Design method, equipment and storage medium of mid-infrared scene projection system

Abstract

The design method, equipment, and storage medium of a mid-infrared scene projection system relate to the field of infrared scene projection technology and solve the lateral chromatic aberration problem caused by a mid-infrared scene projector based on a dual DMD. An RTIR prism is constructed and optimized. The first prism and the second prism form a trapezoidal prism. The first prism and the second prism are triangular prisms made of different materials. Based on the outgoing light beam entering the DMD target surface at 30°, the incident angle of the light beam entering the first prism is determined to obtain an ATIR prism. After the light beam enters the ATIR prism, it is transmitted through the first prism and the second prism before exiting the DMD target surface. The light beam vertically reflected by the DMD target surface is fully emitted at the contact surface of the first prism and the second prism, and the central ray of the light beam is emitted along the projection optical axis. Based on the ATIR prism, a mid-infrared scene projection system is designed. The present invention is used to reduce the lateral chromatic aberration caused by the mid-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 in particular to a design method, equipment and storage medium of a mid-infrared scene projection system. Background Art

[0002] In the field of infrared scene projection technology, the DMD (digital micromirror device), with its advantages such as full-band compatibility and high frame rate projection, has become a core component of medium-wave infrared hardware-in-the-loop simulation systems. Currently, medium-wave infrared scene simulation systems often utilize a separate architecture, with the illumination and projection systems designed independently. The key component connecting the illumination and projection systems often uses a TIR (total internal reflection) prism, which employs a "reflection followed by transmission" mechanism. These devices pass through only one prism material before the medium-wave infrared beam enters the DMD target. This results in significant lateral chromatic aberration of the mid-infrared light emitted by the light source on the DMD target surface. To address this issue, a doublet lens is often used to minimize the impact of chromatic aberration on projection quality. However, this approach inevitably increases the complexity of the projection system and leads to higher manufacturing costs.

[0003] In the prior art, Chinese patent document CN117706851A discloses "a dual-light path common aperture projection optical engine with dual internal total reflection prisms for light splitting". The optical engine includes: a projection optical system, a first digital micromirror device and a second digital micromirror device for loading image information into the incident illumination light 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 micromirror on-state and off-state light 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 used in this technical solution will cause the mid-infrared waves emitted by the light source to cause obvious lateral chromatic aberration on the DMD target surface.

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

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

[0006] The mid-infrared scene projection system design method of the present invention comprises the following steps:

[0007] Step 1, construct the RTIR prism;

[0008] 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 medium-wave infrared output beam of the RTIR prism is incident on the DMD target surface at 30°. The prism angle of the first prism is determined to obtain the ATIR prism.

[0009] After the medium-wave infrared beam enters the ATIR prism, it passes 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 being vertically reflected by the DMD target surface, the medium-wave infrared beam is fully reflected at the contact surface of the first prism and the second prism, and the central ray of the medium-wave infrared beam is emitted along the projection optical axis;

[0010] Step 3: Design a mid-infrared scene projection system based on the ATIR prism described in step 2.

[0011] Furthermore, in an embodiment of the present invention, the optimization of the RTIR prism in step 2 is specifically as follows:

[0012] Step 21, based on the medium-wave infrared output beam of the RTIR prism entering the DMD target surface at 30 degrees, obtaining the value range of the refractive index of the second prism;

[0013] Step 22: Determine the material of the first prism, the material of the second prism, and the prism angle of the first prism according to the value range of the refractive index of the second prism.

[0014] Furthermore, in an 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.

[0015] Furthermore, in an embodiment of the present invention, the second prism is made of lead difluoride.

[0016] Furthermore, in an embodiment of the present invention, the mid-infrared scene projection system in step 3 adopts a dual-light path common aperture optical structure, including a first light path system, a second light path system, a beam combining prism and a common aperture device;

[0017] The beam combining prism combines the light beams output by the first optical path system and the second optical path system to obtain combined light, and the combined light is projected using a common aperture device.

[0018] Furthermore, in an embodiment of the present invention, the first optical path system includes a first medium-wave infrared beam illumination system, a first DMD target surface, a first window glass, and a first ATIR prism arranged in sequence;

[0019] The second optical path system includes a second medium-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;

[0020] The first optical path system is specifically:

[0021] The first medium-wave infrared beam illumination system emits a medium-wave infrared beam to the first ATIR prism, and the first ATIR prism deflects the medium-wave infrared beam through the first window glass to the first DMD target surface, and the first DMD target surface is loaded with image information of the medium-wave infrared beam;

[0022] The second optical path system repeats the operation of the first optical path system.

