A long-focus optical passive athermalized uncooled long-wave infrared optical system

Abstract

The present invention relates to a long-focus optical passive athermalized uncooled long-wave infrared optical system, which is composed of a first meniscus positive lens, an aperture stop, a meniscus negative lens, and a second meniscus positive lens arranged coaxially along the optical axis from the object side to the image side; the convex surface of the first meniscus positive lens faces the object side, the side facing the image plane is an even-order spherical surface, and the side facing the image plane is an aspherical surface; the convex surface of the meniscus negative lens faces the object side and is a spherical lens; the convex surface of the second meniscus positive lens faces the object side, the side facing the object plane is an even-order aspherical surface, and the side facing the image plane is a spherical surface; both the first meniscus positive lens and the second meniscus positive lens are made of chalcogenide glass materials. The present invention uses less materials, has a simple structure, a small volume, and a light weight.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical design, and relates to a low-cost, long-focus optically passive athermalized uncooled long-wave infrared optical system. Background Art

[0002] Due to the unique detection advantages of infrared optical systems and the continuous development and increasing maturity of uncooled detector technology, uncooled long-wave infrared optical systems have been widely used in various fields. However, due to the unique materials of infrared optical systems, when infrared optical systems are used in a large temperature range, the drastic change in working temperature will cause thermal deformation of infrared optical materials and mechanical materials, resulting in changes in the focal length of the optical system, image plane drift, and deterioration of imaging quality. Therefore, it is necessary to perform athermalization design on infrared optical systems. The current athermalization methods mainly include: electro-mechanical active type, mechanical passive type, and optical passive type. The optical passive type realizes the matching of the focal plane position and the change of the lens barrel length by reasonably distributing the optical power and optical materials, so as to ensure the imaging quality of the lens within the specified temperature range. It has the advantages of light weight and simple structure, and is more suitable for the requirements of infrared optical systems. However, in traditional refractive optical systems, only by changing the curvature of the curved surface or using different materials can the aberration be corrected, and at least three or more materials are required, which increases the number of lenses and makes the system structure complex.

[0003] The Chinese Patent Gazette discloses an "optically passive athermalized optical system for uncooled long-wave infrared imaging" (Publication No.: CN216696831U), which uses 4 aspherical lenses, reducing the transmittance of the infrared system and increasing the processing cost. Another existing method for realizing optically passive athermalization is to adopt a binary optical diffraction element in the optical system to form a refractive-diffractive hybrid system, and use the dispersion coefficient of the negative dispersion and the large temperature compensation characteristics of the binary optical diffraction element to eliminate the thermal difference of the optical system. However, when the optical system adopts multiple diffraction surfaces, on the one hand, it will seriously reduce the system efficiency and cause insufficient energy of the optical system. For example, an "aspheric-diffractive hybrid lens-based three-piece passive athermalized long-wave infrared optical system" (CN115639662A) disclosed in the Chinese Patent Gazette, which uses 2 aspheric-diffractive hybrid lenses in the system. On the other hand, it will increase the processing cost, which is not conducive to the popularization of products and has no price advantage. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a low-cost, simple-structured long-focus optically passive athermalized uncooled long-wave infrared optical system.

[0005] To solve the above technical problems, the long-focus optical passive athermalized uncooled long-wave infrared optical system of the present invention is composed of a first meniscus positive lens, an aperture stop, a meniscus negative lens, and a second meniscus positive lens that are coaxially arranged along the optical axis from the object side to the image side; the convex surface of the first meniscus positive lens faces the object side, the side facing the image plane is an even spherical surface, and the side facing the image plane is an aspherical surface; the convex surface of the meniscus negative lens faces the object side and is a spherical lens; the convex surface of the second meniscus positive lens faces the object side, the side facing the object plane is an even aspherical surface, and the side facing the image plane is a spherical surface; both the first meniscus positive lens and the second meniscus positive lens are made of chalcogenide glass material.

[0006] The effective aperture of the front surface of the first meniscus positive lens is 96 - 102 mm, and the effective aperture of the rear surface is 82.9 - 96.2 mm; the effective aperture of the aperture stop is 80.1 mm - 85.8 mm; the effective aperture of the front surface of the meniscus negative lens is 73.7 mm - 78.43 mm, and the effective aperture of the rear surface is 52.26 mm - 55.77 mm; the effective aperture of the front surface of the second meniscus positive lens is 53.59 mm - 60.1 mm, and the effective aperture of the rear surface is 48.7 mm - 55.2 mm.

