Optical lenses and lidar

Abstract

This application provides an optical lens and a lidar, relating to the field of radar technology. The optical lens includes a first lens, a second lens, and a third lens arranged sequentially from the object side to the image side along the optical axis. The first lens has positive optical power; the second lens has positive optical power, with its object side being convex and its image side being concave; the third lens has negative optical power, with one of its object side and image side being concave and the other being either concave or flat. The total optical length (TTL) of the optical lens and its effective focal length (f) satisfy: 0.4 ≤ TTL / f ≤ 0.45. This optical lens can achieve a long focal length while being miniaturized. It also helps reduce distortion and maintain consistency in radar resolution and range. The lidar of this application includes the above-mentioned optical lens, which is easily miniaturized and has better detection performance.

Description

Technical Field

[0001] This application relates to the field of radar technology, and more specifically, to an optical lens and a lidar. Background Technology

[0002] LiDAR, as an information sensing unit, is widely used in industrial sensing and autonomous driving. Its principle is that the radar emits one or more laser beams and receives the reflected laser signals to achieve detection. LiDAR mainly consists of a transmitting module, a receiving module, a scanning module, and a signal processing module. The transmitting module emits the detection laser, the receiving module receives the echo signal, the scanning module expands the radar's detection angle, and the signal processing module converts the received signal into environmental information. If the receiving detector is an array composed of multiple detector units, the distortion of the receiving lens needs to be minimized to maintain the consistency of the receiving system's resolution. The resolution of the radar is related to the focal length of the receiving lens; the longer the focal length, the higher the resolution.

[0003] However, telephoto lenses are often large in size, and existing lidar receiving lenses are difficult to miniaturize while meeting the requirements of long focal length and low distortion. Summary of the Invention

[0004] The purpose of this application is to provide an optical lens and a lidar that can meet the requirements of miniaturization, long focal length, and low distortion. The lidar is small in size, has high resolution, and good detection performance.

[0005] The embodiments of this application can be implemented as follows:

[0006] In a first aspect, this application provides an optical lens, comprising: arranged sequentially from the object side to the image side along the optical axis:

[0007] The first lens has positive optical power;

[0008] The second lens has positive optical power, and the object side of the second lens is convex, while the image side is concave.

[0009] The third lens has negative optical power, and one of the object side and the image side of the third lens is concave, while the other is either concave or flat.

[0010] Among them, the total optical length TTL of the optical lens and the effective focal length f satisfy: 0.4≤TTL / f≤0.45.

[0011] The optical lens provided in this application can be used as a receiving lens for a lidar system. By selecting the optical power of each lens, choosing the shapes of the second and third lenses, and controlling the relationship between the total optical length (TTL) and the effective focal length (f), the optical lens can achieve a long focal length while remaining miniaturized, which is beneficial for improving its resolution as a lidar system. Furthermore, this optical lens helps reduce distortion and maintain consistency in radar resolution and range. By combining the positive and negative optical powers of each lens, aberrations can be reduced, the incident angle of the principal ray on the image plane of the optical lens can be decreased, and the signal-to-noise ratio of the echo signal can be increased.

[0012] In an optional embodiment, the object-side surface of the first lens is convex, and the image-side surface is concave. Setting the first lens as a meniscus lens with a convex object-side surface and a concave image-side surface is beneficial for reducing the lens length while ensuring smaller distortion and higher resolution.

[0013] In an optional implementation, the focal length f1 of the first lens, the focal length f2 of the second lens, and the focal length f3 of the third lens satisfy the following relationship with the effective focal length f of the optical lens:

[0014] f1 / f≤0.43, f2 / f≤0.49, |f3 / f|≥0.049.

[0015] By designing the focal length of each lens and the effective focal length of the optical lens to satisfy the above relationship, the total optical length of the optical lens can be effectively controlled, achieving the goal of miniaturization of the device; and ensuring that the optics have a small distortion, thereby improving the detection capability of the lidar.

[0016] In an optional implementation, the maximum field of view (FOV) of the optical lens satisfies: 1.6° ≤ FOV ≤ 2.2°. When the optical lens is applied to lidar, a relatively small field of view can improve the lidar's resolution, and the laser can output high-quality, high-density point clouds, ensuring the lidar's detection accuracy.

