TOF imaging lens for solid-state laser radar

Abstract

The invention provides a TOF imaging lens for a solid-state laser radar, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a diaphragm, an optical filter and a receiving chip, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are sequentially arranged along an optical axis from an object space to an image space, and the diaphragm is arranged between the second lens and the third lens. The optical filter is located on the image side face of the sixth lens, and the receiving chip is arranged at the rear end of the sixth lens and converts an optical image into an electric signal. The six lenses are adopted, the shape and the center thickness of each lens are optimally arranged, the focal power and the material refractive index are reasonably distributed, the position of the diaphragm is optimized, the cooperation of the air space between each lens and the diaphragm is optimized, and the like, so that a large field angle can be achieved within the wave band of 830-960 nm, the field angle can reach 120 degrees, and the imaging quality is good.

Description

Technical Field

[0001] The present invention relates to the technical field of optical elements, and in particular to a TOF imaging lens for a solid-state laser radar. Background Art

[0002] LiDAR has benefited from the booming development of the domestic new energy vehicle industry. Among them, lateral blindness-filling LiDAR can help intelligent driving systems deal with special situations often encountered in three scenarios: highways, urban roads, and automatic parking. Most lateral blindness-filling LiDARs are mechanical or hybrid, and use a rotating mechanism to increase the field of view.

[0003] Solid-state LiDAR is the development direction of the next generation of LiDAR. Compared with mechanical and semi-solid LiDAR, its structure does not have a rotating mechanism, the system is easier to integrate, has cost and reliability advantages, can make up for the lack of field of view of the main LiDAR, and is a better choice for short-distance blind spot LiDAR. The horizontal viewing angle of blind spot LiDAR is required to be as large as possible to make up for the lack of spatial coverage. The field of view of TOF lenses used for LiDAR in the existing technology is generally less than 100°, with a small shooting area, low relative illumination and large distortion.

[0004] In addition, although general wide-angle lenses with large field of view can meet the field of view requirements of solid-state laser radar, they are generally large in diameter and volume. Solid-state laser radar is limited by the size of the receiving chip, the transmitting chip, and the distance between the receiving chip and the transmitting chip. The diameter and size of the TOF lens on the solid-state laser radar cannot be very large. In addition, in order to meet the high-quality imaging of a wide working distance at a close distance within a large field of view, the design requirements will be higher.

[0005] Patent document CN112731628A (application number: CN202110091279.9) discloses a lens and a TOF imaging device. The present invention provides a lens, wherein a first lens, a second lens, a third lens, a fourth lens and an imaging surface are sequentially arranged along the optical axis from the object side to the image side, and the air gap G12 between the first lens and the second lens of the lens and the total optical length TTL of the lens satisfy G12 / TTL≤0.02; the air gap G23 between the second lens and the third lens and the total optical length TTL of the lens satisfy G23 / TTL≤0.09; the air gap G34 between the third lens and the fourth lens and the total optical length TTL of the lens satisfy G34 / TTL≤0.37. However, the patent cannot completely solve the above technical problems. Summary of the invention

[0006] In view of the defects in the prior art, an object of the present invention is to provide a TOF imaging lens for solid-state laser radar.

[0007] The TOF imaging lens for a solid-state laser radar provided by the present invention comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence along the optical axis from the object side to the image side;

[0008] The first lens has negative optical power, the object side surface of the first lens is convex, and the image side surface is concave;

[0009] The second lens has positive refractive power, the object side surface of the second lens is convex, and the image side surface is concave;

[0010] The third lens has positive power, the object side surface of the third lens is convex, and the image side surface is convex;

[0011] The fourth lens has positive power, the object side surface of the fourth lens is convex, the image side surface is convex, and the object side surface and the image side surface of the fourth lens are aspherical surfaces;

[0012] The fifth lens has positive power, the object side surface of the fifth lens is concave, and the image side surface is concave;

[0013] The sixth lens has positive power, the object side surface of the sixth lens is convex, and the image side surface is convex;

[0014] It also includes an aperture, a filter and a receiving chip. The aperture is arranged between the second lens and the third lens, and the filter is located on the image side of the sixth lens. The receiving chip is placed at the rear end of the sixth lens to convert the optical image into an electrical signal.

