Compact continuous zoom optical system based on high resolution hot devices

Abstract

The utility model discloses a kind of light and small continuous zoom optical system based on high-resolution HOT device, the optical system sequentially includes: front fixed group, zoom group, compensation group, focusing group, secondary imaging group and two mirrors from object side to image side, the utility model is matched with the cooperation of optical power between first lens and second lens and the collocation of silicon single crystal, germanium single crystal material, effectively compresses the optical transverse dimension of zoom group and compensation group lens, by first mirror and second mirror and secondary imaging group reasonable configuration, effectively shorten the longitudinal distance of optical system, by the cooperation of zoom group and compensation group, realize the continuous zoom of entire system, by focusing group axial motion, realize the focusing function of high temperature and near distance imaging, realize the design of optical system continuous focusing and light and small.

Description

Technical Field

[0001] This utility model relates to the field of infrared optical technology, and in particular to a lightweight and compact continuous zoom optical system based on a high-resolution HOT device. Background Technology

[0002] Infrared imaging systems are characterized by passive operation, strong anti-interference capabilities, all-weather operation, and the ability to identify camouflaged targets. They can be widely used in fields such as infrared night vision, infrared reconnaissance, and camouflage identification.

[0003] Detecting distant targets and extracting their feature information can help determine the target's type, operational status, size, and other relevant information, which is of great significance to related fields. Continuous zoom optical systems can achieve large field-of-view search and small field-of-view tracking or identification. During field-of-view transitions, the observed target can be continuously enlarged or reduced in size, which is highly advantageous for searching and tracking high-speed moving targets. This overcomes the deficiency of segmented zoom optical systems in losing high-speed targets during field-of-view switching. Therefore, continuous zoom optical systems have great application prospects in optoelectronic observation, reconnaissance, and tracking equipment.

[0004] With the development and increasing demand for handheld and drone-mounted optoelectronic devices, infrared zoom systems are continuously evolving towards smaller size, compactness, and higher resolution. This places higher demands on the absolute length of mid-wave infrared continuous zoom optical systems and on the focal length range of lenses. Miniaturized, high-magnification-ratio continuous zoom lenses are an inevitable trend in the development of infrared zoom lenses. To adapt to this development, a HOT-type infrared photodetector has emerged, characterized by its compact structure, small size, and light weight. This invention designs a lightweight, compact continuous zoom optical system based on a high-resolution HOT device. This system utilizes only two conventional materials—germanium single crystal and silicon single crystal—to achieve a compact optical system design.

[0005] CN211180377U discloses a 50× continuous zoom mid-wave infrared optical system with a large zoom ratio. The optical system has a focal length of 13.2mm to 665mm and an F-number of 5.5.

[0006] CN112363305A discloses a miniature mid-wave infrared continuous zoom optical system with a focal length of 14-140mm, an F number of 5.5, and the use of multiple binary diffraction surfaces.

[0007] CN111025608A discloses an ultra-compact continuous zoom mid-wave infrared optical system with a focal length of 70–240 mm, a mid-wave detector with 640×512 pixels, an F-number of 4, and multiple binary diffraction surfaces.

[0008] CN110543001A discloses a miniaturized high zoom ratio mid-wave cooled infrared continuous zoom optical system. The optical system has a focal length of 15mm to 300mm, a mid-wave detector with 640×512 pixels, an F number of 4, and uses multiple binary diffraction surfaces.

[0009] CN115268042A discloses a lightweight, high zoom ratio mid-wave infrared continuous zoom optical system with a focal length of 14.8mm to 460mm and an optical envelope of 208mm × 136mm × 120mm.

[0010] The main shortcomings of the above-mentioned existing technologies are: either the magnification ratio is small and the resolution is low; or the use of multiple binary diffraction surfaces increases the system cost, and the presence of binary diffraction surfaces in the system increases the ring energy stray light brought about by the binary diffraction surfaces to a certain extent; or the system envelope size is large, making it difficult to meet the requirements for miniaturization. Summary of the Invention

[0011] To address the numerous shortcomings and deficiencies in the aforementioned background technology, this invention provides improvements and innovations, aiming to offer a compact and lightweight continuous zoom optical system based on a high-resolution HOT device. This system is small in size and has a wide range of applications. In this invention, the lateral optical path is shortened by matching the second lens with the first lens, thereby reducing the overall lateral length of the optical system.