[0007] The materials of the first meniscus positive lens and the second meniscus positive lens are preferably IRG206.

[0008] The material of the meniscus negative lens is ZnSe.

[0009] The front and rear surface curvature radii of the first meniscus positive lens are 80.15 - 100.43 mm and 160 - 180.88 mm respectively; the front and rear surface curvature radii of the meniscus negative lens are 84.37 - 95.14 mm and 35.77 - 45.46 mm respectively; the front and rear surface curvature radii of the second meniscus positive lens are 80.12 - 86.99 mm and 289.73 - 301.54 mm respectively.

[0010] The conic coefficient k of the rear surface of the first meniscus positive lens is 0, and the high-order aspherical coefficients a4, a6, and a8 are 2.817E - 005 to 7.237e - 06, -5.749e - 010 to -1.375e - 15, 3.254e - 017 to 9.723e - 015 respectively. The conic coefficient k of the front surface of the second meniscus positive lens is 0, and the high-order aspherical coefficients a4, a6, and a8 are 3.101e - 008 to 3.245e - 006, 1.785e - 012 to 3.74e - 010, 2.107e - 15 to 3.046e - 13 respectively.

[0011] The thickness of the first meniscus positive lens is 13 - 16 mm, the thickness of the meniscus negative lens is 15.76 - 20.32 mm, and the thickness of the second meniscus positive lens is 12.4 - 18.97 mm.

[0012] The air gap between the first meniscus positive lens and the meniscus negative lens is 8.9 - 20.6 mm, and the air gap between the meniscus negative lens and the second meniscus positive lens is 35.75 - 45.08 mm.

[0013] The air gap between the first meniscus positive lens and the aperture stop is 6.7 - 12.3 mm.

[0014] Advantages of the present invention:

[0015] In the present invention, by using the first meniscus positive lens with the largest aperture in the optical system as an aspherical chalcogenide glass lens, the low cost, low refractive index coefficient, good dispersion performance of the chalcogenide glass, as well as the good aberration correction and the ability to reduce the optical system components of the aspherical surface are maximally utilized, the system focus shift caused by temperature change is solved, the purpose of better achieving athermalization is realized, and the best imaging effect is achieved. It can have good imaging quality and athermalization effect in the 8 - 14 μm long - wave infrared band within the temperature range of - 40°C to + 60°C. Using aspherical chalcogenide glass for athermalization can not only obtain imaging quality close to the diffraction limit in a relatively large field of view and a very wide temperature working range, but also has less material, simple structure, small volume and light weight.

[0016] The present invention uses chalcogenide glass as the aspherical lens. Compared with traditional germanium, etc., chalcogenide glass has low cost, low refractive index coefficient and good dispersion performance. Without reducing the imaging quality of the optical system, the system only uses two aspherical lenses and one spherical lens, greatly reducing the processing and manufacturing cost of the optical system.

[0017] The present invention uses 2 kinds of optical materials, reasonably distributes and combines for athermalization. It has a simple and compact structure, fewer lens elements, good imaging quality and athermal effect. The planar protection window in the prior art is removed, and a total of 3 optical elements are used, with only 2 optical elements being aspherical. Through the combination of lens materials and the distribution of optical power, and in cooperation with the thermal expansion and contraction of the barrel material, the optical passive athermalization effect is achieved. When the system operates at - 40°C to + 60°C, the system transfer function MTF value at each temperature is greater than 0.4 at the spatial cut - off frequency of 30 lp / mm. It has the advantages of low cost, high image quality, wide working temperature range, compact structure, light weight, high imaging resolution, good imaging quality, small volume, high system transmittance, and the modulation transfer function MTF close to the diffraction limit.

