Optical system for a television and infrared dual mode seeker

Abstract

An optical system for a dual-mode television and infrared seeker effectively avoids the impact of visible light detector heat on the imaging quality of the infrared optical system. It can be designed with a long focal length as needed, allowing for a longer recognition distance. The visible light and infrared systems image separately, and it is small in size, lightweight, has excellent imaging quality, and a simple structure that is easy to assemble and adjust. The first infrared lens near the head cover has a central hole. The first visible light lens (8), the second visible light lens (9), the third visible light lens (10), the fourth visible light lens (11), and the fifth visible light lens (12) are set inside the central hole. A reflector is set above the central hole of the first infrared lens. The reflector is used to reflect the visible light image onto the visible light detector, and the angle between the reflector and the optical axis is in the range of 45° to 30°. The visible light detector is set on the side of the infrared lens barrel.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and more particularly to an optical system for a dual-mode seeker that combines television and infrared capabilities, primarily used for all-weather precise target positioning. Background Technology

[0002] In the complex and ever-changing modern battlefield, a single guidance mode can no longer meet the needs of all-weather, multi-mission operations, making multi-mode composite technology an inevitable development trend. Television guidance offers advantages such as low cost and high resolution, but it is limited in nighttime or low-visibility conditions. Infrared guidance technology, on the other hand, boasts strong target identification capabilities and good concealment, enabling day and night operations. Therefore, utilizing dual-mode guidance (television and infrared) can achieve all-weather operations and precise target location.

[0003] Television and infrared dual-mode optical systems mainly have two designs: separate aperture and common aperture. In the early days, in order to reduce design difficulty, optical systems mostly adopted separate aperture systems with independent optical paths. With the improvement of design level and the development of manufacturing technology, considering that common aperture can greatly reduce the system size and weight, multi-mode common aperture has become the development trend.

[0004] The publicly available layout of a two-light composite optomechanical system includes a Cassegrain reflection system with dichroic beam splitting. This design has a large objective aperture, and its size and weight are difficult to control, failing to meet the requirements of a lightweight and compact seeker. Another way to achieve a two-light composite optomechanical system is through a transmission common aperture combined with dichroic beam splitting. This design requires simultaneous transmission of visible and infrared light, which demands high-reflectivity visible and infrared coating processes and presents challenges in fabrication, assembly, and cost. Another type of dual-light composite optomechanical system is the nested dual-light module scheme. For example, patent 201822027153.1 describes a visible light and long-wave infrared coaxial common-aperture composite optical system, in which the entire visible light imaging system is embedded in the first infrared lens of the infrared imaging system. This design strictly limits the system length of the visible light, resulting in a very short focal length and thus a very short recognition distance. Moreover, the visible light detector has at least two electronic boards, occupying a large space and significantly obstructing the optical path of the infrared optical system. At the same time, the detector located on the optical axis of the infrared system emits a large amount of thermal radiation when it is working, and infrared imaging utilizes the radiation energy of the target. Thus, the thermal radiation of the visible light detector will greatly affect the infrared imaging quality. In addition, patent 201910315209.X describes a visible light and long-wave infrared common-aperture composite imaging optical system. In this system, the visible light channel has two optical path reflections, increasing the difficulty of assembly and adjustment. At the same time, the visible light channel still needs to occupy the volume outside the infrared channel, increasing the size and weight. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide an optical system for a dual-mode seeker of television and infrared, which can effectively avoid the impact of visible light detector heat on the imaging quality of infrared optical system, can be designed with a long focal length as required, has a longer recognition distance, and allows visible light and infrared systems to image separately. Moreover, it is small in size, light in weight, has excellent imaging quality, and has a simple structure that is easy to assemble and adjust.