[0012] By employing two plane mirrors, the U-shaped optical path of the first and second mirrors effectively compresses the longitudinal distance of the optical system.

[0013] Continuous zoom is achieved by axial movement between the third, fourth, and fifth lenses along the optical axis, and high / low temperature and close-range imaging focusing functions are achieved by the sixth lens.

[0014] To solve the above problems and achieve the objectives of the invention, this utility model provides a lightweight and compact continuous zoom optical system based on a high-resolution HOT device, achieved through the following design mechanism and technical solutions:

[0015] A lightweight, compact continuous zoom optical system based on a high-resolution HOT device includes an optical system and an infrared detector. The optical system, along the direction of light propagation, sequentially comprises: a front fixed group, a zoom group, a compensation group, a focusing group, a first reflecting mirror, and a secondary imaging group.

[0016] The front fixed group consists of a positive optical power lens group composed of a first lens and a second lens. The second lens compresses the optical path aperture, shortens the axial length of the optical system, and reduces the aperture of the zoom compensation group.

[0017] The zoom group consists of a negative lens composed of a third lens;

[0018] The compensation group consists of a positive optical power lens group composed of a fourth lens and a fifth lens. The compensation group works in conjunction with the zoom group to adjust the focal length.

[0019] The focusing group consists of a negative lens composed of a sixth lens, used to adjust high and low temperatures and close-range focusing;

[0020] The secondary imaging group consists of a positive power lens group composed of a seventh lens, an eighth lens, and a ninth lens. A second reflecting mirror is set between the eighth lens and the ninth lens. The seventh lens and the eighth lens shorten the longitudinal length of the optical system and eliminate chromatic aberration.

[0021] In this process, the object-side imaging beam sequentially passes through the front fixed group, the zoom group, the compensation group, the focusing group, and the first reflecting mirror to deflect the optical path before forming an image for the first time. Then, it passes through the secondary imaging group and the second reflecting mirror to deflect the optical path before forming a second image on the detector. During continuous zooming, the zoom group and the compensation group move relative to each other along the optical axis to obtain a clear image across the entire focal length.

[0022] Preferably, the first lens is a meniscus positive lens with its convex surface facing the object.

[0023] The second lens is a meniscus negative lens with the convex surface facing the object side, used to compress the optical path aperture and reduce the aperture of the zoom compensation group;

[0024] The third lens is a biconcave negative lens;

[0025] The fourth lens is a biconvex negative lens;

[0026] The fifth lens is a meniscus positive lens with its convex surface facing the object.

[0027] The sixth lens is a meniscus negative lens with its convex surface facing the object side;

[0028] The seventh lens is a biconvex positive lens;

[0029] The eighth lens is a biconcave negative lens;

[0030] The ninth lens is a meniscus positive lens with its convex surface facing the object.

[0031] Preferably, the front surface of the third lens, the rear surface of the fourth lens, the front surface of the fifth lens, the front surface of the sixth lens, the front surface of the seventh lens, the front surface of the eighth lens, and the front surface of the ninth lens are aspherical surfaces.

[0032] Preferably, the optical system has a large field of view of 28.72° × 21.74° and a small field of view of 1.63° × 1.22°.

[0033] Preferably, the optical system actively heats up to reduce thermal difference at temperatures ranging from -50°C to +80°C.

[0034] Preferably, the optical system operates in the wavelength range of 3.7μm to 4.8μm, has a focal length of 20mm to 360mm, adopts a U-shaped folding structure, and the total length of the thermal imager is only 130mm, achieving a lightweight and compact design of the optical system.

[0035] Preferably, the detector is a mid-wave HOT cooled focal plane infrared detector with a large area array and small pixels, having a pixel count of 1024×768 and a pixel size of 10μm, and is compatible with a mid-wave HOT cooled focal plane infrared detector with a pixel count of 640×512 and a pixel size of 15μm.

[0036] Preferably, both the first and second reflectors are planar reflectors rotated 45°.

