Near-infrared light lens with 40-degree field of view for low-altitude aerial photography

Abstract

The utility model discloses a 40-degree view field near-infrared light lens for low-altitude aerial photography, and belongs to the technical field of optical lenses. The near-infrared light lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from an object side to an image side, the second lens has positive focal power, and the second lens and the first lens are arranged at an interval; the third lens has positive focal power, and the third lens and the second lens are arranged at an interval; the fourth lens has positive focal power, and the fourth lens and the third lens are arranged at an interval; the diaphragm and the fourth lens are arranged at an interval and the diaphragm is used for limiting the aperture of the light beam; the fifth lens has negative focal power, and the fifth lens and the diaphragm are arranged at an interval; the sixth lens has negative power, and the sixth lens and the fifth lens are arranged at an interval; the seventh lens has negative focal power, and the seventh lens and the sixth lens are arranged at an interval; and the eighth lens has negative focal power, and the eighth lens and the seventh lens are arranged at an interval. The lens is simple in structure, high in imaging transfer function and low in distortion, and the field of view is fixed below 40 degrees.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical lenses, and specifically relates to a near-infrared light lens for low-altitude aerial photography, which is especially suitable for the field of low-altitude aerial mapping and reconnaissance of unmanned aerial vehicles, and can realize low-distortion aerial imaging under a 40° field of view. Background Art

[0002] The aviation field requires that the lens can clearly image ground targets at high altitudes, with constantly changing parameters such as ambient temperature and atmospheric pressure. When drones are used, the aerial photography lenses used by drones have strict requirements on imaging distortion, imaging transfer function and weight. In addition, drones should be able to adapt to all-weather imaging under complex climatic conditions, and can achieve consistent imaging in daytime, darkness, fog or rain, which directly affects the widespread use of drones.

[0003] At present, the optical design of aerial photography lenses cannot meet actual needs, the lens standardization is low, it cannot adapt to different weather conditions, and the imaging quality of the lens is poor. Compared with ordinary near-infrared lenses, due to the particularity of aerial ground shooting, when the field of view is larger, more stringent requirements are put forward for imaging indicators such as resolution, brightness and distortion. The existing security monitoring lenses cannot fully cover the requirements of aerial mapping lenses, especially near-infrared lenses, which greatly increases the limitations of drone aerial mapping and reconnaissance. Utility Model Content

[0004] In view of this, the purpose of the utility model is to provide a near-infrared aerial imaging lens with a 40° field of view. The lens has a simple structure, a fixed field of view of 40°, a high imaging transfer function and low distortion. Since its field of view is fixed at 40°, it can be disassembled and assembled on the drone at any time according to weather conditions as a standard lens. When there is foggy weather or other conditions suitable for near-infrared spectral imaging, the near-infrared lens is assembled. The maximum distortion of the near-infrared lens is <3%, the full field of view transfer function MTF>0.5@50lp / mm, and the full field of view MTF>0.5@50lp / mm. Compared with traditional lenses, the optical parameters are greatly improved at a 40° field of view, which is suitable for large-scale aerial ground search imaging.

[0005] In order to achieve the above purpose, the following technical solutions are adopted:

[0006] The utility model provides a near-infrared lens with a 40° field of view for low-altitude aerial photography, including the following components arranged in sequence from the object side to the image side:

[0007] A first lens having positive optical power;

[0008] a second lens having positive optical power and spaced apart from the first lens;

[0009] a third lens having positive refractive power and spaced apart from the second lens;

[0010] a fourth lens having positive refractive power and spaced apart from the third lens;

[0011] an aperture, which is spaced apart from the fourth lens and is used to limit the beam aperture;

[0012] A fifth lens having negative optical power and spaced apart from the aperture stop;

[0013] a sixth lens having negative focal power and spaced apart from the fifth lens;

[0014] a seventh lens having negative optical power and spaced apart from the sixth lens;

[0015] The eighth lens has negative optical power and is spaced apart from the seventh lens.

[0016] Furthermore,

[0017] The first lens has a concave surface facing the image side and a convex surface facing the object side;

[0018] The second lens has a concave surface facing the image side and a convex surface facing the object side;

[0019] The third lens is a biconvex lens;

[0020] The fourth lens has a concave surface facing the image side and a convex surface facing the object side;

[0021] The fifth lens is a biconvex lens;

[0022] The sixth lens is a biconcave lens;

[0023] The seventh lens is a biconvex lens;

[0024] The eighth lens has a concave surface facing the image side and a convex surface facing the object side.