[0018] The present invention is applicable to a non-cooled long-wave infrared focal plane detector with 640×512 pixels and a pixel size of 17um. When an aluminum alloy lens barrel is adopted, through the paired combination of lens materials and the matching of the linear expansion coefficients and lengths of the lens barrel materials, arranged in sequence, within the temperature range of -40°C to +60°C, no focusing adjustment is required, and the average change in MTF does not exceed 10% at a spatial cut-off frequency of 30 lp / mm. Brief Description of the Drawings

[0019] Figure 1 is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 is the MTF curve at 20°C in Embodiment 1 of the present invention.

[0021] Figure 3 is the spot diagram at 20°C in Embodiment 1 of the present invention.

[0022] Figure 4 is the MTF curve at -40°C in Embodiment 1 of the present invention.

[0023] Figure 5 is the spot diagram at -40°C in Embodiment 1 of the present invention.

[0024] Figure 6 is the MTF curve at 60°C in Embodiment 1 of the present invention.

[0025] Figure 7 is the spot diagram at 60°C in Embodiment 1 of the present invention.

[0026] Figure 8 is the optical transfer function (30 lp / mm) at 20°C in Embodiment 2 of the present invention.

[0027] Figure 9 is the optical transfer function (30 lp / mm) at 20°C in Embodiment 3 of the present invention.

[0028] Figure 10 is the optical transfer function (30 lp / mm) at 20°C in Embodiment 4 of the present invention.

[0029] Figure 11 is the optical transfer function (30 lp / mm) at 20°C in Embodiment 5 of the present invention. Detailed Description of the Invention

[0030] The present invention will be further described in detail below in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the convenience of description, only parts related to the present invention rather than all structures are shown in the drawings.

[0031] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0032] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over", and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath", and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0033] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "left", and "right" are based on the orientation or positional relationship shown in the drawings. It is only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meanings.

[0034] As Figure 1 shown, the long-focus optical passive athermalized uncooled long-wave infrared optical system of the present invention is composed of a first meniscus positive lens 1, an aperture stop I, a meniscus negative lens 2, and a second meniscus positive lens 3 that are coaxially arranged along the optical axis direction from the object side to the image side. The uncooled long-wave infrared detector protection window 4 is coaxially arranged behind the second meniscus positive lens 3. Parallel light from infinity enters the first meniscus positive lens, the aperture stop I, the meniscus negative lens 2, the second meniscus positive lens 3, and the uncooled long-wave infrared detector protection window 4 in sequence from the object surface, balancing the system thermal difference, chromatic aberration, and monochromatic aberration, and finally imaging on the detector focal plane to complete the entire imaging process.

[0035] The first meniscus positive lens 1 has a positive optical power, with the convex surface facing the object side. The side facing the object surface is a spherical surface, and the side facing the image surface is an even aspherical surface; the meniscus negative lens 2 has a negative optical power, with the convex surface facing the object side, and it is a spherical lens; the second meniscus positive lens 3 has a positive optical power, with the convex surface facing the object side. The side facing the object surface is an even aspherical surface, and the side facing the image surface is a spherical surface.

[0036] Both the first meniscus positive lens 1 and the second meniscus positive lens 3 are made of low-cost chalcogenide glass materials, preferably IRG206. The meniscus negative lens 2 is made of ZnSe.

[0037] The first meniscus positive lens 1 includes a front surface s11 and a rear surface s12, the meniscus negative lens 2 includes a front surface s21 and a rear surface s22, and the second meniscus positive lens 3 includes a front surface s31 and a rear surface s32. Among them, the rear surface s12 of the first meniscus positive lens and the front surface s31 of the second meniscus positive lens are even aspherical surfaces, and the rest are spherical surfaces; the protection window 4 of the uncooled long-wave infrared detector includes a front surface s41 and a rear surface s42.

[0038] The formula of the even aspherical surface of the optical system is determined by the following formula:

[0039]

[0040] In the formula: z represents the sagitta of the even aspherical surface along the optical axis direction at a height of r from the vertex of the aspherical surface, c represents the radius of curvature of the surface vertex, k represents the conic coefficient, a 4 、a 6 、a 8 represent the coefficients of the higher-order aspherical surface.

[0041] Example 1

[0042] The parameters of each optical element are shown in Table 1-1, and the coefficients of the even aspherical surface are shown in Table 1-2, where t i is the thickness of the i-th optical element, and d i is the air gap between the i-th optical element and the next optical element.

