Long eye relief mid-wave infrared zoom projection optical system and infrared target simulator

Abstract

The present application relates to the long pupil distance mid-wave infrared zoom projection optical system and infrared target simulator, belong to optical device technical field, solve the short pupil distance problem existing in the present zoom projection system, the working wave band of the system is 3~5, it adopts the inverted structure of diaphragm front, including first fixed lens group, zoom lens group, compensation lens group, second fixed lens group arranged in sequence along the optical axis, the optical power is positive optical power, negative optical power, positive optical power, positive optical power respectively;The first fixed lens group and the second fixed lens group are fixed in position on the optical axis, the zoom lens group and the compensation lens group reciprocatingly move along the optical axis direction to realize the switching between short focus-130mm and long focus-260mm.The projection optical system of the present application has long pupil distance, can realize the far field projection to the infrared target while stabilizing zoom, avoid the interference between the simulator and the equipment to be tested, improve the test precision.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical devices, in particular to a long-telecentricity mid-wave infrared zoom projection optical system and an infrared target simulator. BACKGROUND

[0002] The infrared target simulator is the core unit of the infrared semi-physical simulation system, which can simulate the infrared radiation characteristics of the target in a complex environment, reproduce the real scene in the laboratory, and be used for repeatable performance testing and evaluation of the infrared detector and imaging system, thereby greatly reducing the cost of field test and shortening the research and development cycle.

[0003] In recent years, zoom target simulators are widely used, which can output high-quality infrared images at different fields of view, making the simulator adapt to various testing requirements. However, the design of the existing target simulation projection system usually ignores the problem of telecentricity, resulting in a generally short back working distance. For example, in the paper "Research on Infrared Target Simulation Optical System Based on DMD", a master's thesis of Harbin Institute of Technology, Wang Haipeng, a critical illumination architecture is adopted, a total reflection prism is used for splitting light, and a fixed-focus projection system is used to simulate the infrared scene, but the simulator can only output a single field of view image, and the telecentricity is only 150mm. In the paper "Optical System Design of Infrared Target Simulator", Song Yansong et al., Acta Optica Sinica, Vol. 35, No. 4, April 2015, a compact dual-channel infrared projection system is designed, which has a field of view angle of ±3°, a working wavelength of 3~5 , and a telecentricity of 550mm, which can realize the simultaneous simulation of main targets and interference targets. Although the telecentricity of this system is longer, its fixed-focus structure makes it have certain limitations and cannot adapt to different specifications of the devices to be tested.

[0004] A short telecentricity will make the simulator have to be close to the device to be tested during installation, resulting in unnecessary interference in the structural layout of the two, affecting the evaluation and testing of the performance of the device to be tested, and a fixed-focus optical system with long telecentricity has the problem of insufficient adaptability. SUMMARY

[0005] In order to overcome the problems existing in the prior art, the present application provides a long-telecentricity mid-wave infrared zoom projection optical system and an infrared target simulator. The present application applies the design of long telecentricity to the zoom projection system, taking into account both long telecentricity and zoom, which can ensure a large back working distance while outputting different field of view infrared images, and can meet the testing requirements of different devices to be tested, and has strong adaptability.

[0006] The technical scheme adopted by the present application is as follows:

[0007] The long-telephoto distance mid-wave infrared zoom projection optical system adopts an inverted structure with a light barrier in front, and the inverted structure comprises a first fixed lens group, a zoom lens group, a compensation lens group and a second fixed lens group which are coaxially arranged in sequence along the optical axis, and the first fixed lens group, the compensation lens group and the second fixed lens group all have positive refractive powers, and the zoom lens group has a negative refractive power;

[0008] The first fixed lens group and the second fixed lens group are fixed in position on the optical axis, the zoom lens group and the compensation lens group move reciprocally along the optical axis to realize switching between a short focus and a long focus, and in the zooming process, the zoom lens group is zoomed when moving along the optical axis, and the compensation lens group is focused when moving along the optical axis, wherein the short focus is -130 mm, the long focus is -260 mm, and the telephoto distance is 300 mm;

[0009] The infrared light source emits a light beam with a working wavelength of 3 ~ 5 The light beam passes through an illumination optical system and a digital micromirror device, enters the second fixed lens group, is adjusted in focal length by the compensation lens group and the zoom lens group, and is emitted from the first fixed lens group, thereby completing far-field projection of an infrared image.