[0006] The technical solution of the present invention is: the optical system of this dual-mode television and infrared seeker includes: a head cover (1), an infrared imaging optical system (2), a visible light imaging optical system (3), and an infrared lens tube (15). The infrared imaging optical system includes a first infrared lens (4), a second infrared lens (5), a third infrared lens (6), and an infrared detector (7) arranged sequentially along the optical path and all having the same optical axis. The visible light imaging optical system includes a first visible light lens (8), a second visible light lens (9), a third visible light lens (10), a fourth visible light lens (11), a fifth visible light lens (12), a reflector (13), and a visible light detector (14) arranged sequentially along the optical path. The first infrared lens near the head cover has a central hole. The first visible light lens (8), the second visible light lens (9), the third visible light lens (10), the fourth visible light lens (11), and the fifth visible light lens (12) are disposed in the central hole. A reflector is disposed above the central hole of the first infrared lens. The reflector is used to reflect the image of visible light onto the visible light detector and the angle between the reflector and the optical axis is in the range of 45° to 30°. The visible light detector is disposed on the side of the infrared lens tube.

[0007] This invention provides separate imaging optical systems for visible light and infrared imaging, with the visible light detector positioned on the side of the infrared lens tube. This design effectively prevents the visible light detector's heat from affecting the imaging quality of the infrared optical system. Furthermore, it allows for a longer focal length for the visible light, enabling a greater detection distance. The angle between the reflector and the optical axis is 45°–30°, minimizing obstruction of the infrared light path. The infrared imaging system consists of only three infrared lenses, while the visible light system comprises two cemented lenses, one visible light lens, and a reflector. This results in a simple, compact structure, small size, light weight, low development costs, and reduced processing and assembly complexity, making operation easy. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the optical system of the dual-mode television and infrared seeker according to the present invention.

[0009] Figure 2 This is a simulation diagram of the infrared mode optical system of a dual-mode seeker for television and infrared according to an embodiment of the present invention.

[0010] Figure 3a , 3b These are simulation diagrams of the 25°C infrared mode optical MTF and the circle of confusion diameter of an optical system for a dual-mode television and infrared seeker provided according to an embodiment of the present invention.

[0011] Figure 4a , 4b These are simulation diagrams of the -40℃ infrared mode optical MTF and the circle of confusion diameter of an optical system for a dual-mode television and infrared seeker provided according to an embodiment of the present invention.

[0012] Figure 5a , 5b These are simulation diagrams of the 60°C infrared mode optical MTF and the circle of confusion diameter of an optical system for a dual-mode television and infrared seeker provided according to an embodiment of the present invention.

[0013] Figure 6 This is a simulation diagram of infrared mode field curvature and distortion of an optical system for a dual-mode seeker (TV and infrared) according to an embodiment of the present invention.

[0014] Figure 7 This is a simulation diagram of the television mode optical system of an optical system for a dual-mode seeker (television and infrared) according to an embodiment of the present invention.

[0015] Figure 8a , 8b These are simulation diagrams of the 25°C television mode optical MTF and circle of confusion diameter of an optical system for a dual-mode seeker (television and infrared) according to an embodiment of the present invention.

[0016] Figure 9a , 9b These are simulation diagrams of the -40℃ TV mode optical MTF and circle of confusion diameter of an optical system for a dual-mode TV and infrared seeker provided according to an embodiment of the present invention.

[0017] Figure 10a , 10b These are simulation diagrams of the 60°C television mode optical MTF and circle of confusion diameter of an optical system for a dual-mode seeker (television and infrared) according to an embodiment of the present invention.

[0018] Figure 11 This is a simulation diagram of the television mode field curvature and distortion of an optical system for a dual-mode seeker (television and infrared) according to an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the term "comprising" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products or devices.

[0021] like Figure 1 As shown, the optical system of this dual-mode television and infrared seeker includes: a head cover 1, an infrared imaging optical system 2, a visible light imaging optical system 3, and an infrared lens tube 15. The infrared imaging optical system includes a first infrared lens 4, a second infrared lens 5, a third infrared lens 6, and an infrared detector 7, all arranged sequentially along the optical path and having the same optical axis. The visible light imaging optical system includes a first visible light lens 8, a second visible light lens 9, a third visible light lens 10, a fourth visible light lens 11, a fifth visible light lens 12, a reflector 13, and a visible light detector 14, all arranged sequentially along the optical path. The first infrared lens near the head cover has a central hole. The first visible light lens 8, the second visible light lens 9, the third visible light lens 10, the fourth visible light lens 11, and the fifth visible light lens 12 are disposed in the central hole. A reflector is disposed above the central hole of the first infrared lens. The reflector is used to reflect the image of visible light to the visible light detector and the angle between the reflector and the optical axis is in the range of 45° to 30°. The visible light detector is disposed on the side of the infrared lens tube.