[0043] Table 1-1

[0044]

[0045] Table 1-2

[0046] Surface k <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> S12 0 6.817E-005 -1.315E-015 3.254E-014 S31 0 3.101E-008 1.785E-012 1.107E-015

[0047] The total length of this example is less than 110 mm, the effective focal length of the system is 100 mm, the F number is 1.1, the field of view angle is 14°, the system distortion is <1%, the wavelength range of the transmitted light is 8 μm to 14 μm, the resolution of the uncooled long-wave infrared detector adapted is 640×512 pixels, and the pixel pitch is 17 microns.

[0048] The material of the protection window of the uncooled infrared focal plane detector is Ge, and the thickness is 1 mm.

[0049] The barrel material of the optical system is aluminum alloy material.

[0050] Figures 2 to 7 For the optical system, the optical transfer functions (at 30 lp / mm) and spot diagrams corresponding to 20°C, -40°C, and 60°C are presented. It can be judged from the figures that in the large and small fields of view of the optical system, seven aberrations related to the field of view and aperture, namely axial spherical aberration, tangential spherical aberration, axial chromatic aberration, tangential chromatic aberration, coma, field curvature, and distortion, as well as the corresponding higher-order aberrations, are well corrected, and the imaging is clear without obvious distortion. At room temperature of 20°C, the optical transfer function (at 30 lp / mm) of the optical system is greater than 0.5 and close to the diffraction limit. At -40°C, the optical transfer function (at 30 lp / mm) of the optical system is greater than 0.45. When operating at 60°C, the optical transfer function (at 30 lp / mm) of the optical system is greater than 0.46.

[0051] Example 2

[0052] The parameters of each optical element are shown in Table 2-1, and the coefficients of even aspheres are shown in Table 2-2:

[0053] Table 2-1

[0054]

[0055] Table 2-2

[0056] Surface k <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> S12 0 1.137E-007 -3.342E-012 4.274E-016 S31 0 2.069E-007 2.401E-011 1.209E-014

[0057] The total length of this example is less than 124 mm, the effective focal length of the system is 100 mm, the F number is 1, the field of view angle is 14°, the system distortion is <1%, the wavelength range of the transmitted light is 8 μm to 14 μm, the resolution of the uncooled long-wave infrared detector adapted is 640×512 pixels, and the pixel pitch is 17 μm.

[0058] The material of the protection window of the uncooled infrared focal plane detector is Ge, and the thickness is 1 mm.

[0059] The barrel material of the optical system is aluminum alloy material.

[0060] Figure 8 For the optical transfer function (at 30 lp / mm) of the optical system in Example 2 at 20°C. It can be judged from the figures that in the large and small fields of view of the optical system, seven aberrations related to the field of view and aperture, namely axial spherical aberration, tangential spherical aberration, axial chromatic aberration, tangential chromatic aberration, coma, field curvature, and distortion, as well as the corresponding higher-order aberrations, are well corrected, and the imaging is clear without obvious distortion. At room temperature of 20°C, the transfer function (at 30 lp / mm) of the optical system is close to the diffraction limit, and the transfer function is greater than 0.5 in the full field of view. When the optical system operates at -40°C, the optical transfer function (at 30 lp / mm) is greater than 0.41; when operating at 60°C, the transfer function (at 30 lp / mm) is greater than 0.45. Example 3

[0061] The parameters of each optical element are shown in Table 3-1, and the even aspherical coefficients are shown in Table 3-2:

[0062] Table 3-1

[0063]

[0064] Table 3-2

[0065] Surface k <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> S12 0 1.147E-006 -4.342E-011 7.274E-015 S31 0 1.137E-008 2.201E-012 2.239E-013

[0066] The total length of this embodiment is less than 134 mm, the effective focal length of the system is 100 mm, the F number is 1, the field of view angle is 14°, the system distortion is <1%, the wavelength range of the transmitted light is 8 μm to 14 μm, the resolution of the uncooled long-wave infrared detector adapted is 640×512 pixels, and the pixel pitch is 17 microns.

[0067] The protective window material of the uncooled infrared focal plane detector is Ge, and the thickness is 1 mm.

