Visible light / infrared dual-mode seeker optical imaging system

Abstract

The application discloses a visible light / infrared dual-mode seeker optical imaging system, which comprises a visible light imaging system and an infrared imaging system, wherein the visible light imaging system comprises first to fifth lenses in the direction from an object to an image, and the infrared imaging system comprises sixth to eighth lenses. The dual-mode seeker optical imaging system has the following advantages: (1) clear imaging in the visible light and near-infrared spectrum, realizing all-day imaging in the day and night; (2) realizing imaging in two spectrum bands by one lens, greatly reducing the volume and weight of the imaging system; (3) high spatial resolution, meeting the imaging detection requirements of the seeker on a long-distance target; (4) good thermalization effect, the infrared imaging system and the visible light imaging system are not defocused in the range of -40 DEG C to 60 DEG C, and the imaging quality is excellent; (5) the applicable spectrum range of the visible light imaging system is 0.4-1.1 microns, that is, the imaging band can be extended to the near-infrared band.

Description

Technical Field

[0001] This application belongs to the field of infrared optical technology, and specifically relates to a visible light / infrared dual-mode seeker optical imaging system. Background Technology

[0002] Weaponry and equipment are of paramount importance to national defense. Various optical lenses and weapon seekers, serving as the "eyes" of large equipment, are indispensable, primarily responsible for target detection, identification, and tracking. The guidance methods employed by seekers mainly include semi-active radar guidance, infrared imaging guidance, and television detection guidance. However, with increasingly complex battlefield environments and escalating forms of confrontation, single guidance modes are no longer sufficient to meet operational requirements. Using dual-mode guidance (infrared and visible light) can fully leverage the advantages of each sub-mode and improve composite anti-jamming capabilities. Based on the wave-particle duality of light, visible light has a shorter wavelength and primarily exhibits particle characteristics, resulting in higher resolution and improved guidance accuracy. It is particularly advantageous in well-lit and favorable weather conditions. Infrared light, primarily exhibiting wave characteristics, has stronger penetrating power, making it suitable for operation at night and in low-visibility conditions. Summary of the Invention

[0003] This invention proposes a visible light / infrared dual-mode seeker optical imaging system, in which the infrared and visible light systems adopt a common aperture optical system. The specific technical solution is as follows.

[0004] An optical imaging system for a visible light / infrared dual-mode seeker includes a visible light imaging system and an infrared imaging system. Along the optical axis from the object to the image side, the visible light imaging system includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens; the infrared imaging system includes a sixth lens, a seventh lens, and an eighth lens. In the visible light imaging system, the first lens is a positive power meniscus lens, the second lens is a negative power biconcave lens, the third lens is a positive power biconvex lens, the fourth lens is a negative power plano-concave lens, and the fifth lens is a positive power biconvex lens. In the infrared imaging system, the sixth lens is a positive power meniscus lens, the seventh lens is a negative power meniscus lens, and the eighth lens is a positive power meniscus lens.

[0005] Preferably, the sixth lens has a central hole, and the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are disposed in the central hole. A reflector is disposed above the central hole of the sixth 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 38°. The visible light detector is disposed on the side of the infrared lens tube.

[0006] Preferably, the first lens and the second lens are cemented together to form a first cemented lens, and the fourth lens and the fifth lens are cemented together to form a second cemented lens.

[0007] Preferably, the focal length of the first lens is 10.3911 mm, the focal length of the second lens is -5.1886 mm, the focal length of the third lens is 17.36188 mm, the focal length of the fourth lens is -13.68 mm, and the focal length of the fifth lens is 10.14252 mm.

[0008] Preferably, in the visible light imaging system, the first lens has an object-side radius of curvature of -37.470 mm, an image-side radius of curvature of -6.930 mm, and a thickness of 1.800 mm; the second lens has an image-side radius of curvature of 8.220 mm and a thickness of 1.800 mm; the third lens has an object-side radius of curvature of 12.620 mm, an image-side radius of curvature of -25.730 mm, and a thickness of 1.530 mm; the fourth lens has an object-side radius of curvature of -91.320 mm, an image-side radius of curvature of 9.860 mm, and a thickness of 1.500 mm; the fifth lens has an image-side radius of curvature of -14.620 mm and a thickness of 8.300 mm; the air gap between the second and third lenses is 2.240 mm; and the air gap between the third and fourth lenses is 12.760 mm.

