Unmanned aerial vehicle detection lens

Abstract

An unmanned aerial vehicle detection lens comprises a front fixed group, a zoom group, a compensation group and a rear fixed group which are sequentially arranged from an object side to an image side along an optical axis, the front fixed group comprises a first lens and a second lens which are positive in focal power, and the zoom group comprises a third lens, a fourth lens and a fifth lens which are negative in focal power. The compensation group comprises a sixth lens with positive focal power; the rear fixing group comprises a seventh lens with positive focal power; the positions of the front fixing group and the rear fixing group relative to the image plane are fixed, and the distance of the zoom group relative to the front fixing group on the optical axis is adjustable.

Description

Technical Field

[0001] The invention relates to the technical field of optical technology, and in particular to a detection lens for an unmanned aerial vehicle. Background Art

[0002] With the rapid development of science and technology, drone technology, as an outstanding representative of modern science and technology, has penetrated into every aspect of our lives. From aerial photography to environmental monitoring, from agricultural plant protection to emergency rescue, drones are gradually changing our work and lifestyle with their unique flight capabilities and wide range of application scenarios. As an important part of the drone system, the design level and performance of the drone detection lens directly affect the overall function and efficiency of the drone.

[0003] As the "eyes" of drones, the design of detection lenses not only affects the drone's field of view and image clarity, but also involves target recognition, environmental perception, data collection and other aspects. With the continuous expansion of application scenarios, the performance requirements for drone detection lenses are getting higher and higher. In order to achieve better imaging quality standards, most detection lenses on the market use a large number of lenses, which leads to a series of problems such as heavy lens weight, large size and high production cost. Summary of the invention

[0004] In view of the shortcomings of the background technology, the purpose of the present invention is to provide a drone detection lens.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A drone detection lens comprises a front fixed group, a zoom group, a compensation group and a rear fixed group which are sequentially arranged along an optical axis from an object side to an image side, wherein the front fixed group comprises a first lens and a second lens with positive optical power, the zoom group comprises a third lens, a fourth lens and a fifth lens with negative optical power, the compensation group comprises a sixth lens with positive optical power, and the rear fixed group comprises a seventh lens with positive optical power; the positions of the front fixed group and the rear fixed group relative to the image plane are fixed, and the distance of the zoom group relative to the front fixed group on the optical axis is adjustable.

[0007] Furthermore, the first lens includes a first positive lens and a first negative lens, the front end of the first negative lens is glued to the rear end of the first positive lens, the incident surface of the first negative lens is concave, and the exit surface is convex; the incident surface of the first positive lens is convex, and the exit surface is convex.

[0008] Furthermore, the fourth lens includes a second positive lens and a second negative lens, the front end of the second positive lens is glued to the rear end of the second negative lens, the incident surface of the second negative lens is concave, and the exit surface is concave; the incident surface of the second positive lens is convex, and the exit surface is a plane.

[0009] Furthermore, the fifth lens includes a third positive lens and a third negative lens, the front end of the third negative lens is glued to the rear end of the third positive lens, the incident surface of the third negative lens is concave, and the exit surface is convex; the incident surface of the third positive lens is convex, and the exit surface is convex.

[0010] Furthermore, the sixth lens includes a fourth negative lens and a fifth negative lens, the front end of the fifth negative lens is glued to the rear end of the fourth negative lens, the incident surface of the fourth negative lens is convex, and the exit surface is concave; the incident surface of the fifth negative lens is convex, and the exit surface is concave.

[0011] Furthermore, the seventh lens includes a fourth positive lens and a sixth negative lens, the front end of the sixth negative lens is glued to the rear end of the fourth positive lens, the incident surface of the sixth negative lens is concave, and the exit surface is a plane; the incident surface of the fourth positive lens is convex, and the exit surface is convex.

[0012] Furthermore, the second lens is a lens with a convex incident surface and a flat exit surface, and the third lens is a meniscus lens with a convex surface facing the object side and a concave surface facing the image side.

[0013] Furthermore, it also includes a filter, which is arranged on the image side.