[0023] Furthermore, in an embodiment of the present invention, the common aperture device comprises a first biconcave lens, a second biconvex lens, a third meniscus lens, a fourth meniscus lens and a projection exit pupil, which are placed in sequence;

[0024] The combined light beam passes through the first biconcave lens and the second biconvex lens in sequence for aberration correction. The third meniscus lens and the fourth meniscus lens reduce the aperture of the aberration-corrected combined light beam and project it to the projection exit pupil.

[0025] Furthermore, in an embodiment of the present invention, the mid-infrared scene projection system has an F / # of 2.34, an exit pupil distance of 150 mm, and an exit pupil diameter of 60 mm.

[0026] An electronic device according to the present invention comprises 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;

[0027] Memory for storing computer programs;

[0028] The processor is configured to implement any of the above-mentioned methods for designing a mid-infrared scene projection system when executing a program stored in the memory.

[0029] The present invention provides a computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium. When the computer program is executed by a processor, any of the above-mentioned methods for designing a mid-infrared scene projection system is implemented.

[0030] The present invention solves the lateral chromatic aberration problem caused by the wide operating band of the DMD target surface in the existing mid-infrared scene projection system. Specific beneficial effects include:

[0031] The design method for a mid-infrared scene projection system described in this paper employs a "transmission followed by reflection" ATIR (achromatic internal total reflection) prism. This design utilizes a combination of different prism materials to mitigate chromatic aberration on the DMD target surface caused by the wide operating wavelength band. This method primarily involves the design of the achromatic internal total reflection prism and the projection lens assembly. The achromatic internal total reflection prism is constructed from different materials, utilizing differences in refractive index to mitigate chromatic dispersion due to the operating wavelength. The prism angle is designed to ensure that the light beam enters the DMD target surface at a specific angle. The projection system utilizes a four-lens combination. Scene targets simulated by two DMD groups pass through a beam-combining prism and then enter the projection lens assembly, achieving a dual-optical path, common-aperture optical system design. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0033] Figure 1 is a schematic diagram of the type of the light splitting element described in embodiment 1;

[0034] Figure 2 is a diagram showing the working principle of the ATIR prism described in Embodiment 1;

[0035] Figure 3 1 is a comparison diagram of the dispersion conditions described in the first embodiment;

[0036] Figure 4 3D optical path diagram of the mid-infrared scene projection system according to embodiment 1;

[0037] Figure 5 is the surface serial number of each component of the mid-infrared scene projection system described in embodiment 1;

[0038] Figure 6 This is the diffuse spot situation of each field of view described in the first embodiment;

[0039] Figure 7 is a modulation transfer function curve of the field curvature distortion described in the first embodiment;

[0040] Figure 8 is the modulation transfer function curve described in the first embodiment. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe various embodiments of the present invention in conjunction with the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0042] Implementation method 1. The mid-infrared scene projection system design method described in this implementation method comprises the following steps:

[0043] Step 1, constructing an RTIR (total internal reflection) prism;

[0044] 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 medium-wave infrared output beam of the RTIR prism is incident on the DMD target surface at 30°. The prism angle of the first prism is determined to obtain the ATIR prism.

[0045] After the medium-wave infrared beam enters the ATIR prism, it passes 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 being vertically reflected by the DMD target surface, the medium-wave infrared beam is fully reflected at the contact surface of the first prism and the second prism, and the central ray of the medium-wave infrared beam is emitted along the projection optical axis;

[0046] Step 3: Design a mid-infrared scene projection system based on the ATIR prism described in step 2.

[0047] In this embodiment, the optimization of the RTIR prism in step 2 is specifically as follows:

[0048] Step 21, based on the medium-wave infrared output beam of the RTIR prism entering the DMD target surface at 30 degrees, obtaining the value range of the refractive index of the second prism;

[0049] Step 22: Determine the material of the first prism, the material of the second prism, and the prism angle of the first prism according to the value range of the refractive index of the second prism.

[0050] In this embodiment, the prism angle of the first prism is 29.34°, and the material of the first prism is calcium fluoride.

[0051] In this embodiment, the second prism is made of lead difluoride.

[0052] In this embodiment, the mid-infrared scene projection system in step 3 adopts a dual-light path common aperture optical structure, including a first light path system, a second light path system, a beam combining prism and a common aperture device;

[0053] The beam combining prism combines the light beams output by the first optical path system and the second optical path system to obtain combined light, and the combined light is projected using a common aperture device.

