot detector which are sequentially arranged along an incident light path. The super-structure micro-lens array comprises an object side micro-structure and an image side micro-structure; the image side microstructure is used for realizing focusing; the object side microstructure comprises a plurality of object side units which are periodically distributed; each object side unit comprises a polarization metal wire grating structure and a plurality of metasurface-microcavity structures; the polarization metal wire grating structure is formed by arranging metal wire gratings according to different directions so as to realize detection of different orthogonal polarization states; the metasurface-microcavity structure comprises a middle dielectric layer, distributed Bragg gratings located on the two sides of the middle dielectric layer and a metasurface columnar structure unit array embedded into the middle dielectric layer, and the metasurface columnar structure unit array is used for achieving filtering of light of different wave bands. The system has the advantages of good imaging quality, small size, real-time imaging and the like.

Description

Technical Field

[0001] The utility model belongs to the field of lenses, and more specifically relates to a medium-wave infrared pixel-level spectral polarization optical system. Background Art

[0002] Infrared spectral polarization imaging technology aims to capture irradiance, spectrum, and polarization information and convert them into visible images. The traditional infrared spectral polarization imaging system composed of optical lenses is widely used in various fields, such as night reconnaissance in the military field, infrared guidance, missile warning, and industrial detection.

[0003] Infrared spectral polarization imaging technology combines the imaging and spectral polarization acquisition functions into one, realizing the integration of camera, spectrometer and polarimeter functions. Limited by the complexity of infrared imaging system design, the existing infrared spectral polarization imaging technology often needs to compromise between system size and spectral spatial resolution. The introduction of meta-lens is expected to simplify the design of optical systems and reduce the weight, volume and cost of infrared spectral polarization cameras. At the same time, metasurface technology can accurately control the propagation characteristics of light waves through artificially set microstructures, and can achieve fine manipulation of multi-dimensional parameters such as wavefront, polarization, and phase of light. It is very suitable for the development of snapshot miniaturized imagers that can simultaneously obtain target imaging, spectral and polarization information. Promote the development of infrared spectral polarization imaging technology towards higher performance and wider application.

[0004] Limited by the complexity of infrared optical system design, there is still a lack of miniaturized infrared-band snapshot spectral polarization imaging cameras. Existing miniaturized spectral polarization imaging cameras often work in the visible band and require customized corresponding optical systems. For example, patent CN211401424U discloses a portable snapshot array polarization multi-spectral imager, which consists of a customized optical detection component with multiple channels off-axis. It has the disadvantages of complex design, high actual assembly requirements, and poor mobility, which limits its practical application in optical systems. Therefore, how to design an infrared spectral polarization imaging device with high imaging quality and small size is of great research significance. Utility Model Content

[0005] In view of the defects of the prior art and the need for improvement, the utility model provides a medium-wave infrared pixel-level spectral polarization optical system, which aims to meet the requirements of the spectral polarization imaging optical system for good imaging quality, small size, and real-time imaging.

[0006] To achieve the above-mentioned purpose, the utility model provides a medium-wave infrared pixel-level spectral polarization optical system, comprising: a refractive lens group, a cold aperture, a meta-microlens array and a medium-wave infrared quantum dot detector arranged in sequence along the incident light path; the meta-microlens array comprises an object side microstructure and an image side microstructure; the image side microstructure is used to achieve focusing; the object side microstructure comprises a plurality of periodically distributed object side units; for each of the object side units, a polarization metal wire grid structure and a plurality of metasurface-microcavity structures are included; the polarization metal wire grid structure is formed by metal wire grids arranged in different directions to achieve detection of different orthogonal polarization states; the metasurface-microcavity structure comprises an intermediate dielectric layer, distributed Bragg gratings located on both sides of the intermediate dielectric layer, and a metasurface columnar structure unit array embedded in the intermediate dielectric layer, and the metasurface columnar structure unit array is used to achieve filtering of light of different wavelength bands.

[0007] Furthermore, for each of the object-side units, the distribution of the polarization metal wire grid structure and the plurality of metasurface-microcavity structures is used to realize n×n pixels, where n is a set value within [3,6].