[0068] Figure 9 The optical transfer function (30 lp / mm) of the optical system at 20°C for Example 3. It can be judged from the figure that in the large and small fields of view of the optical system, the seven aberrations related to the field of view and aperture, namely axial spherical aberration, lateral spherical aberration, axial chromatic aberration, lateral chromatic aberration, coma, field curvature, and distortion, and the corresponding higher-order aberrations are well corrected, and the imaging is clear without obvious deformation. At room temperature of 20°C, the transfer function (30 lp / mm) of the optical system is close to the diffraction limit, and the transfer function is greater than 0.5 in the full field of view. When the optical system operates at -40°C, the optical transfer function (30 lp / mm) is greater than 0.4; when it operates at 60°C, the transfer function (30 lp / mm) is greater than 0.43.

[0069] Example 4

[0070] The parameters of each optical element are shown in Table 4-1, and the even aspherical coefficients are shown in Table 4-2:

[0071] Table 4-1

[0072]

[0073] Table 4-2

[0074] Surface k <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> S12 0 5.867E-007 -6.952E-012 9.77E-016 S31 0 8.761E-007 9.409E-011 7.176E-014

[0075] The total length of this embodiment is less than 130 mm, the effective focal length of the system is 100 mm, the F number is 1, the field of view angle is 14°, the system distortion is <1%, the wavelength range of the transmitted light is 8 μm to 14 μm, the resolution of the uncooled long-wave infrared detector adapted is 640×512 pixels, and the pixel pitch is 17 microns.

[0076] The protective window material of the uncooled infrared focal plane detector is Ge, with a thickness of 1 mm.

[0077] Figure 10 It is the optical transfer function (30 lp / mm) of the optical system at 20 °C for Example 4. It can be judged from the figure that in the large and small fields of view of the optical system, the seven aberrations related to the field of view and aperture, namely axial spherical aberration, lateral spherical aberration, axial chromatic aberration, lateral chromatic aberration, coma, field curvature, and distortion, as well as the corresponding higher-order aberrations, have been well corrected, and the imaging is clear without obvious deformation. At room temperature of 20 °C, the transfer function (30 lp / mm) of the optical system is close to the diffraction limit, and the transfer function is greater than 0.5 in the full field of view. When the optical system operates at -40 °C, the transfer function (30 lp / mm) of the optical system is greater than 0.42; when it operates at 60 °C, the transfer function (30 lp / mm) is greater than 0.41.

[0078] Example 5

[0079] The parameters of each optical element are shown in Table 5-1, and the even aspheric coefficients are shown in Table 5-2:

[0080] Table 5-1

[0081]

[0082] Table 5-2

[0083] Surface k <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> S12 0 7.237E-006 -5.749E-010 9.723E-010 S31 0 3.245e-006 3.74e-010 3.046E-013

[0084] The total length of this embodiment is less than 134 mm, the effective focal length of the system is 100 mm, the F number is 1, the field of view angle is 14°, the system distortion is <1%, the wavelength range of the transmitted light is 8 um to 14 um, the resolution of the uncooled long-wave infrared detector adapted is 640×512 pixels, and the pixel pitch is 17 microns.

[0085] The protective window material of the uncooled infrared focal plane detector is Ge, with a thickness of 1 mm.

[0086] Figure 11 It is the optical transfer function (30 lp / mm) of the optical system for Example 5 at 20 °C. It can be judged from the figure that in the large and small fields of view of the optical system, the seven aberrations related to the field of view and aperture, namely axial spherical aberration, lateral spherical aberration, axial chromatic aberration, lateral chromatic aberration, coma, field curvature, and distortion, as well as the corresponding higher-order aberrations, have been well corrected, and the imaging is clear without obvious deformation. At room temperature of 20 °C, the transfer function (30 lp / mm) of the optical system is close to the diffraction limit, and the transfer function is greater than 0.5 in the full field of view. When the optical system operates at -40 °C, the transfer function (30 lp / mm) of the optical system is greater than 0.41; when it operates at 60 °C, the transfer function (30 lp / mm) is greater than 0.45.

[0087] In the above five embodiments, ZNS has also been used for the meniscus negative lens, and the imaging effect differences are relatively small.

