Visible light / infrared dual-mode seeker optical imaging system

Abstract

The invention discloses a visible light / infrared dual-mode seeker optical imaging system which comprises a visible light imaging system and an infrared imaging system, the visible light imaging system comprises a first lens to a fifth lens in the direction from an object side to an image side, and the infrared imaging system comprises a sixth lens to an eighth lens in the direction from the object side to the image side. The dual-mode seeker optical imaging system provided by the invention has the following advantages: (1) clear imaging can be realized in visible light and near-infrared spectrum bands, and all-day imaging in the daytime and at night is realized; (2) one set of lens can be used for imaging in two spectral bands, and the size and the weight of an imaging system are greatly reduced; (3) the spatial resolution is high, and the imaging detection requirement of the seeker on a long-distance target can be met; (4) the athermalization effect is good, an infrared imaging system and a visible light imaging system do not have virtual focus in the range of-40 DEG C to 60 DEG C, and the imaging quality is excellent; and (5) the applicable spectral line range of the visible light imaging system is 0.4-1.1 [mu] m, that is, the imaging wave band can be extended to the near-infrared wave band.

Description

Technical Field

[0001] The present application belongs to the field of infrared optical technology, and in particular relates to a visible light / infrared dual-mode seeker optical imaging system. Background Art

[0002] Weapons and equipment are the top priority of national defense. Various optical lenses and weapon seekers as the "eyes" of various large equipment cannot be ignored. Their main function is to complete the detection, identification, tracking and other functions of the target. The guidance methods adopted by the seeker mainly include: semi-active radar guidance, infrared imaging guidance, television detection guidance, etc. However, with the increasing complexity of the battlefield environment and the upgrading of the confrontation form, a single guidance mode can no longer meet the use requirements. The use of infrared and visible light dual-mode guidance can give full play to the advantages of each sub-mode and improve the composite anti-interference ability. According to the wave-particle duality of light, the wavelength of visible light is shorter and mainly shows particle properties, so the resolution of visible light is higher, which is conducive to the improvement of guidance accuracy. It can play its advantages when there is sufficient light and good weather; infrared light mainly shows volatility, so its penetration is strong, which is conducive to working at night and in weather with low visibility. Summary of the invention

[0003] The present 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, and the specific technical scheme is as follows.

[0004] A visible light / infrared dual-mode seeker optical imaging system comprises a visible light imaging system and an infrared imaging system. Along the optical axis direction from the object 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, and 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 focal meniscus lens, the second lens is a negative focal biconcave lens, the third lens is a positive focal biconvex lens, the fourth lens is a negative focal plano-concave lens, and the fifth lens is a positive focal biconvex lens; in the infrared imaging system, the sixth lens is a positive focal meniscus lens, the seventh lens is a negative focal meniscus lens, and the eighth lens is a positive focal meniscus lens.

[0005] Preferably, the sixth lens is provided with a center hole, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in the center hole, and a reflector is arranged above the center hole of the sixth lens, the reflector is used to reflect the imaging of visible light onto the visible light detector, and the angle between the reflector and the optical axis is 38°, and the visible light detector is arranged on the side of the infrared lens barrel.

[0006] Preferably, the first lens and the second lens are glued together to form a first glued lens, and the fourth lens and the fifth lens are glued together to form a second glued 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 object side curvature radius of the first lens is -37.470mm, the image side curvature radius is -6.930mm, and the thickness is 1.800mm; the image side curvature radius of the second lens is 8.220mm, and the thickness is 1.800mm; the object side curvature radius of the third lens is 12.620mm, the image side curvature radius is -25.730mm, and the thickness is 1.530mm; the object side curvature radius of the fourth lens is -91.320mm, the image side curvature radius is 9.860mm, and the thickness is 1.500mm; the image side curvature radius of the fifth lens is -14.620mm, and the thickness is 8.300mm; the air gap between the second lens and the third lens is 2.240mm; the air gap between the third lens and the fourth lens is 12.760mm.

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

[0011] Preferably, in the infrared imaging system, the sixth lens, the seventh lens, and the eighth lens have a surface facing the image side that is an aspheric surface and satisfies the aspheric surface formula: Among them, Z is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height r along the optical axis; c=1 / R; R is the paraxial curvature fitting radius of the mirror; k is the cone coefficient; A, B, C, D, and E are high-order aspherical coefficients.

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

[0013] Preferably, the focal length of the visible light imaging system is 35 mm, the F number is 7.0, the applicable spectral line range is 0.4 μm~1.1 μm, and it is suitable for a cooled medium-wave infrared detector with a target surface of 1920*1080 and a pixel size of 2.9 um; the focal length of the infrared imaging system is 90 mm, the F number is 0.9, the applicable spectral line range is 8 μm~12 μm, and it is suitable for a non-cooled infrared detector with a target surface of 640*512 and a pixel size of 12 um.