[0015] Preferably, the effective focal length f of the TOF imaging lens for the solid-state laser radar satisfies: 1mm<f<3mm;

[0016] And the following conditions are met: 4.5<|f1 / f|<6; 6.8<|(f1+f2) / f|<10; 2.4<|f3 / f|<3.8;

[0017] Among them, f1, f2, and f3 are the focal lengths of the first lens, the second lens, and the third lens respectively.

[0018] Preferably, a maximum sag z2 of the image-side surface of the first lens satisfies: 0.5<|f / z2|<1.5.

[0019] Preferably, the maximum sag z6 of the object-side surface of the third lens satisfies: 1.5<|f / z6|<3.

[0020] Preferably, the aperture number #F of the TOF imaging lens used for the solid-state lidar is ≤1.3.

[0021] Preferably, the field of view FOV of the TOF imaging lens used for the solid-state laser radar satisfies: FOV ≥ 120°.

[0022] Preferably, the operating band of the TOF imaging lens used for the solid-state laser radar is within the range of 830nm to 960nm.

[0023] Preferably, the total optical length TTL of the TOF imaging lens used for the solid-state laser radar satisfies: TTL≤20mm;

[0024] And meet the following conditions: 0.07 <f / TTL<0.13。

[0025] Preferably, the imaging quality of the TOF imaging lens used for the solid-state laser radar satisfies the following requirements within a short distance range of 0.5m-30m: modulation transfer function MTF ≥ 0.2.

[0026] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are glass lenses, and meet the following conditions:

[0027] 1.7 <n1<1.9;1.7<n2<1.9;1.5<n3<1.7;1.8<n4<2.0;1.7<n5<1.9;1.8<n6<2.0;

[0028] Among them, n1 is the d-light refractive index of the first lens, n2 is the d-light refractive index of the second lens, n3 is the d-light refractive index of the third lens, n4 is the d-light refractive index of the fourth lens; n5 is the d-light refractive index of the fifth lens; n6 is the d-light refractive index of the sixth lens.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The TOF imaging lens for solid-state laser radar of the present invention adopts six lenses. By optimizing the shape and center thickness of each lens, reasonably allocating the focal length and material refractive index, optimizing the aperture position and the coordination of the air space between each lens and the aperture, etc., a large field of view angle of up to 120° is achieved in the 830nm to 960nm band, and the imaging quality is good;

[0031] (2) The present invention can achieve a better aberration correction effect by using a single aspherical surface, and can effectively correct the distortion and other off-axis aberrations in the design process of large field angle and large aperture, improve the relative illumination of the edge field of view, and reduce the total optical length, reduce the production cost, ensure that the lens has good imaging quality when working at a close distance of 0.5m-30m, and realize the design of wide working distance;

[0032] (3) The TOF imaging lens for solid-state laser radar of the present invention has the advantages of large field of view, good temperature performance, simple structure, miniaturization, low cost, high imaging quality, etc. It can be used in optical sensors of various intelligent devices based on TOF technology such as short-range blind spot laser radar to realize depth information detection of close-range objects in a wide range of scenes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0034] Figure 1 is a schematic structural diagram of a TOF imaging lens for a solid-state laser radar provided by an embodiment of the present invention;

[0035] Figure 2 is a point diagram of a TOF imaging lens for a solid-state laser radar provided by an embodiment of the present invention;

[0036] Figure 3 is a distortion diagram of a TOF imaging lens for a solid-state laser radar provided by an embodiment of the present invention;

[0037] Figure 4 is a relative illumination diagram of a TOF imaging lens for a solid-state laser radar provided by an embodiment of the present invention;

[0038] Figure 5 is an MTF curve diagram of a TOF imaging lens for a solid-state laser radar provided by an embodiment of the present invention at an ambient temperature of 0°C;

[0039] Figure 6 is an MTF curve diagram of a TOF imaging lens for a solid-state laser radar provided by an embodiment of the present invention at an ambient temperature of 20° C.;

[0040] Figure 7 This is an MTF curve diagram of a TOF imaging lens for a solid-state laser radar provided by an embodiment of the present invention at an ambient temperature of 40°C.

