A long working distance visible light target detection optical system

Abstract

An optical system for detecting visible light targets at long working distances relates to the field of optical detection technology, and in particular to an optical system capable of detecting visible light targets at long working distances. The system solves the problems of short working distances, low detection accuracy, and poor environmental adaptability that are common in existing optical systems for detecting visible light targets. The system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a detector protective glass, and a detector target surface, which are sequentially arranged along the propagation direction of the incident light. The system has a compact structure and uses seven spherical glass lenses to achieve a large field of view target detection function. It has low cost, compact structure, small size, light weight, low difficulty in production and assembly, and is conducive to mass production applications. It can clearly image and accurately detect targets at a working distance of 60m to 50km.

Description

Technical Field

[0001] The present invention relates to the technical field of optical detection, and in particular to a long working distance visible light target detection optical system, which can perform visible light target detection at a long working distance. Background Art

[0002] With the development of science and technology, optical detection technology plays an increasingly important role in the fields of military, security, aerospace, etc. Existing visible light target detection optical systems usually have problems such as short working distance, low detection accuracy, and poor environmental adaptability, which limit their performance in practical applications. Therefore, it is of great practical significance to study a visible light target detection optical system with long working distance, high accuracy, and strong environmental adaptability. Summary of the invention

[0003] In order to solve the problems of short working distance, low detection accuracy, poor environmental adaptability and the like in existing optical systems, which limit their performance in practical applications, the present invention provides a long working distance visible light target detection optical system to achieve clear imaging and precise detection of targets at a working distance of 60m to 50km.

[0004] A long working distance visible light target detection optical system, comprising a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a detector protection glass and a detector target surface, which are sequentially arranged along the propagation direction of the incident light;

[0005] The incident light beam is imaged on the detector target surface after passing through the first lens, the second lens, the third lens, the aperture, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the detector protection glass in sequence;

[0006] The first lens is a positive lens with a focal length of 65 to 75 mm; the second lens is a positive lens with a focal length of 45 to 55 mm; the third lens is a negative lens with a focal length of -23 to -13 mm; the fourth lens is a positive lens with a focal length of 16 to 26 mm; the fifth lens is a positive lens with a focal length of 150 to 160 mm; the sixth lens is a positive lens with a focal length of 52 to 62 mm; the seventh lens is a negative lens with a focal length of -25 to -15 mm; the pixel size of the detector target surface is 5.5 μm.

[0007] Furthermore, the center thickness of the first lens is 2.9-4.9 mm; the center thickness of the second lens is 2.6-4.6 mm; the center thickness of the third lens is 2-4 mm; the center thickness of the fourth lens is 3-5 mm; the center thickness of the fifth lens is 2.8-4.8 mm; the center thickness of the sixth lens is 2.2-4.2 mm; and the center thickness of the seventh lens is 1.9-3.9 mm.

[0008] Furthermore, the distance between the first lens and the second lens is 0.3-0.8 mm; the distance between the second lens and the third lens is 1.3-3.3 mm; the distance between the third lens and the aperture is 2.8-4.8 mm; the distance between the aperture and the fourth lens is 0.5-2.5 mm; the distance between the fourth lens and the fifth lens is 1-3 mm; the distance between the fifth lens and the sixth lens is 2-4 mm; the distance between the sixth lens and the seventh lens is 1.8-3.8 mm; the distance between the seventh lens and the detector protective glass is 2-6 mm; the distance between the detector protective glass and the detector target surface is 0.5-1.5 mm.

[0009] Preferably, the first lens satisfies the relationship: N d ≥1.4, V d ≥67; the second lens satisfies the relationship: N d ≥1.5, V d ≥68; the third lens satisfies the relationship: N d ≥1.6, V d ≥33; the fourth lens satisfies the relationship: N d ≥1.5, V d ≥75; the fifth lens satisfies the relationship: N d ≥1.9, V d ≥20; the sixth lens satisfies the relationship: N d ≥1.6, V d ≥44; the seventh lens satisfies the relationship: N d ≥1.8, V d ≥25; the detector protection glass satisfies the relationship: N d ≥1.5, V d ≥54; where N d is the refractive index, V d is the Abbe constant.

[0010] Furthermore, the imaging spectrum range of the optical system is between 450nm and 850nm.

[0011] Furthermore, the field of view angle of the optical system is 28°.

[0012] The beneficial effects of the present invention are:

[0013] 1. Achieve clear imaging and precise detection of targets at a working distance of 60m to 50km at a full field of view of 28°.

[0014] 2. The present invention adopts high and low temperature resistant and radiation proof materials to ensure that the optical system can work stably in various harsh environments.

