A large-area, athermalized infrared lens with magnification

Abstract

This invention discloses a large-area athermalized infrared lens with magnification, comprising a basic imaging lens and two magnification lenses of different magnifications: a 2× telephoto lens and a 0.5× short-focus lens. The lenses are located at the front end of the basic athermalized imaging lens and share the same basic athermalized imaging lens. Different focal lengths can be switched by adding or replacing the different magnification lenses. The basic imaging lens is the athermalized imaging lens. The 2× telephoto lens includes, from the object plane to the image plane, a negative refractive index convex-concave lens M1, a positive refractive index convex-concave lens M2, a positive refractive index convex-concave lens M3, a positive refractive index concave-convex lens M4, a negative refractive index concave-convex lens M5, and a positive refractive index convex-convex lens M6. The temperature range of the large-area athermalized infrared lens with magnification is -40°C to +80°C. This invention employs optical passive thermal ablation technology, with a temperature range of -40°C to +80°C, making it suitable for applications with large temperature variations, such as fire monitoring and metallurgy; it also features a large imaging area with pixels up to 17µm.

Description

Technical Field

[0001] This invention relates to a large-area, non-thermal infrared lens with magnification, belonging to the field of long-wave infrared lens technology. Background Technology

[0002] With the development of science and technology, uncooled detector technology has become increasingly mature. Infrared lenses, due to their advantages such as good anti-interference performance, long operating distance at night, and all-weather operation, are finding increasingly widespread applications. The gradually developing infrared temperature measurement technology is a non-contact temperature measurement method with advantages such as non-destructive, rapid real-time measurement, and long-distance measurement, and is widely used in fields such as construction, fire monitoring, and metallurgy. Adding a magnifying lens in front of the basic optical imaging lens can meet the temperature monitoring needs of different distances and ranges. CN114545608A discloses a large-area infrared lens with a magnifying lens, which can achieve temperature monitoring at different distances and ranges at room temperature, but its applicable temperature variation range is small, greatly limiting its application scope. Summary of the Invention

[0003] This invention provides a large-area, athermal infrared lens with a magnifying lens. Through the design of the lens optical system structure, a temperature variation range of -40° to +80° is achieved, making it suitable for applications with large temperature variations, such as fire monitoring and metallurgy.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A large-area, non-thermal infrared lens with magnification lenses consists of a basic imaging lens and two magnification lenses with different magnifications: a 2× telephoto lens and a 0.5× short-focus lens.

[0006] The basic imaging lens is a thermal-free imaging lens; the 2× telephoto lens includes a negative refractive index convex-concave lens M1, a positive refractive index convex-concave lens M2, a positive refractive index convex-concave lens M3, a positive refractive index concave-convex lens M4, a negative refractive index concave-convex lens M5, and a positive refractive index convex-convex lens M6 arranged sequentially from the object plane to the image plane.

[0007] The temperature range of the large-area, athermalized infrared lens with magnification is -40°C to +80°C.

[0008] The above-mentioned method achieves switching between different focal lengths by adding or replacing lenses with different magnifications.

[0009] The above-mentioned basic athermal imaging mirror has a focal length f' of 25mm, a system F number of 1, a diagonal imaging surface of 14mm, a horizontal field of view of 25°, an operating wavelength of 8um to 12um, a temperature range of -40° to +80°, and is suitable for 640*512-17um uncooled long-wave infrared detectors.

[0010] In order to improve imaging quality while accommodating a large temperature variation range, the basic athermal imaging lens comprises a positive-power convex-concave lens L1, a negative-power convex-concave lens L2 and a positive-power convex-concave lens L3 arranged in sequence from an object plane to an image plane; wherein the central thickness of the convex-concave lens L1 is 3.8±0.2 mm, and the central spacing between the convex-concave lens L1 and the convex-concave lens L2 is 2.7±0.2 mm; the central thickness of the convex-concave lens L2 is 4.1±0.2 mm, and the central spacing between the convex-concave lens L2 and the convex-concave lens L3 is 10.8±0.2 mm; the central thickness of the convex-concave lens L3 is 6.0±0.2 mm; the material used for the convex-concave lens L1 is chalcogenide glass, and the materials used for the convex-concave lens L2 and the convex-concave lens L3 are germanium. The protective window of the optical structure is located between the lens L3 and the IMA image plane.