[0009] Preferably, in the infrared imaging system, the focal length of the sixth lens is 91.45719 mm, the focal length of the seventh lens is -93.028 mm, and the focal length of the eighth lens is 61.75951 mm.

[0010] Preferably, in the infrared imaging system, the object-side radius of curvature of the sixth lens is 81.320 mm, the image-side radius of curvature is 147.300 mm, and the thickness is 12.000 mm; the object-side radius of curvature of the seventh lens is 98.910 mm, the image-side radius of curvature is 54.830 mm, and the thickness is 4.500 mm; the object-side radius of curvature of the eighth lens is 30.810 mm, the image-side radius of curvature is 37.630 mm, and the thickness is 5.840 mm; in the infrared imaging system, the air gap between the sixth and seventh lenses is 35.790 mm, and the air gap between the seventh and eighth lenses is 31.370 mm.

[0011] Preferably, in the infrared imaging system, the side of the sixth lens, the seventh lens, and the eighth lens facing the image side are all aspherical surfaces, and satisfy the aspherical formula: Where Z is the distance vector from the vertex of the aspherical surface at a height r along the optical axis; c = 1 / R; R is the paraxial curvature fitting radius of the mirror; k is the conic coefficient; A, B, C, D, and E are higher-order aspherical coefficients.

[0012] Preferably, in the visible light imaging system, the first lens is made of H-ZLAF52A, the second lens is made of H-LAK12, the third lens is made of H-FK61B, the fourth lens is made of H-TF5, and the fifth lens is made of H-ZK50. In the infrared imaging system, the sixth and eighth lenses are made of chalcogenide glass, and the seventh lens is made of zinc selenide.

[0013] Preferably, the visible light imaging system has a focal length of 35mm, an F-number of 7.0, and an applicable spectral range of 0.4μm to 1.1μm, and is compatible with a cooled mid-wave infrared detector with a target surface of 1920*1080 and a pixel size of 2.9μm; the infrared imaging system has a focal length of 90mm, an F-number of 0.9, and an applicable spectral range of 8μm to 12μm, and is compatible with an uncooled infrared detector with a target surface of 640*512 and a pixel size of 12μm.

[0014] The visible light / infrared dual-mode seeker optical imaging system provided by this invention has the following technical effects: (1) For the visible light imaging system, its applicable spectral range is 0.4μm to 1.1μm, that is, the imaging band can be extended to the near-infrared band, so that the visible light band and the near-infrared band can work in daylight and low light environments, respectively; while the infrared imaging system can work in dark environments, especially in the infrared imaging system. By selecting the materials of the three lenses, the sixth and eighth lenses are made of chalcogenide glass, and the seventh lens is made of zinc selenide. Combined with the fact that the side of the three lenses facing the image side is aspherical, the relative aperture of the infrared imaging system can reach 0.9, which increases the amount of light entering the infrared system and greatly improves the imaging clarity of the infrared system. By combining the visible light imaging system and the infrared imaging system, the seeker of the present invention can achieve clear imaging in all weather conditions.

[0015] (2) The imaging system of the present invention enables imaging of two spectral bands with one lens, which greatly reduces the size and weight of the imaging system; (3) High spatial resolution can meet the imaging and detection requirements of the seeker for distant targets. In particular, by using aspherical settings on the image side of the three lenses in the infrared imaging system, aberrations such as spherical aberration, distortion, astigmatism, and field area can be corrected. On the other hand, the cutoff resolution of the imaging system is as high as 42 lp / mm, which is higher than the cutoff resolution of 35 lp / mm of general infrared imaging systems. Therefore, compared with the infrared imaging systems in the prior art, it can provide richer infrared imaging details and has good imaging quality, meeting the imaging requirements.