[0008] Furthermore, in the polarization metal wire grid structure, the metal wire grids are arranged in directions of 0°, 45°, 90°, and 135°, and the metal wire grid in the 0° direction is adjacent to the metal wire grid in the 135° direction, so as to realize detection of two different orthogonal polarization states.

[0009] Furthermore, the metasurface columnar structure unit array includes multiple metasurface columnar structure units, which are arranged in a tetragonal lattice periodic array or a hexagonal lattice periodic array, and each metasurface columnar structure unit has the same height and different cross-sectional dimensions to achieve filtering of light in different bands.

[0010] Furthermore, the distributed Bragg grating is composed of a L The first medium has a thickness of λ / 2n H The second medium is stacked alternately, where λ is the wavelength of the light wave in vacuum, n L is the refractive index of the first medium, n H is the refractive index of the second medium, n L <n H .

[0011] Furthermore, the medium-wave infrared quantum dot detector includes periodically arranged pixels, and the pixel size and arrangement method correspond to the meta-microlens array; the image side microstructure includes periodically arranged pixel units, which are used to focus the incident light to the corresponding pixels of the medium-wave infrared quantum dot detector.

[0012] Furthermore, the phase distribution of the pixel unit in the image side microstructure is satisfy:

[0013]

[0014] ρ≤D

[0015] Among them, λ is the wavelength of light wave in vacuum, f is the radial coordinate of the metasurface within the pixel unit, ρ is the effective focal length of the metastructure microlens array, and D is the size of the pixel unit.

[0016] Furthermore, the refractive lens group has a positive focal length and includes one or more lenses.

[0017] Furthermore, the material of the lens is silicon, germanium, zinc selenide, barium fluoride, magnesium fluoride, sapphire or chalcogenide glass.

[0018] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0019] (1) A pixel-level spectral polarization optical system for mid-wave infrared is provided. The image-side microstructure in the designed meta-microlens array can simultaneously realize the detection of different orthogonal polarization states and the filtering of light in different bands. The refractive lens group is combined with the meta-microlens array to realize the analysis of multi-dimensional parameters of the incident light. The imaging and spectral polarization acquisition functions can be well combined into one, realizing the integration of the camera, spectrometer and polarimeter functions, and significantly reducing the volume of the optical system.

[0020] (2) For the pixel-level spectral polarization optical system of the mid-wave infrared, advanced semiconductor technology can be used to integrate the dielectric substrate layer with a metal wire grid structure and the metasurface-microcavity structure on the front side of the substrate, and the microstructure can be used to achieve pixel-level focusing on the back side of the substrate, and then aligned with the sensor and packaged. There is no need to introduce additional polarization selection and spectral filtering devices in the optical system. Instead, the meta-structured microlens array can be directly assembled in front of the detector target. While reducing the volume of the system, the meta-structured microlens array focuses the light at the pixel level through the microstructure, thereby increasing the light energy collection efficiency of the system and improving the imaging sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of a medium-wave infrared pixel-level spectral polarization optical system provided by an embodiment of the utility model;

[0022] Figure 2 A schematic diagram of ray tracing of a medium-wave infrared pixel-level spectral polarization optical system provided by an embodiment of the utility model;

[0023] Figure 3A schematic diagram of a supersurface-microcavity structure provided by an embodiment of the utility model;

[0024] Figure 4 A schematic diagram of a polarization metal wire grid structure provided by an embodiment of the utility model;

[0025] Figure 5 The focus spot of a single pixel in the super-structured microlens array provided in the embodiment of the utility model on the focal plane;

[0026] Figure 6 An arrangement of object-side microstructures in a superstructure microlens array provided in an embodiment of the utility model;

[0027] Figure 7 Another arrangement of the object-side microstructures in the superstructure microlens array provided in an embodiment of the utility model;

[0028] Figure 8 A schematic diagram showing how the transmission spectrum of a metasurface-microcavity structure provided by an embodiment of the present utility model varies with the width of a nanocolumn;

[0029] Fig. 9 MTF curve diagram of the pixel-level spectral polarization optical system of the medium-wave infrared provided by the embodiment of the utility model;

[0030] Fig.10 A light spot array diagram of a medium-wave infrared pixel-level spectral polarization optical system provided by an embodiment of the utility model.

