Ultra-large target surface short wave system

Abstract

The invention relates to a short-wave system with an ultra-large target surface. The short-wave system comprises a negative meniscus lens A, a positive meniscus lens B, a biconcave negative lens C, a positive meniscus lens D, a negative meniscus lens E, a positive meniscus lens F, a reflector 1, a reflector 2, a positive meniscus lens G, a negative meniscus lens H and a positive meniscus lens I which are sequentially arranged in the direction of an optical path. The matched detector J is a refrigeration type short wave infrared detector, and the size of an imaging target surface of the detector is not less than phi 60mm. The cold diaphragm is located at the tail end of the system, and the efficiency of the cold diaphragm is 100% during design, so that stray light entering is reduced, and the detection sensitivity of the system is improved. According to the system, a secondary imaging Z-shaped turning structure form is adopted, an aspheric surface is combined, materials are reasonably selected, and focal power of each lens is distributed, so that the large target surface design is realized, and meanwhile, the system aperture is compressed, the system length is shortened, and the system volume is reduced.

Description

Technical Field

[0001] The invention relates to a super-large target surface short-wave system. Background Art

[0002] The spectrum range of short-wave infrared imaging is between 0.9um and 2.5um. Its working wavelength is longer than that of visible light, and the atmospheric scattering effect is small. Therefore, short-wave infrared imaging has strong anti-interference and strong penetration capabilities similar to medium- and long-wave thermal imagers in adverse weather conditions such as haze and smoke. In addition, short-wave infrared has imaging detail resolution capabilities similar to visible light, which can obtain more comprehensive and accurate detection information.

[0003] With the development of large array, high sensitivity and wide spectral response band detectors, short-wave infrared will play a greater role in military and civilian fields. At present, the response band of short-wave infrared detectors is basically between 0.9um and 1.7um, and the detector target surface is no larger than Φ25mm. There are fewer short-wave detectors with a response band between 1.8um and 2.5um, and there are fewer short-wave infrared lenses that can match them. At present, there are short-wave infrared detectors on the market whose spectral response range extends to 2.5μm, and the detector imaging target surface is larger than Φ25mm. The existing short-wave infrared lenses with small target surfaces cannot be adapted to short-wave infrared detectors with large target surfaces, and the working band cannot be adapted. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide an ultra-large target surface cooling short-wave infrared optical system, whose detector imaging target surface size is not less than 60mm, and the F number is 2.0. The system material selects several common infrared materials such as germanium single crystal and silicon single crystal for reasonable matching, and combines the use of several aspherical surfaces to reasonably distribute the optical power of each lens to achieve the correction of system chromatic aberration and monochromatic aberration.

[0005] The present invention is implemented by the following scheme: a super large target surface short wave system, comprising a meniscus negative lens A, a meniscus positive lens B, a double concave negative lens C, a meniscus positive lens D, a meniscus negative lens E, a meniscus positive lens F, a reflector 1, a reflector 2, a meniscus positive lens G, a meniscus negative lens H, and a meniscus positive lens I which are sequentially arranged along the light path direction.

[0006] Furthermore, the air gap between the meniscus negative lens A and the meniscus positive lens B is 4.57 mm, the air gap between the meniscus positive lens B and the biconcave negative lens C is 21.53 mm, the air gap between the biconcave negative lens C and the meniscus positive lens D is 34.72 mm, the air gap between the meniscus positive lens D and the meniscus negative lens E is 62.95 mm, the air gap between the meniscus negative lens E and the meniscus positive lens F is 28.5 mm, the air gap between the meniscus positive lens F and the meniscus positive lens G is 375.97 mm, the air gap between the meniscus positive lens G and the meniscus negative lens H is 39.53 mm, and the air gap between the meniscus negative lens H and the meniscus positive lens I is 3.15 mm.