[0016] (4) It has good thermal effect. Both the infrared imaging system and the visible light imaging system are not out of focus in the range of -40℃ to 60℃, and the imaging quality is excellent. Attached Figure Description

[0017] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0018] Figure 1 A schematic diagram of a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment; Figure 2 An infrared optical system diagram of a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment; Figure 3 An optical transfer function diagram of the infrared optical system of a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment at 25°C (cutoff resolution of 42 lp / mm); Figure 4 An infrared optical system optical transfer function diagram at -40℃ (cutoff resolution of 42 lp / mm) for a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment; Figure 5 An optical transfer function diagram of the infrared optical system of a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment at 60°C (cutoff resolution of 42 lp / mm); Figure 6 A dot plot of the infrared optical system at 25°C for an embodiment of the visible light / infrared dual-mode seeker optical imaging system provided in this application; Figure 7 A dot plot of the infrared optical system at -40°C of a visible light / infrared dual-mode seeker optical imaging system provided for an embodiment of this application; Figure 8 A dot plot of the infrared optical system at 60°C for an embodiment of the visible light / infrared dual-mode seeker optical imaging system provided in this application; Figure 9 A visible light optical system diagram of a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment; Figure 10 An optical transfer function diagram of the visible light optical system at 25°C for a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment; Figure 11 An optical transfer function diagram of the visible light optical system at -40℃ for a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment; Figure 12 An optical transfer function diagram of the visible light optical system at 60°C for a visible light / infrared dual-mode seeker optical imaging system provided in this application embodiment; Figure 13 A dot plot of the visible light optical system at 25°C for an embodiment of the visible light / infrared dual-mode seeker optical imaging system provided in this application; Figure 14 A dot plot of the visible light optical system at -40°C of a visible light / infrared dual-mode seeker optical imaging system provided for an embodiment of this application; Figure 15 A dot plot of the visible light optical system at 60°C for a visible light / infrared dual-mode seeker optical imaging system provided in an embodiment of this application.

[0019] Among them, 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. Visible light imaging system, 10. Zinc sulfide fairing, 11. Reflector. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the equipment or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] This invention provides a visible light / infrared dual-mode seeker optical imaging system, as shown in the attached specification. Figure 1 As shown, it includes a visible light imaging system 9 and an infrared imaging system. Along the direction from the object to the image side, the visible light imaging system includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a fifth lens 5, and the infrared imaging system includes a sixth lens 6, a seventh lens 7, and an eighth lens 8.

[0023] As attached Figure 1 , Figure 9 As shown, the sixth lens 6 has a central hole, and the first lens 1, the first lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 are disposed in the central hole. A reflector 11 is disposed above the central hole of the sixth lens 6. The reflector 11 is used to reflect visible light images onto the visible light detector. The angle between the reflector 11 and the optical axis is 38°. The visible light detector is disposed on the side of the infrared lens tube.

[0024] In the visible light imaging system 9, the first lens 1 is a positive optical power meniscus lens, the second lens 2 is a negative optical power biconcave lens, the third lens 3 is a positive optical power biconvex lens, the fourth lens 4 is a negative optical power plano-concave lens, and the fifth lens 5 is a positive optical power biconvex lens; in the infrared imaging system, the sixth lens 6 is a positive optical power meniscus lens, the seventh lens 7 is a negative optical power meniscus lens, and the eighth lens 8 is a positive optical power meniscus lens.

[0025] In the visible light imaging system 9, the first lens 1 and the second lens 2 are cemented together to form a first cemented lens, and the fourth lens 4 and the fifth lens 5 are cemented together to form a second cemented lens. The cemented lenses are used for achromatic purposes.

[0026] As shown in Table 1, the specific parameters of each lens in the visible light imaging system 9 are as follows: the focal length of the first lens is 10.3911 mm, the focal length of the second lens is -5.1886 mm, the focal length of the third lens is 17.36188 mm, the focal length of the fourth lens is -13.68 mm, and the focal length of the fifth lens is 10.14252 mm.

[0027] The object-side surface S1 of the first lens 1 has a radius of curvature of -37.470 mm, the image-side surface S2 has a radius of curvature of -6.930 mm, and a center thickness of 1.800 mm; the image-side surface S3 of the second lens 2 has a radius of curvature of 8.220 mm and a center thickness of 1.800 mm; the object-side surface S4 of the third lens 3 has a radius of curvature of 12.620 mm, the image-side surface S5 has a radius of curvature of -25.730 mm, and a center thickness T3 of 1.530 mm; the fourth... The object-side surface S6 of lens 4 has a radius of curvature of -91.320 mm, the image-side surface S7 has a radius of curvature of 9.860 mm, and the center thickness T4 is 1.500 mm; the image-side surface S8 of the fifth lens 5 has a radius of curvature of -14.620 mm, and the center thickness T5 is 8.300 mm; the air gap D1 between the second lens 2 and the third lens 3 is 2.240 mm; and the air gap D2 between the third lens 3 and the fourth lens 4 is 12.760 mm.

