Intermediate infrared scene projection system design method and device, and storage medium

Abstract

The invention discloses a mid-infrared scene projection system design method and device, and a storage medium, relates to the technical field of infrared scene projection, and solves the problem of transverse chromatic aberration caused by a double-DMD-based mid-infrared scene projector. An RTIR prism, a first prism and a second prism are constructed and optimized to form a trapezoidal prism, the first prism and the second prism are triangular prisms made of different materials, an incident angle of a light beam entering the first prism is determined on the basis that the emergent light beam enters a DMD target surface at an angle of 30 degrees, and an ATIR prism is obtained; after entering the ATIR prism, a light beam is transmitted through the first prism and the second prism and then is emitted to the target surface of the DMD, the light beam vertically reflected by the target surface of the DMD is totally emitted on the contact surface of the first prism and the second prism, and the central light of the light beam is emitted along a projection optical axis; based on an ATIR prism, an intermediate infrared scene projection system is designed. The method is used for reducing the transverse chromatic aberration generated by the medium-wave infrared illumination light beam on the DMD target surface.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared scene projection, and particularly to a design method, device and storage medium for a mid-infrared scene projection system. Background Art

[0002] In the technical field of infrared scene projection, DMD (Digital Micromirror Device) has become the core component of a mid-wave infrared hardware-in-the-loop simulation system due to its advantages such as full-band compatibility and high-frame-rate projection. Currently, mid-wave infrared scene simulation systems often adopt a split structure, that is, the illumination system and the projection system are designed independently. The key component connecting the illumination system and the projection system often uses a TIR (Total Internal Reflection) prism with a "reflection first and then transmission" structure. Such a device only passes through a prism of one material before the mid-wave infrared beam enters the DMD target surface, which causes obvious lateral chromatic aberration of the mid-infrared wave emitted by the light source on the DMD target surface. To solve this problem, a doublet lens is often used to reduce the impact of chromatic aberration on the projection quality. However, this method will inevitably increase the complexity of the projection system and lead to higher manufacturing costs.

[0003] In the prior art, Chinese patent document CN117706851A discloses "a dual-optical-path co-aperture projection optical engine with double internal total reflection prism beam splitting", and the optical engine includes: a projection optical system, a first digital micromirror device and a second digital micromirror device for loading image information on the illumination incident beam; a first internal total reflection prism and a second internal total reflection prism for increasing the angle between the illumination axis and the projection axis and isolating the mirror on-state and off-state beams of the digital micromirror device; a first illumination optical system and a second illumination optical system, the optical axes of which are collinear with the central normal of the incident surface of the internal total reflection prism and improve the illumination uniformity of the digital micromirror device. However, the internal total reflection prism adopted in this technical solution will cause obvious lateral chromatic aberration of the mid-infrared wave emitted by the light source on the DMD target surface.

[0004] In summary, the mid-infrared scene projection system in the prior art has caused the problem of lateral chromatic aberration on the DMD target surface due to its relatively wide working band. Summary of the Invention

[0005] The present invention solves the problem of lateral chromatic aberration on the DMD target surface caused by the relatively wide working band of the mid-infrared scene projection system in the prior art.

[0006] The design method of the mid-infrared scene projection system described in the present invention includes the following steps: Step 1, construct an RTIR prism; Step 2: Optimize the RTIR prism. The first prism and the second prism are combined into a trapezoidal prism through an air gap. The first prism and the second prism are triangular prisms made of different materials. Based on the mid-wave infrared outgoing beam of the RTIR prism entering the DMD target surface at 30°, determine the prism angle of the first prism to obtain the ATIR prism; After the mid-wave infrared beam enters the ATIR prism, it is transmitted through the first prism and the second prism respectively. After entering the DMD target surface from the exit surface of the second prism, the mid-wave infrared beam vertically reflected by the DMD target surface undergoes total internal reflection at the contact surface of the first prism and the second prism, and the central ray of the mid-wave infrared beam exits along the projection optical axis; Step 3: Design a mid-infrared scene projection system based on the ATIR prism described in Step 2.