[0015] 3. Seven spherical glass lenses are used to achieve a large field of view target detection function, with low cost, compact structure, small size, light weight, low production and assembly difficulty, which is conducive to mass production application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of a long working distance visible light target detection optical system according to the present invention.

[0017] Figure 2 Among them, (a) is the modulation transfer function of the optical system of the present invention when the working distance is 60m; (b) is the modulation transfer function of the optical system when the working distance is 50km.

[0018] Figure 3 In the figure, (a) is the optical system point diagram of the present invention when the working distance is 60m; (b) is the optical system point diagram when the working distance is 50km.

[0019] Figure 4 This is a field area and distortion diagram of a long working distance visible light target detection optical system described in the present invention.

[0020] In the figure: 1. first lens, 2. second lens, 3. third lens, 4. aperture, 5. fourth lens, 6. fifth lens, 7. sixth lens, 8. seventh lens, 9. detector window protection glass, 10. detector target surface. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention.

[0022] Figure 1 The schematic diagram of the structure of a long working distance visible light target detection optical system of the present invention is shown, wherein a first lens 1, a second lens 2, a third lens 3, an aperture 4, a fourth lens 5, a fifth lens 6, a sixth lens 7, a seventh lens 8, a detector protection glass 9 and a detector target surface 10 are coaxially arranged in sequence along the direction of light propagation;

[0023] The incident light beam is imaged on the detector target surface 10 after passing through the first lens 1, the second lens 2, the third lens 3, the aperture 4, the fourth lens 5, the fifth lens 6, the sixth lens 7, the seventh lens 8 and the detector protection glass 9 in sequence;

[0024] The first lens 1 is a positive lens with a focal length of 65 to 75 mm; the second lens 2 is a positive lens with a focal length of 45 to 55 mm; the third lens 3 is a negative lens with a focal length of -23 to -13 mm; the fourth lens 5 is a positive lens with a focal length of 16 to 26 mm; the fifth lens 6 is a positive lens with a focal length of 150 to 160 mm; the sixth lens 7 is a positive lens with a focal length of 52 to 62 mm; the seventh lens 8 is a negative lens with a focal length of -25 to -15 mm; the pixel size of the detector target surface 10 is 5.5 μm.

[0025] The center thickness of the first lens 1 is 2.9-4.9 mm; the center thickness of the second lens 2 is 2.6-4.6 mm; the center thickness of the third lens 3 is 2-4 mm; the center thickness of the fourth lens 5 is 3-5 mm; the center thickness of the fifth lens 6 is 2.8-4.8 mm; the center thickness of the sixth lens 7 is 2.2-4.2 mm; and the center thickness of the seventh lens 8 is 1.9-3.9 mm.

[0026] The distance between the first lens 1 and the second lens 2 is 0.3-0.8 mm; the distance between the second lens 2 and the third lens 3 is 1.3-3.3 mm; the distance between the third lens 3 and the diaphragm 4 is 2.8-4.8 mm; the distance between the diaphragm 4 and the fourth lens 5 is 0.5-2.5 mm; the distance between the fourth lens 5 and the fifth lens 6 is 1-3 mm; the distance between the fifth lens 6 and the sixth lens 7 is 2-4 mm; the distance between the sixth lens 7 and the seventh lens 8 is 1.8-3.8 mm; the distance between the seventh lens 8 and the detector protection glass 9 is 2-6 mm; the distance between the detector protection glass 9 and the detector target surface 10 is 0.5-1.5 mm.

[0027] The first lens 1 satisfies the relationship: N d ≥1.4, V d ≥67; the second lens 2 satisfies the relationship: N d ≥1.5, V d ≥68; the third lens 3 satisfies the relationship: N d ≥1.6, V d ≥33; the fourth lens 5 satisfies the relationship: N d ≥1.5, V d ≥75; the fifth lens 6 satisfies the relationship: N d ≥1.9, V d ≥20; the sixth lens 7 satisfies the relationship: N d ≥1.6, V d ≥44; the seventh lens 8 satisfies the relationship: N d ≥1.8, V d≥25; the detector protection glass 9 satisfies the relationship: N d ≥1.5, V d ≥54; where N d is the refractive index, V d is the Abbe constant.

[0028] The imaging spectrum range of the optical system is between 450nm and 850nm.

[0029] The parameters of each lens in the long working distance visible light target detection optical system of this embodiment can be specifically set according to the actual imaging accuracy requirements. This embodiment provides a set of preferred parameters that can achieve high imaging accuracy, but is not limited to this embodiment.

[0030] The long working distance visible light target detection optical system provided in this embodiment has a field of view angle of 28°.