[0037] Working Principle: The above-described lightweight continuous zoom optical system based on a high-resolution HOT device uses object-side rays that converge between the focusing group and the secondary imaging group after passing through the front fixed group, zoom group, compensation group, and focusing group. The rays are then focused onto the detector's focal plane by the secondary imaging group. The diameter of the front fixed group's positive optical power lens is constrained by the double focusing, reducing the size of optical components and achieving 100% cold screen efficiency. The second lens of the front fixed group handles a portion of the optical power, effectively compressing the lateral optical dimensions of the zoom and compensation group lenses. A U-shaped optical path using two plane mirrors (the first and second mirrors) effectively compresses the longitudinal distance of the optical system, limiting the longitudinal length of the lightweight continuous zoom optical system based on the high-resolution HOT device to 130mm. Continuous zoom is achieved through the cooperation of the zoom and compensation groups. Axial movement of the focusing group enables focusing functions for high and low temperatures and close-range imaging.

[0038] In summary, the beneficial effects of this utility model compared with the prior art are as follows:

[0039] 1. This utility model uses optical design software simulation to match silicon single crystals and germanium single crystals to allocate optical power, compensate for the difference in refractive index of light of different wavelengths, and focus multicolor light on the same plane to achieve color difference correction of infrared optical system.

[0040] 2. By adopting a U-shaped folding optical path with a first and a second reflecting mirror, this utility model not only achieves 100% cold screen efficiency but also effectively reduces the length of the optical system. Through reasonable optical focal length construction and material matching, the structure is greatly simplified, and the overall length of the thermal imager is only 130mm when the focal length is 20mm-360mm, realizing a lightweight and compact design of the optical system.

[0041] 3. This utility model uses only aspherical surfaces and does not use binary diffraction surfaces, which effectively avoids the ring-shaped energy stray light caused by binary diffraction surfaces and improves the imaging quality.

[0042] 4. This utility model achieves focusing functions for high and low temperature and close-range imaging by using the movement of the zoom group and the compensation group along the optical axis.

[0043] 5. By optimizing the curvature and position of the lens, this utility model achieves a radiation intensity ratio of less than 0.5, effectively reducing the cold reflection effect. Attached Figure Description

[0044] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings, wherein:

[0045] Figure 1 This is a schematic diagram of the optical system of this utility model;

[0046] Figure 2 This is a schematic diagram of the small field of view (360mm) full field of view of the optical system of this utility model;

[0047] Figure 3 This is a schematic diagram of the optical system of this utility model with a 200mm full field of view in the center.

[0048] Figure 4 This is a schematic diagram of the 20mm full field of view optical system of this utility model.

[0049] Figure 5 This is a schematic diagram of the optical system of this utility model with a small field of view of 360mm optical axis;

[0050] Figure 6 This is a schematic diagram of the optical system of this utility model with a 200mm optical axis in the middle field of view;

[0051] Figure 7 This is a schematic diagram of the optical system of this utility model with a large field of view and a 20mm optical axis;

[0052] Figure 8 This is a 360mm distortion image with a small field of view, according to this utility model.

[0053] Figure 9 This is the 200mm distortion image of the intermediate field of view of this utility model;

[0054] Figure 10 This is a 20mm distortion image with a large field of view of this utility model;

[0055] Figure 11 This is the transfer function curve of this utility model at a small field of view of 360mm and a characteristic frequency of 50mm / lp.

[0056] Figure 12This is the transfer function curve of the intermediate field of view of this utility model at 200mm and 50mm / lp.

[0057] Figure 13 This is the transfer function curve of the large field of view of 20mm at 50mm / lp of this utility model;

[0058] Figure 14 This is a diffusion pattern of the small field-of-view 360mm system of this utility model;

[0059] Figure 15 This is the diffusion pattern of the 200mm intermediate field of view system of this utility model;

[0060] Figure 16 This is the diffusion pattern of the large field-of-view 20mm system of this utility model;

[0061] Figure 17 This is the continuous zoom curve of this utility model;

[0062] The reference numerals in the figure are as follows: 1—first lens, 2—second lens, 3—third lens, 4—fourth lens, 5—fifth lens, 6—sixth lens, 7—seventh lens, 8—eighth lens, 9—ninth lens, 10—first reflecting mirror, 11—second reflecting mirror, R11—front surface of the first lens, R12—rear surface of the first lens, R21—front surface of the second lens, R22—rear surface of the second lens, R31—front surface of the third lens, R32—rear surface of the third lens, R41—front surface of the fourth lens, R42—rear surface of the fourth lens, R51—front surface of the fifth lens, R52—rear surface of the fifth lens, R61—front surface of the sixth lens, R62—rear surface of the sixth lens, R71—front surface of the seventh lens, R72—rear surface of the seventh lens, R81—front surface of the eighth lens, R82—rear surface of the eighth lens, R91—front surface of the ninth lens, R92—rear surface of the ninth lens. Detailed Implementation

[0063] To make the technical means, inventive features, and achieved objectives and effects of this utility model readily understandable, the technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. The present utility model will now be described in detail with reference to the accompanying drawings and embodiments.