[0054] In this embodiment, the first optical path system includes a first medium-wave infrared beam illumination system, a first DMD target surface, a first window glass and a first ATIR prism arranged in sequence;

[0055] The second optical path system includes a second medium-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;

[0056] The first optical path system is specifically:

[0057] The first medium-wave infrared beam illumination system emits a medium-wave infrared beam to the first ATIR prism, and the first ATIR prism deflects the medium-wave infrared beam through the first window glass to the first DMD target surface, and the first DMD target surface is loaded with image information of the medium-wave infrared beam;

[0058] The second optical path system repeats the operation of the first optical path system.

[0059] In this embodiment, the common aperture device includes a first biconcave lens, a second biconvex lens, a third meniscus lens, a fourth meniscus lens and a projection exit pupil placed in sequence;

[0060] The combined light beam passes through the first biconcave lens and the second biconvex lens in sequence for aberration correction. The third meniscus lens and the fourth meniscus lens reduce the aperture of the aberration-corrected combined light beam and project it to the projection exit pupil.

[0061] In this embodiment, the mid-infrared scene projection system has an F / # of 2.34, an exit pupil distance of 150 mm, and an exit pupil diameter of 60 mm.

[0062] The existing mid-infrared scene projection system has a wide operating band, which causes lateral chromatic aberration on the DMD target surface. To solve the above technical problems, this embodiment proposes a design method for a mid-infrared scene projection system, including the following steps:

[0063] Step 1, construct the RTIR prism;

[0064] According to the working characteristics of DMD itself, the medium-wave infrared output beam should be The IR beam hits the DMD target surface. In the spectroscopic optical system, TIR prism is mainly used to achieve this function and complete the separation of the projection light path and the illumination light path. When the medium-wave infrared beam is incident on the contact surface between the two prisms, the light path is deflected by total internal reflection. According to the different prism structures, it can be divided into the following types: Figure 1 The "reflection first then transmission" TIR prism shown on the left, and Figure 1 The "transmit-then-reflect" RTIR prism shown on the right.

[0065] Step 2, ATIR prism design;

[0066] Due to the wide infrared operating band, a single-material prism can produce significant lateral chromatic aberration on the DMD target surface. Therefore, the team decided to optimize the RTIR prism design by combining different materials, ultimately completing the ATIR prism design. The ATIR prism consists of two triangular prisms made of different materials, which deflect the mid-wave infrared beam and reduce lateral chromatic aberration on the DMD target surface.

[0067] During the ATIR prism design process, the medium-wave infrared beam should be able to completely cover the DMD target surface and ensure that the ATIR prism angle has sufficient design margin. Therefore, the side length of the second prism parallel to the DMD target surface can be initially set as 30mm. The design of the ATIR prism angle is more critical, such as Figure 2 As we know the working principle of ATIR prism, the design of ATIR prism angle needs to meet the following two points:

[0068] 1. After the medium-wave infrared beam enters the ATIR prism, it can pass through the contact surface between the two prisms in a transmission manner. At the same time, the medium-wave infrared outgoing beam can Incident on the DMD target surface;

[0069] 2. The medium-wave infrared beam reflected by the DMD target surface can undergo total reflection at the contact surface between the two prisms and emerge along the projection optical axis.

[0070] Since the central ray of the medium-wave infrared beam reflected by the DMD target surface enters perpendicular to the surface of the second prism, the central ray of the medium-wave infrared beam can be emitted along the projection optical axis only when the side section of the second prism is an isosceles right triangle, that is, the prism angle is 45°. In order to meet the requirements of condition 1, it is necessary to find the angle of illumination of the DMD target surface when When the prism angle A of the first prism is equal to the incident angle of the medium-wave infrared beam entering the first prism The relationship between them.