[0031] In all drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0032] 1 is a refractive lens group, 2 is a cold aperture, 3 is a meta-microlens array, 31 is an object side microstructure, 32 is an image side microstructure, and 4 is a medium-wave infrared quantum dot detector. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0034] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0035] Figure 1A schematic diagram of the structure of a medium-wave infrared pixel-level spectral polarization optical system provided by an embodiment of the utility model. Figure 1 , combined with Figure 2-Figure 9 , a detailed description of the pixel-level spectro-polarization optical system for mid-wave infrared is given.

[0036] The pixel-level spectral polarization optical system of the medium-wave infrared comprises: a refractive lens group 1, a cold aperture 2, a super-structured microlens array 3 and a medium-wave infrared quantum dot detector 4 arranged in sequence along the incident light path. The super-structured microlens array 3 comprises an object side microstructure 31 and an image side microstructure 32. The image side microstructure 32 is used to achieve focusing.

[0037] The object-side microstructure 31 includes a plurality of periodically distributed object-side units. For each object-side unit, a polarization metal wire grid structure and a plurality of metasurface-microcavity structures are included. The polarization metal wire grid structure is formed by arranging metal wire grids in different directions to realize detection of different orthogonal polarization states. The metasurface-microcavity structure includes an intermediate dielectric layer, a distributed Bragg grating located on both sides of the intermediate dielectric layer, and a metasurface columnar structure unit array embedded in the intermediate dielectric layer, and the metasurface columnar structure unit array is used to realize filtering of light of different wavelength bands.

[0038] See also Figure 1 , from left to right is the direction from the object side to the image side. The pixel-level spectral polarization optical system of the medium-wave infrared includes a refractive lens group 1, a cold aperture 2, a meta-microlens array 3 and a medium-wave infrared quantum dot detector 4 arranged in sequence. The light tracing in the system is shown in FIG. Figure 2 As shown. The meta-microlens array 3 is used to obtain spectral polarization intensity information and improve light energy collection efficiency. The meta-microlens array 3 is encapsulated near the mid-wave infrared quantum dot detector 4. The resulting mid-wave infrared pixel-level spectral polarization optical system is further reduced in size compared to the existing snapshot spectral polarization imaging system, and is applicable to any optical system that matches the detector.

[0039] The refractive lens group 1 is a front refractive lens group with a positive focal length, including one or more lenses, which are used to correct the aberration in the system and focus the light before emitting it. Preferably, the material of the lens is silicon, germanium, zinc selenide, barium fluoride, magnesium fluoride, sapphire or chalcogenide glass. When the refractive lens group includes multiple lenses, the materials of each lens can be the same or different.

[0040] The cold diaphragm 2 serves as an aperture diaphragm, and its material is a high-transmittance material, such as silicon, germanium, zinc selenide, barium fluoride, calcium fluoride, magnesium fluoride or sapphire.

[0041] The meta-microlens array 3 is a double-sided meta-lens array structure, with periodic microstructures in units of pixels arranged on both the object side and the image side, respectively forming an object side microstructure 31 and an image side microstructure 32. The periodic microstructure units in units of pixels in the object side microstructure 31 have narrowband filtering functions of different bands and different polarization state selection functions; the periodic microstructure units in the image side microstructure 32 have the function of focusing the incident light onto the mid-wave infrared quantum dot detector 4.

[0042] Preferably, in the polarization metal wire grid structure, the metal wire grids are arranged in the directions of 0°, 45°, 90°, and 135°, and the metal wire grid in the 0° direction is adjacent to the metal wire grid in the 135° direction, so as to realize detection of two different orthogonal polarization states, such as Figure 4 The metal wire grid is formed by a plurality of long columnar metal microstructures arranged periodically in the form of a wire grid.