[0007] Furthermore, in the embodiment of the present invention, the optimization of the RTIR prism in Step 2 is specifically as follows: Step 21: Based on the mid-wave infrared outgoing beam of the RTIR prism entering the DMD target surface at 30°, obtain the value range of the refractive index of the second prism; Step 22: According to the value range of the refractive index of the second prism, determine the material of the first prism, the material of the second prism, and the prism angle of the first prism respectively.

[0008] Furthermore, in the embodiment of the present invention, the prism angle of the first prism is 29.34°, and the material of the first prism is calcium fluoride.

[0009] Furthermore, in the embodiment of the present invention, the material of the second prism is lead difluoride.

[0010] Furthermore, in the embodiment of the present invention, the mid-infrared scene projection system in Step 3 adopts a dual-path common-aperture optical structure, including a first optical path system, a second optical path system, a beam combining prism, and a common-aperture device; The beam combining prism combines the beams output by the first optical path system and the second optical path system to obtain a combined beam, and the common-aperture device is used to project the combined beam.

[0011] Furthermore, in the embodiment of the present invention, the first optical path system includes a first mid-wave infrared beam illumination system, a first DMD target surface, a first window glass, and a first ATIR prism arranged in sequence; The second optical path system includes a second mid-wave infrared beam illumination system, a second DMD target surface, a second window glass, and a second ATIR prism arranged in sequence along the optical path; The first optical path system is specifically: The first mid-wave infrared beam illumination system emits a mid-wave infrared beam to the first ATIR prism. The first ATIR prism refracts the mid-wave infrared beam through the first window glass to the first DMD target surface, and the first DMD target surface loads the image information of the mid-wave infrared beam. The second optical path system repeats the operation of the first optical path system.

[0012] Furthermore, in the embodiment of the present invention, the common aperture device includes a first double concave lens, a second double convex lens, a third meniscus lens, a fourth meniscus lens, and a projection exit pupil that are sequentially placed. The combined beam sequentially passes through the first double concave lens and the second double convex lens for aberration correction. After the third meniscus lens and the fourth meniscus lens reduce the aperture of the combined beam after aberration correction, it is projected onto the projection exit pupil.

[0013] Furthermore, in the embodiment of the present invention, the field of view of the mid-infrared scene projection system is ±7°, F / # is 2.34, the exit pupil distance is 150 mm, and the exit pupil diameter is 60 mm.

[0014] An electronic device according to the present invention includes a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete mutual communication through the communication bus. The memory is used to store a computer program. The processor is used to implement the design method of the mid-infrared scene projection system described in any one of the above when executing the program stored on the memory.

[0015] A computer-readable storage medium according to the present invention stores a computer program therein, and when the computer program is executed by a processor, it implements the design method of the mid-infrared scene projection system described in any one of the above.

