Optical lens and lidar

Abstract

The application discloses an optical lens and a laser radar. The optical lens comprises first to fifth lenses and a diaphragm in sequence from an object side to an image side along an optical axis. The first lens has a negative focal length, the object side of the first lens is a convex surface, and the image side of the first lens is a concave surface. The second lens has a positive focal length, the object side of the second lens is a convex surface. The third lens has a negative focal length, the object side of the third lens is a convex surface, and the image side of the third lens is a concave surface. The fourth lens has a positive focal length, the object side of the fourth lens is a concave surface, and the image side of the fourth lens is a convex surface. The fifth lens has a positive focal length, the object side of the fifth lens is a convex surface, and the image side of the fifth lens is a concave surface. At least one lens is an aspheric lens, the object side and the image side of the fifth lens are aspheric surfaces, and the diaphragm is arranged between the second lens and the third lens. The optical lens has good image quality, a small number of lenses, a small volume, low cost and can be applied to the laser radar.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical systems, in particular to an optical lens. The present application also relates to a laser radar. BACKGROUND

[0002] In recent years, with the rapid development of automobile auxiliary driving technology, optical lenses are more and more widely used in the field of automobiles, and the requirement for miniaturization of optical lenses is also more and more prominent. For some special application optical lenses, such as optical lenses applied to laser radars, in order to improve image quality, the number of lenses needs to be increased, but the more the number of lenses, the larger the volume and weight of the lens, which is not conducive to the miniaturization of the lens, and also causes the increase of cost. SUMMARY

[0003] The purpose of the present application is to provide an optical lens applied to a laser radar, which can have good image quality, fewer lenses, smaller volume and low cost. The present application also provides a laser radar.

[0004] To achieve the above purpose, the present application provides the following technical solutions:

[0005] An optical lens comprises, in order from the object side to the image side along the optical axis:

[0006] a first lens having a negative focal power, the object side surface of which is a convex surface, and the image side surface of which is a concave surface;

[0007] a second lens having a positive focal power, the object side surface of which is a convex surface;

[0008] a third lens having a negative focal power, the object side surface of which is a convex surface, and the image side surface of which is a concave surface;

[0009] a fourth lens having a positive focal power, the object side surface of which is a concave surface, and the image side surface of which is a convex surface;

[0010] a fifth lens having a positive focal power, the object side surface of which is a convex surface, and the image side surface of which is a concave surface;

[0011] a diaphragm arranged between the second lens and the third lens;

[0012] At least one of the first lens to the fifth lens is an aspherical lens, and the object side surface and the image side surface of the fifth lens are both aspherical surfaces; and the following conditional expressions are satisfied:

[0013] 1.7≤TTL / EFL≤2.04, TTL represents the distance from the center of the object side surface of the first lens to the imaging surface of the optical lens on the optical axis, and EFL represents the effective focal length of the optical lens;

[0014] | (R 31 -d2) / R22 |≤0.1, R 22 denotes a radius of curvature of the image side surface of the second lens, R 31 denotes a radius of curvature of the object side surface of the third lens, and d2 denotes a separation distance between the image side surface of the second lens and the object side surface of the third lens.

[0015] Optionally, the following conditional expression is also satisfied: 1.1 ≤ |f 12 |EFL| ≤ 2.4, where 1 / f 12 = 1 / f1 + 1 / f2, f1 denotes a focal length of the first lens, f2 denotes a focal length of the second lens, and f 12 denotes a combined focal length of the first lens and the second lens, and EFL denotes an effective focal length of the optical lens.

[0016] Optionally, the following conditional expression is also satisfied: 0.7 ≤ |f 45 |EFL| ≤ 0.9, where 1 / f 45 = 1 / f4 + 1 / f5, f4 denotes a focal length of the fourth lens, f5 denotes a focal length of the fifth lens, and f 45 denotes a combined focal length of the fourth lens and the fifth lens, and EFL denotes an effective focal length of the optical lens.