[0064] like Figures 1 to 7 The lightweight, compact continuous zoom optical system based on a high-resolution HOT device, as shown, includes an optical system and an infrared detector. The optical system, along the direction of light propagation, sequentially comprises: a front fixed group, a zoom group, a compensation group, a focusing group, a first reflecting mirror 10, and a secondary imaging group.

[0065] The front fixed group consists of a positive optical power lens group composed of a first lens 1 and a second lens 2. The second lens 2 compresses the optical path aperture, shortens the axial length of the optical system, and reduces the aperture of the zoom compensation group.

[0066] The zoom group consists of a negative lens composed of the third lens 3;

[0067] The compensation group consists of a positive optical power lens group composed of a fourth lens 4 and a fifth lens 5. The compensation group works in conjunction with the zoom group to adjust the focal length.

[0068] The focusing group consists of a negative lens composed of a sixth lens 6, used to adjust high and low temperatures and close-range focusing;

[0069] The secondary imaging group consists of a positive power lens group composed of a seventh lens 7, an eighth lens 8 and a ninth lens 9. A second reflecting mirror 11 is set between the eighth lens 8 and the ninth lens 9. The longitudinal length of the optical system is shortened and chromatic aberration is eliminated by the seventh lens 7 and the eighth lens 8.

[0070] In this process, the object-side imaging beam sequentially passes through the front fixed group, the zoom group, the compensation group, the focusing group, and the first reflecting mirror 10 to deflect the optical path before forming an image for the first time. Then, it passes through the secondary imaging group and the second reflecting mirror 11 to deflect the optical path again before forming a second image on the detector. During continuous zooming, the zoom group and the compensation group move back and forth relative to each other along the optical axis to obtain a clear image across the entire focal length.

[0071] In this invention, the object-side imaging beam of the optical system is incident on the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6. After being refracted and reflected on the first reflecting mirror 10, it forms an image once. Then, it passes through the seventh lens 7 and the eighth lens 8, and is refracted and reflected on the second reflecting mirror 11, forming a second image on the detector through the ninth lens 9. Through the cooperation of the zoom group and the compensation group, continuous zoom of the entire system is achieved. The high and low temperature and close-range imaging focusing functions are achieved by moving the sixth lens 6 along the optical axis.

[0072] Table 1 lists the technical parameters of the optical system.

[0073] Table 1

[0074]

[0075] Furthermore, the first lens 1 is a meniscus positive lens with its convex surface facing the object, and its material is silicon single crystal;

[0076] The second lens 2 is a meniscus negative lens with the convex surface facing the object side. It is made of germanium single crystal and is used to compress the optical path aperture and reduce the aperture of the zoom compensation group.

[0077] The third lens 3 is a double concave negative lens, and its material is germanium single crystal;

[0078] The fourth lens 4 is a biconvex negative lens made of silicon single crystal.

[0079] The fifth lens 5 is a meniscus positive lens with its convex surface facing the object side, and its material is germanium single crystal;

[0080] The sixth lens 6 is a meniscus negative lens with its convex surface facing the object side, and its material is germanium single crystal.

[0081] The seventh lens 7 is a biconvex positive lens made of silicon single crystal.

[0082] The eighth lens 8 is a double concave negative lens, and its material is germanium single crystal;

[0083] The ninth lens 9 is a meniscus positive lens with its convex surface facing the object side, and its material is silicon single crystal.

[0084] The above-described lightweight continuous zoom optical system based on high-resolution HOT devices has the following specifications regarding lens curvature radius, thickness, spacing, and materials during use:

[0085]

[0086] Furthermore, according to the achromatic formula:

[0087]

[0088] Where φ is the optical power of the lens, and v is the Abbe number of the lens.

[0089] This invention uses only two materials, silicon single crystal and germanium single crystal, and optimizes and calculates the curvature and position of concave and convex lenses through optical design software simulation to compensate for the refractive index differences of different wavelengths of light, so that multicolor light is focused on the same plane, thereby achieving the correction of color difference in the infrared optical system.