[0010] Meanwhile, the application also provides an infrared target simulator, which comprises the long-telephoto distance mid-wave infrared zoom projection optical system as described above, and further comprises an infrared light source, an illumination optical system, a light splitting module and a digital micromirror device, wherein the infrared light source has a working wavelength of 3 ~ 5 .

[0011] The light beam emitted by the infrared light source enters the light splitting module after passing through the illumination optical system, the light splitting module guides the light beam to a modulation surface of the digital micromirror device, the digital micromirror device spatially modulates the incident light according to a target image signal, the reflected light in an open state is selectively diverted by the light splitting module, and then enters the long-telephoto distance mid-wave infrared zoom projection optical system, thereby the long-telephoto distance mid-wave infrared zoom projection optical system projects infrared images of different fields of view in a far field.

[0012] The application has the following beneficial effects:

[0013] (1) The application provides a zoom projection optical system with a long telephoto distance and a working wavelength of 3 ~ 5 by reasonably distributing the refractive powers of the lens groups and systematically optimizing the optical parameters, the zoom projection optical system can realize continuous and smooth zooming, the picture transition is smooth, and high-quality imaging effects can be stably outputted;

[0014] (2) The zoom projection optical system of the present invention has a long exit pupil distance, extending the exit pupil distance to 300mm, which can realize far-field projection of infrared targets while maintaining stable zoom, avoid interference between the infrared target simulator and the device under test, and improve the evaluation and testing accuracy of the device under test performance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a mid-wave infrared zoom projection optical system with long exit pupil distance according to one embodiment of the present invention;

[0016] Figure 2 The modulation transfer function diagram of the long exit pupil distance mid-wave infrared zoom projection optical system provided in the embodiment of the present invention at short focal length;

[0017] Figure 3 The modulation transfer function diagram at the mid-focal distance of the long exit pupil mid-wave infrared zoom projection optical system provided in the embodiment of the present invention;

[0018] Figure 4 The modulation transfer function diagram of the long exit pupil distance mid-wave infrared zoom projection optical system provided in the embodiment of the present invention is shown at the long focal length.

[0019] Explanation of reference numerals in the attached diagram: G1, First fixed lens group; G2, Zoom lens group; G3, Compensating lens group; G4, Second fixed lens group; L1, First lens; L2, Second lens; L3, Third lens; L4, Fourth lens; L5, Fifth lens; L6, Sixth lens; L7, Seventh lens; L8, Eighth lens; L9, Ninth lens; L10, Tenth lens; L11, Eleventh lens; L12, Twelfth lens; L13, Thirteenth lens; L14, Fourteenth lens; L15, Fifteenth lens; L16, Sixteenth lens; L17, Seventeenth lens; L18, Prism replacing flat glass. Detailed Implementation

[0020] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and preferred embodiments.

[0021] like Figure 1 As shown, this embodiment provides a mid-wave infrared zoom projection optical system with a long exit pupil distance for infrared target simulation. The operating wavelength of this system is 3. ~5 The system adopts an inverted structure with a front aperture, which specifically includes first fixed lens group G1, variable magnification lens group G2, compensation lens group G3 and second fixed lens group G4 coaxially arranged in sequence along the optical axis, and the first fixed lens group G1 has positive focal power, the variable magnification lens group G2 has negative focal power, the compensation lens group G3 has positive focal power, and the second fixed lens group G4 has positive focal power. Optionally, the first fixed lens group G1, the variable magnification lens group G2, the compensation lens group G3 and the second fixed lens group G4 can be separately arranged or arranged in the same lens barrel (not shown in the figure). The focal power distribution of the first fixed lens group G1, the variable magnification lens group G2, the compensation lens group G3 and the second fixed lens group G4 makes the exit pupil of the entire projection optical system be pushed far to the rear of the system, effectively extending the exit pupil distance to 300 mm, thereby leaving sufficient physical spacing between the target simulator and the device under test.

[0022] The first fixed lens group G1 and the second fixed lens group G4 are fixedly arranged and have fixed positions on the optical axis, so that the first fixed lens group G1 and the second fixed lens group G4 are stationary relative to the image plane. The variable magnification lens group G2 and the compensation lens group G3 are arranged to move along the optical axis, and reciprocally move along the optical axis to achieve switching between short focus and long focus. During zooming, the variable magnification lens group G2 is zoomed when moving along the optical axis, and the compensation lens group G3 is focused when moving along the optical axis. By adjusting the positions of the variable magnification lens group G2 and the compensation lens group G3 on the optical axis, the focal length of the zoom projection optical system can be adjusted, and the adjustment range of the focal length is -130 mm (W) - -260 mm (T), where W represents short focus and T represents long focus.