[0071] Starting from the DMD target surface, reversely solve the problem to the incident surface of the medium-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:

[0072] ; (1)

[0073] Where, is the incident angle of the medium-wave infrared beam transmitted to the inner surface of the second prism, is the refractive index of the air gap between the contact surfaces of 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, , and because the contact surfaces of the two prisms are parallel to each other, the light path deflection in the air gap can be ignored during calculation. According to Snell's refraction law:

[0074] ; (2)

[0075] Where, is the incident angle of the medium-wave infrared beam transmitted to the contact surface of the two prisms, is the angle of incidence of the medium-wave infrared beam transmitted to the contact surface of 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 relationship between the internal angles of the triangle:

[0076] ; (3)

[0077] therefore, is the transmission angle of the medium-wave infrared beam entering the first prism. According to Snell's refraction law, the incident angle of the medium-wave infrared beam entering the first prism can be obtained. for:

[0078] ; (4)

[0079] Combining and simplifying formulas (1) to (4), we can see that the prism angle A of the first prism and the incident angle of the medium-wave infrared beam entering the first prism are , should satisfy the following formula:

[0080] ; (5)

[0081] Where, 、 are the refractive indices of the first prism and the second prism respectively. According to formula (5), the combination of different prism materials will directly affect the prism angle A of the first prism and the incident angle of the medium-wave infrared beam entering the first prism. Therefore, the selection of ATIR prism material also requires numerical calculation.

[0082] Since there is an air gap between the two prisms, in order to ensure that the medium-wave infrared beam can smoothly pass through the air gap from the first prism to the second prism, It should be smaller than the critical angle of the first prism. According to formula (2):

[0083] ; (6)

[0084] After the medium-wave infrared beam is reflected by the DMD target surface, there is a light cone angle. Because the flip angle of the small micromirror on the DMD target surface is ±12°, the reflected light cone angle of the target surface is generally 10°~12° during the design of the DMD type projection equipment. To ensure the design accuracy of the ATIR prism, this embodiment takes the maximum value of 12° for calculation. When the edge light of the medium-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 medium-wave infrared beam reflected by the DMD target surface can both be totally reflected inside the second prism, and the central ray of the medium-wave infrared beam can be emitted along the projection optical axis. Therefore, the incident angle of the marginal ray of the medium-wave infrared beam at the contact surface of the two prisms should be greater than the critical angle of the second prism:

[0085] ; (7)

[0086] when When , according to formulas (6) and (7), the refractive index of the second prism can be calculated as follows: Therefore, PbF2 (lead difluoride) with a refractive index of 1.70~1.72 in the mid-infrared band is used as the base material of the second prism. Substitute into formula (5) and calculate the prism angle A and refractive index of the first prism Perform the assignment calculation, and we can know from formula (2) The value is not limited 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 calculated data of various materials in the 4.5μm infrared band as shown in Table 1. According to the data of Groups 1 to 3, when the first prism is made of common chalcogenide glasses such as Ge (germanium), ZnSe (zinc selenide), and ZnS (zinc sulfide), the refractive index of chalcogenide glasses is relatively high, which will lead to This is close to the critical angle, which is detrimental to the overall optimization of the illumination system. Therefore, chalcogenide glass is not the optimal material for the first prism. Comparing data from Groups 5 and 6, we found that fluoride glass meets the ATIR prism's angle design requirements. However, compared to CaF2 (calcium fluoride), BaF2 (barium fluoride) is less resistant to humid environments when used as the base material for the first prism. Therefore, we chose CaF2 due to its greater stability. Group 4 of the data in Table 1 uses the same PbF2 material for the first prism as for the second prism. This group serves as a control group to explore the effects of different material combinations on lateral chromatic aberration.

[0087] Table 1

[0088]

[0089] From the above analysis, it can be seen that if the two prisms are made of the same PbF2 material, or if the first prism is made of CaF2 material and the second prism is made of PbF2 material, the requirements for the use of ATIR prisms are met. Therefore, the two sets of prism data are imported into Lighttools (optical system modeling software) and the lateral chromatic aberration caused by the medium-wave infrared beam on the DMD target surface is observed by ray tracing. In order to ensure that the medium-wave infrared beam completely covers the DMD target surface, the right-angle side length of the second prism is set to 30mm. According to formula (5), if the two prisms are made of the same PbF2 material and the prism angle A of the first prism is 20°, the incident angle of the medium-wave infrared beam entering the first prism is 20° compared to when the first prism uses other prism angles. is 13.8°, and the angle between the medium-wave infrared beam and the normal line of the DMD target surface when it enters the first prism is 11.18°. Figure 3 As shown in (a), the mid-wave infrared outgoing beam can be When the light is projected onto the DMD target, the lateral chromatic aberration generated on the DMD target is 24.25μm, which is much larger than the DMD pixel size of 13.68μm. When the first prism is made of CaF2 and the second prism is made of PbF2, the prism angle of the first prism is increased. Compared with the first prism using other prism angles, the incident angle of the medium-wave infrared beam entering the first prism is The angle between the medium-wave infrared beam and the normal line of the DMD target surface when it enters the first prism is 7.78°. Figure 3 As shown in (b), the mid-wave infrared outgoing beam can be When hitting the DMD target surface, the lateral chromatic aberration produced on the DMD target surface is 10.49μm, which is smaller than the DMD pixel size of 13.68μm.