[0007] Furthermore, the air gap between the meniscus positive lens F and the reflector 1 is 80mm-120mm; the air gap between the reflector 1 and the reflector 2 is 135.97mm-225.97mm; and the air gap between the reflector 2 and the meniscus positive lens G is 70mm-120mm.

[0008] Furthermore, the convex surface of the meniscus negative lens A faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens B faces the object plane, and the material is silicon single crystal; the material of the double concave negative lens C is calcium fluoride; the concave surface of the meniscus positive lens D faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus negative lens E faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens F faces the object plane, and the material is silicon single crystal; the convex surface of the meniscus positive lens G faces the object plane, and the material is silicon single crystal; the convex surface of the meniscus negative lens H faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens I faces the object plane, and the material is silicon single crystal.

[0009] Further, the focal length of the optical system is f´, the focal length of the meniscus negative lens A is f1´, the focal length of the meniscus positive lens B is f2´, the focal length of the biconcave negative lens C is f3´, the focal length of the meniscus positive lens D is f4´, the focal length of the meniscus negative lens E is f5´, the focal length of the meniscus positive lens F is f6´, the focal length of the meniscus positive lens G is f7´, the focal length of the meniscus negative lens H is f8´, and the focal length of the meniscus positive lens I is f9´. The relationship between the focal length of each lens in the system and the focal length of the system is as follows: |f1´ / f´|≤5, |f2´ / f´|≤5, |f3´ / f´|≤5, |f4´ / f´|≤5, |f5´ / f´|≤5, |f6´ / f´|≤5, |f7´ / f´|≤5, |f8´ / f|´≤5, |f9´ / f´|≤5.

[0010] Compared with the prior art, the present invention has the following beneficial effects: a) The optical system of the present invention is matched with an ultra-large target detector and a large relative aperture design, which is conducive to improving the performance of the entire optical system, not only increasing the imaging range, but also further improving the picture clarity; b) The optical system of the present invention matches the detector spectral response range to extend to 2.5um, filling the gap in the short-wave infrared imaging spectral range; c) The optical system of the present invention adopts a secondary imaging Z-shaped turning structure, which realizes a large relative aperture and a large target surface design while compressing the system aperture, shortening the system length, and reducing the system volume; d) The system of the present invention adopts a nearly symmetrical structural form to optimize the design, which is conducive to improving the relative illumination of the system and ensuring uniform illumination of the entire image surface while meeting the image quality requirements.

[0011] Compared with the prior art, the present invention has the following beneficial effects: The optical system of the present invention is matched with an ultra-large target detector and a large relative aperture design, which is conducive to improving the performance of the entire optical system, not only increasing the imaging range, but also further improving the picture clarity; The optical system of the present invention matches the detector spectral response range to 2.5um, filling the gap in the short-wave infrared imaging spectral range; c) The optical system of the present invention adopts a secondary imaging Z-shaped turning structure, which realizes a large relative aperture and a large target surface design while compressing the system aperture, shortening the system length, and reducing the system volume; d) The system of the present invention adopts a nearly symmetrical structural form to optimize the design, which is conducive to improving the relative illumination of the system and ensuring uniform illumination of the entire image surface while meeting the image quality requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a structural diagram of an optical system of the present invention; Figure 2 is a graph of the MTF of the optical system of the present invention; Figure 3 is a spherical aberration curve diagram of the optical system of the present invention; Figure 4 It is a relative illumination curve diagram of the optical system of the present invention.

[0013] like Figures 1 to 4As shown, a short-wave system with an ultra-large target surface is composed of six lenses and two reflectors, including a meniscus negative lens A, a meniscus positive lens B, a double concave negative lens C, a meniscus positive lens D, a meniscus negative lens E, a meniscus positive lens F, a reflector 1, a reflector 2, a meniscus positive lens G, a meniscus negative lens H, and a meniscus positive lens I, which are arranged in sequence along the optical path. The matched detector J is a refrigerated short-wave infrared detector, and the imaging target surface size of the detector is not less than Ф60mm. The cold stop is located at the end of the system, and the cold stop efficiency is 100% during design to reduce the entry of stray light and improve the detection sensitivity of the system. This optical system adopts a secondary imaging Z-shaped turning structure, combined with the use of aspherical surfaces and reasonable selection of materials and distribution of the optical power of each lens, while realizing a large target surface design, compressing the system aperture, shortening the system length, and reducing the system volume.