[0017] Optionally, the following conditional expression is also satisfied: 1.9 ≤ |f 12 / f 45 | ≤ 2.7, where 1 / f 12 = 1 / f1 + 1 / f2, f1 denotes a focal length of the first lens, f2 denotes a focal length of the second lens, and f 12 denotes a combined focal length of the first lens and the second lens, 1 / f 45 = 1 / f4 + 1 / f5, f4 denotes a focal length of the fourth lens, f5 denotes a focal length of the fifth lens, and f 45 denotes a combined focal length of the fourth lens and the fifth lens.

[0018] Optionally, the following conditional expression is also satisfied: |f3 / f 12 | ≥ 1.2, where 1 / f 12 = 1 / f1 + 1 / f2, f1 denotes a focal length of the first lens, f2 denotes a focal length of the second lens, and f 12 denotes a combined focal length of the first lens and the second lens, and f3 denotes a focal length of the third lens.

[0019] Optionally, the following condition is also met: 0.45≤EPD / TTL≤0.6, EPD represents an entrance pupil diameter of the optical lens, and TTL represents a distance from a center of an object side surface of the first lens to an imaging surface of the optical lens on an optical axis.

[0020] Optionally, the following condition is also met: BFL / TTL≥0.15, BFL represents a distance from a center of an image side surface of the fifth lens to the imaging surface of the optical lens on the optical axis, and TTL represents the distance from the center of the object side surface of the first lens to the imaging surface of the optical lens on the optical axis.

[0021] Optionally, the following condition is also met: dn / dt(2)+dn / dt(4)≥-5×10 -6 dn / dt(2)+dn / dt(4)≥-5×10-6 / ℃, dn / dt(2) represents a coefficient of a change in a refractive index of a material of the second lens with temperature, dn / dt(4) represents a coefficient of a change in a refractive index of a material of the fourth lens with temperature, dn / dt(2) is negative, dn / dt(4) is negative, n represents a refractive index of a material of a lens, and t represents temperature.

[0022] A laser radar comprises:

[0023] A receiving end for collecting light returned from the outside, comprising a receiving lens and a photoelectric device, the receiving lens converging the collected light to the photoelectric device, the receiving lens adopting the optical lens according to any one of the preceding aspects;

[0024] A transmitting end comprising a light source and a projecting lens, the projecting lens being used for projecting light emitted by the light source, the projecting lens adopting the optical lens according to any one of the preceding aspects.

[0025] Optionally, when the light source is a dot array light source, the light source is arranged at a position deviating from a focal plane of the projecting lens, so that the light projected by the projecting lens is uniformly distributed in a surface array; or when the light source is a dot array light source, the light source further comprises a light homogenizing device arranged on a light emitting side of the projecting lens, and used for making the light projected by the projecting lens uniformly distributed in a surface array after passing through the light homogenizing device.

[0026] Optionally, the projecting lens is an optical lens obtained by reducing the size of the receiving lens by a preset ratio.

[0027] According to the technical scheme, the optical lens comprises a first lens to a fifth lens and a diaphragm along an optical axis from an object side to an image side, wherein the first lens has a negative focal length, the object side is a convex surface, and the image side is a concave surface; the second lens has a positive focal length, the object side is a convex surface; the third lens has a negative focal length, the object side is a convex surface, and the image side is a concave surface; the fourth lens has a positive focal length, the object side is a concave surface, and the image side is a convex surface; the fifth lens has a positive focal length, the object side is a convex surface, and the image side is a concave surface; and the diaphragm is arranged between the second lens and the third lens. The optical lens comprises a small number of lenses, which is helpful to reduce the volume of the optical lens and reduce the cost. The lenses of the optical lens are arranged according to the above lens arrangement, the lens surface shape is designed, and the focal length is distributed, so that the aberration distribution is reasonable, the optical lens can have good image quality, the total length of the optical lens is reduced, and the volume is reduced. At least one lens is a non-spherical lens, and the object side and the image side of the fifth lens are non-spherical surfaces, which can improve the imaging quality of the off-axis field of view beam. The diaphragm is arranged between the second lens and the third lens, so that the optical lens can avoid increasing the aperture of the first lens under the condition of receiving more light energy. Therefore, the optical lens of the present application can have good image quality, a small number of lenses, a small volume and low cost, and can be applied to laser radar.

