Low-cost long-wave refrigeration athermalization optical system based on chalcogenide material

Abstract

A chalcogenide material-based low-cost long-wave refrigeration athermalization optical system belongs to the technical field of optical imaging, and is sequentially and coaxially provided with a fairing, a first lens, a second lens, a third lens, detector protection glass, a cold diaphragm and an image plane from outside to inside in a light propagation direction. The optical system is used for receiving inherent infrared radiation passing through a target and a background and converging the infrared radiation to the photosensitive surface of the long-wave infrared refrigeration detector, optical signals are converted into electric signals through photoelectric conversion, and the system has high sensitivity and small spatial resolution and can be used for detecting the target and the background. Detection, identification and accurate positioning of a target can be realized at night or under a complex meteorological condition. The system has the prominent advantages of excellent imaging quality in a working temperature range of-40 DEG C to + 70 DEG C, strong light collecting capability, good environmental adaptability, strong anti-interference capability, capability of working all day long and the like, and can be widely applied to the fields of spaceflight optical remote sensing, optical imaging guidance, astronomical observation, civil safety monitoring and the like.

Description

Technical Field

[0001] The present invention belongs to the field of optical imaging technology, and in particular relates to a low-cost long-wave refrigeration athermal optical system based on chalcogenide materials. Background Art

[0002] With the rapid development of infrared detectors, infrared imaging detection technology plays an increasingly important role in science and technology, national economy, national defense and military fields. Based on a high-resolution small-pixel long-wave infrared refrigeration detector with a response band of 7.7μm to 10.3μm, a resolution of 640×512, and a pixel size of 15μm, the present invention designs a low-cost long-wave refrigeration athermal optical system based on chalcogenide materials. The system has outstanding advantages such as excellent imaging quality, strong light collection ability, good environmental adaptability, strong anti-interference ability and full-day operation within the working temperature range of -40℃ to +70℃. It can be widely used in aerospace optical remote sensing, optical imaging guidance, astronomical observation, civil security monitoring and other fields, and has broad application prospects and huge economic benefits.

[0003] In summary, a low-cost long-wave refrigeration athermalized optical system based on chalcogenide materials is proposed. Summary of the invention

[0004] In view of this, the present invention aims to achieve a low-cost, athermal, high-resolution design of a long-wave cooled infrared imaging detection system. The present invention provides a low-cost long-wave cooled athermal optical system based on chalcogenide materials.

[0005] To achieve the above object, the present invention adopts the following technical scheme to provide a low-cost long-wave refrigeration athermal optical system based on chalcogenide materials, comprising:

[0006] A low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials is provided, in the direction of light propagation, a fairing, a first lens, a second lens, a third lens, a detector protection glass, a cold stop and an image plane are arranged in sequence from the outside to the inside. The first lens, the second lens, the third lens, the detector protection glass, the cold stop and the image plane are arranged coaxially with the fairing. The optical system is used to receive infrared radiation inherent to the target and the background, and converge it onto the photosensitive surface of the long-wave infrared refrigeration detector, and convert the optical signal into an electrical signal through photoelectric conversion.

[0007] Furthermore, the first lens and the third lens are both spherical lenses; the outer surface of the second lens is a binary surface, and the inner surface is a spherical surface.

[0008] Furthermore, the outer surface of the fairing has a radius of curvature of 115 mm, the inner surface has a radius of curvature of 110 mm, and the thickness is 5 mm; the outer surface of the first lens has a radius of curvature of 50.6 mm, the inner surface has a radius of curvature of 135.19 mm, and the thickness is 8.3 mm; the outer surface of the second lens has a radius of curvature of 174.25 mm, the inner surface has a radius of curvature of 68.05 mm, and the thickness is 4.2 mm; the outer surface of the third lens has a radius of curvature of 77.22 mm, the inner surface has a radius of curvature of 199.99 mm, and the thickness is 4 mm; the diffraction surface parameters of the outer surface of the second lens are quadratic surface constants K=0, C=1 / 135.19, and the second-order, fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, and fourteenth-order coefficients are a2=0, a4=-3.224×10 －7 、a6=-1.917×10 －10 、a8=-8.486×10 －14 , a 10 =2.867×10 －15 , a 12 =8.520×10 －19 、a 14 =9.635×10 －21 , the diffraction order is 1, the number of diffraction rings is 8, C1 = -1.56305×10 －5 .