[0041] Figure 8 This is an MTF curve diagram of a TOF imaging lens for a solid-state laser radar provided by an embodiment of the present invention at an ambient temperature of 60°C.

[0042] Fig. 9 This is an MTF curve diagram of a TOF imaging lens for a solid-state laser radar at a working distance of 0.5m provided in an embodiment of the present invention.

[0043] Fig.10 This is an MTF curve diagram of a TOF imaging lens for a solid-state laser radar at a working distance of 5m provided in an embodiment of the present invention.

[0044] Fig.11 This is an MTF curve diagram of a TOF imaging lens for a solid-state laser radar at a working distance of 15m provided in an embodiment of the present invention.

[0045] Fig.12 This is an MTF curve diagram of a TOF imaging lens for a solid-state laser radar at a working distance of 30m provided in an embodiment of the present invention;

[0046] In the figure: 100 - TOF imaging lens for solid-state laser radar; 10 - first lens; 20 - second lens; 30 - third lens; 40 - fourth lens; 50 - fifth lens; 60 - sixth lens; 101 - aperture; 102 - filter; 103 - receiving chip. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0048] Example 1

[0049] like Figure 1 As shown, in a preferred embodiment of the present invention, the TOF imaging lens 100 for solid-state laser radar includes a first lens 10, a second lens 20, an aperture 101, a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, a filter 102 and a receiving chip 103, which are arranged in sequence along the optical axis from the object side to the image side;

[0050] In particular, in a preferred embodiment of the present invention, the left side of the TOF imaging lens 100 for solid-state laser radar, which is away from the first lens 10, is defined as the object side, and the side where the photosensitive chip 103 is located is defined as the image side. When the TOF imaging lens 100 for solid-state laser radar is used to collect target object information, the light from the object passes through the first lens 10, the second lens 20, the aperture 101, the third lens 30, the fourth lens 40, the fifth lens 50 and the filter 102 in sequence, and finally reaches the receiving chip 103.

[0051] In particular, the first lens 10 may have a negative optical power, which is conducive to the contraction of light, thereby increasing the field of view. The object side of the first lens 10 is a convex surface, which is conducive to collecting large-angle light to enter the subsequent lens; at the same time, the convex side has better adaptability in the process of direct contact with the external environment. The object side refers to the surface facing the object side, and the image side of the lens refers to the surface facing the image side.

[0052] The second lens 20 may have negative optical focal length to share the negative optical focal length of the first lens 10 at the front end, and further diverge the collected large-angle off-axis light. The second lens 20 may have a convex-concave surface, which can control the aperture and size of subsequent lenses, reduce the angle of off-axis light entering the rear end lens, and reduce the difficulty of off-axis aberration correction.

[0053] In particular, the first lens 10 and the second lens 20 are both convex and concave, and are meniscus lenses. The combination of the first lens 10 and the second lens 20 improves the light collection capability of a large field of view, and is beneficial to the correction of aberrations and improves the imaging quality.

[0054] The third lens 30 may have positive power and a convex surface, which can converge light and compress the overall working aperture. The third lens 30 can balance the overall diopter configuration of the system while providing the main diopter, thereby balancing various aberrations.

[0055] The fourth lens 40 may have positive focal power, and may have a convex surface. In particular, the fourth lens 40 may be an aspherical lens, and both the object side surface and the image side surface of the fourth lens 40 may be aspherical surfaces, and the curvature radius of the aspherical surface is variable, and its aberration correction ability is better than that of the spherical surface. This is beneficial for controlling the direction of light, reducing the deflection angle of light entering the rear lens, and eliminating the various aberrations accumulated from the first lens 10 to the third lens 30, reducing the difficulty of aberration correction of subsequent lenses.

[0056] The fifth lens 50 may have a negative optical power and a concave surface to avoid excessive light deflection caused by excessive optical power concentration, thereby making the light trend smooth. The fifth lens 50 can well compensate for distortion.