[0017] In an optional implementation, the principal ray incident angle CRA of the optical lens image plane satisfies: CRA ≤ 8.5°. Controlling the principal ray incident angle CRA within a small range reduces the center wavelength shift of the narrowband filter, keeps the bandwidth within a small range, which is beneficial for ambient light suppression, thereby improving the signal-to-noise ratio of the received signal.

[0018] In an optional embodiment, the radius of curvature of the object side of the first lens is 30-35 mm, and the radius of curvature of the image side of the first lens is 650-750 mm.

[0019] And / or, the radius of curvature of the object side of the second lens is 15-20 mm, and the radius of curvature of the image side of the second lens is 20-30 mm;

[0020] And / or, the radius of curvature of the object side of the third lens is -20 to -30 mm, and the radius of curvature of the image side of the third lens is 5 to 10 mm.

[0021] By rationally designing the curvature radii of the object-side and image-side surfaces of each lens, imaging quality can be improved and distortion reduced; it also helps to reduce lens length and achieve device miniaturization.

[0022] In an optional embodiment, a window glass is also included, which is disposed on the image side of the third lens. The window glass can prevent foreign objects from entering the optical lens and affecting its operation; it can also protect the photosensitive surface of the receiving chip from dust and dirt, preventing the radar detection capability from being reduced due to dirt on the photosensitive surface.

[0023] In an optional embodiment, a narrowband filter is also included, disposed between the third lens and the window glass. The narrowband filter can filter the wavelength of the received light, suppressing the energy of light of other wavelengths except for the laser band emitted by the lidar, thereby improving the signal-to-noise ratio.

[0024] In an optional embodiment, the thickness of the first lens at the optical axis position is 4 to 6 mm;

[0025] And / or, the thickness of the second lens is 7–9 mm;

[0026] And / or, the thickness of the third lens is 1.5–2.5 mm;

[0027] And / or, the thickness of the narrowband filter is 0.2–0.5 mm;

[0028] And / or, the thickness of the window glass is 0.3 to 0.6 mm.

[0029] By rationally selecting the thickness of each lens, narrowband filter, and window glass, the device can be miniaturized while ensuring image quality.

[0030] In an optional embodiment, the distance between the first lens and the second lens at the optical axis position is 0.4 to 0.6 mm;

[0031] And / or, the distance between the second lens and the third lens is 13 to 16 mm;

[0032] And / or, the distance between the third lens and the narrowband filter is 2.5–3.5 mm;

[0033] And / or, the distance between the narrowband filter and the window glass is 18–22 mm;

[0034] And / or, the distance between the window glass and the image plane of the optical lens is 0.3 to 0.5 mm.

[0035] By rationally selecting the spacing of each lens, narrowband filter, and window glass, the device can be miniaturized while ensuring image quality.

[0036] In an optional embodiment, an aperture stop is also included, which is disposed on the object-side surface of the first lens. Disposing of the aperture stop on the object-side surface of the first lens helps to concentrate all the light incident on the optical lens onto the receiving chip, maximizing the receiving aperture, increasing the received echo signal energy, and improving the detection capability of the lidar.

[0037] In an optional implementation, the aperture value of the optical lens is 4.5 ≤ F ≤ 5.9. By setting a larger aperture value F (i.e., a smaller aperture), the depth of focus of the optical lens can be increased, the sensitivity of the distance between the receiver chip and the optical lens can be reduced, and the difficulty of assembling and adjusting the optical lens can be reduced.

[0038] In an optional implementation, the first lens, the second lens, and the third lens are all spherical lenses. Using spherical lenses meets performance requirements and also helps reduce manufacturing costs.

[0039] In an optional embodiment, the refractive index of the first lens is 1.45–1.65, and the refractive indices of the second and third lenses are 1.68–1.96. By rationally selecting the refractive indices of each lens and designing the shape and size of each lens appropriately, it is beneficial to improve the imaging quality of the optical lens and to miniaturize the device.

[0040] In an optional implementation, the Abbe numbers of the first lens, the second lens, and the third lens decrease sequentially.

[0041] In an optional embodiment, the Abbe number of the first lens is 60 to 70, the Abbe number of the second lens is 50 to 60, and the Abbe number of the third lens is 15 to 25.

[0042] By appropriately selecting the Abbe number of each lens, it is beneficial to improve the imaging quality of the lens and enhance the detection performance of the lidar.