[0023] At the short focus position, the ratio of the focal length of the first fixed lens group G1 to the focal length F of the entire projection optical system is -1.836, the ratio of the focal length of the variable magnification lens group G2 to the focal length F of the entire projection optical system is 1.396, the ratio of the focal length of the compensation lens group G3 to the focal length F of the entire projection optical system is -1.356, and the ratio of the focal length of the second fixed lens group G4 to the focal length F of the entire projection optical system is -1.317.

[0024] At the mid-focus position, the ratio of the focal length of the first fixed lens group G1 to the focal length F of the entire projection optical system is -1.379, the ratio of the focal length of the variable magnification lens group G2 to the focal length F of the entire projection optical system is 1.049, the ratio of the focal length of the compensation lens group G3 to the focal length F of the entire projection optical system is -1.019, and the ratio of the focal length of the second fixed lens group G4 to the focal length F of the entire projection optical system is -0.989.

[0025] The ratio of the focal length of the first fixed lens group G1 to the focal length F of the entire projection optical system is -0.918, the ratio of the focal length of the variable magnification lens group G2 to the focal length F of the entire projection optical system is 0.698, the ratio of the focal length of the compensation lens group G3 to the focal length F of the entire projection optical system is -0.678, and the ratio of the focal length of the second fixed lens group G4 to the focal length F of the entire projection optical system is 0.658 when in the long-focus position.

[0026] By controlling the ratios of the focal lengths of the first fixed lens group G1, the variable magnification lens group G2, the compensation lens group G3, and the second fixed lens group G4 to the total focal length of the system within the ranges described above, the image plane position is kept stable and the zooming is smoother when the projection optical system continuously zooms within the focal length range of -130 mm to -260 mm.

[0027] Since the zoom projection optical system adopts an inverted structure design, the light beam emitted by the infrared light source enters the second fixed lens group G4 after passing through the illumination optical system (not shown in the figure) and the digital micromirror device (DMD) (not shown in the figure), and is emitted from the first fixed lens group G1 after the focal length is adjusted by the compensation lens group G3 and the variable magnification lens group G2, thereby completing the far-field projection of the infrared image. The working wavelength of the infrared light source in this embodiment is 3 ~5 .

[0028] This embodiment proposes a continuously zoomable projection optical system with a long exit pupil distance in view of the application characteristics of a mid-wave infrared band target simulator. By optimizing the optical path configuration, the exit pupil distance is significantly increased under the premise of ensuring high imaging quality and multi-field-of-view switching capability, which not only provides necessary space for equipment layout and heat dissipation, but also makes the infrared target simulator using the projection optical system more advantageous in complex test environments.

[0029] Since the projection optical system adopts an inverted structure design, the digital micromirror device can be regarded as an image plane when designed. As a specific implementation, the first fixed lens group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged in order from an aperture to an image plane. The first lens L1 has positive refractive power, the second lens L2 has negative refractive power, and the third lens L3 has positive refractive power. The first lens L1, the second lens L2, and the third lens L3 are all spherical glass, and the glass grades are ZNSE, ZNS_BROAD, and ZNSE, respectively. The parameters of the first fixed lens group G1 are shown in Table 1.

[0030] Table 1 Detailed parameters of the first fixed lens group G1

[0031]

[0032] As a specific embodiment, the zoom lens group G2 includes, in order from the stop to the image plane, a fourth lens L4, a fifth lens L5. The fourth lens L4 has a negative refractive power, and the fifth lens L5 has a positive refractive power. The fourth lens L4 and the fifth lens L5 are both spherical glasses, and the glass grades are GERMANIUM and GERMANIUM, respectively. The parameters of the zoom lens group G2 are shown in Table 2.

[0033] Table 2 Detailed parameters of zoom lens group G2

[0034]

[0035] As a specific embodiment, the zoom lens group G2 includes, in order from the stop to the image plane, a fourth lens L4, a fifth lens L5. The fourth lens L4 has a negative refractive power, and the fifth lens L5 has a positive refractive power. The fourth lens L4 and the fifth lens L5 are both spherical glasses, and the glass grades are GERMANIUM and GERMANIUM, respectively. The parameters of the zoom lens group G2 are shown in Table 2.