[0014] In this embodiment, the air gap between the meniscus negative lens A and the meniscus positive lens B is 4.57 mm, the air gap between the meniscus positive lens B and the biconcave negative lens C is 21.53 mm, the air gap between the biconcave negative lens C and the meniscus positive lens D is 34.72 mm, the air gap between the meniscus positive lens D and the meniscus negative lens E is 62.95 mm, the air gap between the meniscus negative lens E and the meniscus positive lens F is 28.5 mm, the air gap between the meniscus positive lens F and the meniscus positive lens G is 375.97 mm, the air gap between the meniscus positive lens G and the meniscus negative lens H is 39.53 mm, and the air gap between the meniscus negative lens H and the meniscus positive lens I is 3.15 mm.

[0015] In this embodiment, the air gap between the meniscus positive lens F and the reflector 1 is 118 mm; the air gap between the reflector 1 and the reflector 2 is 182.97 mm; and the air gap between the reflector 2 and the meniscus positive lens G is 75 mm.

[0016] In this embodiment, the convex surface of the meniscus negative lens A faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens B faces the object plane, and the material is silicon single crystal; the material of the double concave negative lens C is calcium fluoride; the concave surface of the meniscus positive lens D faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus negative lens E faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens F faces the object plane, and the material is silicon single crystal; the convex surface of the meniscus positive lens G faces the object plane, and the material is silicon single crystal; the convex surface of the meniscus negative lens H faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens I faces the object plane, and the material is silicon single crystal.

[0017] In this embodiment, the focal length of the optical system is f', the focal length of the meniscus negative lens A is f1', the focal length of the meniscus positive lens B is f2', the focal length of the biconcave negative lens C is f3', the focal length of the meniscus positive lens D is f4', the focal length of the meniscus negative lens E is f5', the focal length of the meniscus positive lens F is f6', the focal length of the meniscus positive lens G is f7', the focal length of the meniscus negative lens H is f8', and the focal length of the meniscus positive lens I is f9'. The relationship between the focal lengths of the lenses of the system and the focal length of the system is as follows: |f1´ / f´|≤5, |f2´ / f´|≤5, |f3´ / f´|≤5, |f4´ / f´|≤5, |f5´ / f´|≤5, |f6´ / f´|≤5, |f7´ / f´|≤5, |f8´ / f|´≤5, |f9´ / f´|≤5.

[0018] The specific parameters of each lens in the optical system of the present invention are shown in the following table: The aspheric surface equations of the above lenses are as follows: ; Z represents the position in the direction of the optical axis, r represents the height in the vertical direction relative to the optical axis, c represents the radius of curvature, and k represents the cone coefficient. Represents the aspheric coefficient.

[0019] Aspherical data of each lens:

[0020] The optical system composed of the above lenses achieves the following optical indicators: (1) Diagonal viewing angle: ≥45°; (2) Imaging circle diameter: ≥ Ф60mm; (3) F number: 2.0; (4) Working band: 2.0um-2.5um.

[0021] When optimizing the cooled infrared optical system, for surfaces with severe cold reflection, constraints on the radius of curvature are added to change the angles of the paraxial principal ray and the edge ray of the surface to reduce the value of cold reflection; the optical power is reasonably distributed and combined with the use of even-order aspherical surfaces to balance the system aberrations, and the sensitivity of each optical component is reduced by adjusting the curvature and thickness, making the lens easier to process and assemble.