[0009] Furthermore, the fairing is a concentric convex lens made of zinc sulfide; the first lens and the third lens are meniscus convex lenses, the first lens material is chalcogenide glass IRG206, and the third lens material is germanium; the second lens is a meniscus concave lens made of germanium.

[0010] Furthermore, the distance between the fairing and the first lens is 5 mm; the distance between the first lens and the second lens is 1.5 mm; the distance between the second lens and the third lens is 34.6 mm; the distance between the third lens and the detector protective glass is 11.45 mm; the distance between the detector protective glass and the cold light stop is 2.86 mm; and the distance between the cold light stop and the image plane is 20.47 mm.

[0011] Furthermore, the optical system has an operating band of 7.7 μm to 10.3 μm, a focal length of 50 mm, an F number of 2, a field of view of 10.9°×8.7°, and at 33 lp / mm, a modulation transfer function value of 0 field of view is ≥0.28, and transfer function values ​​of the remaining fields of view are ≥0.24, and system distortion is ≤1%.

[0012] Furthermore, the optical system is designed with a one-time imaging 3-piece structure, chalcogenide glass IRG206 and germanium are selected as lens materials, and only one binary surface is used to realize a wide-temperature athermal design of the optical system. In the temperature range of -40°C to +70°C, the maximum distortion design value of the optical system is -0.96%; at -40°C, at 33lp / mm, the transfer function value of 0 field of view is ≥0.27, and the transfer function values ​​of the remaining fields of view are ≥0.22; at 20°C, at 33lp / mm, the transfer function value of 0 field of view is ≥0.28, and the transfer functions of the remaining fields of view are ≥0.24; at +70°C, at 33lp / mm, the transfer function of 0 field of view is ≥0.27, and the transfer functions of the remaining fields of view are ≥0.23.

[0013] Furthermore, the outer dimensions of the optical system are less than φ50 mm×63 mm, and the total optical weight is less than 150 g.

[0014] Beneficial effects:

[0015] 1. The optical system described in the present invention has an operating band of 7.7 μm to 10.3 μm, a focal length of 50 mm, an F number of 2, a full field distortion of ≤1%, a field of view of 10.9°×8.7°, and a Stirling cooled detector with a resolution of 640×512 and a pixel size of 15 μm. It is a small F number long-wave cooled infrared optical system with the characteristics of large relative aperture, high resolution and strong light collecting ability.

[0016] 2. The optical system described in the present invention adopts a three-piece optical structure of one-shot imaging IRG206-GE-GE, with an overall size of <φ50mm×63mm and a total weight of <150g. It has the characteristics of simple structure, small size, light weight and easy installation and calibration.

[0017] 3. The detector of the optical system described in the present invention selects an optical system whose transfer function is 33lp / mm, 0 field of view ≥0.28, other fields of view ≥0.24, excellent imaging quality, and single pixel angle of less than 0.3mrad.

[0018] 4. The optical system uses chalcogenide glass IRG206 and germanium, two of the most commonly used optical materials with good stability and mature processing technology, as lens materials. Advanced aberration theory is used to effectively balance the contradiction between optical aberration and thermal difference. Only one binary surface is used to achieve a wide temperature athermal design of the optical system. The imaging quality is excellent in the range of -40℃ to +70℃. The number of lenses is small, the transmittance is high, the environmental adaptability is strong, the cost is low, and it is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It is a schematic diagram of the overall structure of A of the present invention;

[0021] Figure 2 Modulation transfer function curve at +70℃;

[0022] Figure 3 Modulation transfer function curve at +20℃;

[0023] Figure 4 Modulation transfer function curve at -40℃;

[0024] Figure 5 is the optical system distortion and field curve.