[0028] The laser radar provided by the present application can achieve the above beneficial effects. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 The structure and optical path schematic diagram of the optical lens provided by an embodiment of the present application are shown in the figure.

[0031] Figure 2 The structure and optical path schematic diagram of the optical lens provided by another embodiment of the present application are shown in the figure.

[0032] Figure 3 The structure and optical path schematic diagram of the optical lens provided by another embodiment of the present application are shown in the figure.

[0033] Figure 4 The figure shows the selection of the defocus surface of the projection lens in the transmitting end of the laser radar of the embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the person skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should fall within the protection scope of the present application.

[0035] The present embodiment provides an optical lens, which comprises, in sequence from the object side to the image side along the optical axis:

[0036] a first lens having negative refractive power, the object side surface of which is convex, and the image side surface of which is concave;

[0037] a second lens having positive refractive power, the object side surface of which is convex;

[0038] a third lens having negative refractive power, the object side surface of which is convex, and the image side surface of which is concave;

[0039] a fourth lens having positive refractive power, the object side surface of which is concave, and the image side surface of which is convex;

[0040] a fifth lens having positive refractive power, the object side surface of which is convex, and the image side surface of which is concave;

[0041] a diaphragm arranged between the second lens and the third lens;

[0042] at least one of the first lens to the fifth lens is an aspherical lens, and both the object side surface and the image side surface of the fifth lens are aspherical; and the following conditional expressions are satisfied:

[0043] 1.7≤TTL / EFL≤2.04, TTL represents the distance on the optical axis from the center of the object side surface of the first lens to the imaging surface of the optical lens, and EFL represents the effective focal length of the optical lens;

[0044] |(R 31 -d2) / R 22 |≤0.1, R 22 represents the radius of curvature of the image side surface of the second lens, R 31 represents the radius of curvature of the object side surface of the third lens, and d2 represents the interval distance between the image side surface of the second lens and the object side surface of the third lens.

[0045] The optical lens comprises a small number of lenses, which helps to reduce the volume and cost of the optical lens. The lenses in the optical lens adopt the above lens arrangement, lens surface shape design and refractive power distribution, so that the aberration distribution is reasonable, the optical lens can have good image quality, and the total length of the optical lens is reduced, so that the volume is reduced.

[0046] The lens being an aspheric lens means that the object side surface and the image side surface of the lens are aspheric, and the object side surface and the image side surface of the fifth lens are aspheric, which can improve the imaging quality of the off-axis field light beam, so that the optical lens can have better image quality. The diaphragm is arranged between the second lens and the third lens, so that the optical lens can avoid increasing the aperture of the first lens while receiving more light energy.

[0047] The distance TTL between the center of the object side surface of the first lens and the imaging surface of the optical lens on the optical axis and the effective focal length EFL of the optical lens satisfy the condition formula 1.7≤TTL / EFL≤2.04, so that the parameter design combination of the entire lens group of the optical lens is more reasonable, and the miniaturization of the optical lens is facilitated. The image side surface of the second lens, the object side surface of the third lens, and the distance d2 between the two lenses satisfy the condition formula |(R 31 -d2) / R 22 ≤0.1, which can make the diaphragm aperture as large as possible.

[0048] Therefore, the optical lens of the embodiment can have better image quality, has fewer lenses, smaller volume, and lower cost, and can be applied to a laser radar.

[0049] Optionally, the image side surface of the fifth lens has at least one inflection point from the center to the edge, which can improve the imaging quality of the off-axis field light beam.