[0011] From the object plane to the image plane, the two surfaces of the convex-concave lens L1 are an object-side surface S1 and an image-side surface S2 in sequence, the two surfaces of the convex-concave lens L2 are an object-side surface S3 and an image-side surface S4 in sequence, and the two surfaces of the convex-concave lens L3 are an object-side surface S5 and an image-side surface S6 in sequence; in order to ensure imaging performance within a large temperature range, the curvature radius of the object-side surface S1 satisfies 10<R<30, and the curvature radius of the image-side surface S2 satisfies 20<R<50; the curvature radius of the object-side surface S3 satisfies 10<R<40, and the curvature radius of the image-side surface S4 satisfies 10<R<30; the curvature radius of the object-side surface S5 satisfies 40<R<80, and the curvature radius of the image-side surface S6 satisfies 300<R<800; the image-side surface S2, the object-side surface S5 and the image-side surface S6 are all aspheric surfaces, and the object-side surface S3 is a diffractive surface.

[0012] According to a further preferred solution, the curvature radius of the object-side surface S1 is 19.8±0.2 mm, and the curvature radius of the image-side surface S2 is 26.8±0.2 mm; the curvature radius of the object-side surface S3 is 20.3±0.2 mm, and the curvature radius of the image-side surface S4 is 14.9±0.2 mm; the curvature radius of the object-side surface S5 is 58.6±0.2 mm, and the curvature radius of the image-side surface S6 is 515.23±0.2 mm.

[0013] After the above basic athermal imaging lens is combined with a 2× teleconverter, the focal length f' of the optical structure of the lens system is 50 mm, the F-number of the system is 1, the diagonal length of the image plane is 14 mm, the horizontal field of view reaches 12.5°, the operating wavelength band is 8 µm to 12 µm, and the temperature variation range is -40° to +80°.

[0014] In order to better expand the temperature range, in the 2× telephoto lens, the central thickness of the convex-concave lens M1 is 6.0±0.2 mm, and the central spacing between the convex-concave lens M1 and the convex-concave lens M2 is 2.0±0.2 mm; the central thickness of the convex-concave lens M2 is 8.0±0.2 mm, and the central spacing between the convex-concave lens M2 and the convex-concave lens M3 is 42.9±0.2 mm; the central thickness of the convex-concave lens M3 is 3.0±0.2 mm, and the central spacing between the convex-concave lens M3 and the concave-convex lens M4 is 19.9±0.2 mm; the central thickness of the concave-convex lens M4 is 5.5±0.2 mm, and the central spacing between the concave-convex lens M4 and the concave-convex lens M5 is 4.9±0.2 mm; the central thickness of the concave-convex lens M5 is 4.0±0.2 mm, and the central spacing between the concave-convex lens M5 and the biconvex lens M6 is 15.8±0.2 mm; the central thickness of the biconvex lens M6 is 5.0±0.2 mm; the materials of the convex-concave lens M1, the convex-concave lens M3, the concave-convex lens M4 and the biconvex lens M6 are germanium, and the materials of the convex-concave lens M2 and the concave-convex lens M5 are chalcogenide glass.

[0015] From the object plane to the image plane, the two surfaces of the convex-concave lens M1 are sequentially the object side surface S'1 and the image side surface S'2, the two surfaces of the convex-concave lens M2 are sequentially the object side surface S'3 and the image side surface S'4, the two surfaces of the convex-concave lens M3 are sequentially the object side surface S'5 and the image side surface S'6, the two surfaces of the concave-convex lens M4 are sequentially the object side surface S'7 and the image side surface S'8, the two surfaces of the concave-convex lens M5 are sequentially the object side surface S'9 and the image side surface S'10, and the two surfaces of the biconvex lens M6 are sequentially the object side surface S'11 and the image side surface S'12; in order to better balance imaging quality and temperature range, the curvature radius of the object side surface S'1 satisfies 70<R<100, and the curvature radius of the image side surface S'2 satisfies 40<R<70; the curvature radius of the object side surface S'3 satisfies 40<R<70, and the curvature radius of the image side surface S'4 satisfies 200<R<800; the curvature radius of the object side surface S'5 satisfies 30<R<60, and the curvature radius of the image side surface S'6 satisfies 30<R<60; the curvature radius of the object side surface S'7 satisfies -40<R<-10, and the curvature radius of the image side surface S'8 satisfies -40<R<-10; the curvature radius of the object side surface S'9 satisfies -40<R<-10, and the curvature radius of the image side surface S'10 satisfies -60<R<-20; the curvature radius of the object side surface S'11 satisfies 100<R<400, and the curvature radius of the image side surface S'12 satisfies -300<R<-100; the image side surface S'2, the object side surface S'5, the image side surface S'8, the image side surface S'10 and the object side surface S'11 are all aspheric surfaces, and the object side surface S'3 is a diffractive surface.