[0016] The present invention solves the problem of lateral chromatic aberration caused by the relatively wide working band of the mid-infrared scene projection system in the prior art on the DMD target surface. The specific beneficial effects include: The design method of the mid-infrared scene projection system according to the present invention reduces the chromatic aberration problem caused by the relatively wide working band on the DMD target surface by designing an ATIR (achromatic internal total reflection) prism with a "transmission first and reflection later" structure and using a combination of different prism materials. It mainly includes the design of the achromatic internal total reflection prism and the design of the projection lens group. The achromatic internal total reflection prism is composed of different materials, and the dispersion problem caused by the working wavelength is solved through the refractive index difference, and the prism angle is designed to ensure that the beam can enter the DMD target surface at a specific angle. The projection system design uses a combination of four lenses. The scene targets simulated by two groups of DMDs enter the projection lens group together after passing through the beam combining prism, realizing the design of a dual-optical-path common-aperture optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, where: Figure 1 is a schematic diagram of the type of beam splitting element described in Embodiment 1; Figure 2 is a working principle diagram of the ATIR prism described in Embodiment 1; Figure 3 is a comparison diagram of the dispersion conditions described in Embodiment 1; Figure 4 is a 3D optical path schematic diagram of the mid-infrared scene projection system described in Embodiment 1; Figure 5 is the surface serial number of each element of the mid-infrared scene projection system described in Embodiment 1; Figure 6 is the spot diagram situation of each field of view described in Embodiment 1; Figure 7 is the modulation transfer function curve of the field curvature distortion situation described in Embodiment 1; Figure 8 is the modulation transfer function curve described in Embodiment 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following will clearly and completely describe various embodiments of the present invention in conjunction with the accompanying drawings. The embodiments described by referring to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0019] Embodiment 1. The design method of the mid-infrared scene projection system described in this embodiment includes the following steps: Step 1, construct an RTIR (total internal reflection) prism; Step 2, optimize the RTIR prism. The first prism and the second prism are combined into a trapezoidal prism through an air gap. The first prism and the second prism are triangular prisms made of different materials. The mid-wave infrared outgoing beam based on the RTIR prism is incident on the DMD target surface at 30°, and the prism angle of the first prism is determined to obtain an ATIR prism; After the mid-wave infrared beam enters the ATIR prism, it is transmitted through the first prism and the second prism respectively. After entering the DMD target surface from the exit surface of the second prism, the mid-wave infrared beam vertically reflected by the DMD target surface undergoes total internal reflection at the contact surface of the first prism and the second prism, and the central ray of the mid-wave infrared beam exits along the projection optical axis; Step 3, design a mid-infrared scene projection system based on the ATIR prism described in Step 2.

[0020] In this embodiment, the optimization of the RTIR prism in Step 2 is specifically: Step 21: The mid-wave infrared outgoing beam based on the RTIR prism enters the DMD target surface at an angle of 30°, and the value range of the refractive index of the second prism is obtained. Step 22: According to the value range of the refractive index of the second prism, the material of the first prism, the material of the second prism, and the prism angle of the first prism are respectively determined.

[0021] In this embodiment, the prism angle of the first prism is 29.34°, and the material of the first prism is calcium fluoride.

[0022] In this embodiment, the material of the second prism is lead difluoride.

[0023] In this embodiment, the mid-wave infrared scene projection system in step 3 adopts a double-path common-aperture optical structure, including a first optical path system, a second optical path system, a beam-combining prism, and a common-aperture device. The beam-combining prism combines the beams output by the first optical path system and the second optical path system to obtain a combined beam, and the common-aperture device projects the combined beam.

[0024] In this embodiment, the first optical path system includes a first mid-wave infrared beam illumination system, a first DMD target surface, a first window glass, and a first ATIR prism arranged in sequence. The second optical path system includes a second mid-wave infrared beam illumination system, a second DMD target surface, a second window glass, and a second ATIR prism arranged in sequence along the optical path. The first optical path system is specifically: The first mid-wave infrared beam illumination system emits a mid-wave infrared beam to the first ATIR prism. The first ATIR prism refracts the mid-wave infrared beam through the first window glass to the first DMD target surface, and the first DMD target surface loads the image information of the mid-wave infrared beam. The second optical path system repeats the operation of the first optical path system.

[0025] In this embodiment, the common-aperture device includes a first bi-concave lens, a second bi-convex lens, a third meniscus lens, a fourth meniscus lens, and a projection exit pupil arranged in sequence. The combined beam passes through the first bi-concave lens and the second bi-convex lens in sequence for aberration correction. After the third meniscus lens and the fourth meniscus lens reduce the aperture of the combined beam after aberration correction, it is projected onto the projection exit pupil.

[0026] In this embodiment, the mid-wave infrared scene projection system has a field of view of ±7°, an F / # of 2.34, an exit pupil distance of 150 mm, and an exit pupil diameter of 60 mm.