[0025] In the figure: fairing 1; first lens 2; second lens 3; third lens 4; detector protection glass 5; cold aperture 6; image plane 7. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0027] It should be noted that the descriptions of the present invention regarding directions such as "left", "right", "left side", "right side", "upper", "lower", "top", and "bottom" are all defined based on the relationship between the orientations or positions shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the structure must be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention. In the description of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0028] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Referring to the accompanying drawings, this embodiment is described, providing a low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials, wherein a fairing 1, a first lens 2, a second lens 3, a third lens 4, a detector protection glass 5, a cold stop 6 and an image plane 7 are sequentially arranged in the direction of light propagation. The first lens 2, the second lens 3, the third lens 4, the detector protection glass 5, the cold stop 6 and the image plane 7 are coaxially arranged with the fairing 1. The optical system is used to receive infrared radiation inherent to the target and the background, and converge it onto the photosensitive surface of the long-wave infrared refrigeration detector, and convert the optical signal into an electrical signal through photoelectric conversion. The system has high sensitivity and small spatial resolution, and can detect, identify and accurately locate the target at night or under complex meteorological conditions.

[0030] The specific purpose of this technical solution is to achieve a low-cost, athermal design of a cooled infrared seeker. Based on chalcogenide glass IRG206 and germanium optical materials, a one-shot imaging three-piece optical structure IRG206-Ge-Ge is used. A Stirling-cooled array-scale 640×512 pixel long-wave infrared detector with a size of 15μm is selected as the receiving device to design an athermal, high-resolution, low-cost long-wave cooled infrared imaging detection optical system that can realize the detection, identification and precise positioning of targets.

[0031] In this embodiment, the first lens 2 and the third lens 4 are both spherical lenses; the outer surface of the second lens 3 is a binary surface, and the inner surface is a spherical surface. The binary surface includes an aspherical surface and a diffractive surface;

[0032] The aspheric equation is

[0033]

[0034] Where: H is the sum of the squares of the horizontal and vertical coordinates, H 2 =X 2 +Y 2 ; K is the quadratic surface constant; C is the curvature, a2, a4, a6, a8, a 10 、a 12 is the aspheric coefficient.

[0035] The diffraction surface equation is:

[0036]

[0037] Where: H is the sum of the squares of the horizontal and vertical coordinates, H 2 =X 2 +Y 2 ; m is the number of diffraction rings; n0 is the refractive index of the material; C1 is the secondary phase coefficient.

[0038] In this embodiment, the outer surface of the fairing 1 has a radius of curvature of 115 mm, the inner surface has a radius of curvature of 110 mm, and the thickness is 5 mm; the outer surface of the first lens 2 has a radius of curvature of 50.6 mm, the inner surface has a radius of curvature of 135.19 mm, and the thickness is 8.3 mm; the outer surface of the second lens 3 has a radius of curvature of 174.25 mm, the inner surface has a radius of curvature of 68.05 mm, and the thickness is 4.2 mm; the outer surface of the third lens 4 has a radius of curvature of 77.22 mm, the inner surface has a radius of curvature of 199.99 mm, and the thickness is 4 mm; the outer surface diffraction surface parameters of the second lens 3 are quadratic surface constants K=0, C=1 / 135.19, and the second-order, fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, and fourteenth-order coefficients are a2=0, a4=-3.224×10 －7 、a6=-1.917×10 －10 、a8=-8.486×10 －14 , a 10 =2.867×10 －15 , a 12 =8.520×10 －19 、a 14 =9.635×10 －21 , the diffraction order is 1, the number of diffraction rings is 8, C1 = -1.56305×10 －5 .

[0039] In this embodiment, the fairing 1 is a concentric convex lens made of zinc sulfide; the first lens 2 and the third lens 4 are meniscus convex lenses, the first lens 2 is made of chalcogenide glass IRG206, and the third lens 4 is made of germanium; the second lens 3 is a meniscus concave lens made of germanium.

[0040] In this embodiment, the distance between the fairing 1 and the first lens 2 is 5 mm; the distance between the first lens 2 and the second lens 3 is 1.5 mm; the distance between the second lens 3 and the third lens 4 is 34.6 mm; the distance between the third lens 4 and the detector protection glass 5 is 11.45 mm; the distance between the detector protection glass 5 and the cold light stop 6 is 2.86 mm; the distance between the cold light stop 6 and the image plane 7 is 20.47 mm.

[0041] The first lens and the third lens are both spherical lenses; the outer surface of the second lens is a binary surface, and the inner surface is a spherical surface.