[0043] Secondly, this application provides a lidar including an optical lens as provided in any of the implementations of the first aspect. Because it is equipped with the aforementioned optical lens, the lidar is easily miniaturized and has better detection performance. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of an optical lens in one embodiment of this application;

[0046] Figure 2 This is an F-Theta distortion curve of an optical lens in one embodiment of this application;

[0047] Figure 3 This is a relative illumination curve of an optical lens in one embodiment of this application.

[0048] Icons: 100 - Optical lens; 110 - First lens; 120 - Second lens; 130 - Third lens; 140 - Narrowband filter; 150 - Window glass. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0050] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0051] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0052] In the description of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0053] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0054] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0055] The resolution of a lidar system is related to the focal length of its receiving lens; a longer focal length results in higher resolution. However, telephoto lenses are often mechanically larger, hindering lidar miniaturization. Furthermore, to increase the lidar's detection capability, the receiving lens needs to receive more reflected laser signals emitted by the radar while minimizing the reception of other environmental stray signals such as sunlight. To suppress ambient light and improve the radar's signal-to-noise ratio, a narrowband filter is required in the receiving lens. The passband bandwidth of the narrowband filter determines the effectiveness of ambient light suppression; a narrower bandwidth results in better suppression. The center wavelength of the filter is related to the chief ray angle (CRA). A larger CRA leads to a greater shift in the filter's center wavelength, resulting in a wider bandwidth and reduced ambient light suppression. Therefore, the receiving lens design needs to reduce the CRA for better ambient light suppression. Additionally, if the lidar's receiving detector is an array composed of multiple detector units, the distortion of the receiving lens needs to be minimized to maintain consistent system resolution. Meanwhile, in order to ensure that the detection capability is the same for different fields of view, the relative illumination of the receiving system's image plane must be high.

[0056] However, the receiving lenses used in related LiDAR technologies often struggle to achieve long focal lengths, low distortion, and low CRA (Cost Reduction Aspect Ratio) while being miniaturized. This makes it difficult for the receiving lenses to achieve optimal performance during miniaturization, thus affecting the detection effectiveness of the LiDAR.

[0057] Therefore, this application provides an optical lens and a lidar including the optical lens. This achieves a balance between device miniaturization and related performance.

[0058] Figure 1 This is a schematic diagram of an optical lens 100 in one embodiment of this application. Figure 1 As shown, the optical lens 100 provided in this embodiment can be applied to lidar as a receiving lens. The optical lens 100 of this embodiment includes a section extending along the optical axis (dashed line L in the figure) from the object side to the image side (i.e.,...). Figure 1The optical lens 100 comprises a first lens 110, a second lens 120, and a third lens 130 arranged sequentially from left to right. It may also include a narrowband filter 140 and a window glass 150 arranged sequentially from the object side to the image side along the optical axis (dashed line L in the figure). The first lens 110 has positive optical power, the second lens 120 has positive optical power, and the third lens 130 has negative optical power. The total optical length TTL of the optical lens 100 satisfies the condition: 0.4 ≤ TTL / f ≤ 0.45. The total optical length TTL of the optical lens 100 is the distance from the object side of the first lens 110 to the image side of the optical lens 100. The optical lens 100 of this embodiment can effectively shorten its total optical length, achieving the goal of device miniaturization.

[0059] exist Figure 1 In the illustrated embodiment, the object-side surface of the first lens 110 is convex, and the image-side surface is concave; the object-side surface of the second lens 120 is convex, and the image-side surface is concave; both the object-side and image-side surfaces of the third lens 130 are concave. In other optional embodiments, both the object-side and image-side surfaces of the first lens 110 may be convex, or one of them may be convex and the other may be planar. In other optional embodiments, one of the object-side and image-side surfaces of the third lens 130 may be concave, and the other may be planar or concave.