[0016] Further preferably, the radius of curvature of the object-side surface S'1 is 82.9±0.2mm, and the radius of curvature of the image-side surface S'2 is 56.5±0.2mm; the radius of curvature of the object-side surface S'3 is 52.5±0.2mm, and the radius of curvature of the image-side surface S'4 is 513.3±0.2mm; the radius of curvature of the object-side surface S'5 is 49.9±0.2mm, and the radius of curvature of the image-side surface S'6 is 48.4±0.2mm; the radius of curvature of the object-side surface S'7 is -22.1±0.2mm, and the radius of curvature of the image-side surface S'8 is -19.6±0.2mm; the radius of curvature of the object-side surface S'9 is -21.2±0.2mm, and the radius of curvature of the image-side surface S'10 is -42.9±0.2mm; the radius of curvature of the object-side surface S'11 is 260.4±0.2mm, and the radius of curvature of the image-side surface S'12 is -162.6±0.2mm.

[0017] After the basic athermalization imaging lens is added with a 0.5× short focal length multiplier, the focal length f' of the optical structure of the lens system is 12.5mm, the F-number of the system is 1, the diagonal imaging surface is 14mm, the horizontal field of view reaches 50°, the operating wavelength band is 8um~12um, and the temperature variation range is -40°~+80°; the 0.5× short focal length multiplier comprises, from the object surface to the image surface, a convex-concave lens N1 with negative refractive power and a convex-concave lens N2 with positive refractive power which are arranged in sequence; wherein the central thickness of the convex-concave lens N1 is 2.5±0.2mm, the central distance between the convex-concave lens N1 and the concave-convex lens N2 is 70±0.2mm, and the central thickness of the concave-convex lens N2 is 2.6±0.2mm; both the convex-concave lens N1 and the concave-convex lens N2 are made of germanium.

[0018] In order to improve imaging quality, from the object surface to the image surface, the two surfaces of the convex-concave lens N1 are sequentially an object-side surface S”1 and an image-side surface S”2, and the two surfaces of the concave-convex lens N2 are sequentially an object-side surface S”3 and an image-side surface S”4; the radius of curvature of the object-side surface S”1 satisfies 80<R<200, the radius of curvature of the image-side surface S”2 satisfies 60<R<100, the radius of curvature of the object-side surface S”3 satisfies -120<R<-70, and the radius of curvature of the image-side surface S”4 satisfies -100<R<-50; both the image-side surface S”2 and the image-side surface S”4 are aspheric surfaces.

[0019] Further preferably, the radius of curvature of the object-side surface S”1 is 141.1±0.2mm, and the radius of curvature of the image-side surface S”2 is 85.6±0.2mm; the radius of curvature of the object-side surface S”3 is -93.2±0.2mm, and the radius of curvature of the image-side surface S”4 is -78.5±0.2mm.

[0020] The aspheric surface expression of the present application is:

[0021]

[0022] The meanings of each quantity are as follows:

[0023] ZA: The lens sagitta along the optical axis of the aspherical surface;

[0024] R: Radius of curvature at the intersection of the surface and the optical axis;

[0025] Y: Half-aperture of the lens perpendicular to the optical axis;

[0026] k: Conic coefficient.

[0027] The expression for the diffraction surface in this application is:

[0028] Φ=A1Y 2 +A2Y 4 +A3Y 6

[0029] in:

[0030] Φ: Phase of the diffraction plane;

[0031] Y: Half-aperture of the lens perpendicular to the optical axis;

[0032] Phase coefficients of diffraction planes A1, A2, and A3.

[0033] The above-mentioned aspherical correlation data for the basic thermal-free imaging mirror:

[0034] S2 0 -5.0689E-06 3.9676E-08 -4.1314E-010 3.6781E-012 -1.0529E-014 S3 0 -8.8836E-06 3.6027E-08 -7.0523E-010 7.7277E-012 -2.5799E-014 S5 0 -4.3281E-05 4.5653E-07 -2.7917E-08 3.7035E-010 -2.4583E-012 S6 0 -4.3281E-05 -4.7964E-07 -1.5149E-09 1.0876E-011 0

[0035] The diffraction plane data of the above-mentioned basic thermal imaging mirror are as follows:

[0036] S3 +1 10um -3.7074E-04 -7.2404E-07 0

[0037] The aspherical correlation data for the above 2× telephoto lens:

[0038] S’2 0 -1.8103E-06 2.6816E-09 -2.5374E-012 9.2283E-016 0 S’3 0 -3.1423E-06 3.8986E-09 -3.6195E-012 1.2722E-015 0 S’5 0 1.2969E-06 2.0370E-09 -1.0649E-010 2.4837E-013 0 S’8 0 1.4342E-05 -2.6181E-08 1.0636E-011 2.7855E-013 0 S’10 0 -2.7485E-05 8.4940E-08 -2.1233E-010 1.7805E-013 0 S’11 0 -2.5272E-06 3.4372E-09 -3.8627E-012 1.6142E-015 0

[0039] The diffraction plane data for the above 2× telephoto lens are as follows:

[0040] S’3 +1 10um -2.1312E-04 1.2098E-08 0

[0041] The above aspherical correlation data for a 0.5× short focal length lens:

[0042] S”2 0 -4.4570E-07 3.6591E-09 -8.8226E-012 1.0292E-014 -4.6252E-018 S”4 0 3.0283E-07 -3.0417E-09 1.2055E-011 -1.5263E-014 -2.2115E-018

[0043] Any techniques not mentioned in this invention are based on existing technologies.

[0044] The large-target-area, non-thermal infrared lens with magnification of the present invention has the following beneficial effects:

[0045] 1) The lens consists of a basic thermal imaging lens and magnification lenses of different magnifications. The basic thermal imaging lens can be used for imaging alone. By adding or replacing magnification lenses of different magnifications, the focal length of the system can be changed, thereby increasing the monitoring range.

[0046] 2) It adopts optical passive thermal differential technology, with a temperature change range of -40° to +80°, which is suitable for occasions with large temperature change ranges such as fire monitoring and metallurgy, and has high reliability;

[0047] 3) The 2x scope adopts a secondary imaging structure, which reduces the aperture of the first element in the system, making the lens lightweight and easy to use;

[0048] 4) Large imaging area, suitable for 640 camera module, with pixel size up to 17um. Attached Figure Description

[0049] Figure 1 This is an optical structure diagram of the thermal-free imaging mirror based on the present invention;

[0050] Figure 2 This is an optical structure diagram of the present invention after adding a 2× telephoto lens;

[0051] Figure 3 This is an optical structure diagram of the present invention after adding a 0.5× short focal length lens;

[0052] Figure 4 This is the MTF value of the thermal imaging mirror based on this invention at 20°C;

[0053] Figure 5 This is the MTF value of the thermal imaging mirror at -40℃, which is the basis of this invention.

[0054] Figure 6 This is the MTF value of the thermal imaging mirror at 80°C, which is the basis of this invention.

[0055] Figure 7 The MTF value at 20°C after adding a 2× telephoto lens according to this invention;

[0056] Figure 8 This invention provides the MTF value at -40℃ after adding a 2× telephoto lens.

[0057] Figure 9 This invention provides the MTF value at 80°C after adding a 2× telephoto lens.

[0058] Figure 10 The MTF value at 20°C after adding a 0.5× short focal length lens according to this invention;

[0059] Figure 11 The MTF value at -40℃ after adding a 0.5× short focal length lens according to this invention;

[0060] Figure 12The MTF value at 80°C after adding a 0.5× short focal length lens according to this invention. Detailed Implementation

[0061] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0062] An optical system for a large-target, athermalized infrared lens with integrated magnification comprises a basic athermalized imaging lens and two magnification lenses of different magnifications: a 2× telephoto lens and a 0.5× short-focus lens. Figure 1 As shown, the basic calorimetric imaging lens consists of three lenses, arranged from the object plane to the image plane as a positive refractive index convex-concave lens L1, a negative refractive index convex-concave lens L2, and a positive refractive index convex-concave lens L3; as... Figure 2 As shown, the 2× telephoto lens consists of six lenses, arranged from the object plane to the image plane as follows: a negative refractive index convex-concave lens M1, a positive refractive index convex-concave lens M2, a positive refractive index convex-concave lens M3, a positive refractive index concave-convex lens M4, a negative refractive index concave-convex lens M5, and a positive refractive index convex-convex lens M6; Figure 3 As shown, the 0.5× short focal length lens consists of two lenses, namely, a convex-concave lens N1 with negative refractive index and a concave-convex lens N2 with positive refractive index, arranged from the object plane to the image plane.