[0090] Furthermore, the front surface R31 of the third lens 3, the rear surface R42 of the fourth lens 4, the front surface R51 of the fifth lens 5, the front surface R61 of the sixth lens 6, the front surface R71 of the seventh lens 7, the front surface R81 of the eighth lens 8, and the front surface R91 of the ninth lens 9 are aspherical surfaces.

[0091] Furthermore, the aspherical form is as follows:

[0092]

[0093] In the formula: Z represents the distance sag from the vertex of the aspherical surface at a height of r along the optical axis; c is the radius of curvature; k is the conic coefficient; and A, B, C, and D are higher-order aspherical coefficients.

[0094] The aspherical coefficients are shown in the table below:

[0095]

[0096] In the table: K is the conic coefficient, A is the fourth-order coefficient, B is the sixth-order coefficient, C is the eighth-order coefficient, and D is the tenth-order coefficient.

[0097] Furthermore, the front fixing assembly adopts a spherical design, which simplifies the manufacturing process and reduces costs.

[0098] Furthermore, along the optical axis, the distance from the vertex of the front surface of the third lens 3 to the vertex of the rear surface of the second lens 2 is 25.2mm–53.1mm; the distance from the vertex of the rear surface of the third lens 3 to the vertex of the front surface of the fourth lens is 45.9mm–3mm; and the distance from the vertex of the rear surface of the fifth lens 5 to the vertex of the front surface of the sixth lens 6 is 5mm–18.1mm. Figure 17 As shown in the (relative distance) diagram.

[0099] In this invention, when the zoom group approaches the compensation group, the optical system is at a long focal length. When the zoom group moves away from the compensation group, the optical system is at a short focal length.

[0100] Furthermore, the optical system has a large field of view of 28.72° × 21.74° and a small field of view of 1.63° × 1.22°.

[0101] Furthermore, the optical system operates in the wavelength range of 3.7μm to 4.8μm and has a focal length of 20mm to 360mm. It adopts a U-shaped folding structure, and the total length of the thermal imager is only 130mm, achieving a lightweight and compact design for the optical system.

[0102] Furthermore, this invention uses a secondary imaging group to converge and focus the light onto the detector's focal plane. It employs a double-focusing optical method to constrain the diameter of the front fixed-group positive optical power lens, reducing the size of optical components and achieving 100% cold screen efficiency. The second lens of the front fixed group bears a portion of the optical power, effectively compressing the optical lateral dimensions of the zoom and compensation group lenses. The use of two planar mirrors, specifically a U-shaped folding optical path between the first and second mirrors, effectively compresses the longitudinal distance of the optical system, limiting the longitudinal length of the lightweight continuous zoom optical system for high-resolution HOT devices to 130mm. This greatly simplifies the structure, achieving an overall length of only 130mm for thermal imagers with focal lengths ranging from 20mm to 360mm, thus realizing a lightweight and compact optical system design.

[0103] Specifically, through simulation using optical design software, such as Figure 8 , Figure 9 , Figure 10 As shown, the optical system exhibits distortion of less than 2% at focal lengths of 360mm, 200mm, and 20mm, meeting the application requirements.

[0104] Furthermore, such as Figure 11 , Figure 12 , Figure 13 As shown, this is the transfer function of the optical system at focal lengths of 360mm, 200mm, and 20mm when the characteristic frequency is 50mm / lp.

[0105] Furthermore, such as Figure 14 , Figure 15 , Figure 16 As shown, the dot plots are for optical systems with focal lengths of 360mm, 200mm, and 20mm. The RMS values ​​of the speckle blur at each focal length are similar to the size of the detector pixels, indicating good imaging quality.

[0106] Furthermore, this invention satisfies the requirement of active heat dissipation within a temperature range of -50℃ to +80℃, resulting in an overall system distortion of less than 2% and high imaging quality.

[0107] Furthermore, by optimizing the curvature and position of the lens, this invention achieves a radiation intensity ratio of less than 0.5, effectively reducing the cold reflection effect.

[0108] Furthermore, the optical system does not incorporate a binary diffraction surface, effectively avoiding the ring-shaped energy stray light caused by the binary diffraction surface, and to a certain extent reducing and simplifying the manufacturing process.

[0109] Furthermore, the detector adopts a large-area array with small pixels, a mid-wave HOT cooled focal plane infrared detector with a pixel count of 1024×768 and a pixel size of 10μm, and is compatible with a mid-wave HOT cooled focal plane infrared detector with a pixel count of 640×512 and a pixel size of 15μm.