[0050] Preferably, the object side surface and the image side surface of the third lens are aspheric, so that the diaphragm can be enlarged while improving the imaging quality of the on-axis and off-axis field light beams. Enlarging the diaphragm can increase the amount of light entering, and the optical lens applied to the laser radar can improve the ability of the laser radar to measure long distances.

[0051] Optionally, the optical lens of the embodiment further satisfies the following condition formula: 1.1≤|f 12 / EFL|≤2.4, wherein 1 / f 12 =1 / f1+1 / f2, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, f 12 represents the combined focal length of the first lens and the second lens, and EFL represents the effective focal length of the optical lens. The first lens and the second lens satisfy the above condition formula, so that the focal length distribution is more reasonable, each lens shares the light gathering ability, and the yield is higher.

[0052] Optionally, the optical lens of the embodiment further satisfies the following condition formula: 0.7≤|f 45 / EFL|≤0.9, wherein 1 / f 45 =1 / f4+1 / f5, f4 represents the focal length of the fourth lens, f5 represents the focal length of the fifth lens, f 45EFL represents the effective focal length of the optical lens. The fourth lens and the fifth lens satisfy the above conditional expression so that the focal length distribution is more reasonable, each lens shares the light gathering ability, and the yield in mass production is higher.

[0053] Optionally, the optical lens of the embodiment further satisfies the following conditional expression: 1.9≤|f 12 / f 45 |≤2.7, wherein 1 / f 12 =1 / f1+1 / f2, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, and f 12 represents the combined focal length of the first lens and the second lens, and 1 / f 45 =1 / f4+1 / f5, f4 represents the focal length of the fourth lens, f5 represents the focal length of the fifth lens, and f 45 represents the combined focal length of the fourth lens and the fifth lens. Satisfying the conditional expression can make the entire lens group as small as possible, and the assembly and yield in mass production are better.

[0054] Optionally, the optical lens of the embodiment further satisfies the following conditional expression: |f3 / f 12 |≥1.2, wherein 1 / f 12 =1 / f1+1 / f2, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, and f 12 represents the combined focal length of the first lens and the second lens, and f3 represents the focal length of the third lens. Satisfying the conditional expression can make the stop aperture as large as possible, and the optical power distribution of the optical lens is more reasonable.

[0055] Optionally, the optical lens of the embodiment can be set according to the light quantity level: EFL / EPD≤1.2, or EFL / EPD≤1.02, or EFL / EPD≤0.95, EFL represents the effective focal length of the optical lens, and EPD represents the entrance pupil diameter of the optical lens, which helps to make the optical lens receive more light energy.

[0056] Optionally, the optical lens of the embodiment further satisfies the following conditional expression: 0.45≤EPD / TTL≤0.6, EPD represents the entrance pupil diameter of the optical lens, and TTL represents the distance from the center of the object side of the first lens to the imaging plane of the optical lens on the optical axis. Satisfying the conditional expression helps to miniaturize the optical lens lens combination.

[0057] Optionally, the optical lens of the embodiment further satisfies the following conditional expression: BFL / TTL≥0.15, wherein BFL represents the distance from the center of the image side surface of the fifth lens to the imaging surface of the optical lens on the optical axis, and TTL represents the distance from the center of the object side surface of the first lens to the imaging surface of the optical lens on the optical axis. Satisfying the conditional expression helps miniaturize the lens combination of the optical lens and provides more space for focusing.

[0058] Preferably, the optical lens of the embodiment further satisfies the following conditional expression: dn / dt(2)+dn / dt(4)≥-5×10 -6 / ℃, wherein dn / dt(2) represents the coefficient of the change of the refractive index of the material of the second lens with temperature, dn / dt(4) represents the coefficient of the change of the refractive index of the material of the fourth lens with temperature, dn / dt(2) is negative, dn / dt(4) is negative, n represents the refractive index of the material of the lens, and t represents temperature. Satisfying the conditional expression makes the optical lens match different temperature scenarios and does not affect the imaging quality.