[0063] The basic athermal imaging mirror optical structure has a focal length f' of 25mm, a system F number of 1, a diagonal imaging surface of 14mm, a horizontal field of view of 25°, an operating wavelength of 8um to 12um, a temperature range of -40° to +80°, and is suitable for 640*512-17um uncooled long-wave infrared detectors.

[0064] The spacing of the basic thermal imaging lens optical structure from left to right is as follows: the center-to-center spacing between convex and concave lenses L1 and L2 is 2.7 mm; the center-to-center spacing between convex and concave lenses L2 and L3 is 10.8 mm; the center thickness of convex and concave lens L1 is 3.8 mm, the center thickness of convex and concave lens L2 is 4.1 mm, and the center thickness of convex and concave lens L3 is 6.0 mm; the protective window of this optical structure is located between lens L3 and the IMA imaging plane.

[0065] When the basic athermal imaging lens is combined with a 2× telephoto lens, the focal length f' of the lens system's optical structure is 50mm, the system F-number is 1, the diagonal imaging plane is 14mm, the horizontal field of view reaches 12.5°, the working wavelength is 8um~12um, and the temperature variation range is -40°~+80°.

[0066] The spacing of the 2× telephoto lens from left to right is as follows: the center-to-center spacing between convex and concave lenses M1 and M2 is 2.0 mm; the center-to-center spacing between convex and concave lenses M2 and M3 is 42.9 mm; the center-to-center spacing between convex and concave lenses M3 and M4 is 19.9 mm; the center-to-center spacing between M4 and M5 is 4.9 mm; the center-to-center spacing between M5 and M6 is 15.8 mm; the center thickness of convex and concave lens M1 is 6.0 ± 0.2 mm, the center thickness of convex and concave lens M2 is 8.0 mm, the center thickness of convex and concave lens M3 is 3.0 mm, the center thickness of convex and concave lens M4 is 5.5 mm, the center thickness of convex and concave lens M5 is 4.0 mm, and the center thickness of convex and concave lens M6 is 5.0 mm.

[0067] When a 0.5× short focal length lens is added to the basic athermal imaging lens, the focal length f' of the lens system's optical structure is 12.5mm, the system F-number is 1, the diagonal imaging plane is 14mm, the horizontal field of view reaches 50°, the working wavelength is 8um~12um, and the temperature variation range is -40°~+80°.

[0068] The optical structure of the 0.5× short focal length lens has the following spacing from left to right: the center spacing between the convex-concave lens N1 and the concave-convex lens N2 is 70mm; the center thickness of the convex-concave lens N1 is 2.5mm, and the center thickness of the concave-convex lens N2 is 2.6mm.

[0069] From the object plane to the image plane, the two sides of the convex-concave lens L1 are the object-side surface S1 and the image-side surface S2, the two sides of the convex-concave lens L2 are the object-side surface S3 and the image-side surface S4, and the two sides of the convex-concave lens L3 are the object-side surface S5 and the image-side surface S6; the optical element parameter table of the basic thermal-free imaging mirror is as follows:

[0070] S1 19.8 3.8 Chalcogenide Glass 26 S2 26.8 2.7 aspherical 22 S3 20.3 4.1 germanium Diffraction surface 22 S4 14.9 10.8 17 S5 58.6 6.0 germanium aspherical 18 S6 515.23 aspherical 22

[0071] Aspherical correlation data for basic thermal-free imaging mirrors:

[0072] S2 0 -5.0689E-06 3.9676E-08 -4.1314E-010 3.6781E-012 -1.0529E-014 S3 0 -8.8836E-06 3.6027E-08 -7.0523E-010 7.7277E-012 -2.5799E-014 S5 0 -4.3281E-05 4.5653E-07 -2.7917E-08 3.7035E-010 -2.4583E-012 S6 0 -4.3281E-05 -4.7964E-07 -1.5149E-09 1.0876E-011 0

[0073] Data related to the diffraction plane of a basic thermal imaging mirror:

[0074] S3 +1 10um -3.7074E-04 -7.2404E-07 0

[0075] From the object plane to the image plane, the two sides of the convex-concave lens M1 are, in order, the object-side surface S'1 and the image-side surface S'2; the two sides of the convex-concave lens M2 are, in order, the object-side surface S'3 and the image-side surface S'4; the two sides of the convex-concave lens M3 are, in order, the object-side surface S'5 and the image-side surface S'6; the two sides of the concave-convex lens M4 are, in order, the object-side surface S'7 and the image-side surface S'8; the two sides of the concave-convex lens M5 are, in order, the object-side surface S'9 and the image-side surface S'10; and the two sides of the convex-convex lens M6 are, in order, the object-side surface S'11 and the image-side surface S'12. Optical element parameter table for a 2× telephoto lens:

[0076]

[0077]

[0078] Aspherical correlation data for a 2× telephoto lens:

[0079] S’2 0 -1.8103E-06 2.6816E-09 -2.5374E-012 9.2283E-016 0 S’3 0 -3.1423E-06 3.8986E-09 -3.6195E-012 1.2722E-015 0 S’5 0 1.2969E-06 2.0370E-09 -1.0649E-010 2.4837E-013 0 S’8 0 1.4342E-05 -2.6181E-08 1.0636E-011 2.7855E-013 0 S’10 0 -2.7485E-05 8.4940E-08 -2.1233E-010 1.7805E-013 0 S’11 0 -2.5272E-06 3.4372E-09 -3.8627E-012 1.6142E-015 0

[0080] Data related to the diffraction plane of a 2× telephoto lens:

[0081] S’3 +1 10um -2.1312E-04 1.2098E-08 0

[0082] From the object plane to the image plane, the two sides of the convex-concave lens N1 are the object-side surface S”1 and the image-side surface S”2, respectively; the two sides of the concave-convex lens N2 are the object-side surface S”3 and the image-side surface S”4, respectively; Optical element parameter table for a 0.5× short focal length lens:

[0083] S”1 141.1 2.5 germanium 58 S”2 85.6 70.0 aspherical 54 S”3 -93.2 2.6 germanium 33 S”4 -78.5 aspherical 35

[0084] Aspherical correlation data for a 0.5× short focal length lens:

[0085] S”2 0 -4.4570E-07 3.6591E-09 -8.8226E-012 1.0292E-014 -4.6252E-018 S”4 0 3.0283E-07 -3.0417E-09 1.2055E-011 -1.5263E-014 -2.2115E-018

[0086] The expression for an aspherical surface is:

[0087]

[0088] The meanings of each quantity are as follows:

[0089] ZA: The lens sagitta along the optical axis of the aspherical surface;

[0090] R: Radius of curvature at the intersection of the surface and the optical axis;

[0091] Y: Half-aperture of the lens perpendicular to the optical axis;

[0092] k: Conic coefficient.

[0093] The expression for the diffraction plane is:

[0094] Φ=A1Y 2 +A2Y4 +A3Y 6

[0095] in:

[0096] Φ: Phase of the diffraction plane;

[0097] Y: Half-aperture of the lens perpendicular to the optical axis;

[0098] Phase coefficients of diffraction planes A1, A2, and A3.

[0099] The aforementioned lens consists of a basic thermal imaging lens and two telescopes with different magnifications, such as... Figure 2-3 As shown, the telephoto lens is located at the front end of the basic athermalized imaging lens and shares the same basic athermalized imaging lens. The basic athermalized imaging lens consists of three lenses made of chalcogenide glass and single-crystal germanium. The system uses three aspherical surfaces and one diffraction surface to correct system aberrations and pyrometric distortion. The 2× telephoto lens consists of six lenses. This lens system uses both single-crystal germanium and chalcogenide glass. Chalcogenide glass is used to correct system chromatic aberration, and aspherical and diffraction surfaces are used to correct system aberrations and pyrometric distortion. The 2× telephoto lens adopts a secondary imaging structure, reducing the aperture of the first lens element, making the lens lightweight and compact, and easy for users to carry and change. The 0.5× short-focus lens consists of two lenses, both made of single-crystal germanium. The system uses two aspherical surfaces to correct system aberrations and pyrometric distortion. The system has a simple structure, good manufacturability, and is easy to manufacture.

[0100] Depend on Figures 4-6 It can be seen that, within a temperature range of -40°C to +80°C, this basic thermal imaging mirror exhibits high resolution, meeting the transfer function requirements of a 640*512-17µm uncooled detector. Figures 7-12 It can be seen that both magnification lenses have high resolution in the temperature range of -40° to +80° and good calorification effect.