[0022] This invention provides separate imaging optical systems for visible light and infrared imaging, with the visible light detector positioned on the side of the infrared lens tube. This design effectively prevents the visible light detector's heat from affecting the imaging quality of the infrared optical system. Furthermore, it allows for a longer focal length for the visible light, enabling a greater detection distance. The angle between the reflector and the optical axis is 45°–30°, minimizing obstruction of the infrared light path. The infrared imaging system consists of only three infrared lenses, while the visible light system comprises two cemented lenses, one visible light lens, and a reflector. This results in a simple, compact structure, small size, light weight, low development costs, and reduced processing and assembly complexity, making operation easy.

[0023] Preferably, the reflector is angled to the visible light detector, and the sum of twice the angle between the reflector and the optical axis and the angle between the visible light detector and the optical axis is 90°, wherein the angle between the reflector and the optical axis is less than or equal to 45° and greater than 0°, so that the optical axis passes through the center of the visible light detector.

[0024] Preferably, the first infrared lens is a positive power meniscus lens, the second infrared lens is a negative power meniscus lens, and the third infrared lens is a negative power meniscus lens; the first visible light lens is a negative power biconcave lens, the second visible light lens is a positive power biconvex lens, the third visible light lens is a positive power biconvex lens, the fourth visible light lens is a positive power plano-convex lens, and the fifth visible light lens is a negative power plano-concave lens. The first and second visible light lenses are cemented together to form a first visible light composite lens, and the fourth and fifth visible light lenses are cemented together to form a second visible light composite lens, with the convex surface of the fourth visible light lens facing the object side. The cementing of the positive and negative lenses in the visible light composite lens reduces the number of optical elements and the manufacturing process. This combination improves the reliability of optical elements, reduces interfaces and connections between elements, lowers the failure rate and maintenance costs of optical elements, and can correct spherical aberration, chromatic aberration, and sine aberration while ensuring optical power.

[0025] Preferably, the convex surfaces of the first infrared lens, the second infrared lens, and the third infrared lens all face the object side.

[0026] Preferably, the first infrared lens has a spherical surface on one side facing the object and a binary diffraction surface on the other side, while both surfaces of the second and third infrared lenses are spherical. Diffractive optical elements have negative dispersion coefficients; directly fabricating the diffraction structure onto the lens allows for lightweight and heat-free design without increasing the number of lenses, effectively reducing costs. Adding a diffraction surface to the rear surface of the first lens can simultaneously eliminate chromatic aberration and thermal aberration, further improving image quality.

[0027] Preferably, the binary diffraction surface in the first infrared lens satisfies the following expression: , Where ρ = r / r1, r1 is the normalized radius of the binary diffraction surface, Ai is the phase coefficient of the binary diffraction surface, and N is the order of the polynomial coefficients in the series.

[0028] Preferably, the first infrared lens has a radius of curvature of 80.905 mm on the object-side surface, a thickness of 11.5 mm, and an effective aperture of 45 mm; the first infrared lens has a radius of curvature of 167.725 mm on the image-side surface, a thickness of 5.9 mm, and an effective aperture of 42.5 mm; the second infrared lens has a radius of curvature of 26.235 mm on the object-side surface, a thickness of 3.2 mm, and an effective aperture of 17.5 mm; the second infrared lens has a radius of curvature of 20.517 mm on the image-side surface. The first visible light lens has a radius of curvature of 60.268 mm, a thickness of 3 mm, and an effective aperture of 13.5 mm. The second visible light lens has a radius of curvature of -21.095 mm, a thickness of 1.5 mm, and an effective aperture of 7.25 mm. The third infrared lens has a radius of curvature of 142.060 mm, a thickness of 15.115 mm, and an effective aperture of 12 mm. The third infrared lens has a radius of curvature of -21.095 mm, a thickness of 1.5 mm, and an effective aperture of 7.25 mm. The first visible light lens has a radius of curvature of 58.534 mm on its image-side surface, a thickness of 3.25 mm, and an effective aperture of 8.5 mm. The second visible light lens has a radius of curvature of -26.968 mm on its image-side surface, a thickness of 0.3 mm, and an effective aperture of 8.5 mm. The third visible light lens has a radius of curvature of 71.396 mm on its object-side surface, a thickness of 2.75 mm, and an effective aperture of 8.5 mm. The radius of curvature of the third visible light lens on its image-side surface is -49.2 mm. The first visible light lens has a radius of curvature of 22mm, a thickness of 1.5mm, and an effective aperture of 8.5mm; the second visible light lens has a radius of curvature of 15.187mm on the object-side surface, a thickness of 4mm, and an effective aperture of 8.25mm; the third visible light lens has a radius of curvature of 130.852mm on the image-side surface, a thickness of 1.5mm, and an effective aperture of 8.25mm; the fourth visible light lens has a radius of curvature of 12.634mm on the image-side surface, a thickness of 27mm, and an effective aperture of 6.5mm.