[0059] The light from the object sequentially passes through each lens and is finally imaged on the imaging receiving surface (i.e., the imaging surface of the optical lens). The optical lens can further include a filter and / or a protective glass arranged between the fifth lens and the imaging receiving surface. The filter can be used to correct color deviation, pass the light waveband required by the detector, and filter the light waveband range that is not desired to participate in detection. The protective glass can be used to protect the detector located on the imaging receiving surface.

[0060] It should be noted that the optical power refers to the deflection of the propagation direction of light when parallel light passes through an optical system, and is used to characterize the deflection ability of the optical system to incident parallel light. An optical system has positive optical power, indicating that the deflection of light is convergent; an optical system has negative optical power, indicating that the deflection of light is divergent. In the present application, if the optical power or focal length of a lens is not defined in a region position, it means that the optical power or focal length of the lens can be the optical power or focal length of the lens at the near optical axis.

[0061] The optical lens will be described in detail below with specific embodiments.

[0062] Embodiment 1

[0063] Please refer to Figure 1 , Figure 1 The structure and optical path of an optical lens provided by an embodiment are shown in the following figure: Figure 1As shown, the optical lens of the embodiment includes, in sequence along the optical axis, a first lens 101, a second lens 102, a diaphragm 100, a third lens 103, a fourth lens 104, and a fifth lens 105. The first lens 101 has a negative focal power, the object side S1 is a convex surface, and the image side S2 is a concave surface; the second lens 102 has a positive focal power, the object side S3 is a convex surface, and the image side S4 is a concave surface; the third lens 103 has a negative focal power, the object side S6 is a convex surface, and the image side S7 is a concave surface; the fourth lens 104 has a positive focal power, the object side S8 is a concave surface, and the image side S9 is a convex surface; the fifth lens 105 has a positive focal power, the object side S10 is a convex surface, and the image side S11 is a concave surface with a turning point from the center to the edge. Both the object side S10 and the image side S11 of the fifth lens 105 are aspheric surfaces. A filter 106 is arranged between the fifth lens 105 and an imaging receiving surface 108. An object side 107 is located on the left side of the optical lens.

[0064] Specifically, the detailed optical data of the optical lens of the embodiment is shown in Table 1-1, where STO represents the diaphragm, S12 and S13 represent the object side and the image side of the filter 106 respectively, and IMA represents the imaging receiving surface. The curvature radius R and the interval d determine the focal length f, and Nd, Vd, and dn / dt determine the material of the lens.

[0065] Table 1-1

[0066]

[0067]

[0068] The curve equation of the aspheric surface of the lens can be but not limited to represented as follows:

[0069]

[0070] Where X represents the distance from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis, c represents the paraxial curvature of the aspheric surface, c = 1 / R (i.e., the paraxial curvature c is the inverse of the curvature radius R in Table 1), k represents the conic coefficient, and Ai represents the correction coefficient of the i-th order of the aspheric surface. The following Table 1-2 gives the conic coefficient k and the high-order term coefficients A4, A6, A8, A10, and A12 that can be used for the surfaces S10 and S11 of the fifth lens 105 in Embodiment 1.

[0071] Table 1-2

[0072] S10 S11 K 6.10E-01 4.84E+00 A4 -2.88E-05 5.38E-05 A6 -6.86E-06 -7.05E-06 A8 1.08E-07 -1.36E-08 A10 -1.48E-09 -5.16E-10 A12 -4.42E-12 8.57E-12 A14 0 0 A16 0 0

[0073] Embodiment 2

[0074] Please refer to Figure 2 , Figure 2A schematic diagram of the structure and optical path of an optical lens is provided for another embodiment, as shown below. Figure 2 As shown, the optical lens of this embodiment includes a first lens 201, a second lens 202, an aperture stop 200, a third lens 203, a fourth lens 204, and a fifth lens 205 arranged sequentially along the optical axis. The first lens 201 has negative optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens 202 has positive optical power, with its object-side surface S3 being convex and its image-side surface S4 being convex. The third lens 203 has negative optical power, with its object-side surface S6 being convex and its image-side surface S7 being concave; both object-side surface S6 and image-side surface S7 of the third lens 203 are aspherical. The fourth lens 204 has positive optical power, with its object-side surface S8 being concave and its image-side surface S9 being convex. The fifth lens 205 has positive optical power, with its object-side surface S10 being convex and its image-side surface S11 being concave and having a point of inflection from the center to the edge. Both object-side surface S10 and image-side surface S11 of the fifth lens 205 are aspherical. A filter 206 is disposed between the fifth lens 205 and the imaging receiving surface 208. The object surface 207 is located on the left side of the optical lens.