[0090] 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 should be reduced. Finally, the length of the right-angled side of the second prism is 30 mm.

[0091] Based on the above, the first prism and the second prism are selected CaF2 and The lateral chromatic aberration is minimized when the first prism's prism angle A is 29.34°. The right-angle side of the second prism is 30 mm, and both the first and second prisms are 30 mm thick. The final design results of the ATIR prism are shown in Table 2.

[0092] Table 2

[0093]

[0094] Step 3, design the mid-infrared scene projection system;

[0095] This embodiment provides a dual-light 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 adopted, 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. In order to ensure that the target simulation system is working normally, the mid-wave infrared output light beam can fill the field of view of the infrared system to be measured, and the field of view angle of the mid-infrared scene projection system should at least be consistent with the field of view angle of the system to be measured. However, considering that the infrared receiving system may have a certain range of jitter and angular rotation in actual testing, in order for the infrared system to be measured to still be able to receive the simulated 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 to determine the full field of view angle of the mid-infrared scene projection system. 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:

[0096] ; (8)

[0097] According to the chip specifications of DMD, calculate its diagonal size , substitute the data into the formula to calculate the focal length of the mid-infrared scene projection system , 143mm is taken as the design focal length of the mid-infrared scene projection system.

[0098] The spatial resolution of the mid-infrared scene projection system must match the DMD spatial resolution. Based on the DMD pixel size, its spatial resolution is obtained by the Nyquist sampling theorem:

[0099] ; (9)

[0100] Where, is the DMD pixel size, that is, the size of a single micromirror, and the maximum spatial resolution can be calculated In order to meet the pupil connection principle, 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 According to the focal length calculated above, the target , according to the relationship between exit pupil diameter and focal length:

[0101] ; (10)

[0102] You can get the mid-infrared scene projection system ,Table 3 shows the design parameters of the mid-infrared scene ,projection system.

[0103] Table 3

[0104]

[0105] like Figure 4 The design results of the mid-infrared scene projection system are shown below. From left to right, they are the first DMD target, the first window glass, the first ATIR prism, the beam-combining prism, the first biconcave lens, the second biconvex lens, the third meniscus lens, the fourth meniscus lens, and the projection exit pupil. Below the beam-combining prism are the second DMD target, the second window glass, and the second ATIR prism. The fourth meniscus lens, the third meniscus lens, and the second biconvex lens are all spherical lenses. The S9 surface of the first biconcave lens is an even-order aspheric surface with a fourth-order term of 6.084E-7, a sixth-order term of 1.546E-10, and an eighth-order term of 7.317E-14. The fourth meniscus lens uses GE as the substrate material; the third meniscus lens uses ZNS as the substrate material; the second biconvex lens uses ZNS as the substrate material; and the first biconcave lens uses PbF2 as the substrate material. The beam-combining prism has dimensions of 50 mm × 50 mm × 50 mm and is made of ZNS.

[0106] The two light beams modulated by the DMD target surface are combined by the beam-combining prism. The combined light beam first passes through the first biconcave lens. The even-order aspheric S9 refractive surface of the first biconcave lens can well correct spherical aberration, coma, etc. The second biconvex lens has positive optical power, which is very close to the opposite number of the first biconcave lens in value. It and the first biconcave lens form an achromatic unit with a combination of positive and negative optical power, which has the ability to correct the chromatic aberration of the combined light beam and can also suppress the beam aperture. The third and fourth meniscus lenses are mainly responsible for reducing the beam aperture and projecting it to the exit pupil position, which also has a certain corrective effect on the aberration of the system. The first and second biconcave lenses are mainly responsible for correcting the aberration of the combined light beam, while the third and fourth meniscus lenses are mainly responsible for projecting the aberration-corrected combined light beam to the projection exit pupil.

[0107] The specific parameters of the optical components in the mid-infrared scene projection system are shown in Table 4.

[0108] The two optical systems are completely consistent in parameters. Since the reverse design idea is adopted in the design, the first surface of the entire 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.