[0029] Preferably, the total length of the infrared optical system is <111mm, the F-number is 1, and the focal length is 95mm; the wavelength range of the transmitted light is 8um to 14um; the total length of the visible light optical system is greater than 58mm, the F-number is 5, the focal length is 70mm, and the wavelength range of the transmitted light is 435nm to 650nm.

[0030] Preferably, the headgear material is zinc sulfide, which transmits both visible and infrared light; the second infrared lens is a germanium crystal, and the first and third infrared lenses are both made of infrared chalcogenide glass; the first visible light lens is made of heavy flint glass, the second visible light lens is made of heavy phosphorus crown glass, the third visible light lens is made of heavy flint glass, the fourth visible light lens is made of heavy crown glass, and the fifth visible light lens is made of heavy flint glass. Through the rational distribution of optical power and the combination of optical glasses with different material properties, the total optical length is reduced, while aberrations and thermal differences are corrected, thus improving image quality.

[0031] Preferably, the angle between the reflector and the optical axis is in the range of 30° to 35°. Within this angle range, there is less obstruction to the infrared light path, resulting in better imaging quality.

[0032] The present invention will now be described in more detail.

[0033] like Figure 1 As shown, the optical system structure of a dual-mode television and infrared seeker includes: a head cover 1, an infrared imaging optical system 2, and a television imaging optical system 3. The infrared imaging system has a central aperture on a first infrared lens 4 near the head cover. A visible light lens and a reflector are positioned at the aperture, and the visible light image is projected onto a visible light detector located on the side of the infrared lens barrel via the reflector.

[0034] The headgear is made of zinc sulfide, which can transmit both visible and infrared light.

[0035] The infrared imaging system includes a positive optical power meniscus-shaped first infrared lens 4, a negative optical power meniscus-shaped second infrared lens 5, a negative optical power meniscus-shaped third infrared lens 6, and an infrared detector 7 arranged sequentially along the optical path. The first infrared lens has the central aperture. The convex surfaces of the first, second, and third infrared lenses all face the object side. Both surfaces of the second and third infrared lenses are spherical, while the object-facing side of the first infrared lens is spherical, and the other side is a binary diffraction surface on an aspherical substrate.

[0036] The specific parameters of the infrared optical system in this embodiment are as follows: the first infrared lens has a radius of curvature of 80.905 mm on the object-side surface, a thickness of 11.5 mm, and an effective aperture of 45 mm; the first infrared lens has a radius of curvature of 167.725 mm on the image-side surface, a thickness of 5.9 mm, and an effective aperture of 42.5 mm; the second infrared lens has a radius of curvature of 26.235 mm on the object-side surface, a thickness of 3.2 mm, and an effective aperture of 17.5 mm; the second infrared lens has a radius of curvature of 20.517 mm on the image-side surface, a thickness of 5.623 mm, and an effective aperture of 14 mm; the third infrared lens has a radius of curvature of 60.268 mm on the object-side surface, a thickness of 3 mm, and an effective aperture of 13.5 mm; the third infrared lens has a radius of curvature of 142.060 mm on the image-side surface, a thickness of 15.115 mm, and an effective aperture of 12 mm.

[0037] To increase the system transmittance, an infrared multilayer broadband antireflective coating is deposited on the surface of the infrared lens.