[0027] In the mid-infrared scene projection system in the prior art, the relatively wide working band causes a lateral chromatic aberration problem on the DMD target surface. To solve the above technical problems, the present embodiment proposes a design method for a mid-infrared scene projection system, including the following steps: Step 1, construct an RTIR prism; According to the working characteristics of the DMD itself, the mid-wave infrared outgoing beam should be incident on the DMD target surface. In a spectroscopic optical system, this function is mainly realized by using a TIR prism, and the separation of the projection optical path and the illumination optical path is completed. When the mid-wave infrared beam is incident on the contact surface between the two prisms, the folding of the optical path is realized through total reflection. According to the different prism structures, it can be divided into, for example, Figure 1 the "reflect first then transmit" TIR prism shown on the left, and Figure 1 the "transmit first then reflect" RTIR prism shown on the right.

[0028] Step 2, design of the ATIR prism; Since the working band in the infrared band is relatively wide, a relatively serious lateral chromatic aberration will occur on the DMD target surface after the beam passes through a prism of a single material. Therefore, it is decided to complete the optimization of the RTIR prism through the combination of different materials on the basis of the RTIR prism design, that is, to complete the design of the ATIR prism. The ATIR prism: includes two triangular prisms of different materials, which can fold the optical path of the mid-wave infrared beam and reduce the lateral chromatic aberration generated on the DMD target surface.

[0029] During the design process of the ATIR prism, the mid-wave infrared beam should be able to completely cover the DMD target surface, and ensure that there is sufficient design margin for the angle of the ATIR prism. Therefore, the side length of the second prism parallel to the DMD target surface can be initially taken as 30 mm. The design of the ATIR prism angle is relatively critical. As Figure 2 can be seen from the working principle of the ATIR prism, the design of the ATIR prism angle needs to meet the following two points: 1. After the mid-wave infrared beam enters the ATIR prism, it can pass through the contact surface between the two prisms in a transmitted manner, and at the same time, the mid-wave infrared outgoing beam can be incident on the DMD target surface; 2. The mid-wave infrared beam reflected by the DMD target surface can undergo total reflection at the contact surface between the two prisms and exit along the projection optical axis direction.

[0030] Since the central ray of the mid-wave infrared beam reflected by the DMD target surface enters perpendicular to the surface of the second prism, therefore, only when the side cut surface of the second prism is an isosceles right triangle, that is, the prism angle is 45°, the central ray of the mid-wave infrared beam can exit along the projection optical axis. To meet the requirements of condition 1, it is necessary to find that when the illumination angle of the DMD target surface is When, the relationship between the prism angle A of the first prism and the incident angle of the mid-wave infrared beam entering the first prism is as follows.

[0031] Backward solving is carried out from the DMD target surface to the incident surface of the mid-wave infrared beam of the first prism. At the DMD target surface, according to the geometric relationship, it can be known that , and according to Snell's law of refraction, it can be known that: ; (1) In the formula, is the incident angle of the mid-wave infrared beam transmitted to the inner surface of the second prism, is the refractive index of the air gap in the middle of the contact surface between the two prisms, is the refractive index of the second prism. Since the prism angle of the second prism is 45°, according to the geometric relationship, it can be known that , and since the contact surfaces of the two prisms are parallel to each other, the optical path refraction occurring in the air gap can be ignored during calculation. According to Snell's law of refraction, it can be known that: ; (2) In the formula, is the incident angle of the mid-wave infrared beam transmitted to the contact surface between the two prisms, is the exit angle of the mid-wave infrared beam transmitted to the contact surface between the two prisms, is the refractive index of the first prism. Inside the first prism, when the prism angle of the first prism is A, according to the triangle interior angle relationship, it can be known that: ; (3) Therefore, is the transmission angle of the mid-wave infrared beam entering the first prism. According to Snell's law of refraction, the incident angle of the mid-wave infrared beam entering the first prism can be obtained as: ; (4) Combining and simplifying formulas (1) to (4), it can be known that the prism angle A of the first prism and the incident angle of the mid-wave infrared beam entering the first prism should satisfy the following formula: ; (5) In the formula, , are the refractive indices of the first prism and the second prism respectively. According to formula (5), it can be known that different combinations of prism materials will directly affect the values of the prism angle A of the first prism and the incident angle of the mid-wave infrared beam entering the first prism. Therefore, numerical calculations are also required for the selection of the ATIR prism material.