[0057] The sixth lens 60 may have a positive focal power to optimize the aberration generated by the front lens and balance the relationship between distortion and relative illumination. The sixth lens 60 may have a convex surface. This is beneficial to suppress the angle of the edge field of view incident on the receiving chip 103 and perform aberration correction on the edge light of the large aperture. More light is effectively transmitted to the receiving chip 103 to better match the chief ray angle (CRA) requirements of the receiving chip 103 and improve the light energy receiving efficiency of the photosensitive chip 103.

[0058] In particular, the combination of the third lens 30, the fourth lens 40, the fifth lens 50 and the sixth lens 60 enables the lens 100 to have a larger relative aperture as a whole, which is beneficial to shortening the total length of the lens 100 and realizing the miniaturization of the overall structure. At the same time, the relative illumination of the edge field of view is improved, the generation of dark corners is avoided, and the imaging quality is improved.

[0059] In a preferred embodiment of the present invention, the TOF imaging lens 100 for solid-state laser radar uses six lenses. By optimizing the shape and center thickness of each lens, reasonably distributing the focal length and material refractive index, optimizing the aperture position and the coordination of the air space between each lens and the aperture, etc., the lens 100 has a large aperture, a large field of view, and improves the relative illumination of the edge field of view and the imaging quality. A good aberration correction effect can be achieved by using an aspherical surface, and distortion and other off-axis aberrations can be corrected extremely well in the process of large field of view and large aperture design, and the total optical length can be reduced to reduce production costs. It is ensured that the lens has good imaging quality when working at a close distance of 0.5m-30m, and a wide working distance design is achieved.

[0060] The aspheric lens satisfies:

[0061]

[0062] Among them, z represents the vector height along the optical axis, r represents the distance from a point on the optical surface to the optical axis, c represents the curvature of the surface, k represents the quadratic surface constant of the surface, and a1, a2, a3, a4, a5, a6, a7, and a8 are the aspheric coefficients of the 2nd, 4th, 6th, 8th, 10th, 12th, 14th, and 16th orders, respectively.

[0063] In a preferred embodiment of the present invention, the TOF imaging lens 100 for solid-state laser radar uses six lenses, has a simple structure and a small size. Only one aspherical surface is used to achieve a better aberration correction effect, which improves image quality, reduces aberrations such as distortion, and reduces production costs.

[0064] It should be noted that the present application does not limit the specific number of aspheric lenses. When focusing on imaging quality, the number of aspheric lenses can be increased if necessary. In particular, in order to improve the resolution quality of the optical system, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50 and the sixth lens 60 can all be aspheric lenses.

[0065] In particular, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50 and the sixth lens 60 may be made of glass lenses. Compared with plastic lenses, glass lenses have more stable high and low temperature performance and longer service life. They can effectively suppress the deviation of the back focus with temperature changes, and glass lenses have higher light transmittance. Plastic lenses are lighter and cheaper, and their surfaces can be easily made aspherical, which makes the lens design more free and can better correct aberrations.

[0066] In particular, the lens materials disclosed herein are only examples and not limitations. For example, in some application scenarios with lower temperature stability requirements, the first lens 10 to the sixth lens 60 can also be made of plastic, or a glass-plastic combination.

[0067] In a preferred embodiment of the present invention, the TOF imaging lens 100 for solid-state laser radar further includes an aperture 101 and a filter 102, wherein the aperture 101 is disposed between the second lens 20 and the third lens 30. The filter 102 is located on the image side of the sixth lens 60.

[0068] In particular, the aperture 101 limits the light beam, preventing unexpected light and harmful light from entering the receiving chip 103 , thereby improving the imaging quality of the lens 100 .

[0069] In particular, the combination of the first lens 10 and the second lens 20 can be defined as a front group, and the combination of the third lens 30, the fourth lens 40, the fifth lens 50, and the sixth lens 60 can be defined as a rear group. The aperture is arranged between the second lens 20 and the third lens 30 to take into account the structure of the front group and the rear group and balance the aberration between the front group and the rear group.

[0070] In particular, the position of the aperture 101 disclosed herein is merely an example and not a limitation; in alternative embodiments, the aperture 101 may also be disposed at other positions according to actual needs.

[0071] In particular, the filter 102 is used to screen the light entering the lens 100 and filter out other stray light in the non-working band, so that the lens 100 has an imaging band in a specified range, ensuring the high transmittance characteristics of the light in the 830nm~960nm band, and improving the imaging quality of the lens 100.