[0038] The second infrared lens is a germanium crystal, and the first and third infrared lenses are both made of infrared chalcogenide glass, specifically IRG206 chalcogenide glass from Xinhua Optoelectronics Co., Ltd.

[0039] The visible light imaging system includes a first visible light lens 8 with negative optical power and biconcave shape, a second visible light lens 9 with positive optical power and biconvex shape, a third visible light lens 10 with positive optical power and biconvex shape, a fourth visible light lens 11 with positive optical power and plano-convex shape, a fifth visible light lens 12 with negative optical power and plano-concave shape, a reflector 13, and a visible light detector 14, arranged sequentially along the optical path. The first and second visible light lenses are cemented together to form a first visible light combined lens, and the fourth and fifth visible light lenses are cemented together to form a second visible light combined lens. The convex surface of the fourth visible light lens faces the object side.

[0040] The specific parameters of the visible light system in this embodiment are as follows: the radius of curvature of the first visible light lens facing the object-side surface is -21.095 mm, its thickness is 1.5 mm, and its effective aperture is 7.25 mm; the radius of curvature of the first visible light lens facing the image-side surface s4 is 58.534 mm, its thickness is 3.25 mm, and its effective aperture is 8.5 mm; the radius of curvature of the second visible light lens facing the image-side surface is -26.968 mm, its thickness is 0.3 mm, and its effective aperture is 8.5 mm; the radius of curvature of the third visible light lens facing the object-side surface is 71.396 mm, its thickness is 2.75 mm, and its effective aperture is... The third visible light lens has an effective aperture of 8.5 mm; its radius of curvature on the image-side surface is -49.222 mm, its thickness is 1.5 mm, and its effective aperture is 8.5 mm; the fourth visible light lens has a radius of curvature on the object-side surface is 15.187 mm, its thickness is 4 mm, and its effective aperture is 8.25 mm; the fifth visible light lens has a radius of curvature on the image-side surface is 130.852 mm, its thickness is 1.5 mm, and its effective aperture is 8.25 mm; the sixth visible light lens has a radius of curvature on the image-side surface is 12.634 mm, its thickness is 27 mm, and its effective aperture is 6.5 mm.

[0041] The first visible light lens is made of heavy flint glass, the second visible light lens is made of heavy phosphorus crown glass, the third visible light lens is made of heavy flint glass, the fourth visible light lens is made of heavy crown glass, and the fifth visible light lens is made of heavy flint glass.

[0042] The device also includes an infrared lens tube 15, wherein the angle between the reflector and the optical axis is matched with the angle of the visible light detector, so as to make the visible light lens group coaxial with the center of the visible light detector.

[0043] The optical system specifications of a dual-mode seeker for television and infrared provided in this invention are as follows: operating wavelength: television band 435nm~650nm, infrared band 8mm~14mm; infrared mode F-number 1, television mode F-number 5; infrared system focal length 95mm, visible light system focal length 70mm; infrared imaging system adapted to a 640×512 resolution, 12um pixel size long-wave infrared thermal imaging detector, television imaging system adapted to a 1600×1600 resolution, 3.75um pixel size visible light imaging detector; temperature range -40℃~60℃.

[0044] This invention employs a nested system structure, where the visible light system and the infrared optical system image independently without interference. Each system reduces the incident angle of the off-axis principal ray on the lens surfaces by selecting optical materials and initial optical structures, allocating optical power, and incorporating aspherical surfaces and binary diffraction surfaces with negative refractive index characteristics. This reduces the influence of optical aberrations such as coma and astigmatism, eliminates the effect of temperature on the optical system performance, and achieves image clarity within a temperature range of -40℃ to 60℃ without focusing.