[0075] Specifically, the detailed optical data of the optical lens in this embodiment are shown in Table 2-1, where STO represents the aperture stop, S12 and S13 represent the object side and image side of the filter 206, respectively, and IMA represents the imaging receiving surface.

[0076] Table 2-1

[0077]

[0078]

[0079] Table 2-2 below gives the conic coefficient k and higher-order coefficients A4, A6, A8, A10, A12 of the surfaces S6 and S7 of the third lens 203 and the surfaces S10 and S11 of the fifth lens 205 in Embodiment 2.

[0080] Table 2-2

[0081] S6 S7 S10 S11 K -1.54E+00 -5.51E-01 9.55E-01 -1.05E+00 A4 -1.53E-04 -6.20E-04 -8.26E-05 7.81E-05 A6 -8.96E-07 -2.78E-06 -6.43E-06 -8.04E-06 A8 -2.15E-08 -2.15E-08 3.81E-08 -2.39E-08 A10 3.46E-10 1.75E-12 -1.02E-11 -5.85E-10 A12 -3.52E-12 -3.41E-12 -2.76E-11 1.83E-11 A14 0 0 0 0 A16 0 0 0 0

[0082] Example 3

[0083] Please refer to Figure 3 , Figure 3 A schematic diagram of the structure and optical path of an optical lens is provided for another embodiment, as shown below. Figure 3As shown, the optical lens of the embodiment includes, in sequence along the optical axis, a first lens 301, a second lens 302, a diaphragm 300, a third lens 303, a fourth lens 304, and a fifth lens 305. The first lens 301 has a negative focal power, the object side S1 is a convex surface, and the image side S2 is a concave surface; the second lens 302 has a positive focal power, the object side S3 is a convex surface, and the image side S4 is a convex surface; the third lens 303 has a negative focal power, the object side S6 is a convex surface, and the image side S7 is a concave surface, and both the object side S6 and the image side S7 of the third lens 303 are aspheric surfaces. The fourth lens 304 has a positive focal power, the object side S8 is a concave surface, and the image side S9 is a convex surface; the fifth lens 305 has a positive focal power, the object side S10 is a convex surface, and the image side S11 is a concave surface and has a reverse point from the center to the edge. Both the object side S10 and the image side S11 of the fifth lens 305 are aspheric surfaces. A filter 306 is arranged between the fifth lens 305 and an imaging receiving surface 308. An object surface 307 is located on the left side of the optical lens.

[0084] Specifically, the detailed optical data of the optical lens of the embodiment is shown in Table 3-1, wherein STO represents a diaphragm, S12 and S13 represent the object side and the image side of the filter 306 respectively, and IMA represents an imaging receiving surface.

[0085] Table 3-1

[0086]

[0087] The following Table 3-2 gives the conic coefficients k and high-order term coefficients A4, A6, A8, A10, A12 of the surfaces S6, S7 of the third lens 303 and the surfaces S10, S11 of the fifth lens 305 which can be used in the embodiment 3.

[0088] Table 3-2

[0089]

[0090]

[0091] The optical lens data of each of the embodiments 1 to 3 is as follows, wherein FOV represents the field of view angle of the optical lens.

[0092] Table 4

[0093]

[0094]

[0095] The embodiment also provides a laser radar, comprising:

[0096] The receiving end is used to collect light reflected from the outside, including a receiving lens and a photoelectric device. The receiving lens focuses the collected light onto the photoelectric device. The receiving lens adopts the optical lens described in any of the above embodiments.