[0110] Furthermore, both the first reflector 10 and the second reflector 11 are planar reflectors that are rotated 45°.

[0111] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model without departing from its technical solution shall still fall within the protection scope of this utility model.

Claims

1. A compact continuous zoom optical system based on high resolution HOT devices, comprising an optical system and an infrared detector, characterized in that, The optical system comprises, in sequence along the direction of light propagation, a front fixed group, a zoom group, a compensation group, a focusing group, a first reflecting mirror (10), and a secondary imaging group. The front fixed group consists of a positive optical power lens group composed of a first lens (1) and a second lens (2). The second lens (2) compresses the optical path aperture, shortens the axial length of the optical system, and reduces the aperture of the zoom compensation group. The zoom group consists of a negative lens composed of a third lens (3); The compensation group consists of a positive focal length lens group composed of a fourth lens (4) and a fifth lens (5). The compensation group works in conjunction with the zoom group to adjust the focal length. The focusing group consists of a negative lens composed of a sixth lens (6), used to adjust high and low temperatures and close-range focusing; The secondary imaging group consists of a positive power lens group composed of a seventh lens (7), an eighth lens (8) and a ninth lens (9). A second reflecting mirror (11) is provided between the eighth lens (8) and the ninth lens (9). The longitudinal length of the optical system is shortened and chromatic aberration is eliminated by the seventh lens (7) and the eighth lens (8). In this process, the object-side imaging beam passes through the front fixed group, the zoom group, the compensation group, the focusing group and the first reflecting mirror (10) in sequence to form an image for the first time, and then passes through the secondary imaging group and the second reflecting mirror (11) to form an image for the second time on the detector. During continuous zooming, the zoom group and the compensation group move back and forth along the optical axis to obtain a clear image across the entire focal length.

2. The lightweight and compact continuous zoom optical system based on a high-resolution HOT device according to claim 1, characterized in that: The first lens (1) is a meniscus positive lens with its convex surface facing the object; The second lens (2) is a meniscus negative lens with the convex surface facing the object side, used to compress the optical path aperture and reduce the aperture of the zoom compensation group; The third lens (3) is a double concave negative lens; The fourth lens (4) is a biconvex negative lens; The fifth lens (5) is a meniscus positive lens with its convex surface facing the object. The sixth lens (6) is a meniscus negative lens with its convex surface facing the object. The seventh lens (7) is a biconvex positive lens; The eighth lens (8) is a double concave negative lens; The ninth lens (9) is a meniscus positive lens with its convex surface facing the object.

3. The high-resolution HOD-based compact continuous zoom optical system according to claim 1, wherein The front surface (R31) of the third lens (3), the rear surface (R42) of the fourth lens (4), the front surface (R51) of the fifth lens (5), the front surface (R61) of the sixth lens (6), the front surface (R71) of the seventh lens (7), the front surface (R81) of the eighth lens (8), and the front surface (R91) of the ninth lens (9) are aspherical.

4. The compact high-resolution HOD-based optical system according to any one of claims 1 to 3, wherein The optical system has a large field of view of 28.72° × 21.74° and a small field of view of 1.63° × 1.22°.

5. The compact high-resolution HOD-based optical system according to any one of claims 1 to 3, wherein The optical system actively heats up to reduce thermal difference between -50℃ and +80℃.

6. The high-resolution HOD-based compact continuous zoom optical system according to any one of claims 1 to 3, wherein The optical system operates in the 3.7μm to 4.8μm band and has a focal length of 20mm to 360mm. It adopts a U-shaped folding structure, and the total length of the thermal imager is only 130mm, achieving a lightweight and compact design of the optical system.

7. The high-resolution HOD-based compact continuous zoom optical system according to any one of claims 1 to 3, wherein The detector adopts a large-array small-pixel mid-wave HOT refrigeration type focal plane infrared detector, pixel number is 1024*768, pixel size is 10 mu m, and the detector is compatible with a mid-wave HOT refrigeration type focal plane infrared detector with pixel number 640*512 and pixel size 15 mu m.

8. The high-resolution HOD-based compact continuous zoom optical system according to claim 1, wherein The first reflector (10) and the second reflector (11) are both plane reflectors with a folding angle of 45 degrees.

Images