[0060] In this embodiment, the radius of curvature of the object-side surface of the first lens 110 is 30–35 mm, and the radius of curvature of the image-side surface is 650–750 mm; the radius of curvature of the object-side surface of the second lens 120 is 15–20 mm, and the radius of curvature of the image-side surface is 20–30 mm; the radius of curvature of the object-side surface of the third lens 130 is -20 to -30 mm, and the radius of curvature of the image-side surface is 5–10 mm. It should be noted that a positive radius of curvature means that the center of curvature is located on the image-side of the lens, i.e., the surface arches towards the object side; a negative radius of curvature means that the center of curvature is located on the object-side of the lens, i.e., the surface arches towards the image side. In other words, when the radius of curvature of the object-side surface is positive, the object-side surface is convex, and vice versa; when the radius of curvature of the image-side surface is positive, the image-side surface is concave, and vice versa.

[0061] Furthermore, at the optical axis position, the distance between the first lens 110 and the second lens 120 is 0.4–0.6 mm; the distance between the second lens 120 and the third lens 130 is 13–16 mm; the distance between the third lens 130 and the narrowband filter 140 is 2.5–3.5 mm; the distance between the narrowband filter 140 and the window glass 150 is 18–22 mm; and the distance between the window glass 150 and the image plane of the optical lens 100 is 0.3–0.5 mm. It should be noted that the distance between the two components refers to the gap width between them, i.e., the air thickness.

[0062] Furthermore, at the optical axis position, the thickness of the first lens 110 is 4-6 mm; the thickness of the second lens 120 is 7-9 mm; the thickness of the third lens 130 is 1.5-2.5 mm; the thickness of the narrow band filter 140 is 0.2-0.5 mm; and the thickness of the window glass 150 is 0.3-0.6 mm.

[0063] Furthermore, in this embodiment, the focal length f1 of the first lens 110, the focal length f2 of the second lens 120, and the focal length f3 of the third lens 130 satisfy the following relationship with the effective focal length f of the optical lens 100: f1 / f≤0.43, f2 / f≤0.49, |f3 / f|≥0.049.

[0064] The optical lens 100 of this embodiment is designed with the optical power, shape, size of each lens and the spacing of each component in mind. This results in a smaller size along the optical axis while maintaining a longer focal length, thus improving the resolution of the lidar. Furthermore, the optical lens 100 balances distortion and image plane relative illumination, maintaining consistency in radar resolution and range, and reducing aberrations.

[0065] In this embodiment, the narrowband filter 140 is a flat plate perpendicular to the optical axis, used to filter the wavelength of received light, so that the light passing through it has a narrow wavelength range, which should include the wavelength of the detection laser emitted by the lidar's transmitting module. By setting the narrowband filter 140, the light passing through the optical lens 100 is mostly reflected laser signals from the outside, reducing the reception of other environmental stray signals such as sunlight. Therefore, the narrowband filter 140 can suppress ambient light signals and improve the signal-to-noise ratio of the lidar. The passband bandwidth of the narrowband filter 140 determines the effect of ambient light suppression; the narrower the bandwidth, the better the suppression of ambient light. Since the center wavelength of the narrowband filter 140 is related to the principal ray incident angle CRA, a large CRA results in a larger center wavelength shift, leading to a wider bandwidth, which is not conducive to ambient light suppression. In this embodiment, the optical lens 100, through the design of the optical power, shape, and spacing of each lens, has a small principal ray incident angle CRA. In an optional embodiment, the principal ray incident angle CRA of the optical lens 100 is ≤8.5°, and the optical lens 100 has a better ambient light suppression effect, which can increase the signal-to-noise ratio of the radar echo signal.

[0066] In this embodiment, the optical lens 100 further includes an aperture stop (not shown in the figure). In this embodiment, the aperture stop is disposed on the object side of the first lens 110, which maximizes the receiving aperture so that the light incident on the optical lens 100 is ultimately focused on the detector, increasing the received echo signal energy, improving the detection capability of the lidar, and also helping to improve the relative illumination of the image plane.

[0067] In this embodiment, the aperture value of the optical lens 100 is 4.5 ≤ F ≤ 5.9. Setting the aperture value F at a higher level increases the depth of field of the optical lens 100, thereby reducing the sensitivity of the distance between the receiver chip and the receiver lens, and simplifying the installation and adjustment process. It can be understood that the theoretical installation position of the receiver chip is at the image plane position of the optical lens 100. With a deep depth of field, even slight deviations in the position of the receiver chip along the optical axis will not easily affect the reception effect, thus reducing the difficulty of installation and adjustment.