[0088] During the experiment, other chalcogenide materials such as IG6 have also been used for the first meniscus positive lens 1 and the second meniscus positive lens 3, but the modulation transfer function (MTF) is less than 0.3; while for the combinations of IRG206 and ZnSe, and IRG206 and ZNS proposed by the present invention, the optical transfer functions are both greater than 0.4, approaching the diffraction limit.

[0089] The present invention solves the system focal shift occurring under large temperature changes by using the lens with the largest aperture in the optical system as a chalcogenide glass lens, maximizing the use of low-cost chalcogenide glass and its low refractive index coefficient and good dispersion performance, and at the same time using the good aberration correction of the aspherical surface, the ability to reduce the optical system components, and the large temperature compensation characteristics, better achieving the purpose of eliminating thermal aberration and achieving the best imaging effect.

[0090] In summary, the above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A long-focus optical passive athermalized uncooled long-wave infrared optical system, characterized in that: It is composed of a first meniscus positive lens, an aperture stop, a meniscus negative lens, and a second meniscus positive lens that are sequentially arranged along the optical axis from the object side to the image side; the convex surface of the first meniscus positive lens faces the object side, the side facing the image plane is an even spherical surface, and the side facing the image plane is an aspherical surface; the convex surface of the meniscus negative lens faces the object side and is a spherical lens; the convex surface of the second meniscus positive lens faces the object side, the side facing the object plane is an even aspherical surface, and the side facing the image plane is a spherical surface; both the first meniscus positive lens and the second meniscus positive lens are made of chalcogenide glass materials; the front and rear surface curvature radii of the first meniscus positive lens are 80.15 - 100.43 mm and 160 - 180.88 mm respectively; the front and rear surface curvature radii of the meniscus negative lens are 84.37 - 95.14 mm and 35.77 - 45.46 mm respectively; the front and rear surface curvature radii of the second meniscus positive lens are 80.12 - 86.99 mm and 289.73 - 301.54 mm respectively; the conic coefficient k of the rear surface of the first meniscus positive lens is 0, and the high-order aspherical coefficients a4, a6, and a8 are 2.817E-005 to 7.237e-06, -5.749e-010 to -1.375e-15, 3.254e-017 to 9.723e-015 respectively. The conic coefficient k of the front surface of the second meniscus positive lens is 0, and the high-order aspherical coefficients a4, a6, and a8 are 3.101e-008 to 3.245e-006, 1.785e-012 to 3.74e-010, 2.107e-15 to 3.046e-13 respectively.

2. The long-focus optical passive athermalized uncooled long-wave infrared optical system according to claim 1, wherein: The effective aperture of the front surface of the first meniscus positive lens is 96 - 102 mm, and the effective aperture of the rear surface is 82.9 - 96.2 mm; the effective aperture of the aperture stop is 80.1 mm - 85.8 mm; the effective aperture of the front surface of the meniscus negative lens is 73.7 mm - 78.43 mm, and the effective aperture of the rear surface is 52.26 mm - 55.77 mm; the effective aperture of the front surface of the second meniscus positive lens is 53.59 mm - 60.1 mm, and the effective aperture of the rear surface is 48.7 mm - 55.2 mm.

3. The long-focus optical passive athermalized uncooled long-wave infrared optical system according to claim 1, characterized in that: The materials of the first meniscus positive lens and the second meniscus positive lens are IRG206.

4. The long focal length optical passive athermalized uncooled long wavelength infrared optical system according to claim 1, characterized in that: The material of the meniscus negative lens is ZnSe.

5. The long-focus optical passive athermalized uncooled long-wave infrared optical system according to claim 1, characterized in that: The thickness of the first meniscus positive lens is 13 - 16 mm, the thickness of the meniscus negative lens is 15.76 - 20.32 mm, and the thickness of the second meniscus positive lens is 12.4 - 18.97 mm.

6. The long focal length optical passive athermalized uncooled long-wave infrared optical system according to claim 1, characterized in that: The air gap between the first meniscus positive lens and the meniscus negative lens is 8.9 - 20.6 mm, and the air gap between the meniscus negative lens and the second meniscus positive lens is 35.75 - 45.08 mm.

7. The long focal length optical passive athermalized uncooled long wave infrared optical system according to claim 1, characterized in that: The air gap between the first meniscus positive lens and the aperture stop is 6.7 - 12.3 mm.

Images