[0036] Table 3 Detailed parameters of zoom lens group G2

[0037]

[0038] As a specific embodiment, the second fixed lens group G4 includes, in order from the stop to the image plane, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, a seventeenth lens L17, and a prism substitute flat glass L18, wherein the prism substitute flat glass L18 mainly functions to fold the light path and is used to fold the light beam reflected by the DMD into the projection optical system. The ninth lens L9 has a negative refractive power, the tenth lens L10 has a positive refractive power, the eleventh lens L11 has a positive refractive power, the twelfth lens L12 has a negative refractive power, the thirteenth lens L13 has a positive refractive power, the fourteenth lens L14 has a positive refractive power, the fifteenth lens L15 has a negative refractive power, the sixteenth lens L16 has a positive refractive power, the seventeenth lens L17 has a positive refractive power, and the prism substitute flat glass L18 is a flat glass that substitutes for an actual prism and has a refractive power of 0. The ninth lens L9, the tenth lens L10, the eleventh lens L11, the twelfth lens L12, the thirteenth lens L13, the fourteenth lens L14, the fifteenth lens L15, the sixteenth lens L16, and the seventeenth lens L17 are all spherical glasses, and the glass grades are GERMANIUM, GERMANIUM, GERMANIUM, ZNSE, ZNSE, ZNSE, GERMANIUM, ZNSE, and ZNS_BROAD, respectively. The prism substitute flat glass L18 is a flat glass that substitutes for an actual prism and has a glass grade of ZNS_BROAD. The parameters of the second fixed lens group G4 are shown in Table 4.

[0039] The prism substitute flat glass L18 specifically includes a first total reflection prism, a first compensation prism, and a second compensation prism that are closely adjacent, and the lower side of the first total reflection prism is parallel to the upper side of the first compensation prism. The first total reflection prism is responsible for folding the light path of the illumination optical system to the DMD, and the first compensation prism and the second compensation prism are compensation flats responsible for compensating for the optical path difference, i.e., the lower side of the first total reflection prism is parallel to the upper side of the first compensation prism. The second compensation prism is also responsible for folding the off-state light rays so that they are away from the projection light path, thereby avoiding stray light interference. The light emitted by the infrared light source is incident from the left side of the first total reflection prism through the illumination optical system, is totally reflected by the inclined surface of the first total reflection prism, and then is incident onto the DMD through the lower side of the first total reflection prism. The on-state light rays reflected by the DMD pass through the lower side of the first total reflection prism, the first total reflection prism, the first compensation prism, and the second compensation prism in order, and then enter the projection system. The prism group is equivalent to a flat glass in system design.

[0040] Table 4: Detailed parameters of the second fixed lens group G4

[0041]

[0042] The projection optical system for infrared target simulation provided by the application adopts a zoom structure design, which is sequentially composed of a first fixed lens group G1, a zoom lens group G2, a compensation lens group G3, and a second fixed lens group G4. The power distribution and lens surface parameters of each group are reasonably configured, and the motion trajectories of the zoom lens group G2 and the compensation lens group G3 are accurately controlled through an existing mechanical structure such as a zoom cam mechanism (not shown in the figure), so that continuous and smooth zooming can be achieved within a field of view angle range of 1.97°-3.94°, wherein 3.94° is the field of view angle corresponding to the short-focus position, 1.97° is the field of view angle corresponding to the long-focus position, the maximum light aperture is 59.3712 mm, and the image size is 8.9 mm.

[0043] The projection optical system adopts an inverted structure with a diaphragm in front, and the diaphragm is arranged at the front end to ensure that the light beam from the infrared light source enters the projection optical system after being reflected by the DMD after passing through the illumination optical system, thereby completing the far-field projection of the infrared scene. To achieve the requirements of telecentricity and long exit pupil distance, the projection optical system adopts a two-imaging structure: the first fixed lens group G1 and the zoom lens group G2 form a zoom front group to achieve two times zooming; and the second fixed lens group G4 as an imaging rear group with a magnification is spliced with the front group to effectively realize the telecentricity design and ensure that the exit pupil distance is 300 mm.

[0044] The overall performance indicators of the long-exit-pupil-distance mid-wave infrared zoom projection optical system of the application are as follows:

[0045] Working waveband: 3 ~5 ;

[0046] Focal length: -130 mm at the short-focus position (W) and -260 mm at the long-focus position (T);

[0047] Field of view angle: 3.94° at the short-focus position (W) and 1.97° at the long-focus position (T);

[0048] Maximum light aperture: 59.3712 mm;

[0049] Image size: 8.9 mm;

[0050] Exit pupil distance: 300 mm.