[0025] Furthermore, the material of the first lens is H-ZLAF4LA, the thickness is 4 mm, and the curvature radii of the front and rear surfaces of the first lens are 32.91 mm and 18.76 mm, respectively.

[0026] Furthermore, the material of the second lens is H-FK71, the distance between the second lens and the first lens is 4.44 mm, the thickness is 2 mm, and the curvature radii of the front and rear surfaces of the second lens are 107.11 mm and 21.62 mm respectively.

[0027] Furthermore, the material of the third lens is H-ZLAF68C, the distance between the third lens and the second lens is 29.72 mm, the thickness is 4.2 mm, and the curvature radii of the front and rear surfaces of the third lens are 67.09 mm and -89.24 mm respectively.

[0028] Furthermore, the material of the fourth lens is H-ZLAF53B, the distance between the fourth lens and the third lens is 11.83 mm, the thickness is 3 mm, and the curvature radii of the front and rear surfaces of the fourth lens are 13.89 mm and 13.30 mm respectively.

[0029] Furthermore, the distance between the aperture stop and the fourth lens is 3.88 mm, and the distance between the aperture stop and the fifth lens is 0.2 mm.

[0030] Furthermore, the material of the fifth lens is H-ZLAF68C, the thickness is 3.6 mm, and the curvature radii of the front and rear surfaces of the fifth lens are 21.59 mm and -86.90 mm respectively.

[0031] Furthermore, the sixth lens is made of H-ZF88, has a distance of 1.63 mm from the fifth lens, a thickness of 1.8 mm, and curvature radii of the front and rear surfaces of the sixth lens are -33.82 mm and 14.19 mm, respectively.

[0032] Furthermore, the seventh lens is made of H-FK71, the distance between the seventh lens and the sixth lens is 1.40 mm, the thickness is 5.3 mm, and the curvature radii of the front and rear surfaces of the seventh lens are 17.05 mm and -28.12 mm respectively.

[0033] Furthermore, the material of the eighth lens is H-ZF88, the distance between the eighth lens and the seventh lens is 0.24 mm, the thickness is 4.2 mm, and the curvature radii of the front and rear surfaces of the eighth lens are 35.10 mm and 76.03 mm respectively.

[0034] The 40° field of view near-infrared light lens for low-altitude aerial photography of the utility model can also include a lens barrel. There is no special restriction on the lens barrel, and it can fix the above-mentioned first lens, second lens, third lens, fourth lens, aperture, fifth lens, sixth lens, seventh lens and eighth lens.

[0035] Compared with the prior art, the beneficial effects of the utility model are:

[0036] The utility model uses a 40° field of view near-infrared lens for low-altitude aerial photography, which can realize near-infrared imaging in the band of 1.36μm to 2.08μm, has good transmittance, and can clearly image in bad weather such as rain and fog. It has a simple structure, a fixed viewing angle of 40°, and a greatly improved lens transfer function, with a full-field transfer function MTF>0.5@50lp / mm, reduced distortion, and a full-field maximum distortion of <3%. It meets the large-field imaging requirements of aerial ground observation and aerial mapping in complex and bad weather. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 This is a schematic diagram of the structure of a 40° field of view near-infrared light lens for low-altitude aerial photography of the utility model;

[0039] In the figure, 1 is the first lens, 2 is the second lens, 3 is the third lens, 4 is the fourth lens, 5 is the aperture, 6 is the fifth lens, 7 is the sixth lens, 8 is the seventh lens, and 9 is the eighth lens.

[0040] Figure 2 This is the full-field MTF diagram of the near-infrared light lens in Example 1 of the utility model;

[0041] Figure 3 This is the maximum distortion diagram of the entire field of view of the near-infrared light lens in Example 1 of the utility model;

[0042] Figure 4 The uniformity of illumination over the entire field of view of the near-infrared light lens in Example 1 of the utility model;

[0043] Figure 5 This is a full-field spot diagram of the near-infrared light lens in Example 1 of the utility model. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0045] Example 1

[0046] The technical indicators of the optical lens are as follows: size: φ27×100mm; wavelength 1.36μm~2.08μm; back working distance: 18.56mm; maximum aperture of the lens: φ27mm; full field MTF>0.5@50lp / mm, full field maximum distortion <3%; illumination full field uniformity better than 90%; full field point diagram RMS radius ≤7.5μm;

[0047] Based on the above technical indicators, the designed optical lens, such as Figure 1 As shown, the parameters of each optical element (radius, curvature, thickness, spacing, material, etc.) are shown in Table 1.