[0043] In the metasurface-microcavity structure, the metasurface columnar structure unit array includes a plurality of metasurface columnar structure units, and the plurality of metasurface columnar structure units are arranged in a tetragonal lattice periodic array or a hexagonal lattice periodic array. The heights of the metasurface columnar structure units are the same and the cross-sectional dimensions are not completely the same. The metasurface columnar structure units with different cross-sectional dimensions can achieve filtering of light of different wavelength bands. The shape of the metasurface columnar structure unit is, for example, cylindrical, square, or diamond. The height of each metasurface columnar structure unit is between the wavelength of the incident light, and the diameter and period are between the sub-wavelength order. The metasurface-microcavity structure is as follows: Figure 3 shown.

[0044] The distributed Bragg grating consists of a L The first medium has a thickness of λ / 2n H The second medium is stacked alternately, where λ is the wavelength of the light wave in vacuum, n L is the refractive index of the first medium, n H is the refractive index of the second medium, n L <n H .

[0045] The metasurface-microcavity structure also includes a dielectric substrate layer, and the intermediate dielectric layer, the distributed Bragg grating, and the metasurface columnar structure unit array are all located on the same side of the dielectric substrate layer. The material of the metasurface columnar structure unit is, for example, silicon or silicon dioxide; the material of the distributed Bragg grating is, for example, infrared high refractive index material silicon or germanium, or low refractive index material silicon dioxide. The distributed Bragg grating is, for example, formed by alternating stacking of multiple periods of silicon dioxide-silicon layers.

[0046] Phase distribution of pixel units in the image side microstructure 32 satisfy:

[0047]

[0048] ρ≤D

[0049] Wherein, λ is the wavelength of light in vacuum, f is the radial coordinate of the metasurface in the pixel unit, ρ is the effective focal length of the meta-microlens array 3, and D is the size of the pixel unit. The focal length of the pixel unit in the image side microstructure 32 is, for example, 30 μm.

[0050] Preferably, for each object-side unit, the polarization metal wire grid structure and the distribution of multiple metasurface-microcavity structures are used to realize n×n pixels, where n is a set value in [3,6]. Figure 6 As shown, the sub-band filtering and sub-polarization functions of different pixels are repeated in 3×3 pixels, and the size of each pixel is 30μm, which correspondingly realizes different orthogonal polarization state detection and filtering of light in different bands; or, as Figure 7 As shown, the sub-band filtering and sub-polarization functions of different pixels are repeated in a cycle of 4×4 pixels.

[0051] The mid-wave infrared quantum dot detector 4 includes periodically arranged pixels, and the pixel size and arrangement correspond to the super-microlens array 3. The image-side microstructure 32 includes periodically arranged pixel units, which are used to focus the incident light to the corresponding pixel of the mid-wave infrared quantum dot detector 4. The super-microlens array 3 is placed close to the mid-wave infrared quantum dot detector 4, so that each pixel of the mid-wave infrared quantum dot detector 4 can obtain spectral polarization information with a high signal-to-noise ratio. The focal spot of a single pixel in the super-microlens array 3 on the focal plane of the mid-wave infrared quantum dot detector 4 is as follows: Figure 5 shown. Figure 5 In the figure, the three focused spots from left to right are the intensity of the focused spots at 30 μm in the focal plane at wavelengths of 3.7 μm, 4.25 μm, and 4.8 μm, respectively.

[0052] Further preferably, in the pixel-level spectral polarization optical system of the medium-wave infrared, a double-sided metal lens can be arranged between the refractive lens group 1 and the cold aperture 2. The refractive lens group 1, the double-sided metal lens and the cold aperture 2 constitute an optical lens for converging the incident light, filtering out stray light and focusing on the focal plane of the medium-wave infrared quantum dot detector 4.

[0053] The pixel-level spectral polarization optical system of the mid-wave infrared is explained below with reference to specific examples.