[0072] Particularly, one side of the filter 102 is coated with a bandpass cutoff film, and the other side is coated with a broadband antireflection film, which satisfies the light transmittance T≥92% within the incident angle range of 0° to 20° and the wavelength range of 830nm to 960nm.

[0073] In particular, the material and shape structure of the filter 102 are not limited.

[0074] In a preferred embodiment of the present invention, the receiving chip of the TOF imaging lens 100 for solid-state laser radar may be APD, SPAD or SiPM.

[0075] In addition, in a preferred embodiment of the present invention, the following technical features may also be provided:

[0076] In a preferred embodiment of the present invention, the effective focal length f of the TOF imaging lens 100 for solid-state laser radar satisfies: 1mm<f<3mm.

[0077] And the following conditions are met:

[0078] 4.5<|f1 / f|<6; 6.8<|(f1+f2) / f|<10; 2.4<|f3 / f|<3.8;

[0079] By satisfying the above conditions, the first lens 10 and the second lens 20 can have appropriate negative focal lengths, which is beneficial to expanding the field of view of the lens 100; the third lens 30 can provide the main refractive power for the lens 100, so that the front and rear group aberrations tend to the system balance point and obtain the optimal solution. At the same time, the relationship between distortion and relative illumination is balanced. The overall length of the lens 10 can be reduced to meet the application requirements of miniaturization.

[0080] In a preferred embodiment of the present invention, the maximum sag z2 of the image-side surface of the first lens 10 satisfies: 0.5<|f / z2|<1.5.

[0081] In a preferred embodiment of the present invention, the maximum sag z6 of the object-side surface of the third lens 30 satisfies: 1.5<|f / z6|<3.

[0082] In particular, the manufacturability of the lens is mainly determined by the two parameters of the sag and curvature of the curved surface. Meeting the above conditions can enable the surface shapes of the first lens 10 and the third lens 30 to be preset and changed within a reasonable range, reduce tolerance sensitivity, and ensure processing feasibility;

[0083] In particular, the first lens 10 and the third lens 30 are mainly responsible for achieving the optical performance of a large field of view and a large aperture of the lens 100. Meeting the above conditions can effectively avoid the generation of high-order aberrations during light transition, and more scientifically correct on-axis aberrations and off-axis aberrations, making the coordination between the front and rear lens groups more coordinated.

[0084] In a preferred embodiment of the present invention, the aperture number #F of the TOF imaging lens 100 for solid-state laser radar is ≤1.3.

[0085] Specifically, the TOF imaging lens 100 for solid-state lidar has a large aperture and a short focal length, enabling the lens 100 to have a large light flux and facilitating the control of the overall volume of the lens 100.

[0086] Specifically, in order to increase the optical transmittance, the light-passing surfaces of all lenses are coated with a broadband antireflection film with a transmittance T of 99.3 - 99.7% at a wavelength of 400nm to 1100nm.

[0087] In a preferred embodiment according to the present invention, the maximum field of view angle of the TOF imaging lens 100 for solid-state lidar satisfies: FOV≥120°, having a larger shooting range.

[0088] In a preferred embodiment according to the present invention, the working band of the TOF imaging lens 100 for solid-state lidar is 830nm to 960nm; meeting the above range can help improve the signal-to-noise ratio of the lens 100.

[0089] In a preferred embodiment according to the present invention, the overall optical length TTL of the TOF imaging lens 100 for solid-state lidar satisfies: TTL≤20mm, and satisfies the condition: 0.07 < f / TTL < 0.13; meeting the above conditions is beneficial to increasing the field of view angle of the lens 100 while reducing the overall volume and weight of the lens 100, achieving miniaturization and lightweight.

[0090] In a preferred embodiment according to the present invention, the imaging quality of the TOF imaging lens 100 for solid-state lidar satisfies: MTF≥0.2@50lp / mm in the short-distance range of 0.5m - 30m.