[0014] Furthermore, the zoom group performs linear motion on the optical axis along opposite directions or opposite directions, so that the lens switches between a short-focus state, a medium-focus state and a long-focus state.

[0015] Furthermore, the three lens groups of the zoom group, the compensation group and the front lens group of the rear fixed group all need to achieve relative movement through a zoom cam.

[0016] The beneficial effects of the present invention are:

[0017] 1. The drone detection lens proposed in the present invention selects and arranges twelve lenses, so that the present invention can achieve zooming and continuous zooming of a fixed-focus lens with fewer lenses. Since the number of lenses is reduced and the lens length is shortened, the lens structure of the present invention is compact, the imaging effect is good, and it is easy to adjust and assemble.

[0018] 2. The drone detection lens proposed in the present invention realizes continuous zooming of a fixed-focus lens through twelve lenses. Especially for large-aperture, long-focal-length, long-distance monitoring, it can solve the contradiction between the narrow field of view of a fixed-focus lens and the high price of a large-aperture, long-focal-length zoom lens, thereby expanding the monitoring distance and saving costs.

[0019] 3. The drone detection lens proposed in the present invention effectively filters out stray light in non-working bands by setting filters to reduce optical noise, thereby improving imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A short-focus optical path diagram of a drone detection lens of the present invention;

[0022] Figure 2 A mid-focus optical path diagram of a drone detection lens of the present invention;

[0023] Figure 3 A telephoto optical path diagram of a drone detection lens of the present invention;

[0024] Figure 4 A short focal length diagram of a drone detection lens of the present invention;

[0025] Figure 5 A center focus diagram of a drone detection lens of the present invention;

[0026] Figure 6 A long focal length diagram of a drone detection lens of the present invention;

[0027] Figure 7 It is a short-focus MTF curve diagram of a drone detection lens of the present invention;

[0028] Figure 8 A mid-focus MTF curve diagram of a drone detection lens of the present invention;

[0029] Fig. 9 A telephoto MTF curve diagram of a drone detection lens of the present invention;

[0030] Fig.10 It is a short-focus distortion diagram of a drone detection lens of the present invention;

[0031] Fig.11A mid-focus distortion diagram of a drone detection lens of the present invention;

[0032] Fig.12 This is a telephoto distortion diagram of a drone detection lens of the present invention.

[0033] In the figure, 101 is a first positive lens; 102 is a first negative lens; 103 is a second lens; 201 is a third lens; 202 is a second positive lens; 203 is a second negative lens; 301 is a third positive lens; 302 is a third negative lens; 401 is a fourth negative lens; 402 is a fifth negative lens; 403 is a fourth positive lens; and 404 is a sixth negative lens. DETAILED DESCRIPTION

[0034] Combine the following Figure 1-12 The present invention is described in detail.

[0035] A drone detection lens, such as Figure 1-3 As shown, it includes a front fixed group, a zoom group, a compensation group and a rear fixed group which are arranged in sequence from the object side to the image side along the optical axis, the front fixed group includes a first lens and a second lens 103 with positive optical focal length, the zoom group includes a third lens 201, a fourth lens and a fifth lens with negative optical focal length, the compensation group includes a sixth lens with positive optical focal length, and the rear fixed group includes a seventh lens with positive optical focal length; the positions of the front fixed group and the rear fixed group relative to the image plane are fixed, and the distance of the zoom group relative to the front fixed group on the optical axis is adjustable.

[0036] Table 1 shows a basic parameter table of an infrared continuous zoom lens 100 according to an exemplary embodiment of the present application, wherein the units of the curvature radius, the spacing and the aperture are all millimeters (mm).

[0037] Table 1-Parameters

[0038]

[0039]

[0040] After optimizing the system structure and image quality, the final structure is shown in the figure below. The lens contains 0 aspherical lenses and 12 glass spherical lenses, with a total length of 117mm and a back focus of 8.543mm. The glass is all domestic spherical glass, and the ambient temperature is 20℃; the focal lengths of the short-focus structure, medium-focus structure, and long-focus structure are 7.598mm, 38.769mm, and 76.984mm respectively.