[0048] Table 1 Parameters of the optical elements of the optical lens of Example 1

[0049]

[0050] After testing, the full-field MTF of the optical lens of Example 1 is as follows: Figure 2 As shown, the maximum distortion of the entire field of view is Figure 3 As shown, the uniformity of illumination over the entire field of view is as follows Figure 4 As shown, the full field point diagram is as follows Figure 5 It can be seen that the optical lens of Example 1 has a high imaging transfer function, low distortion, good imaging clarity, good uniformity, and strong anti-interference ability.

[0051] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention of the utility model.

Claims

1. 40° field of view near-infrared lens for low-altitude aerial photography, characterized by: Including the following arranged from the object side to the image side: A first lens (1) having positive optical power; a second lens (2) having positive optical power and spaced apart from the first lens (1); a third lens (3) having positive optical power and spaced apart from the second lens (2); a fourth lens (4) having positive refractive power and spaced apart from the third lens (3); An aperture (5) which is spaced apart from the fourth lens (4) and is used to limit the aperture of the light beam; a fifth lens (6) having negative optical power and spaced apart from the aperture stop (5); a sixth lens (7) having negative focal power and spaced apart from the fifth lens (6); a seventh lens (8) having negative optical power and spaced apart from the sixth lens (7); The eighth lens (9) has negative optical power and is spaced apart from the seventh lens (8).

2. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The first lens (1) has a concave surface facing the image side and a convex surface facing the object side; The second lens (2) has a concave surface facing the image side and a convex surface facing the object side; The third lens (3) is a biconvex lens; The fourth lens (4) has a concave surface facing the image side and a convex surface facing the object side; The fifth lens (6) is a biconvex lens; The sixth lens (7) is a biconcave lens; The seventh lens (8) is a biconvex lens; The eighth lens (9) has a concave surface facing the image side and a convex surface facing the object side.

3. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The material of the first lens (1) is H-ZLAF4LA, with a thickness of 4 mm. The curvature radii of the front and rear surfaces of the first lens (1) are 32.91 mm and 18.76 mm respectively.

4. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The material of the second lens (2) is H-FK71, the distance between the second lens (2) and the first lens (1) is 4.44 mm, the thickness is 2 mm, and the curvature radii of the front and rear surfaces of the second lens (2) are 107.11 mm and 21.62 mm respectively.

5. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The material of the third lens (3) is H-ZLAF68C, the distance between the third lens (3) and the second lens (2) is 29.72 mm, the thickness is 4.2 mm, and the curvature radii of the front and rear surfaces of the third lens (3) are 67.09 mm and -89.24 mm respectively.

6. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The fourth lens (4) is made of H-ZLAF53B, has a distance of 11.83 mm from the third lens (3), a thickness of 3 mm, and a curvature radius of the front and rear surfaces of the fourth lens (4) of 13.89 mm and 13.30 mm respectively.

7. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The distance between the aperture (5) and the fourth lens (4) is 3.88 mm, and the distance between the aperture (5) and the fifth lens (6) is 0.2 mm; The material of the fifth lens (6) is H-ZLAF68C, with a thickness of 3.6 mm. The curvature radii of the front and rear surfaces of the fifth lens (6) are 21.59 mm and -86.90 mm respectively.

8. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The sixth lens (7) is made of H-ZF88, has a distance of 1.63 mm from the fifth lens (6), a thickness of 1.8 mm, and a curvature radius of the front and rear surfaces of the sixth lens (7) of -33.82 mm and 14.19 mm respectively.

9. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The seventh lens (8) is made of H-FK71, has a distance of 1.40 mm from the sixth lens (7), a thickness of 5.3 mm, and a curvature radius of the front and rear surfaces of the seventh lens (8) of 17.05 mm and -28.12 mm, respectively.

10. The 40° field of view near-infrared lens for low-altitude aerial photography according to claim 1, characterized in that: The eighth lens (9) is made of H-ZF88, has a distance of 0.24 mm from the seventh lens (8), a thickness of 4.2 mm, and a curvature radius of the front and rear surfaces of the eighth lens (9) of 35.10 mm and 76.03 mm respectively.

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