[0028] The first lens 1 is made of H-ZLAF52A, the second lens 2 is made of H-LAK12, the third lens 3 is made of H-FK61B, the fourth lens 4 is made of H-TF5, and the fifth lens 5 is made of H-ZK50.

[0029] Table 1. Lens parameters of the visible light imaging system In the infrared imaging system, the focal length of the sixth lens 6 is 91.45719mm, the focal length of the seventh lens 7 is -93.028mm, and the focal length of the eighth lens 8 is 61.75951mm.

[0030] The object-side surface S11 of the sixth lens 6 has a radius of curvature of 81.320 mm, the image-side surface S21 has a radius of curvature of 147.300 mm, and a thickness of 12.000 mm. The object-side surface S12 of the seventh lens 7 has a radius of curvature of 98.910 mm, the image-side surface S22 has a radius of curvature of 54.830 mm, and a thickness of 4.500 mm. The object-side surface S13 of the eighth lens 8 has a radius of curvature of 30.810 mm, the image-side surface S23 has a radius of curvature of 37.630 mm, and a thickness of 5.840 mm. In the infrared imaging system, the air gap between the sixth lens 6 and the seventh lens 7 is 35.790 mm, and the air gap between the seventh lens and the eighth lens is 31.370 mm.

[0031] Table 2 Parameters of each lens in the infrared imaging system The side of the sixth lens 6, the seventh lens 7, and the eighth lens 8 facing the image are all aspherical, and each satisfies the aspherical formula: Where Z is the distance vector from the vertex of the aspherical surface at a height r along the optical axis; c = 1 / R; R is the paraxial curvature fitting radius of the mirror; k is the conic coefficient; A, B, C, D, and E are higher-order aspherical coefficients.

[0032] The data for each aspherical surface are shown in Table 3.

[0033] Table 3 Aspherical data of each lens in infrared mode The sixth lens 6 and the eighth lens 8 are made of chalcogenide glass, and the seventh lens 7 is made of zinc selenide.

[0034] The visible light imaging system 9 has a focal length of 35mm, an F-number of 7.0, and an applicable spectral range of 0.4μm to 1.1μm. It is compatible with a cooled mid-wave infrared detector with a target area of ​​1920*1080 and a pixel size of 2.9μm. The infrared imaging system has a focal length of 90mm, an F-number of 0.9, and an applicable spectral range of 8μm to 12μm. It is compatible with an uncooled infrared detector with a target area of ​​640*512 and a pixel size of 12μm.

[0035] The modulation transfer function (MTF) of the infrared imaging system in this embodiment at 25℃, -40℃, and 60℃ is as follows: Figures 3-5 As shown, the modulation transfer function (MTF) of the visible light imaging system at 25℃, -40℃, and 60℃ is as follows: Figures 10-12 As shown in the figure, especially for the infrared imaging system, it can be seen from the figure that it has a high transfer function at temperatures of 25℃, -40℃, and 60℃. Furthermore, compared to the MTF curve at 25℃, the MTF curves at -40℃ and 60℃ show no significant change, indicating that the system has good temperature adaptability and meets temperature requirements. The infrared imaging system of this embodiment has a cutoff resolution as high as 42 lp / mm, which is higher than the typical cutoff resolution of 35 lp / mm for infrared imaging systems. Therefore, compared to existing infrared imaging systems, the infrared imaging system of this embodiment can provide richer detail information in the infrared imaging image, possesses good imaging quality, and meets imaging requirements.

[0036] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A visible light / infrared dual-mode seeker optical imaging system, comprising a visible light imaging system and an infrared imaging system, characterized in that, Along the optical axis from the object side to the image side, the visible light imaging system comprises a first lens, a second lens, a third lens, a fourth lens, and a fifth lens; the infrared imaging system comprises a sixth lens, a seventh lens, and an eighth lens. In the visible light imaging system, the first lens is a positive power meniscus lens with its convex surface facing the image side; the second lens is a negative power biconcave lens; the third lens is a positive power biconvex lens; the fourth lens is a negative power biconcave lens; and the fifth lens is a positive power biconvex lens. In the infrared imaging system, the sixth lens is a positive power meniscus lens with its convex surface facing the object side; the seventh lens is a negative power meniscus lens with its convex surface facing the object side; and the eighth lens is a positive power meniscus lens with its convex surface facing the object side. The sixth lens has a central hole, and the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are disposed in the central hole. A reflector is disposed above the central hole of the sixth lens. The reflector is used to reflect the image of visible light to the visible light detector. The angle between the reflector and the optical axis is 38°. The visible light detector is disposed on the side of the infrared lens tube. The first lens has a focal length of 10.3911 mm, the second lens has a focal length of -5.1886 mm, the third lens has a focal length of 17.36188 mm, the fourth lens has a focal length of -13.68 mm, and the fifth lens has a focal length of 10.14252 mm.