[0054] The pixel size of the medium-wave infrared quantum dot detector 4 used in this embodiment is 30 μm, and the number of pixels (resolution) is 320×256. The spectral transmittance of each narrowband filter (metasurface-microcavity structure) is as follows: Figure 8As shown. The central wavelengths of the five spectral pixels in the super-structured microlens array 4 selected in this embodiment are 3.9μm, 4.1μm, 4.3μm, 4.5μm, and 4.7μm respectively; the metal wire grids of adjacent polarization pixels are arranged in the directions of 0°, 45°, 90°, and 135°. The pixel-level spectral polarization optical system for mid-wave infrared provided in this embodiment is designed to realize multi-dimensional detection in the mid-infrared band of 3-5μm with a central wavelength of 4.25μm. The system volume does not exceed 40×30mm, the weight does not exceed 150g, the field of view angle is 10°×8°, the thermal difference is -40℃-+70℃, the F number is 2, the full field of view distortion is <2%, MTF≥0.3@33lp, and the effective focal length is 55mm.

[0055] In this embodiment, an aspherical refractive lens and a meta-lens are used as the refractive lens group 1. The parameters of the object side surface (first aspherical surface) of the aspherical refractive lens are, for example: cone coefficient 0.337, fourth-order coefficient -1.221×10 -6 , Sixth-order coefficient -1.208×10 -8 , eighth-order coefficient -1.133×10 -12 The parameters of the image side surface (second aspheric surface) of the aspheric refractive lens are, for example: cone coefficient 1.185, fourth-order coefficient -6.448×10 -7 , Sixth-order coefficient -4.436×10 -8 , eighth-order coefficient -7.515×10 -11 The parameters of the object side (first binary surface) of the meta-lens are, for example: 2 =12.830,ρ 4 =-0.418, ρ 6 =-1.134×10 -3 , 8 =2.325×10 -5 The parameters of the image side surface (second binary surface) of the meta-lens are, for example: 2 =12.187,ρ 4 =0.452, ρ 6 =2.041×10 -3 , 8 =-3.545×10 -5 Other parameters of the refractive lens group 1 and the cold stop 2 are shown in Table 1.

[0056] Table 1

[0057]

[0058]

[0059] The parameters of the metasurface-microcavity structure in the metastructure microlens array in this embodiment are shown in Table 2. The height of the silicon pillars between the various metasurface columnar structure units is the same, only the width of the silicon pillars is different, and the rest of the microcavity structures are exactly the same. In Table 2, the film layer No. 8 includes two parts, one part is the SiO2 dielectric layer, and the other part is the silicon pillar embedded in the SiO2 dielectric layer.

[0060] Table 2

[0061]

[0062] The MTF curves of the medium-wave infrared pixel-level spectral polarization imaging camera optical system provided by the embodiment of the utility model working at -40°C, 27°C, and 70°C are as follows: Fig. 9 As shown, Fig. 9 The three MTF curves from top to bottom are the MTF curves of the system working at -40℃, 27℃, and 70℃. At the cutoff frequency of 33lp / mm, the MTF values ​​in all fields of view are higher than 0.38. For the range of -40℃-70℃, the MTF curves all reach the performance of about 0.35@33lp / mm, and the MTF curves are close to the diffraction limit. The system point diagram is shown in Fig.10 As shown, the RMS radius is less than 35 μm, achieving near-diffraction-limited imaging.

[0063] In this embodiment, the meta-microlens array 3 in the optical system of the medium-wave infrared pixel-level spectral polarization imaging camera can be designed by the following method, and the specific process is as follows.

[0064] The dimensional parameters of the polarization metal wire grid structure in the object-side microstructure 31 are simulated using the time-domain finite-difference algorithm to determine the corresponding relationship between the material, grating layer thickness, period, duty cycle of the polarization metal wire grid structure and the polarization state, extinction ratio, and transmittance of the output light, and the light field distribution on the output surface is simulated and calculated based on this.

[0065] The transfer matrix method is used to calculate the metasurface-microcavity structure parameters. The finite-difference time-domain algorithm is then used to simulate the metasurface-microcavity structure parameters, determine the relationship between the material, thickness, microcavity length, width and height of the distributed Bragg gratings on both sides and the spectral transmittance, and then simulate and calculate the light field distribution of the output surface.

[0066] The light field distribution passing through the object side microstructure 31 is projected onto the image side microstructure 32 , and the focal spot information of a single pixel superlens at the focal plane in the image side microstructure 32 array is obtained according to the phase distribution simulation of the image side microstructure 32 .