[0109] Table 4

[0110]

[0111] The beam-combining prism and common aperture device are used to converge and project the two beams modulated by the digital micromirror device. This component consists of a cubic prism, four lenses, and a projection exit pupil. The mid-infrared scene projection system also includes a first DMD target and a second DMD target, which are used to load image information and modulate the mid-wave infrared beam to form the projected image.

[0112] 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 radius of the Airy disk, 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 As can be seen from the figure, when the Nyquist spatial frequency is 36.8lp / mm, the MTF (which measures 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 system has high imaging quality and meets the requirements. Figure 8 The "T" stands for meridian and the "S" stands for sagittal.

[0113] 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;

[0114] Memory for storing computer programs;

[0115] The processor is configured to implement the mid-infrared scene projection system design method described in the first embodiment when executing the program stored in the memory.

[0116] 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.

[0117] The above is a detailed introduction to the design method, device and storage medium of the mid-infrared scene projection system proposed in the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for designing a mid-infrared scene projection system, characterized in that: The following steps are involved: Step 1, constructing an RTIR prism, wherein 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. The medium-wave infrared output beam of the RTIR prism is incident on the DMD target surface at 30°. The prism angle of the first prism is determined to obtain the ATIR prism. After the medium-wave infrared beam enters the ATIR prism, it passes 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 being vertically reflected by the DMD target surface, the medium-wave infrared beam is fully reflected at the contact surface of the first prism and the second prism, and the central ray of the medium-wave infrared beam is emitted along the projection optical axis; The refractive index of the second prism ranges from ; Step 3, designing a mid-infrared scene projection system based on the ATIR prism described in step 2; The mid-infrared scene projection system includes a common aperture device, which includes a first biconcave lens, a second biconvex lens, a third meniscus lens, a fourth meniscus lens and a projection exit pupil placed in sequence; The mid-infrared scene projection system has an F / # of 2.34, an exit pupil distance of 150 mm, and an exit pupil diameter of 60 mm; The curvature radius of the even aspheric surface S9 of the first biconcave lens is 116.860, and the curvature radius of the spherical surface S8 is -190.908; The curvature radius of the spherical surface S7 of the second biconcave lens is -656.758, and the curvature radius of the spherical surface S6 is 148.870; The curvature radius of the spherical surface S5 of the third meniscus lens is 182.922, and the curvature radius of the spherical surface S4 is 97.395; The curvature radius of the spherical surface S3 of the fourth meniscus lens is -177.366, and the curvature radius of the spherical surface S2 is -143.585; The combined light beam passes through the first biconcave lens and the second biconvex lens in sequence for aberration correction. The third meniscus lens and the fourth meniscus lens reduce the aperture of the aberration-corrected combined light beam and project it to the projection exit pupil.

2. The mid-infrared scene projection system design method according to claim 1, characterized in that: The optimized RTIR prism in step 2 is specifically: Step 21, based on the medium-wave infrared output beam of the RTIR prism entering the DMD target surface at 30 degrees, obtaining the value range of the refractive index of the second prism; Step 22: Determine the material of the first prism, the material of the second prism, and the prism angle of the first prism according to the value range of the refractive index of the second prism.

3. The mid-infrared scene projection system design method 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 mid-infrared scene projection system design method according to claim 2, characterized in that: The second prism is made of lead difluoride.

5. The mid-infrared scene projection system design method according to claim 1, characterized in that: The mid-infrared scene projection system in step 3 adopts a dual-light path common aperture optical structure, including a first light path system, a second light path system, a beam combining prism and a common aperture device; The beam combining prism combines the light beams output by the first optical path system and the second optical path system to obtain combined light, and the combined light is projected using a common aperture device.

6. The method for designing a mid-infrared scene projection system according to claim 5, wherein: The first optical path system includes a first medium-wave infrared beam illumination system, a first DMD target surface, a first window glass and a first ATIR prism which are arranged in sequence; The second optical path system includes a second medium-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 medium-wave infrared beam illumination system emits a medium-wave infrared beam to the first ATIR prism, and the first ATIR prism deflects the medium-wave infrared beam through the first window glass to the first DMD target surface, and the first DMD target surface is loaded with image information of the medium-wave infrared beam; The second optical path system repeats the operation of the first optical path system.

7. An electronic device, characterized in that: It 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 for storing computer programs; The processor is configured to implement the mid-infrared scene projection system design method according to any one of claims 1 to 6 when executing the program stored in the memory.

8. 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 a processor, the method for designing a mid-infrared scene projection system according to any one of claims 1 to 6 is implemented.

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