[0045] Figures 3, 4, and 5 respectively show simulation diagrams of the optical transfer function (OPF) values ​​and circle of confusion diameter of an optical system for a dual-mode television and infrared seeker provided according to an embodiment of the present invention, operating at room temperature (25°C), low temperature (-40°C), and high temperature (60°C) in infrared mode without focusing. As can be seen from the figures, the root mean square (RMS) value of the circle of confusion of the optical system in this embodiment is no greater than 10.14 μm, which is less than the pixel size of 12 μm, meeting the imaging requirements. At a spatial frequency of 30 lp / mm, the central field-of-view transfer function of this embodiment is greater than 0.45 within the temperature range of -40°C to +60°C, approaching the diffraction limit, indicating excellent imaging quality. Figures 8, 9, and 10 respectively show simulation diagrams of the OPF values ​​and circle of confusion diameter of an optical system for a dual-mode television and infrared seeker provided according to an embodiment of the present invention, operating at room temperature (25°C), low temperature (-40°C), and high temperature (60°C) in television mode without focusing. As shown in the figure, the root mean square (RMS) value of the circle of confusion of the optical system in this embodiment is no greater than 1.21 μm, which is smaller than the pixel size of 3.75 μm, thus meeting the imaging requirements. The figure also shows that at a spatial frequency of 120 lp / mm, the central field transfer function of this embodiment is approximately 0.5 within a temperature range of -40℃ to +60℃, indicating excellent imaging quality.

[0046] Figure 6 A schematic diagram simulating the infrared mode field curvature and distortion of an optical system for a dual-mode seeker (television and infrared) according to an embodiment of the present invention is shown. Figure 11 A schematic diagram illustrating the television mode field curvature and distortion simulation of an optical system for a dual-mode (television and infrared) seeker according to an embodiment of the present invention is shown. Figure 6 and Figure 11 As shown, the optical system provided in this embodiment of the invention exhibits less imaging distortion in both television mode and infrared mode.

[0047] Compared with the prior art, the present invention has the following advantages and features: (1) The present invention uses visible light and infrared systems for separate imaging, and sets the visible light detector on the side of the infrared tube. This design can effectively avoid the visible light detector from heating up and affecting the imaging quality of the infrared optical system. On the other hand, the focal length of the visible light can be designed to be a long focal length, so that the recognition distance is farther. At the same time, the angle between the reflector and the optical axis is 45° to 30°, which can minimize the obstruction of the infrared light path.

[0048] (2) The infrared system introduces aspherical surfaces and binary diffraction surfaces with negative refractive index characteristics. On the one hand, it reduces the incident angle of the off-axis beam principal ray on each lens surface, reduces the influence of optical aberrations such as chromatic aberration, coma, and astigmatism, eliminates the influence of temperature on the performance of the optical system, effectively helps to achieve calorimetric design, and has excellent imaging quality. On the other hand, infrared materials are expensive and have a high specific gravity. The application of aspherical substrate diffraction elements reduces the number of lenses, which can effectively reduce costs and lighten the system weight.

[0049] (3) At the same time, the infrared imaging system consists of only 3 infrared lenses and the visible light system consists of only 2 cemented lenses, 1 visible light lens and a reflector. The structure is simple and compact, small in size and light in weight, with low research and development costs, effectively reducing the difficulty of processing and assembly, and easy to operate.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An optical system for a television and infrared dual mode seeker, characterized by: It includes: The head cover (1), infrared imaging optical system (2), visible light imaging optical system (3), infrared lens tube (15) are arranged sequentially along the optical path and all have the same optical axis. The infrared imaging optical system includes a first infrared lens (4), a second infrared lens (5), a third infrared lens (6), and an infrared detector (7). The visible light imaging optical system includes a first visible light lens (8), a second visible light lens (9), a third visible light lens (10), a fourth visible light lens (11), a fifth visible light lens (12), a reflector (13), and a visible light detector (14) arranged sequentially along the optical path. The first infrared lens near the head cover has a central hole. The first visible light lens (8), the second visible light lens (9), the third visible light lens (10), the fourth visible light lens (11), and the fifth visible light lens (12) are set in the central hole. A reflector is set above the central hole of the first infrared lens. The reflector is used to reflect the image of visible light to the visible light detector and the angle between the reflector and the optical axis is in the range of 45° to 30°. The visible light detector is set on the side of the infrared lens tube. The first infrared lens is a positive power meniscus lens, the second infrared lens is a negative power meniscus lens, and the third infrared lens is a negative power meniscus lens; the first visible light lens is a negative power biconcave lens, the second visible light lens is a positive power biconvex lens, the third visible light lens is a positive power biconvex lens, the fourth visible light lens is a positive power plano-convex lens, and the fifth visible light lens is a negative power plano-concave lens. The first and second visible light lenses are cemented together to form a first visible light combined lens, and the fourth and fifth visible light lenses are cemented together to form a second visible light combined lens. The convex surface of the fourth visible light lens faces the object side. The first infrared lens has a spherical surface on one side facing the object and a binary diffraction surface on the other side. Both surfaces of the second and third infrared lenses are spherical.