[0051] The long-exit-pupil-distance mid-wave infrared zoom projection optical system of the application works in the 3 ~5 mid-wave infrared waveband, and can simulate infrared target scenes with different fields of view to provide matching field of view conditions for the rear detection system. Each group works cooperatively to realize the zoom function while ensuring image stability and optical performance.

[0052] Figures 2-4 The modulation transfer function (MTF) diagrams of the long-standoff mid-wave infrared zoom projection optical system at short, medium and long focal lengths are shown in the figures. ~5 The on-axis, 0.7 field and full field positions of the system have MTFs greater than 0.4 at a spatial frequency of 35 lp / mm, and approach the diffraction limit at low spatial frequencies of 5-10 lp / mm. The system maintains a high contrast at spatial frequencies of 25 lp / mm and above, indicating that the system has good high-frequency response capability. The MTF curves change smoothly from the on-axis to the full field, indicating that the system is fully corrected for off-axis aberrations such as astigmatism, coma and field curvature, and has excellent image quality uniformity.

[0053] Another embodiment of the present application provides an infrared target simulator, which includes the long-standoff mid-wave infrared zoom projection optical system of the above embodiment, and further includes an infrared light source, an illumination optical system, a light splitting module and a digital micromirror device.

[0054] Specifically, the light beam emitted by the infrared light source is incident on the light splitting module at a predetermined specific angle after passing through the illumination optical system. The light splitting module guides the light beam to the modulation surface of the digital micromirror device. The digital micromirror device spatially modulates the incident light according to the target image signal, and the reflected light in the on state is selectively diverted by the light splitting module and then enters the long-standoff mid-wave infrared zoom projection optical system. In the long-standoff mid-wave infrared zoom projection optical system, the focal length is continuously adjusted by the zoom structure, and finally the infrared image of different fields of view is projected in the far field.

[0055] The infrared target simulator proposed in the embodiment has a working wavelength of 3 ~5 The mid-wave infrared band, which can simulate infrared target scenes of different fields of view, provides matching field of view conditions for the rear detection system, and has higher image plane stability and optical performance while having a continuous zoom function.

[0056] The technical features of the above embodiments can be combined in any way. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the present application.

[0057] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A mid-wave infrared zoom projection optical system with a long exit pupil distance, characterized in that, The system employs an inverted structure with the aperture stop positioned in front. This inverted structure includes a first fixed lens group (G1), a zoom lens group (G2), a compensating lens group (G3), and a second fixed lens group (G4) arranged coaxially along the optical axis. The first fixed lens group (G1), the compensating lens group (G3), and the second fixed lens group (G4) all have positive optical power, while the zoom lens group (G2) has negative optical power. The first fixed lens group (G1) and the zoom lens group (G2) form the front zoom group, achieving a 2x zoom. The second fixed lens group (G4) serves as the magnification factor. The image of the rear group is stitched together with the image of the front group; The first fixed lens group (G1) and the second fixed lens group (G4) are fixed in position on the optical axis. The zoom lens group (G2) and the compensating lens group (G3) reciprocate along the optical axis to achieve switching between short focal length and long focal length. During the zooming process, the zoom lens group (G2) zooms while moving along the optical axis, and the compensating lens group (G3) focuses while moving along the optical axis. The short focal length is -130mm, the long focal length is -260mm, and the exit pupil distance is 300mm. The operating wavelength is 3 ~5 The beam emitted by the infrared light source passes through the illumination optical system and digital micromirror device, then enters the second fixed lens group (G4). After the focal length is adjusted by the compensation lens group (G3) and the zoom lens group (G2), it exits from the first fixed lens group (G1) to complete the far-field projection of the infrared image. The second fixed lens group (G4) includes, from the aperture stop to the image plane, the ninth lens (L9), tenth lens (L10), eleventh lens (L11), twelfth lens (L12), thirteenth lens (L13), fourteenth lens (L14), fifteenth lens (L15), sixteenth lens (L16), seventeenth lens (L17), and a prism replacing the flat glass (L18); the ninth lens (L9), twelfth lens (L12), and fifteenth lens (L15) all have negative optical power, the tenth lens (L10), eleventh lens (L11), thirteenth lens (L12), and eleventh lens (L13) all have negative optical power, and the tenth lens (L10), eleventh lens (L11), and thirteenth lens (L14) all have negative optical power. Lens (L13), the fourteenth lens (L14), the sixteenth lens (L16), and the seventeenth lens (L17) all have positive optical power, while the optical power of the prism replacing the flat glass (L18) is 0; the ninth lens (L9) to the seventeenth lens (L17) are all spherical glass, with glass grades of GERMANIUM, GERMANIUM, GERMANIUM, ZNSE, ZNSE, ZNSE, GERMANIUM, ZNSE, and ZNS_BROAD, respectively; the glass grade of the prism replacing the flat glass (L18) is ZNS_BROAD.