[0091] Specifically, the MTF (Modulation Transfer Function) curve graph is the most authoritative and objective reference basis for the imaging quality of the lens, and can be directly calculated from the design data of the lens 100. Staff engaged in optical system design using this method can predict the performance of the optical system. MTF is a comprehensive reflection of the resolution ability and contrast of the lens 100. An MTF greater than 0.2 at the Nyquist frequency is a typical value for acceptable image quality.

[0092] Specifically, taking an example of a commercially available lidar receiving chip IMX459SPAD (Single Photon Avalanche Diode) with the best performance of SONY (Sony), the size of a single pixel is 10μm. According to the definition, the Nyquist frequency is one cycle for every 2 pixels. For a pixel size of 10μm, one cycle of it is 20μm, so the corresponding Nyquist frequency is 50lp / mm.

[0093] Within the distance range of 0.5m to 30m, the MTF of the TOF imaging lens 100 for solid-state laser radar is ≥0.2@50lp / mm, which proves that the TOF imaging lens 100 for solid-state laser radar has good imaging effect within the short distance of 0.5m to 30m.

[0094] Example 2

[0095] Embodiment 2 is a preferred example of Embodiment 1.

[0096] Specifically, see Figure 1 , which is a schematic diagram of the structure of a TOF imaging lens 100 for a solid-state laser radar provided in a specific embodiment of the present invention, uses 6 glass lenses, including a first lens 10 with negative optical power arranged in sequence from the object side to the image side along the optical axis, whose object side surface is convex and the image side surface is concave; a second lens 20 with negative optical power, whose object side surface is convex and the image side surface is concave; a third lens 30 with positive optical power, whose object side surface is convex and the image side surface is convex; a fourth lens 40 with positive optical power, whose object side surface is convex and the image side surface is convex, and a fifth lens 50 with negative optical power, whose object side surface is concave and the image side surface is concave; a sixth lens 60 with positive optical power, whose object side surface is convex and the image side surface is convex. Among them, the object side surface and the image side surface of the fourth lens 40 are set as aspherical surfaces.

[0097] Furthermore, the lens 100 further includes an aperture 101 and a filter 102, wherein the aperture is disposed between the second lens 20 and the third lens 30, and the filter is disposed on the image side of the sixth lens. Light from the object passes through the first lens 10, the second lens 20, the aperture 101, the third lens 30, the fourth lens 40, the fifth lens 50 and the filter 102 in sequence, and finally reaches the receiving chip 103.

[0098] Furthermore, the lens 100 uses 6 types of optical glasses with high spectral transmittance in the near-infrared band, including heavy lanthanum flint glass with a large refractive index nd and a small chromaticity coefficient νd, to solve the problem that the incident angle of light in a large field of view is large but cannot provide a sufficiently large optical focal length, and also reduce the incident and exit angles of light, thereby improving the system tolerance. The middle lens group uses flint glass with a small refractive index nd and a large chromaticity coefficient νd, and is equipped with an air layer thickness to finely modulate the light.

[0099] Specifically, the specific parameters of each lens in the TOF imaging lens for solid-state laser radar provided in the specific embodiment of the present invention are shown in Table 1.

[0100] Table 1

[0101]

[0102] Among them, OBJ represents the object plane, IMG represents the image plane, and STO represents the aperture. When the curvature radius of the aperture and filter is Infinity, it means that the surface is a plane.

[0103] Among them, the aspheric coefficients satisfy the following equation:

[0104]

[0105] Among them, z represents the vector height along the optical axis, r represents the distance from a point on the optical surface to the optical axis, c represents the curvature of the surface, k represents the quadratic surface constant of the surface, and a1, a2, a3, a4, a5, a6, a7, and a8 are the aspheric coefficients of the 2nd, 4th, 6th, 8th, 10th, 12th, 14th, and 16th orders, respectively.

[0106] Specifically, the aspheric coefficients in the specific embodiment of the present invention are shown in Table 2.