[0032] Since there is an air gap between the two prisms, to ensure that the mid-wave infrared beam can smoothly pass through the air gap from the first prism into the second prism, it should be less than the critical angle of the first prism. According to formula (2), it can be known that: ; (6) There is a light cone angle after the mid-wave infrared beam is reflected by the DMD target surface. Also, since the flipping angle of the micromirrors on the DMD target surface is ±12°, in the design process of the DMD-based projection device, the reflected light cone angle of the target surface is generally 10° - 12°. To ensure the design accuracy of the ATIR prism, the maximum value of 12° is taken for calculation in this embodiment. When the marginal ray of the mid-wave infrared beam enters the second prism, the angle deflection generated is . According to the working principle of the ATIR prism, the central ray and the marginal ray of the mid-wave infrared beam reflected by the DMD target surface can both undergo total internal reflection inside the second prism, and the central ray of the mid-wave infrared beam can exit along the projection optical axis. Therefore, the incident angle of the marginal ray of the mid-wave infrared beam at the contact surface of the two prisms should be greater than the critical angle of the second prism: ; (7) When , according to the calculations of formulas (6) and (7), the refractive index value range of the second prism is . Therefore, PbF2 (lead difluoride) with a refractive index of 1.70 - 1.72 in the mid-infrared band is selected as the base material of the second prism. Subsequently, is substituted into formula (5), and the prism angle A and refractive index of the first prism are assigned values for calculation. From formula (2), it can be known that is not restricted by the prism angle A of the first prism. Therefore, we first select the material of the first prism from several common chalcogenide glasses and fluoride glasses on the market, and obtain the calculation data of various materials at the 4.5 μm infrared band as shown in Table 1. According to the data in groups 1 - 3, when the first prism is made of common chalcogenide glass materials such as Ge (germanium), ZnSe (zinc selenide), and ZnS (zinc sulfide), since the refractive index of the chalcogenide glass material is relatively large, it will cause It is relatively close to the critical angle, which is not conducive to the overall optimization design of the lighting system. Therefore, chalcogenide glass is not the best choice for the first prism material. According to the comparison of the data in groups 5-6, we found that when fluoride glass is selected as the first prism material, it can meet the requirements of the ATIR prism for angle design. Compared with CaF2 (calcium fluoride) as the base material of the first prism, BaF2 (barium fluoride) has weaker resistance to humid environments as the base material of the first prism. Therefore, we choose CaF2 with better stability as the base material of the first prism. The first prism material and the second prism material in the fourth group of data in Table 1 are the same, both PbF2. The fourth group of data is used as a control group to explore the influence of different material combinations on lateral chromatic aberration.