[0067] The medium-wave infrared pixel-level spectral polarization optical system provided by the embodiment of the utility model adopts the form of combining a refractive lens group with a multi-dimensional hybrid meta-microlens array, thereby realizing the analysis of multi-dimensional parameters of the incident light, and can well combine the imaging and spectral polarization acquisition functions into one, realizing the integration of the functions of the camera, spectrometer and polarimeter, and significantly reducing the volume of the optical system, which is easy to install and adjust.

[0068] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pixel-level spectral polarization optical system for mid-wave infrared, characterized in that: include: A refractive lens group (1), a cold aperture (2), a meta-microlens array (3) and a medium-wave infrared quantum dot detector (4) are sequentially arranged along an incident light path; The metastructure microlens array (3) comprises an object side microstructure (31) and an image side microstructure (32); the image side microstructure (32) is used to achieve focusing; The object-side microstructure (31) comprises a plurality of periodically distributed object-side units; each of the object-side units comprises a polarization metal wire grid structure and a plurality of super-surface-microcavity structures; The polarization metal wire grid structure is formed by arranging metal wire grids in different directions to achieve detection of different orthogonal polarization states; The metasurface-microcavity structure includes an intermediate dielectric layer, distributed Bragg gratings located on both sides of the intermediate dielectric layer, and a metasurface columnar structure unit array embedded in the intermediate dielectric layer, wherein the metasurface columnar structure unit array is used to achieve filtering of light of different wavelength bands.

2. The medium-wave infrared pixel-level spectral polarization optical system according to claim 1, characterized in that: For each of the object-side units, the distribution of the polarization metal wire grid structure and the multiple metasurface-microcavity structures is used to realize n×n pixels, where n is a set value in [3,6].

3. The medium-wave infrared pixel-level spectral polarization optical system according to claim 1, characterized in that: In the polarization metal wire grid structure, the metal wire grids are arranged in directions of 0°, 45°, 90°, and 135°, and the metal wire grid in the 0° direction is adjacent to the metal wire grid in the 135° direction, so as to realize detection of two different orthogonal polarization states.

4. The pixel-level spectral polarization optical system for medium-wave infrared according to claim 1, characterized in that: The supersurface columnar structure unit array includes multiple supersurface columnar structure units, which are arranged in a tetragonal lattice periodic array or a hexagonal lattice periodic array. The heights of the supersurface columnar structure units are the same and the cross-sectional dimensions are not completely the same, so as to achieve filtering of light in different bands.

5. The pixel-level spectral polarization optical system for mid-wave infrared according to claim 1, characterized in that: The distributed Bragg grating has a thickness of λ / 2n L The first medium has a thickness of λ / 2n H The second medium is stacked alternately, where λ is the wavelength of the light wave in vacuum, n L is the refractive index of the first medium, n H is the refractive index of the second medium, n L <n H .

6. The medium-wave infrared pixel-level spectral polarization optical system according to any one of claims 1 to 5, characterized in that: The medium-wave infrared quantum dot detector (4) comprises periodically arranged pixels, and the pixel size and arrangement method correspond to the superstructure microlens array (3); The image-side microstructure (32) comprises periodically arranged pixel units, which are used to focus incident light onto corresponding pixels of the medium-wave infrared quantum dot detector (4).

7. The pixel-level spectral polarization optical system for mid-wave infrared according to claim 6, characterized in that: Phase distribution of pixel units in the image side microstructure (32) satisfy: ρ≤D Wherein, λ is the wavelength of light in vacuum, f is the radial coordinate of the metasurface within the pixel unit, ρ is the effective focal length of the metastructure microlens array (3), and D is the size of the pixel unit.

8. The mid-wave infrared pixel-level spectral polarization optical system according to claim 1, characterized in that: The refractive lens group (1) has a positive focal length and comprises one or more lenses.

9. The medium-wave infrared pixel-level spectral polarization optical system according to claim 8, characterized in that: The material of the lens is silicon, germanium, zinc selenide, barium fluoride, magnesium fluoride, sapphire or chalcogenide glass.

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