[0041] The working wavelength range of the lens is 0.4μm to 0.8μm. The front fixed group has positive focal power. The first lens and the second lens 103 can provide sufficient working distance and balance the aberration before the rear fixed group, reducing the correction pressure of the rear fixed group. The zoom group has negative focal power, and the purpose of changing the magnification is achieved by moving the third lens 201, the fourth lens and the fifth lens. The compensation group used to compensate for the movement of the phase plane is composed of the fifth lens and has positive focal power. The rear fixed group is composed of the sixth lens and the seventh lens and has positive focal power.

[0042] In this embodiment, the first lens includes a first positive lens 101 and a first negative lens 102, the front end of the first negative lens 102 is glued to the rear end of the first positive lens 101, the incident surface of the first negative lens 102 is a concave surface, and the exit surface is a convex surface; the incident surface of the first positive lens 101 is a convex surface, and the exit surface is a convex surface.

[0043] In this embodiment, the fourth lens includes a second positive lens 202 and a second negative lens 203, the front end of the second positive lens 202 is glued to the rear end of the second negative lens 203, the incident surface of the second negative lens 203 is concave, and the exit surface is concave; the incident surface of the second positive lens 202 is convex, and the exit surface is a plane.

[0044] In this embodiment, the fifth lens includes a third positive lens 301 and a third negative lens 302, the front end of the third negative lens 302 is glued to the rear end of the third positive lens 301, the incident surface of the third negative lens 302 is concave, and the exit surface is convex; the incident surface of the third positive lens 301 is convex, and the exit surface is convex.

[0045] Furthermore, the sixth lens includes a fourth negative lens 401 and a fifth negative lens 402, the front end of the fifth negative lens 402 is glued to the rear end of the fourth negative lens 401, the incident surface of the fourth negative lens 401 is convex, and the exit surface is concave; the incident surface of the fifth negative lens 402 is convex, and the exit surface is concave.

[0046] In this embodiment, the seventh lens includes a fourth positive lens 403 and a sixth negative lens 404. The front end of the sixth negative lens 404 is glued to the rear end of the fourth positive lens 403. The incident surface of the sixth negative lens 404 is a concave surface, and the exit surface is a plane. The incident surface of the fourth positive lens 403 is a convex surface, and the exit surface is a convex surface. The working wavelength range is 0.4μm to 0.8μm. The wavelength range is relatively long, and the chromatic aberration will be relatively large. Therefore, the first lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens use double glued lenses to reduce chromatic aberration.

[0047] In this embodiment, the second lens 103 is a lens with a convex incident surface and a flat exit surface, and the third lens 201 is a meniscus lens with a convex surface facing the object side and a concave surface facing the image side.

[0048] In this embodiment, a filter is also included, and the filter is arranged on the image side. Stray light not only affects the imaging quality and measurement accuracy, but also reduces the contrast and image quality. Arranging a filter on the image side of the lens system can effectively filter out stray light in non-working bands to reduce optical noise, thereby improving imaging quality.

[0049] In this embodiment, the zoom group performs linear motion along the optical axis in the opposite directions or the opposite directions, so that the infrared continuous zoom lens is switched between the short-focus state, the medium-focus state and the long-focus state.

[0050] In this embodiment, the three lens groups of the zoom group, the compensation group and the front lens group of the rear fixed group all need to achieve relative movement through the zoom cam.

[0051] like Figure 4-6 As shown in the figure, the central field of view of the telephoto lens has the best imaging, and the diffuse spot diameter is only 5.24um, which is close to the pixel size of the sensor of 3.45um. The diffuse spot diameter of the central field of view of the short and medium focal lengths is about 8um, which is close to the pixel size of the two sensors, and the imaging quality is very good. From the perspective of the diffuse spot size, the imaging of the medium focal length is the best, and the diffuse spot size of each field of view is consistent, all below 9um, which is close to the pixel size of the two sensors. The imaging quality of the short focal length is slightly worse, and the diffuse spot diameter of the full field of view is 20um, which meets the conditions for clear imaging.