[0033] Table 1

[0034] From the above analysis, it can be seen that if the two prisms are made of the same PbF2 material, or the first prism is made of CaF2 and the second prism is made of PbF2, both meet the usage requirements of the ATIR prism. Therefore, the data of the two groups of prisms are imported into Lighttools (optical system modeling software), and the size of the lateral chromatic aberration generated by the mid-wave infrared beam on the DMD target surface is observed by ray tracing. To ensure that the mid-wave infrared beam completely covers the DMD target surface, the right-angle side length of the second prism is set to 30 mm. According to the calculation of formula (5), when the two prisms are made of the same PbF2 material and the prism angle A of the first prism is 20°, compared with other prism angles of the first prism, the incident angle of the mid-wave infrared beam entering the first prism is 13.8°, and the angle between the mid-wave infrared beam entering the first prism and the normal of the DMD target surface is 11.18°. As shown in Figure 3 (a), the mid-wave infrared outgoing beam can hit the DMD target surface at , and the lateral chromatic aberration generated on the DMD target surface is 24.25 μm, which is much larger than the DMD pixel size of 13.68 µm; when the first prism is made of CaF2 and the second prism is made of PbF2, and the prism angle of the first prism is increased, let , compared with other prism angles of the first prism, the incident angle of the mid-wave infrared beam entering the first prism is 7.88°, and the angle between the mid-wave infrared beam entering the first prism and the normal of the DMD target surface is 7.78°. As shown in Figure 3 (b), the mid-wave infrared outgoing beam can hit the DMD target surface at , and the lateral chromatic aberration generated on the DMD target surface is 10.49 μm, which is smaller than the DMD pixel size of 13.68 µm.

[0035] The design of the ATIR prism should also take into account the overall size of the mid-infrared scene projection system. While ensuring that the mid-wave infrared beam can completely cover the DMD target surface, the length of the right-angled side of the second prism is reduced. Finally, the length of the right-angled side of the second prism is taken as 30 mm.

[0036] In summary, the first prism and the second prism are respectively selected CaF2 and PbF2 as the substrate materials. When the prism angle A of the first prism is 29.34°, the lateral chromatic aberration is the smallest. The length of the right-angled side of the second prism is 30 mm, and the thicknesses of both the first prism and the second prism are 30 mm. The final design results of the ATIR prism are shown in Table 2.

[0037] Table 2

[0038] Step 3: Design the mid-infrared scene projection system; This embodiment provides a dual-path common-aperture projection optical system based on an achromatic internal total reflection prism. During the design process of the mid-infrared scene projection system, since the optical parameters of the object to be detected are known, the reverse design method is often used, that is, the object plane is set at the exit pupil of the projection system, and the image plane is set at the DMD target surface. To ensure that the mid-wave infrared output beam of the target simulation system can fill the field of view of the infrared system under test during normal operation, the field of view angle of the mid-infrared scene projection system should be at least the same as that of the system under test. However, considering that the infrared receiving system may have a certain range of jitter and angular rotation during actual testing, to enable the infrared system under test to still receive the simulation image well under such conditions, the field of view angle of the mid-infrared scene projection system needs to be slightly larger than that of the infrared detection system. The field of view angle of the mid-infrared scene projection system is determined to be . According to the field of view angle of the mid-infrared scene projection system and the known DMD chip specifications, the focal length of the mid-infrared scene projection system can be calculated using the formula: ; (8) According to the DMD chip specifications, calculate its diagonal size , substitute the data into the formula to calculate the focal length of the mid-infrared scene projection system , and take 143 mm as the designed focal length of the mid-infrared scene projection system.

[0039] The spatial resolution of the mid-infrared scene projection system should match the DMD spatial resolution. According to the DMD pixel size, its spatial resolution is obtained from the Nyquist sampling theorem: ; (9) In the formula, The size of the DMD pixel, that is, the size of a single micromirror, can be used to calculate the maximum spatial resolution. . To meet the principle of pupil conjugation, the exit pupil of the mid-infrared scene projection system needs to be larger than the entrance pupil of the system under test. The exit pupil diameter of the mid-infrared scene projection system is determined to be . Based on the focal length calculated above, the target can be calculated according to the relationship between the exit pupil diameter and the focal length: ; (10) The of the mid-infrared scene projection system can be obtained. Table 3 shows the design parameters of the mid-infrared scene projection system.