2. The optical system of the dual-mode television and infrared seeker according to claim 1, characterized in that: The reflector is angled to the visible light detector, and the sum of twice the angle between the reflector and the optical axis and the angle between the visible light detector and the optical axis is 90°. The angle between the reflector and the optical axis is less than or equal to 45° and greater than 0°, so that the optical axis passes through the center of the visible light detector.

3. The optical system of the dual-mode television and infrared seeker according to claim 2, characterized in that: The convex surfaces of the first infrared lens, the second infrared lens, and the third infrared lens all face the object side.

4. The optical system of the dual-mode television and infrared seeker according to claim 3, characterized in that: The binary diffraction surface in the first infrared lens satisfies the following expression: ， Where ρ = r / r1, r1 is the normalized radius of the binary diffraction surface, Ai is the phase coefficient of the binary diffraction surface, and N is the order of the polynomial coefficients in the series.

5. The optical system of the dual-mode television and infrared seeker according to claim 4, characterized in that: The first infrared lens has a radius of curvature of 80.905 mm on its object-side surface, a thickness of 11.5 mm, and an effective aperture of 45 mm. The first infrared lens also has a radius of curvature of 167.725 mm on its image-side surface, a thickness of 5.9 mm, and an effective aperture of 42.5 mm. The second infrared lens has a radius of curvature of 26.235 mm on its object-side surface, a thickness of 3.2 mm, and an effective aperture of 17.5 mm. The second infrared lens also has a radius of curvature of 20.517 mm on its image-side surface. Its thickness is 5.623 mm, and its effective aperture is 14 mm; the radius of curvature of the third infrared lens facing the object-side surface is 60.268 mm, its thickness is 3 mm, and its effective aperture is 13.5 mm; the radius of curvature of the third infrared lens facing the image-side surface is 142.060 mm, its thickness is 15.115 mm, and its effective aperture is 12 mm; the radius of curvature of the first visible light lens facing the object-side surface is -21.095 mm, its thickness is 1.5 mm, and its effective aperture is 7.25 mm; the first The first visible light lens has a radius of curvature of 58.534 mm on the image-side surface, a thickness of 3.25 mm, and an effective aperture of 8.5 mm. The second visible light lens has a radius of curvature of -26.968 mm on the image-side surface, a thickness of 0.3 mm, and an effective aperture of 8.5 mm. The third visible light lens has a radius of curvature of 71.396 mm on the object-side surface, a thickness of 2.75 mm, and an effective aperture of 8.5 mm. The third visible light lens has a radius of curvature of -49.22 mm on the image-side surface. The fourth visible light lens has a radius of curvature of 15.187 mm on the object-side surface, a thickness of 4 mm, and an effective aperture of 8.25 mm. The fifth visible light lens has a radius of curvature of 12.634 mm on the image-side surface, a thickness of 27 mm, and an effective aperture of 6.5 mm.

6. The optical system of the dual-mode television and infrared seeker according to claim 5, characterized in that: The infrared optical system has a total length of <111mm, an F-number of 1, and a focal length of 95mm; the wavelength range of transmitted light is 8um to 14um. The visible light optical system has a total length of >58mm, an F-number of 5, a focal length of 70mm, and the wavelength range of transmitted light is 435nm to 650nm.

7. The optical system of the dual-mode television and infrared seeker according to claim 6, characterized in that: The headgear is made of zinc sulfide and transmits both visible and infrared light. The second infrared lens is a germanium crystal, and the first and third infrared lenses are both made of infrared chalcogenide glass. The first visible light lens is made of heavy flint glass, the second visible light lens is made of heavy phosphorus crown glass, the third visible light lens is made of heavy flint glass, the fourth visible light lens is made of heavy crown glass, and the fifth visible light lens is made of heavy flint glass.

8. The optical system of the dual-mode television and infrared seeker according to claim 1, characterized in that: The angle between the reflector and the optical axis is in the range of 30° to 35°.

Images