[0022] Compared with the prior art, the present invention has the following beneficial effects: a) The optical system of the present invention is matched with an ultra-large target detector and a large relative aperture design, which is conducive to improving the performance of the entire optical system, not only increasing the imaging range, but also further improving the picture clarity; b) The optical system of the present invention matches the detector spectral response range to extend to 2.5um, filling the gap in the short-wave infrared imaging spectral range; c) The optical system of the present invention adopts a secondary imaging Z-shaped turning structure, which realizes a large relative aperture and a large target surface design while compressing the system aperture, shortening the system length, and reducing the system volume; d) The system of the present invention adopts a nearly symmetrical structural form to optimize the design, which is conducive to improving the relative illumination of the system and ensuring uniform illumination of the entire image surface while meeting the image quality requirements.

[0023] Unless otherwise stated, any technical solution disclosed in the present invention disclosed above, if it discloses a numerical range, then the disclosed numerical range is a preferred numerical range, and any technician in the field should understand that the preferred numerical range is only a numerical value with a more obvious technical effect or representative value among many implementable numerical values. Since there are too many numerical values ​​to be exhaustive, the present invention discloses some numerical values ​​to illustrate the technical solution of the present invention, and the numerical values ​​listed above should not constitute a limitation on the scope of protection of the present invention.

[0024] In addition, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in the present invention include states or shapes that are approximate, similar, or close to them.

[0025] Any component provided by the present invention may be assembled from a plurality of separate components, or may be a separate component manufactured by an integral forming process.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. An ultra-large target shortwave system, characterized by: It includes a meniscus negative lens A, a meniscus positive lens B, a double concave negative lens C, a meniscus positive lens D, a meniscus negative lens E, a meniscus positive lens F, a meniscus positive lens G, a meniscus negative lens H, and a meniscus positive lens I which are arranged in sequence along the light path direction.

2. The ultra-large target area short wave system according to claim 1, characterized in that: The optical system also includes a detector J, which is a short-wave cooling detector with an imaging target surface size of not less than Φ60 mm and an F number of 2.

0.

3. The ultra-large target area short wave system according to claim 1, characterized in that: The optical system further comprises a reflector 1 and a reflector 2; the reflector 1 and the reflector 2 are located between the meniscus positive lens F and the meniscus positive lens G.

4. The ultra-large target area shortwave system according to claim 1, characterized in that: The air gap between the meniscus negative lens A and the meniscus positive lens B is 4.57 mm, the air gap between the meniscus positive lens B and the biconcave negative lens C is 21.53 mm, the air gap between the biconcave negative lens C and the meniscus positive lens D is 34.72 mm, the air gap between the meniscus positive lens D and the meniscus negative lens E is 62.95 mm, the air gap between the meniscus negative lens E and the meniscus positive lens F is 28.5 mm, the air gap between the meniscus positive lens F and the meniscus positive lens G is 375.97 mm, the air gap between the meniscus positive lens G and the meniscus negative lens H is 39.53 mm, and the air gap between the meniscus negative lens H and the meniscus positive lens I is 3.15 mm.

5. The ultra-large target area short wave system according to claim 1, characterized in that: The air gap between the meniscus positive lens F and the reflector 1 is 80mm-120mm; the air gap between the reflector 1 and the reflector 2 is 135.97mm-225.97mm; the air gap between the reflector 2 and the meniscus positive lens G is 70mm-120mm.

6. The ultra-large target area shortwave system according to claim 1, characterized in that: The convex surface of the meniscus negative lens A faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens B faces the object plane, and the material is silicon single crystal; the material of the double concave negative lens C is calcium fluoride; the concave surface of the meniscus positive lens D faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus negative lens E faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens F faces the object plane, and the material is silicon single crystal; the convex surface of the meniscus positive lens G faces the object plane, and the material is silicon single crystal; the convex surface of the meniscus negative lens H faces the object plane, and the material is germanium single crystal; the convex surface of the meniscus positive lens I faces the object plane, and the material is silicon single crystal.

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