2. The mid-wave infrared zoom projection optical system with long exit pupil distance according to claim 1, characterized in that, The first fixed lens group (G1) includes a first lens (L1), a second lens (L2), and a third lens (L3) arranged sequentially from the aperture stop to the image plane; the first lens (L1) and the third lens (L3) both have positive optical power, and the second lens (L2) has negative optical power; the first lens (L1), the second lens (L2), and the third lens (L3) are all spherical glass, and the glass grades are ZNSE, ZNS_BROAD, and ZNSE, respectively.

3. The mid-wave infrared zoom projection optical system with long exit pupil distance according to claim 1, characterized in that, The zoom lens group (G2) includes a fourth lens (L4) and a fifth lens (L5) arranged sequentially from the aperture stop to the image plane; the fourth lens (L4) has negative optical power and the fifth lens (L5) has positive optical power; both the fourth lens (L4) and the fifth lens (L5) are spherical glass, and the glass grade is GERMANIUM.

4. The mid-wave infrared zoom projection optical system with long exit pupil distance according to claim 1, characterized in that, The compensating lens group (G3) includes the sixth lens (L6), the seventh lens (L7), and the eighth lens (L8) arranged sequentially from the aperture stop to the image plane; the sixth lens (L6) and the eighth lens (L8) both have positive optical power, and the seventh lens (L7) has negative optical power; the sixth lens (L6), the seventh lens (L7), and the eighth lens (L8) are all spherical glass, with glass grades ZNSE, ZNS_BROAD, and ZNSE, respectively.

5. The mid-wave infrared zoom projection optical system with long exit pupil distance according to claim 1, characterized in that, At the short focal length position, the ratio of the focal length of the first fixed lens group (G1) to the focal length F of the entire projection optical system is -1.836, the ratio of the focal length of the zoom lens group (G2) to the focal length F is 1.396, the ratio of the focal length of the compensation lens group (G3) to the focal length F is -1.356, and the ratio of the focal length of the second fixed lens group (G4) to the focal length F is -1.

317.

6. The mid-wave infrared zoom projection optical system with long exit pupil distance according to claim 1, characterized in that, At the mid-focal position, the ratio of focal length to focal length F of the first fixed lens group (G1) is -1.379, the ratio of focal length to focal length F of the zoom lens group (G2) is 1.049, the ratio of focal length to focal length F of the compensating lens group (G3) is -1.019, and the ratio of focal length to focal length F of the second fixed lens group (G4) is -0.

989.

7. The mid-wave infrared zoom projection optical system with long exit pupil distance according to claim 1, characterized in that, At the telephoto position, the ratio of focal length to focal length F of the first fixed lens group (G1) is -0.918, the ratio of focal length to focal length F of the zoom lens group (G2) is 0.698, the ratio of focal length to focal length F of the compensating lens group (G3) is -0.678, and the ratio of focal length to focal length F of the second fixed lens group (G4) is 0.

658.

8. The mid-wave infrared zoom projection optical system with long exit pupil distance according to claim 1, characterized in that, The first fixed lens group (G1), the zoom lens group (G2), the compensating lens group (G3), and the second fixed lens group (G4) are housed in the same lens barrel.

9. An infrared target simulator, characterized in that, The system includes a long exit pupil distance mid-wave infrared zoom projection optical system as described in any one of claims 1 to 8, and further includes an infrared light source, an illumination optical system, a beam splitting module, and a digital micromirror device, wherein the infrared light source operates at a wavelength of 3... ~5 ; The light beam emitted by the infrared light source is incident on the beam splitting module after passing through the illumination optical system. The beam splitting module guides the light beam to the modulation surface of the digital micromirror device. The digital micromirror device spatially modulates the incident light according to the target image signal. Its open-state reflected light is then selectively redirected by the beam splitting module and enters the long exit pupil distance mid-wave infrared zoom projection optical system. The long exit pupil distance mid-wave infrared zoom projection optical system projects infrared images of different fields of view in the far field.

Images