[0068] In this embodiment, the first lens 110, the second lens 120, and the third lens 130 are all spherical lenses. The manufacturing process of spherical lenses is relatively simple, which can reduce the cost of the optical lens 100. In other optional embodiments, the image-side and object-side surfaces of the first lens 110, the second lens 120, and the third lens 130 can also be aspherical.

[0069] Optionally, the Abbe numbers of the first lens 110, the second lens 120, and the third lens 130 decrease sequentially. In this embodiment, the Abbe number of the first lens 110 is 60-70, the Abbe number of the second lens 120 is 50-60, and the Abbe number of the third lens 130 is 15-25. Optionally, the refractive index of the first lens 110 is 1.45-1.65, and the refractive indices of the second lens 120 and the third lens 130 are 1.68-1.96. The materials of the first lens 110, the second lens 120, and the third lens 130 can be glass. Glass has better stability, which can reduce the temperature sensitivity of the focal length of the optical lens 100, increase the working stability of the lidar in different temperature environments, and thus adapt to more complex environments.

[0070] In this embodiment, the maximum field of view (FOV) of the optical lens 100 satisfies: 1.6° ≤ FOV ≤ 2.2°. A relatively small field of view can improve the resolution of the lidar, allowing it to output high-quality, high-density point clouds and improve detection accuracy.

[0071] In this embodiment, the window glass 150 is used to protect the photosensitive surface of the receiving chip from dust and dirt, and to prevent the radar detection capability from being reduced due to dirt on the photosensitive surface.

[0072] The table below shows the relevant parameters of the optical lens 100 in a specific embodiment of this application.

[0073]

[0074] In the table above, each component (except the image plane) corresponds to two thickness values. The upper thickness value represents the component's own thickness, and the lower thickness value represents the distance between the component and the next component, i.e., the air thickness. ST represents the setting position of the aperture stop.

[0075] The above table shows the F-Theta distortion curve and relative illumination curve of the optical lens 100 in the embodiment. Figure 2 and Figure 3 As shown. Figure 2 The mid-field angle is measured in degrees, from Figure 2 It can be seen that as the field of view deflection increases, the increase in distortion is relatively slow. At a position deflected by 0.9° from the center of the field of view, the distortion is only 0.27%, which is at a low level. It should be understood that due to the lens's symmetry, at a position deflected by -0.9° from the center of the field of view, the distortion is also 0.27%. Figure 3 As can be seen, the relative illumination decreases more slowly as the field of view angle deflection increases; at a position deflected by 0.9° from the center of the field of view, the relative illumination is still 98%. Similarly, due to the symmetry of the lens, the relative illumination is also 98% at a position deflected by -0.9° from the center of the field of view. Therefore, the optical lens 100 of this embodiment has the advantages of low distortion and high relative illumination at the edge of the field of view. When used in lidar, it can improve the consistency of resolution and detection capabilities (such as range) across different fields of view.

[0076] The optical lens provided in this application embodiment can be called an optical module. This application does not limit the name of the optical lens. The optical lens 100 can be applied to various electronic devices, such as lidar or automobiles.

[0077] This application also provides a lidar (not shown in the figures), including the optical lens 100 provided in the above embodiments of this application. Optionally, the optical lens 100 may be disposed in the receiving module of the lidar. It should be understood that the lidar should also include a transmitting module and other modules for realizing the detection function, such as a scanning module and a signal processing module. The structure and working principle of the above modules can be referred to the prior art, and will not be repeated here.

[0078] Optionally, the receiving module also includes a receiving chip, which can be positioned at the image plane of the optical lens 100 to receive echo signals.

[0079] In summary, the embodiments of this application, through the design of the optical power, shape, size of each lens in the optical lens 100 and the spacing of each component, give the optical lens 100 and the lidar the following advantages:

[0080] While miniaturizing the lens, the focal length was increased to improve the resolution;

[0081] By combining the positive and negative optical powers of each lens, aberrations are reduced, the image plane CRA of the optical lens 100 is reduced, and the signal-to-noise ratio of the radar echo signal is increased.

[0082] By setting the first lens 110 to positive optical power, the second lens 120 to positive optical power, and the third lens 130 to negative optical power, the length of the optical lens 100 can be shortened (to 55mm), and the image plane CRA can be reduced.

[0083] By balancing the distortion of the optical lens 100 and the relative illumination of the image plane, the consistency of radar resolution and range is maintained.