Claims

1. A large-target-surface athermal infrared lens with multipliers, which consists of a basic imaging lens and two multipliers with different magnifications, wherein the two multipliers with different magnifications are a 2× telephoto multiplier and a 0.5× short-focus multiplier respectively; Its features are: The basic imaging lens is a basic athermal imaging lens; the 2× telephoto multiplier consists of a convex-concave lens M1 with negative refractive power, a convex-concave lens M2 with positive refractive power, a convex-concave lens M3 with positive refractive power, a convex-concave lens M4 with positive refractive power, a concave-convex lens M5 with negative refractive power and a convex-convex lens M6 with positive refractive power, which are arranged in sequence from an object side to an image side; The temperature variation range of the large-target-surface athermal infrared lens with multipliers is -40° to +80°; The basic athermal imaging lens has a focal length f' of 25 mm, a horizontal field of view of up to 25°, and a temperature variation range of -40° to +80°, and is suitable for 640*512-17um uncooled long-wave infrared detectors; The basic athermal imaging lens consists of a convex-concave lens L1 with positive refractive power, a convex-concave lens L2 with negative refractive power and a convex-concave lens L3 with positive refractive power, which are arranged in sequence from an object side to an image side; wherein the central thickness of the convex-concave lens L1 is 3.8±0.2mm, and the central distance between the convex-concave lens L1 and the convex-concave lens L2 is 2.7±0.2mm; the central thickness of the convex-concave lens L2 is 4.1±0.2mm, and the central distance between the convex-concave lens L2 and the convex-concave lens L3 is 10.8±0.2mm; the central thickness of the convex-concave lens L3 is 6.0±0.2mm; the material of the convex-concave lens L1 is chalcogenide glass, and the materials of the convex-concave lens L2 and the convex-concave lens L3 are germanium; From the object side to the image side, the two surfaces of the convex-concave lens M1 are an object side surface S'1 and an image side surface S'2 in sequence, the two surfaces of the convex-concave lens M2 are an object side surface S'3 and an image side surface S'4 in sequence, the two surfaces of the convex-concave lens M3 are an object side surface S'5 and an image side surface S'6 in sequence, the two surfaces of the concave-convex lens M4 are an object side surface S'7 and an image side surface S'8 in sequence, the two surfaces of the concave-convex lens M5 are an object side surface S'9 and an image side surface S'10 in sequence, and the two surfaces of the convex-convex lens M6 are an object side surface S'11 and an image side surface S'12 in sequence; The curvature radius of the object side surface S'1 satisfies 70<R<100, and the curvature radius of the image side surface S'2 satisfies 40<R<70; the curvature radius of the object side surface S'3 satisfies 40<R<70, and the curvature radius of the image side surface S'4 satisfies 200<R<800; the curvature radius of the object side surface S'5 satisfies 30<R<60, and the curvature radius of the image side surface S'6 satisfies 30<R<60; the curvature radius of the object side surface S'7 satisfies -40<R<-10, and the curvature radius of the image side surface S'8 satisfies -40<R<-10; the curvature radius of the object side surface S'9 satisfies -40<R<-10, and the curvature radius of the image side surface S'10 satisfies -60<R<-20; the curvature radius of the object side surface S'11 satisfies 100<R<400, and the curvature radius of the image side surface S'12 satisfies -300<R<-100; the image side surface S'2, the object side surface S'5, the image side surface S'8, the image side surface S'10 and the object side surface S'11 are all aspheric surfaces, and the object side surface S'3 is a diffractive surface; After adding a 0.5× short focal length multiplier to the basic athermalized imaging lens, the focal length f' of the optical structure of the lens system is 12.5mm, the horizontal field of view reaches 50°, and the temperature variation range is -40°~+80°; The 0.5× short focal length multiplier consists of a convex-concave lens N1 with negative refractive power and a concave-convex lens N2 with positive refractive power arranged in sequence from the object plane to the image plane; wherein the central thickness of the convex-concave lens N1 is 2.5±0.2mm, the central spacing between the convex-concave lens N1 and the concave-convex lens N2 is 70±0.2mm, and the central thickness of the concave-convex lens N2 is 2.6±0.2mm; both the convex-concave lens N1 and the concave-convex lens N2 are made of germanium.

2. The large-target-area athermal infrared lens with magnification according to claim 1, characterized in that: From the object plane to the image plane, the two surfaces of the convex-concave lens L1 are sequentially the object side surface S1 and the image side surface S2, the two surfaces of the convex-concave lens L2 are sequentially the object side surface S3 and the image side surface S4, and the two surfaces of the convex-concave lens L3 are sequentially the object side surface S5 and the image side surface S6; The radius of curvature of the object side surface S1 satisfies 10<R<30, and the radius of curvature of the image side surface S2 satisfies 20<R<50; the radius of curvature of the object side surface S3 satisfies 10<R<40, and the radius of curvature of the image side surface S4 satisfies 10<R<30; the radius of curvature of the object side surface S5 satisfies 40<R<80, and the radius of curvature of the image side surface S6 satisfies 300<R<800; the image side surface S2, the object side surface S5 and the image side surface S6 are all aspheric surfaces, and the object side surface S3 is a diffractive surface.