[0031] Figure 2 This is the modulation transfer function of the optical system provided by the present invention, wherein the abscissa represents the spatial modulation frequency, and the ordinate represents the optical modulation function. Figure 2 In the figure, (a) is the modulation transfer function of the optical system when the working distance is 60m. At the spatial modulation frequency of 91lp / mm, the modulation transfer function of each field of view is better than 0.36. (b) is the modulation transfer function of the optical system when the working distance is 50km. At the spatial modulation frequency of 91lp / mm, the modulation transfer function of each field of view is better than 0.35. The optical system has a strong resolution capability.

[0032] Figure 3 The spot diagram of the optical system provided by the present invention. Figure 3 In the figure, (a) is the optical system point diagram when the working distance is 60m, and the diffuse spot radius of each field angle is better than 5.3μm, (b) is the optical system point diagram when the working distance is 50km, and the diffuse spot radius of each field angle is better than 4.9μm.

[0033] Figure 4 The optical system field area and distortion diagram provided by the present invention. The arc field curvature and meridian field curvature are within the focal depth range, and the maximum distortion of the system is less than 0.32%.

[0034] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. Long working distance visible light target detection optical system, characterized by: The optical system comprises a first lens (1), a second lens (2), a third lens (3), an aperture (4), a fourth lens (5), a fifth lens (6), a sixth lens (7), a seventh lens (8), a detector protection glass (9) and a detector target surface (10) which are coaxially arranged in sequence; The incident light beam passes through the first lens (1), the second lens (2), the third lens (3), the aperture (4), the fourth lens (5), the fifth lens (6), the sixth lens (7), the seventh lens (8) and the detector protection glass (9) in sequence, and then forms an image on the detector target surface (10); The first lens (1) is a positive lens with a focal length of 65 to 75 mm; the second lens (2) is a positive lens with a focal length of 45 to 55 mm; the third lens (3) is a negative lens with a focal length of -23 to -13 mm; the fourth lens (5) is a positive lens with a focal length of 16 to 26 mm; the fifth lens (6) is a positive lens with a focal length of 150 to 160 mm; the sixth lens (7) is a positive lens with a focal length of 52 to 62 mm; the seventh lens (8) is a negative lens with a focal length of -25 to -15 mm; The first lens (1) satisfies the relationship: N d ≥1.4, V d ≥67; the second lens (2) satisfies the relationship: N d ≥1.5, V d ≥68; the third lens (3) satisfies the relationship: N d ≥1.6, V d ≥33; the fourth lens (5) satisfies the relationship: N d ≥1.5, V d ≥75; the fifth lens (6) satisfies the relationship: N d ≥1.9, V d ≥20; the sixth lens (7) satisfies the relationship: N d ≥1.6, V d ≥44; the seventh lens (8) satisfies the relationship: N d ≥1.8, V d ≥25; the detector protection glass (9) satisfies the relationship: N d ≥1.5, V d ≥54; where N d is the refractive index, V d is the Abbe constant.

2. The long working distance visible light target detection optical system according to claim 1, characterized in that: The center thickness of the first lens (1) is 2.9 to 4.9 mm; The central thickness of the second lens (2) is 2.6 to 4.6 mm; The central thickness of the third lens (3) is 2 to 4 mm; The center thickness of the fourth lens (5) is 3 to 5 mm; The central thickness of the fifth lens (6) is 2.8 to 4.8 mm; The central thickness of the sixth lens (7) is 2.2 to 4.2 mm; The central thickness of the seventh lens (8) is 1.9-3.9 mm.

3. The long working distance visible light target detection optical system according to claim 1, characterized in that: The distance between the first lens (1) and the second lens (2) is 0.3 to 0.8 mm; The distance between the second lens (2) and the third lens (3) is 1.3 to 3.3 mm; The distance between the third lens (3) and the aperture (4) is 2.8 to 4.8 mm; The distance between the aperture (4) and the fourth lens (5) is 0.5 to 2.5 mm; The distance between the fourth lens (5) and the fifth lens (6) is 1 to 3 mm; The distance between the fifth lens (6) and the sixth lens (7) is 2 to 4 mm; The distance between the sixth lens (7) and the seventh lens (8) is 1.8 to 3.8 mm; The distance between the seventh lens (8) and the detector protection glass (9) is 2 to 6 mm; The distance between the detector protection glass (9) and the detector target surface (10) is 0.5 to 1.5 mm.

4. The long working distance visible light target detection optical system according to claim 1, characterized in that: The pixel size of the detector target surface (10) is 5.5 μm.

5. The long working distance visible light target detection optical system according to claim 1, characterized in that: The imaging spectrum range of the optical system is between 450nm and 850nm.

6. The long working distance visible light target detection optical system according to claim 1, characterized in that: The optical system has a viewing angle of 28°.

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