[0014] The visible light / infrared dual-mode seeker optical imaging system provided by the present 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 the daytime and low-light environment respectively; while the infrared imaging system can work in the dark night environment, especially in the infrared imaging system, by selecting the materials of the three lenses, wherein the sixth lens and the eighth lens are made of chalcogenide glass, and the seventh lens is made of zinc selenide, combined with the setting that the sides of the three lenses facing the image side are all aspherical, the relative aperture of the infrared imaging system can be achieved to 0.9, the amount of light entering the infrared system is increased, and the imaging clarity of the infrared system is greatly improved. 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 can realize imaging of two spectral bands with one set of lenses, which greatly reduces the volume and weight of the imaging system; (3) High spatial resolution, which can meet the imaging detection requirements of the seeker for distant targets. In particular, in the infrared imaging system, by using the image-side aspherical surface setting for the three lenses, on the one hand, spherical aberration, distortion, astigmatism, field area and other aberrations can be corrected. On the other hand, the cutoff resolution of the imaging system is as high as 42lp / mm, which is higher than the cutoff resolution of 35lp / mm of the general infrared imaging system. Therefore, compared with the infrared imaging system in the prior art, it can provide richer infrared imaging picture detail information, have good imaging quality, and meet the imaging requirements.

[0016] (4) The athermal effect is good. Both the infrared imaging system and the visible light imaging system are not out of focus in the range of -40℃~60℃, and the imaging quality is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide further understanding of the present application and constitute a part of the specification. They are used to explain the present application together with the embodiments of the present application and do not constitute a limitation of the present application.

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

[0019] Among them, 1. the first lens, 2. the second lens, 3. the third lens, 4. the fourth lens, 5. the fifth lens, 6. the sixth lens, 7. the seventh lens, 8. the eighth lens, 9. the visible light imaging system, 10. the zinc sulfide fairing, 11. the reflector. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0021] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0022] The embodiment of the present 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 , Fig. 9 As shown, the sixth lens 6 is provided with a central hole, the first lens 1, the first lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 are arranged in the central hole, and a reflector 11 is arranged above the central hole of the sixth lens 6. The reflector 11 is used to reflect the visible light imaging onto the visible light detector. The angle between the reflector 11 and the optical axis is 38°, and the visible light detector is arranged on the side of the infrared lens barrel.

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

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

[0026] As shown in Table 1, the specific parameters of each lens in the visible light imaging system 9 are: 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 S1 of the first lens 1 has a curvature radius of -37.470mm, the image side S2 has a curvature radius of -6.930mm, and the center thickness is 1.800mm; the image side S3 of the second lens 2 has a curvature radius of 8.220mm, and the center thickness is 1.800mm; the object side S4 of the third lens 3 has a curvature radius of 12.620mm, the image side S5 has a curvature radius of -25.730mm, and the center thickness T3 is 1.530mm; the fourth The object side surface S6 of lens 4 has a curvature radius of -91.320 mm, the image side surface S7 has a curvature radius 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 curvature radius 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 material of the first lens 1 is H-ZLAF52A, the material of the second lens 2 is H-LAK12, the material of the third lens 3 is H-FK61B, the material of the fourth lens 4 is H-TF5, and the material of the fifth lens 5 is H-ZK50.

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

[0030] The object side surface S11 of the sixth lens 6 has a curvature radius of 81.320 mm, the image side surface S21 has a curvature radius of 147.300 mm, and the thickness is 12.000 mm; the object side surface S12 of the seventh lens 7 has a curvature radius of 98.910 mm, the image side surface S22 has a curvature radius of 54.830 mm, and the thickness is 4.500 mm; the object side surface S13 of the eighth lens 8 has a curvature radius of 30.810 mm, the image side surface S23 has a curvature radius of 37.630 mm, and the thickness is 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 of infrared imaging system The sixth lens 6, the seventh lens 7, and the eighth lens 8 are all aspherical surfaces facing the image side, and each satisfies the aspherical surface formula: Among them, Z is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height r along the optical axis; c=1 / R; R is the paraxial curvature fitting radius of the mirror; k is the cone coefficient; A, B, C, D, and E are high-order aspherical coefficients.

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

[0033] Table 3 Aspheric surface 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 focal length of the visible light imaging system 9 is 35mm, the F number is 7.0, the applicable spectral line range is 0.4μm~1.1μm, and it is suitable for a cooled medium-wave infrared detector with a target surface of 1920*1080 and a pixel size of 2.9μm; the focal length of the infrared imaging system is 90mm, the F number is 0.9, the applicable spectral line range is 8μm~12μm, and it is suitable for a non-cooled infrared detector with a target surface of 640*512 and a pixel size of 12μm.