[0042] This technical solution limits the material, quantity and surface shape of each lens. The design adopts a one-shot imaging 3-piece IRG206-Ge-Ge structure, uses advanced aberration theory, considers the thermal expansion coefficients of optical and mechanical materials, effectively balances the contradiction between optical aberrations and thermal differences, and selects chalcogenide glass and germanium, two most commonly used optical materials with good stability and mature processing technology, as lens materials, and aluminum as the lens barrel material. Only one binary diffraction surface is used to achieve a wide temperature athermal design of the optical system. The imaging quality is excellent in the range of -40℃ to +70℃, the structure is simple, the number of lenses is small, the transmittance is high, the single pixel angle is 0.3mrad, the detection distance is long, the environmental adaptability is strong, it is easy to calibrate, the cost is low, and it is suitable for mass production.

[0043] In this embodiment, the working band of the optical system is 7.7μm~10.3μm, the focal length is 50mm, the F number is 2, the field of view is 10.9°×8.7°, and at 33lp / mm, the modulation transfer function value of 0 field of view is ≥0.28, the transfer function values ​​of the remaining fields of view are ≥0.24, and the system distortion is ≤1%.

[0044] The optical system has an operating band of 7.7 μm to 10.3 μm, a focal length of 50 mm, an F number of 2, a full field distortion of ≤1%, a field of view of 10.9°×8.7°, and a Stirling cooled detector with a resolution of 640×512 and a pixel size of 15 μm. It is a small F number long-wave cooled infrared optical system with the characteristics of large relative aperture, high resolution, and strong light collecting capability.

[0045] This technical solution defines the technical parameters of the optical system's operating band, focal length, F number, field of view, detector resolution and pixel size, and has the characteristics of high resolution, large relative aperture and strong light-gathering ability.

[0046] In this embodiment, the optical system is designed to adopt a one-time imaging 3-piece structure, chalcogenide glass IRG206 and germanium are selected as lens materials, and only one binary surface is used to realize a wide-temperature athermal design of the optical system. In the temperature range of -40°C to +70°C, the maximum distortion design value of the optical system is -0.96%; at -40°C, at 33lp / mm, the transfer function value of 0 field of view is ≥0.27, and the transfer function values ​​of the remaining fields of view are ≥0.22; at 20°C, at 33lp / mm, the transfer function value of 0 field of view is ≥0.28, and the transfer functions of the remaining fields of view are ≥0.24; at +70°C, at 33lp / mm, the transfer function of 0 field of view is ≥0.27, and the transfer functions of the remaining fields of view are ≥0.23.

[0047] Within the temperature range of -40°C to +70°C, the maximum designed distortion value of the optical system is -0.96%; at 33lp / mm, the transfer function value of the zero field of view is ≥0.27, and the transfer function values ​​of the remaining fields of view are ≥0.22; at 20°C, at 33lp / mm, the transfer function value of the zero field of view is ≥0.28, and the transfer functions of the remaining fields of view are ≥0.24; at +70°C, at 33lp / mm, the transfer function of the zero field of view is ≥0.27, and the transfer functions of the remaining fields of view are ≥0.23.

[0048] The optical system recorded in the technical solution has a modulation transfer function curve design value close to the diffraction limit within the temperature range of -40°C to +70°C, has excellent imaging quality, good environmental adaptability, and outstanding performance characteristics.

[0049] In this embodiment, the outer dimensions of the optical system are less than φ50 mm×63 mm, and the total optical weight is less than 150 g.

[0050] The optical system fairing is a concentric lens made of zinc sulfide, with an outer surface curvature radius of 120 mm, an inner surface curvature radius of 115 mm, and a thickness of 5 mm. The optical system has an overall size of <φ50 mm×63 mm, and a total optical weight of <150 g.

[0051] Working principle of infrared imaging guidance system:

[0052] The infrared imaging guidance system consists of three parts: a fairing, an optical system, and a long-wave cooled detector. The fairing is an optical detection window with high transmittance in the system's operating band. It forms a closed space with other parts of the seeker to protect the internal components of the seeker and enable it to work normally under thermal shock. The optical system is used to receive infrared radiation inherent to the target and background, and converge it onto the photosensitive surface of the long-wave infrared cooled detector. Through photoelectric conversion, the optical signal is converted into an electrical signal. The system has high sensitivity and small spatial resolution, and can detect, identify and accurately locate targets at night or under complex weather conditions.