[0107] Table 2

[0108] surface K 4nd 6nd 8nd 10nd S7 -32.35 1.990E-002 -4.234E-003 5.677E-004 -3.693E-005 S8 -7.25 1.330E-002 -6.271E-004 2.448E-004 -2.310E-005

[0109] Furthermore, the TOF imaging lens 100 for solid-state laser radar provided in the specific embodiment of the present invention has the following parameters: the maximum field of view angle is FOV of 120°, the working band is 920nm-960nm, the focal length f=1.85mm, the aperture number #F=1.2, and the total optical length TTL is 18.9mm. As shown in Table 1 above, |f1 / f|=5.84, |(f1+f2) / f|=8.62, |f3 / f|=3.17, |f / z2|=0.69, |f / z6|=1.71 and f / TTL=0.1. It is suitable for 1 / 3-inch receiving chips. It has the advantages of large field of view angle, good temperature performance, simple structure, miniaturization, low cost, high imaging quality, etc., and can be well matched with flash laser radar.

[0110] Furthermore, if Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 In order, they are the point arrangement diagram, distortion diagram, relative illumination diagram and thermal analysis MTF curve diagram of the TOF imaging lens 100 for solid-state laser radar configured with the parameters of the above specific embodiment.

[0111] Specifically, Figure 2The spot diagram of the full field of view of the TOF imaging lens 100 for solid-state laser radar is listed. The spot diagram can reflect the distribution of the intersection points of light from different fields of view with the image plane after passing through the lens 100. The smaller the diffuse spot in the spot diagram, the smaller the aberration. Figure 2 It can be seen from the data that the image points in each field of view are uniform in size, and the RMS value from the central field of view to the maximum field of view is always controlled below 10um, indicating that the imaging quality of lens 100 is relatively high.

[0112] Specifically, from the full-field spot diagram ( Figure 2 The data obtained in ) are shown in Table 3.

[0113] Table 3

[0114] OBJ / ° 0 15 30 45 60 RMS radius / um 2.70 7.34 8.36 7.68 8.47 GEO radius / um 5.77 13.73 16.17 27.21 49.93

[0115] In the table, RMSradius represents the root mean square radius, and GEOradius represents the diameter of all diffuse spots.

[0116] Specifically, Figure 3 The F-Tan (Theta) distortion curve of the TOF imaging lens 100 for the solid-state laser radar in this embodiment is listed, which represents the F-Tan (Theta) distortion of light of different wavelengths at different image heights on the imaging surface. The horizontal axis represents the F-Tan (Theta) distortion, unit: percentage (%), and the vertical axis represents the half field of view angle, unit: degree (°). It can be seen that the corresponding distortion is the largest at the maximum field of view angle, and the maximum distortion rate is >-30%. The F-Tan (Theta) distortion of the lens 100 is controlled within -30% to 0, indicating that the F-Tan (Theta) distortion of the lens 100 is effectively controlled.

[0117] Specifically, Figure 4 The relative illumination curve of the TOF imaging lens 100 for the solid-state laser radar in this embodiment is listed. The relative illumination refers to the ratio of the illumination at different coordinate points on the image plane to the illumination at the center point. It represents the relative illumination value at different field of view angles on the imaging plane. The horizontal axis represents the half field of view angle, in degrees (°), and the vertical axis represents the relative illumination. Figure 4 It can be seen that the relative illumination value of the lens 100 is not less than 55% at the maximum image plane, which means that the relative illumination of 100 is high and the imaging effect is good.

[0118] Specifically, Figure 5-Figure 8 The MTF curve of the TOF imaging lens 100 for the solid-state laser radar in this embodiment under the condition of temperature environment change is listed. It can be seen from the figure that the defocus effect of the lens 100 is not obvious, it is less affected by temperature changes, and has good environmental adaptability.

[0119] The final imaging effect of the TOF imaging lens 100 for solid-state laser radar in this embodiment is achieved by Figure 6-Figure 9 The MTF curve is used for evaluation. The MTF (Modulation Transfer Function) curve is the most authoritative and objective reference for the imaging quality of lens products.

[0120] Figure 9-12 It can reflect the imaging quality of the lens 100 when the working distance changes during close-range imaging.