[0052] like Figure 7-Figure 9 As shown in Table 2, the MTF curves of the zoom lens in the three states of short focus, medium focus and long focus can be obtained by ZEMAX simulation. The MTF curves of different fields of view are compactly clustered, indicating that the imaging quality of the entire field of view is consistent. It can be obtained that a large mid-frequency MTF value indicates a good sense of imaging layering, and a large high-frequency MTF value indicates high resolution, good sharpness, and small details that can be distinguished. At a spatial frequency of 201p / mm, MTF>0.80, and at a spatial frequency of 50lp / mm, MTF>0.3. The table shows that at three focal lengths, the minimum MTF in the 0-0.8 field of view is 0.56. Therefore, the system can present good images at short, medium and long focal lengths.

[0053] Table 2 - MTF values ​​for different fields of view

[0054]

[0055] Depend on Figure 10-12As shown, the maximum distortion of the short-focus group and the medium-focus group is around 0.9%, which meets the requirement of less than 1%. The maximum distortion of the long-focus group is only 0.4%, the imaging deformation is small, the imaging is stable, and the imaging requirements of the system for zoom lenses are met.

[0056] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A drone detection lens, characterized in that: The optical lens comprises a front fixed group, a zoom group, a compensation group and a rear fixed group which are arranged in sequence from the object side to the image side along the optical axis, wherein the front fixed group comprises a first lens and a second lens with positive optical power, the zoom group comprises a third lens and a fourth lens with negative optical power, the compensation group comprises a fifth lens with positive optical power, and the rear fixed group comprises a sixth lens and a seventh lens with positive optical power; the positions of the front fixed group and the rear fixed group relative to the image plane are fixed, and the distance of the zoom group relative to the front fixed group on the optical axis is adjustable.

2. The drone detection lens according to claim 1, characterized in that: The first lens includes a first positive lens and a first negative lens, the front end of the first negative lens is glued to the rear end of the first positive lens, the incident surface of the first negative lens is concave, and the exit surface is convex; the incident surface of the first positive lens is convex, and the exit surface is convex.

3. The drone detection lens according to claim 1, characterized in that: The fourth lens includes a second positive lens and a second negative lens, the front end of the second positive lens is glued to the rear end of the second negative lens, the incident surface of the second negative lens is concave, and the exit surface is concave; the incident surface of the second positive lens is convex, and the exit surface is a plane.

4. The drone detection lens according to claim 1, characterized in that: The fifth lens includes a third positive lens and a third negative lens, the front end of the third negative lens is glued to the rear end of the third positive lens, the incident surface of the third negative lens is concave, and the exit surface is convex; the incident surface of the third positive lens is convex, and the exit surface is convex.

5. The drone detection lens according to claim 1, characterized in that: The sixth lens includes a fourth negative lens and a fifth negative lens, the front end of the fifth negative lens is glued to the rear end of the fourth negative lens, the incident surface of the fourth negative lens is convex, and the exit surface is concave; the incident surface of the fifth negative lens is convex, and the exit surface is concave.

6. The drone detection lens according to claim 1, characterized in that: The seventh lens includes a fourth positive lens and a sixth negative lens, the front end of the sixth negative lens is glued to the rear end of the fourth positive lens, the incident surface of the sixth negative lens is a concave surface, and the exit surface is a plane; the incident surface of the fourth positive lens is a convex surface, and the exit surface is a convex surface.

7. The drone detection lens according to claim 1, characterized in that: The second lens is a lens with a convex incident surface and a flat exit surface, and the third lens is a meniscus lens with a convex surface facing the object side and a concave surface facing the image side.

8. The drone detection lens according to claim 1, characterized in that: Also included is a filter, which is arranged on the image side.

9. The drone detection lens according to claim 1, characterized in that: The zoom group performs linear motion along the optical axis in the opposite directions or the opposite directions, so that the lens switches between the short-focus state, the medium-focus state and the long-focus state.

10. The drone detection lens according to claim 1, characterized in that: The three lens groups, namely the zoom group, the compensation group and the front lens group of the rear fixed group, all need to achieve relative movement through the zoom cam.

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