[0040] Table 3

[0041] As Figure 4 shown, the design result of the mid-infrared scene projection system is as follows. From left to right, they are the first DMD target surface, the first window glass, the first ATIR prism, the beam combining prism, the first double concave lens, the second double convex lens, the third meniscus lens, the fourth meniscus lens, and the projection exit pupil. Below the beam combining prism are the second DMD target surface, the second window glass, and the second ATIR prism. Among them, the fourth meniscus lens, the third meniscus lens, and the second double convex lens are all spherical lenses. The S9 surface of the first double concave lens is an even aspherical surface, with its 4th order term being 6.084E-7, 6th order term being 1.546E-10, and 8th order term being 7.317E-14. The fourth meniscus lens selects GE as the substrate material; the third meniscus lens selects ZNS as the substrate material; the second double convex lens selects ZNS as the substrate material; the first double concave lens selects PbF2 as the substrate material. The geometric size of the beam combining prism is 50mm×50mm×50mm, and the material selected is ZNS.

[0042] Two beams of light modulated by the DMD target surface are combined by the beam combining prism. The combined beam of light first passes through the first double concave lens. The even aspherical S9 refracting surface of the first double concave lens can well correct spherical aberration, coma, etc. The second double convex lens has a positive optical power, which is numerically very close to the opposite number of the first double concave lens. It forms an achromatic unit with positive and negative optical powers with the first double concave lens, has the ability to correct the chromatic aberration of the combined beam of light, and can also suppress the beam diameter. The third meniscus lens and the fourth meniscus lens are mainly responsible for reducing the beam diameter and projecting it to the exit pupil position, and also have a certain role in correcting the aberration of the system. The first double concave lens and the second double convex lens are mainly responsible for correcting the aberration of the combined beam of light, and the third meniscus lens and the fourth meniscus lens are mainly responsible for projecting the combined beam of light with corrected aberration to the projection exit pupil.

[0043] The specific parameters of the optical elements in the mid-infrared scene projection system are shown in Table 4.

[0044] The parameters of the two optical systems are exactly the same. Since the reverse design idea is adopted in the design, the first surface of the whole system is the projection exit pupil. The surface serial numbers of each component of the mid-infrared scene projection system are as follows: Figure 5 shown.

[0045] Table 4

[0046] The beam combining prism and common aperture device are used to converge and project the two beams modulated by the digital micromirror device. This part consists of a cubic prism, four lenses and a projection exit pupil. The mid-infrared scene projection system also includes a first DMD target surface and a second DMD target surface: used to load image information, modulate the mid-wave infrared beam, and then form a projection image.

[0047] like Figure 6 The figure shows the diffuse spots in each field of view. It can be seen that the diffuse spots are all located within the Airy disk. The RMS (root mean square) radius of the central field of view is 0.546μm, and the RMS radius of the edge field of view is 1.355μm. The RMS radius is much smaller than the Airy disk radius, indicating that the degree of light diffusion is small. Figure 7 As shown, the vertical coordinate Y+ is the field of view, from Figure 7 It can be seen that the maximum distortion of the mid-infrared scene projection system does not exceed 0.05%, indicating that the distortion of the mid-infrared scene projection system has been well corrected, ensuring the accuracy of the geometric shape of the projected image and the relative position of the target object. Figure 8 It can be seen that when the Nyquist spatial frequency is 36.8lp / mm, the MTF (which is used to test the sharpness of the lens based on the concept of contrast) curves under each field of view are all greater than 0.5 and close to the diffraction limit, indicating that the imaging quality of the system is high and meets the usage requirements. Figure 8 The "T" stands for meridian and the "S" stands for sagittal.

[0048] Embodiment 2. The electronic device described in this embodiment includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus; Memory, used to store computer programs; The processor is used to implement the mid-infrared scene projection system design method described in Implementation Mode 1 when executing the program stored in the memory.

[0049] Implementation method three. The computer-readable storage medium described in this implementation method stores a computer program, and when the computer program is executed by a processor, the mid-infrared scene projection system design method described in implementation method one is implemented.