[0121] Fig. 9 It is the MTF curve of the lens 100 when the working distance is 0.5m, and the full field MTF is > 0.2@50lp / mm at this time;

[0122] Fig.10 This is the MTF curve of the lens 100 when the working distance is 5m, and the full field MTF is > 0.2@50lp / mm;

[0123] Fig.11 This is the MTF curve of the lens 100 when the working distance is 15m, and the full field MTF is > 0.2@50lp / mm;

[0124] Fig.12 This is the MTF curve of the lens 100 when the working distance is 30m, and the full field MTF is > 0.2@50lp / mm;

[0125] It can be seen that the TOF imaging lens 100 used for the solid-state laser radar in this embodiment has good imaging effects at different working distances of 0.5m-30m at close range, and can meet the resolution requirements of solid-state blind spot laser radars currently on the market.

[0126] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0127] Those skilled in the art know that, in addition to implementing the system, device and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0128] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A TOF imaging lens for solid-state laser radar, characterized in that: It comprises a first lens (10), a second lens (20), a third lens (30), a fourth lens (40), a fifth lens (50) and a sixth lens (60) which are arranged in sequence along the optical axis from the object side to the image side; The first lens (10) has negative optical power, the object side surface of the first lens (10) is convex, and the image side surface is concave; The second lens (20) has positive refractive power, the object side surface of the second lens (20) is convex, and the image side surface is concave; The third lens (30) has positive optical power, and the object side surface of the third lens (30) is a convex surface, and the image side surface is a convex surface; The fourth lens (40) has positive refractive power, the object side surface of the fourth lens (40) is a convex surface, the image side surface is a convex surface, and the object side surface and the image side surface of the fourth lens (40) are aspherical surfaces; The fifth lens (50) has positive refractive power, and the object side surface of the fifth lens (50) is a concave surface, and the image side surface is a concave surface; The sixth lens (60) has positive refractive power, and the object side surface of the sixth lens (60) is a convex surface, and the image side surface is a convex surface; The optical system further comprises an aperture (101), a filter (102) and a receiving chip (103); the aperture (101) is arranged between the second lens (10) and the third lens (30); the filter (102) is located on the image side of the sixth lens (60); and the receiving chip (103) is placed at the rear end of the sixth lens (60) to convert the optical image into an electrical signal.

2. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The effective focal length f of the TOF imaging lens (100) for the solid-state laser radar satisfies: 1 mm < f < 3 mm; And the following conditions are met: 4.5<|f1 / f|<6; 6.8<|(f1+f2) / f|<10; 2.4<|f3 / f|<3.8; Wherein, f1, f2, and f3 are the focal lengths of the first lens (10), the second lens (20), and the third lens (30) respectively.

3. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The maximum sagittal height z2 of the image-side surface of the first lens (10) satisfies: 0.5<|f / z2|<1.

5.

4. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The maximum sagittal height z6 of the object-side surface of the third lens (30) satisfies: 1.5<|f / z6|<3.

5. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The aperture number #F≤1.3 of the TOF imaging lens (100) used for solid-state laser radar.

6. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The field of view angle FOV of the TOF imaging lens (100) used for the solid-state laser radar satisfies: FOV≥120°.

7. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The operating wavelength band of the TOF imaging lens (100) used for the solid-state laser radar is within the range of 830nm to 960nm.

8. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The total optical length TTL of the TOF imaging lens (100) for solid-state laser radar satisfies: TTL≤20 mm; And meet the following conditions: 0.07 <f / TTL<0.13。 9. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The imaging quality of the TOF imaging lens (100) for a solid-state laser radar satisfies the following requirements within a short distance range of 0.5 m to 30 m: the modulation transfer function MTF≥0.

2.

10. The TOF imaging lens for solid-state laser radar according to claim 1, characterized in that: The first lens (10), the second lens (20), the third lens (30), the fourth lens (40), the fifth lens (50) and the sixth lens (60) are glass lenses and meet the following conditions: 1.7 <n1<1.9;1.7<n2<1.9;1.5<n3<1.7;1.8<n4<2.0;1.7<n5<1.9;1.8<n6<2.0; Wherein, n1 is the d-light refractive index of the first lens (10), n2 is the d-light refractive index of the second lens (20), n3 is the d-light refractive index of the third lens (30), n4 is the d-light refractive index of the fourth lens (40); n5 is the d-light refractive index of the fifth lens (50); and n6 is the d-light refractive index of the sixth lens (60).

Images