2. The visible light / infrared dual-mode seeker optical imaging system as described in claim 1, characterized in that, The first lens and the second lens are cemented together to form a first cemented lens, and the fourth lens and the fifth lens are cemented together to form a second cemented lens.

3. The visible light / infrared dual-mode seeker optical imaging system as described in claim 1, characterized in that, In the visible light imaging system, the first lens has an object-side radius of curvature of -37.470 mm, an image-side radius of curvature of -6.930 mm, and a thickness of 1.800 mm; the second lens has an image-side radius of curvature of 8.220 mm and a thickness of 1.800 mm; the third lens has an object-side radius of curvature of 12.620 mm, an image-side radius of curvature of -25.730 mm, and a thickness of 1.530 mm; the fourth lens has an object-side radius of curvature of -91.320 mm, an image-side radius of curvature of 9.860 mm, and a thickness of 1.500 mm; the fifth lens has an image-side radius of curvature of -14.620 mm and a thickness of 8.300 mm; the air gap between the second and third lenses is 2.240 mm; and the air gap between the third and fourth lenses is 12.760 mm.

4. The visible light / infrared dual-mode seeker optical imaging system as described in claim 1, characterized in that, In the infrared imaging system, the focal length of the sixth lens is 91.45719 mm, the focal length of the seventh lens is -93.028 mm, and the focal length of the eighth lens is 61.75951 mm.

5. The visible light / infrared dual-mode seeker optical imaging system as described in claim 4, characterized in that, In the infrared imaging system, the object-side radius of curvature of the sixth lens is 81.320 mm, the image-side radius of curvature is 147.300 mm, and the thickness is 12.000 mm; the object-side radius of curvature of the seventh lens is 98.910 mm, the image-side radius of curvature is 54.830 mm, and the thickness is 4.500 mm; the object-side radius of curvature of the eighth lens is 30.810 mm, the image-side radius of curvature is 37.630 mm, and the thickness is 5.840 mm; in the infrared imaging system, the air gap between the sixth and seventh lenses is 35.790 mm, and the air gap between the seventh and eighth lenses is 31.370 mm.

6. The visible light / infrared dual-mode seeker optical imaging system as described in claim 1, characterized in that, In the infrared imaging system, the side of the sixth lens, the seventh lens, and the eighth lens facing the image side are all aspherical surfaces, and satisfy the aspherical surface formula: Where Z is the distance vector from the vertex of the aspherical surface at a height r along the optical axis; c = 1 / R; R is the paraxial curvature fitting radius of the mirror; k is the conic coefficient; A, B, C, D, and E are higher-order aspherical coefficients.

7. The visible light / infrared dual-mode seeker optical imaging system as described in claim 1, characterized in that, In the visible light imaging system, the first lens is made of H-ZLAF52A, the second lens is made of H-LAK12, the third lens is made of H-FK61B, the fourth lens is made of H-TF5, and the fifth lens is made of H-ZK50; in the infrared imaging system, the sixth and eighth lenses are made of chalcogenide glass, and the seventh lens is made of zinc selenide.

8. The visible light / infrared dual-mode seeker optical imaging system as described in claim 1, characterized in that, The visible light imaging system has a focal length of 35mm, an F-number of 7.0, and an applicable spectral range of 0.4μm to 1.1μm. It is compatible with a cooled mid-wave infrared detector with a target area of ​​1920*1080 and a pixel size of 2.9μm. The infrared imaging system has a focal length of 90mm, an F-number of 0.9, and an applicable spectral range of 8μm to 12μm. It is compatible with an uncooled infrared detector with a target area of ​​640*512 and a pixel size of 12μm.

Images