[0050] The above has introduced in detail the design method, device and storage medium of the mid-infrared scene projection system proposed by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A design method for a mid-infrared scene projection system, characterized in that, It includes the following steps: Step 1, construct an RTIR prism, and the RTIR prism includes a first prism and a second prism; Step 2, optimize the RTIR prism. The first prism and the second prism are combined into a trapezoidal prism through an air gap. The first prism and the second prism are triangular prisms made of different materials. Based on the mid-wave infrared outgoing beam of the RTIR prism entering the DMD target surface at 30°, determine the prism angle of the first prism to obtain an ATIR prism; After the mid-wave infrared beam enters the ATIR prism, it is transmitted through the first prism and the second prism respectively, and then enters the DMD target surface from the exit surface of the second prism. After that, the mid-wave infrared beam vertically reflected by the DMD target surface undergoes total internal reflection at the contact surface of the first prism and the second prism, and the central ray of the mid-wave infrared beam exits along the projection optical axis; Step 3, based on the ATIR prism described in Step 2, design a mid-infrared scene projection system.

2. The method for designing a mid-infrared scene projection system according to claim 1, wherein The optimization of the RTIR prism in Step 2 is specifically as follows: Step 21, based on the mid-wave infrared outgoing beam of the RTIR prism entering the DMD target surface at 30°, obtain the value range of the refractive index of the second prism; Step 22, according to the value range of the refractive index of the second prism, determine the material of the first prism, the material of the second prism, and the prism angle of the first prism respectively.

3. The design method of the mid-infrared scene projection system according to claim 2, characterized in that, The prism angle of the first prism is 29.34°, and the material of the first prism is calcium fluoride.

4. The design method of the mid-infrared scene projection system according to claim 2, wherein, The material of the second prism is lead difluoride.

5. The design method of the mid-infrared scene projection system according to claim 1, characterized in that The mid-infrared scene projection system in Step 3 adopts a double-path common-aperture optical structure, including a first optical path system, a second optical path system, a beam-combining prism, and a common-aperture device; The beam-combining prism combines the beams output by the first optical path system and the second optical path system to obtain a combined beam, and the common-aperture device projects the combined beam.

6. The design method of the mid-infrared scene projection system according to claim 5, wherein The first optical path system includes a first mid-wave infrared beam illumination system, a first DMD target surface, a first window glass, and a first ATIR prism arranged in sequence; The second optical path system includes a second mid-wave infrared beam illumination system, a second DMD target surface, a second window glass, and a second ATIR prism arranged in sequence along the optical path; The first optical path system is specifically as follows: The first mid-wave infrared beam illumination system emits a mid-wave infrared beam to the first ATIR prism. The first ATIR prism refracts the mid-wave infrared beam through the first window glass to the first DMD target surface, and the first DMD target surface loads the image information of the mid-wave infrared beam; The second optical path system repeats the operation of the first optical path system.

7. The method for designing a mid-infrared scene projection system according to claim 5, wherein The common-aperture device includes a first bi-concave lens, a second bi-convex lens, a third meniscus lens, a fourth meniscus lens, and a projection exit pupil arranged in sequence; The combined beam sequentially passes through the first bi-concave lens and the second bi-convex lens for aberration correction. After the third meniscus lens and the fourth meniscus lens reduce the aperture of the combined beam after aberration correction, it is projected onto the projection exit pupil.

8. The method for designing a mid-infrared scene projection system according to claim 1, wherein The field of view of the mid-infrared scene projection system is ±7°, F / # is 2.34, the exit pupil distance is 150 mm, and the exit pupil diameter is 60 mm.

9. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete mutual communication through the communication bus; A memory for storing a computer program; A processor, when executing the program stored on the memory, implements the mid-infrared scene projection system design method according to any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and when the computer program is executed by the processor, it implements the mid-infrared scene projection system design method according to any one of claims 1-8.

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