3. The large-target-area pyrolysis infrared lens with magnification according to claim 2, characterized in that: The radius of curvature of the object side surface S1 is 19.8±0.2mm, the radius of curvature of the image side surface S2 is 26.8±0.2mm; the radius of curvature of the object side surface S3 is 20.3±0.2mm, the radius of curvature of the image side surface S4 is 14.9±0.2mm; the radius of curvature of the object side surface S5 is 58.6±0.2mm, and the radius of curvature of the image side surface S6 is 515.23±0.2mm.

4. The large-area, athermalized infrared lens with magnification according to any one of claims 1-3, characterized in that: After adding a 2× long focal length multiplier to the basic athermalized imaging lens, the focal length f' of the optical structure of the lens system is 50mm, the horizontal field of view reaches 12.5°, and the temperature variation range is -40°~+80°; In the 2× long focal length multiplier, the central thickness of the convex-concave lens M1 is 6.0±0.2mm, and the central spacing between the convex-concave lens M1 and the convex-concave lens M2 is 2.0±0.2mm; the central thickness of the convex-concave lens M2 is 8.0±0.2mm, and the central spacing between the convex-concave lens M2 and the convex-concave lens M3 is 42.9±0.2mm; the central thickness of the convex-concave lens M3 is 3.0±0.2mm, and the central spacing between the convex-concave lens M3 and the concave-convex lens M4 is 19.9±0.2mm; the central thickness of the concave-convex lens M4 is 5.5±0.2mm, and the central spacing between the concave-convex lens M4 and the concave-convex lens M5 is 4.9±0.2mm; the central thickness of the concave-convex lens M5 is 4.0±0.2mm, and the central spacing between the concave-convex lens M5 and the convexo-convex lens M6 is 15.8±0.2mm; the central thickness of the convexo-convex lens M6 is 5.0±0.2mm; the convex-concave lens M1, convex-concave lens M3, concave-convex lens M4 and convexo-convex lens M6 are made of germanium, and the convex-concave lens M2 and concave-convex lens M5 are made of chalcogenide glass.

5. The large-area, athermalized infrared lens with magnification according to any one of claims 1-3, characterized in that: The radius of curvature of the object side surface S'1 is 82.9±0.2mm, and the radius of curvature of the image side surface S'2 is 56.5±0.2mm; the radius of curvature of the object side surface S'3 is 52.5±0.2mm, and the radius of curvature of the image side surface S'4 is 513.3±0.2mm; the radius of curvature of the object side surface S'5 is 49.9±0.2mm, and the radius of curvature of the image side surface S'6 is 48.4±0.2mm; the radius of curvature of the object side surface S'7 is -22.1±0.2mm, and the radius of curvature of the image side surface S'8 is -19.6±0.2mm; the radius of curvature of the object side surface S'9 is -21.2±0.2mm, and the radius of curvature of the image side surface S'10 is -42.9±0.2mm; the radius of curvature of the object side surface S'11 is 260.4±0.2mm, and the radius of curvature of the image side surface S'12 is -162.6±0.2mm.

6. The large-area, athermalized infrared lens with magnification according to any one of claims 1-3, characterized in that: From the object plane to the image plane, the two surfaces of the convex-concave lens N1 are the object side surface S"1 and the image side surface S"2 in sequence, and the two surfaces of the concave-convex lens N2 are the object side surface S"3 and the image side surface S"4 in sequence; the radius of curvature of the object side surface S"1 satisfies 80<R<200, the radius of curvature of the image side surface S"2 satisfies 60<R<100, the radius of curvature of the object side surface S"3 satisfies -120<R<-70, and the radius of curvature of the image side surface S"4 satisfies -100<R<-50; both the image side surface S"2 and the image side surface S"4 are aspheric surfaces.

7. The large-target-area athermal infrared lens with magnification according to claim 6, characterized in that: The radius of curvature of the object side surface S"1 is 141.1±0.2mm, and the radius of curvature of the image side surface S"2 is 85.6±0.2mm; the radius of curvature of the object side surface S"3 is -93.2±0.2mm, and the radius of curvature of the image side surface S"4 is -78.5±0.2mm.

Images