[0084] By setting the aperture stop on the object side of the first lens 110, the receiving aperture is maximized, the received echo signal energy is increased, and the radar's detection capability is improved.

[0085] By increasing the aperture value F of the receiving lens, the depth of focus of the optical lens 100 is increased, the distance sensitivity between the receiving chip and the optical lens 100 is reduced, and the assembly and adjustment difficulty is reduced.

[0086] By balancing the refractive index and Abbe number of each lens in the optical lens 100, the temperature sensitivity of the focal length of the optical lens 100 is reduced, thereby increasing the working stability of the lidar in different temperature environments.

[0087] The optical lens 100 uses only three lenses and allows the use of spherical lenses, thereby reducing costs.

[0088] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An optical lens characterized in that, Comprise, in order from the object side to the image side along the direction of extension of the optical axis: A first lens having positive refractive power; A second lens having positive refractive power, and the object side of the second lens is convex, and the image side is concave; A third lens having negative refractive power, and one of the object side and the image side of the third lens is concave, and the other is concave or flat; Wherein, the total optical length TTL of the optical lens and the effective focal length f satisfy: 0.4≤TTL / f≤0.

45.

2. The optical lens of claim 1, wherein, The object side of the first lens is convex, and the image side is concave.

3. The optical lens according to claim 1 or 2, characterized in that, The focal length f1 of the first lens, the focal length f2 of the second lens, and the focal length f3 of the third lens, and the effective focal length f of the optical lens satisfy the following relationship: f1 / f≤0.43, f2 / f≤0.49, |f3 / f|≥0.

049.

4. The optical lens according to claim 1 or 2, characterized in that, The maximum field angle FOV of the optical lens satisfies: 1.6°≤FOV≤2.2°.

5. The optical lens according to claim 1 or 2, characterized in that, The image side chief ray angle CRA of the optical lens satisfies: CRA≤8.5°.

6. The optical lens of claim 1 or 2, wherein, The curvature radius of the object side of the first lens is 30-35mm, and the curvature radius of the image side of the first lens is 650-750mm; And / or, the curvature radius of the object side of the second lens is 15-20mm, and the curvature radius of the image side of the second lens is 20-30mm; And / or, the curvature radius of the object side of the third lens is -20--30mm, and the curvature radius of the image side of the third lens is 5-10mm.

7. The optical lens of claim 1 or 2, wherein, Further comprising a window glass, the window glass is arranged on the image side of the third lens.

8. The optical lens of claim 7, wherein, Further comprising a narrow band filter, the narrow band filter is arranged between the third lens and the window glass.

9. The optical lens of claim 8, wherein, At the position of the optical axis, the thickness of the first lens is 4-6mm; And / or, the thickness of the second lens is 7-9mm; And / or, the thickness of the third lens is 1.5-2.5mm; And / or, the thickness of the narrow band filter is 0.2-0.5mm; And / or, the thickness of the window glass is 0.3-0.6mm.

10. The optical lens of claim 8, wherein, At the position of the optical axis, the distance between the first lens and the second lens is 0.4-0.6mm; And / or, the distance between the second lens and the third lens is 13-16mm; And / or, the distance between the third lens and the narrow band filter is 2.5-3.5mm; And / or, the distance between the narrow band filter and the window glass is 18-22mm; And / or, the distance between the window glass and the image plane of the optical lens is 0.3-0.5mm.

11. The optical lens of claim 1 or 2, wherein, Further comprising an aperture stop, the aperture stop is arranged on the object side of the first lens.

12. The optical lens of claim 11, wherein, The aperture value of the optical lens is 4.5≤F≤5.

9.

13. The optical lens of claims 1 or 2, wherein, The first lens, the second lens and the third lens are all spherical lenses.

14. The optical lens of claims 1 or 2, wherein, The refractive index of the first lens is 1.45-1.65, and the refractive index of the second lens and the third lens is 1.68-1.

96.

15. The optical lens of claims 1 or 2, wherein, The Abbe number of the first lens, the second lens and the third lens decreases in turn.

16. The optical lens of claim 15, wherein, The first lens has an Abbe number of 60-70, the second lens has an Abbe number of 50-60, and the third lens has an Abbe number of 15-25.

17. A lidar, comprising: An optical lens comprising the optical lens according to any one of claims 1-16.

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