[0035] The modulation transfer function (MTF) of the infrared imaging system of this embodiment at 25°C, -40°C, and 60°C is as follows: Figures 3-5 As shown in Figure 2, the modulation transfer function (MTF) of the visible light imaging system at 25°C, -40°C, and 60°C is as follows: Figures 10-12 As shown. Especially for the infrared imaging system, it can be seen from the figure that at 25°C, -40°C, and 60°C, it has a higher transfer function, and relative to the MTF curve at 25°C, the MTF curve at -40°C and 60°C has no obvious change, indicating that the system has good temperature adaptability and meets the temperature requirements. The cutoff resolution of the infrared imaging system of this embodiment is as high as 42lp / mm, which is higher than the cutoff resolution of 35lp / mm of the general infrared imaging system. Therefore, compared with the infrared imaging system in the prior art, the infrared imaging system of this embodiment can provide richer infrared imaging picture detail information, has good imaging quality, and meets the imaging requirements.

[0036] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application 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 direction 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, and 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 focal meniscus lens, the second lens is a negative focal biconcave lens, the third lens is a positive focal biconvex lens, the fourth lens is a negative focal plano-concave lens, and the fifth lens is a positive focal biconvex lens; in the infrared imaging system, the sixth lens is a positive focal meniscus lens, the seventh lens is a negative focal meniscus lens, and the eighth lens is a positive focal meniscus lens.

2. A visible light / infrared dual-mode seeker optical imaging system as claimed in claim 1, characterized in that: The sixth lens is provided with a central hole, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are arranged in the central hole, a reflector is arranged above the central hole of the sixth lens, the reflector is used to reflect the imaging of visible light onto the visible light detector, the angle between the reflector and the optical axis is 38°, and the visible light detector is arranged on the side of the infrared lens barrel.

3. A visible light / infrared dual-mode seeker optical imaging system as claimed 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.

4. A visible light / infrared dual-mode seeker optical imaging system as claimed in claim 1, characterized in that: 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.

5. A visible light / infrared dual-mode seeker optical imaging system as claimed in claim 4, characterized in that: In the visible light imaging system, the object side surface curvature radius of the first lens is -37.470mm, the image side surface curvature radius is -6.930mm, and the thickness is 1.800mm; the image side surface curvature radius of the second lens is 8.220mm, and the thickness is 1.800mm; the object side surface curvature radius of the third lens is 12.620mm, the image side surface curvature radius is -25.730mm, and the thickness is 1.530mm; the object side surface curvature radius of the fourth lens is -91.320mm, the image side surface curvature radius is 9.860mm, and the thickness is 1.500mm; the image side surface curvature radius of the fifth lens is -14.620mm, and the thickness is 8.300mm; the air gap between the second lens and the third lens is 2.240mm; and the air gap between the third lens and the fourth lens is 12.760mm.

6. A visible light / infrared dual-mode seeker optical imaging system as claimed 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.

7. A visible light / infrared dual-mode seeker optical imaging system as claimed in claim 6, characterized in that: In the infrared imaging system, the object side surface of the sixth lens has a curvature radius of 81.320 mm, the image side surface has a curvature radius of 147.300 mm, and the thickness is 12.000 mm; the object side surface of the seventh lens has a curvature radius of 98.910 mm, the image side surface has a curvature radius of 54.830 mm, and the thickness is 4.500 mm; the object side surface of the eighth lens has a curvature radius of 30.810 mm, the image side surface has a curvature radius of 37.630 mm, and the thickness is 5.840 mm; in the infrared imaging system, the air gap between the sixth lens and the seventh lens is 35.790 mm, and the air gap between the seventh lens and the eighth lens is 31.370 mm.

8. The visible light / infrared dual-mode seeker optical imaging system as claimed in claim 1, characterized in that: In the infrared imaging system, the sixth lens, the seventh lens, and the eighth lens have a surface facing the image side that is an aspheric surface and satisfies the aspheric surface formula: Among them, Z is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height r along the optical axis; c=1 / R; R is the paraxial curvature fitting radius of the mirror; k is the cone coefficient; A, B, C, D, and E are high-order aspherical coefficients.

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

10. The visible light / infrared dual-mode seeker optical imaging system as claimed in claim 1, characterized in that: The focal length of the visible light imaging system is 35mm, the F number is 7.0, the applicable spectral line range is 0.4μm~1.1μm, and it is suitable for a cooled medium-wave infrared detector with a target surface of 1920*1080 and a pixel size of 2.9um; the focal length of the infrared imaging system is 90mm, the F number is 0.9, the applicable spectral line range is 8μm~12μm, and it is suitable for a non-cooled infrared detector with a target surface of 640*512 and a pixel size of 12um.

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