[0053] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials, characterized by: A fairing (1), a first lens (2), a second lens (3), a third lens (4), a detector protection glass (5), a cold stop (6) and an image plane (7) are arranged in sequence in the direction of light propagation; the first lens (2), the second lens (3), the third lens (4), the detector protection glass (5), the cold stop (6) and the image plane (7) are arranged coaxially with the fairing (1); the optical system is used to receive infrared radiation inherent to the target and the background, and to converge it onto the photosensitive surface of the long-wave infrared refrigeration detector, and to convert the optical signal into an electrical signal through photoelectric conversion.

2. According to claim 1, a low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials is characterized by: The first lens (2) and the third lens (4) are both spherical lenses; the outer surface of the second lens (3) is a binary surface, and the inner surface is a spherical surface.

3. The low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials according to claim 1, characterized in that: The outer surface of the fairing (1) has a radius of curvature of 115 mm, the inner surface has a radius of curvature of 110 mm, and the thickness is 5 mm; the outer surface of the first lens (2) has a radius of curvature of 50.6 mm, the inner surface has a radius of curvature of 135.19 mm, and the thickness is 8.3 mm; the outer surface of the second lens (3) has a radius of curvature of 174.25 mm, the inner surface has a radius of curvature of 68.05 mm, and the thickness is 4.2 mm; the outer surface of the third lens (4) has a radius of curvature of 77.22 mm, the inner surface has a radius of curvature of 199.99 mm, and the thickness is 4mm; the diffraction surface parameters of the outer surface of the second lens (3) are quadratic surface constant K=0, C=1 / 135.19, the second-order, fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order and fourteenth-order coefficients are a2=0, a4=-3.224×10-7, a6=-1.917×10-10, a8=-8.486×10-14, a10=2.867×10-15, a12=8.520×10-19, a14=9.635×10-21, the diffraction order is 1, the number of diffraction rings is 8, and C1=-1.56305×10-5.

4. The low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials according to claim 1, characterized in that: The fairing (1) is a concentric convex lens made of zinc sulfide; the first lens (2) and the third lens (4) are meniscus convex lenses, the first lens (2) is made of chalcogenide glass IRG206, and the third lens (4) is made of germanium; the second lens (3) is a meniscus concave lens made of germanium.

5. The low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials according to claim 1, characterized in that: The distance between the fairing (1) and the first lens (2) is 5 mm; the distance between the first lens (2) and the second lens (3) is 1.5 mm; the distance between the second lens (3) and the third lens (4) is 34.6 mm; the distance between the third lens (4) and the detector protection glass (5) is 11.45 mm; the distance between the detector protection glass (5) and the cold light stop (6) is 2.86 mm; and the distance between the cold light stop (6) and the image plane (7) is 20.47 mm.

6. The low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials according to claim 1, characterized in that: The optical system has an operating band of 7.7 μm to 10.3 μm, a focal length of 50 mm, an F number of 2, a field of view of 10.9°×8.7°, a modulation transfer function value of 0 field of view ≥0.28 at 33 lp / mm, and transfer function values ​​of the remaining fields of view ≥0.24, and a system distortion ≤1%.

7. The low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials according to claim 1, characterized in that: The optical system is designed with a one-shot imaging 3-piece structure, chalcogenide glass IRG206 and germanium are selected as lens materials, and only one binary surface is used to realize a wide-temperature athermal design of the optical system. Within the temperature range of -40°C to +70°C, the maximum distortion design value of the optical system is -0.96%; at -40°C, at 33lp / mm, the transfer function value of 0 field of view is ≥0.27, and the transfer function values ​​of the remaining fields of view are ≥0.22; at 20°C, at 33lp / mm, the transfer function value of 0 field of view is ≥0.28, and the transfer functions of the remaining fields of view are ≥0.24; at +70°C, at 33lp / mm, the transfer function value of 0 field of view is ≥0.27, and the transfer functions of the remaining fields of view are ≥0.

23.

8. The low-cost long-wave refrigeration athermalization optical system based on chalcogenide materials according to claim 1, characterized in that: The outer dimensions of the optical system are less than φ50 mm×63 mm, and the total optical weight is less than 150 g.

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