[0097] The transmitting end includes a light source and a projection lens, wherein the projection lens is used to project the emitted light from the light source, and the projection lens adopts the optical lens described in any of the above embodiments.

[0098] The laser radar projects light from a light source through a projection lens. This light then strikes the target object and is reflected. A receiving lens collects the reflected light and focuses it onto a photoelectric device, thus detecting the target object. The laser radar in this embodiment features a receiving lens and a projection lens that offer good image quality, require fewer lenses, have a smaller size, and are less expensive.

[0099] This embodiment does not limit the type or structure of the light source. When the light source is a dot matrix light source, the light source is positioned offset from the focal plane of the projection lens, so that the light projected through the projection lens is evenly distributed in an array; or when the light source is a dot matrix light source, it further includes a light-diffusing device disposed on the light-emitting side of the projection lens, used to make the light projected by the projection lens evenly distributed in an array after passing through the light-diffusing device. The light source can be a dot matrix light source, and the projection lens can project the emitted light from the dot matrix light source onto the object and make it evenly distributed in an array. Preferably, the light source is a dot matrix light source, and the light source is offset from the focal plane of the projection lens, so that the light projected through the projection lens is evenly distributed in an array. An exemplary reference can be made to... Figure 4 , Figure 4 This is a schematic diagram showing the selection of the defocus surface for the projection lens in the transmitter of a lidar system according to one embodiment. Figure 4 The projection lens shown corresponds to Figure 1 The optical lens shown is as follows: Figure 4 As shown, a plane on the side of the imaging receiving surface 108 of the optical lens away from the optical lens is selected as the defocus surface 109, and the defocus amount is Δdec, that is, the distance between the defocus surface 109 and the imaging receiving surface 108 is Δdec. The light source of the transmitting end is set on this defocus surface 109. The defocus method makes the dot matrix light spot projected through the projection lens uniformly distributed in an array. In this embodiment, the amount of defocus of the dot matrix light source from the focal plane of the projection lens is not limited. In practical applications, it can be set according to the dot matrix light source and the requirements of the projected array light spot. Optionally, corresponding to the optical lens of Embodiment 1, Δdec can be set to ≥ 0.5mm, where Δdec represents the amount of defocus of the light source from the focal plane of the projection lens. The light source can be, but is not limited to, a vertical-cavity surface-emitting laser (VCSEL).

[0100] Further preferably, when being a dot array light source, if the dot array light source is not arranged on the defocus plane, the emitting end further comprises a light homogenizing device arranged on the light emitting side of the projection lens, for making the light projected by the projection lens uniformly distributed in a surface array after passing through the light homogenizing device. The light homogenizing device can adopt but is not limited to a diffusion plate or a light diffuser.

[0101] The photoelectric device generates an electrical signal based on the received light as a detector. In this embodiment, the type and structure of the photoelectric device are not limited, and the photoelectric device can adopt but is not limited to a surface array photoelectric device, such as a surface array photoelectric device composed of a single photon avalanche diode (SPAD).

[0102] If the projection lens of the emitting end and the receiving lens of the receiving end adopt the same optical lens, i.e., the optical data of the projection lens and the receiving lens are the same, the imaging receiving surface of the receiving lens has almost the same length-width ratio or size as the dot array light source of the emitting end. Alternatively, the projection lens is an optical lens based on the receiving lens and reduced in size by a preset ratio, and in order to keep the dot array light source of the emitting end small in size, the method of reducing the size of the receiving lens by a certain ratio is adopted to obtain an optical lens similar to the projection lens, so as to ensure that the emission and reception of the laser radar have similar distortion models and temperature change trends.

[0103] The laser radar of this embodiment can detect target objects within a range of 30-300 m. The optical lens and laser radar provided by the present application have the advantages of good resolution, large aperture, low cost, small size, good temperature performance, etc., and are suitable for vehicle installation.

[0104] The optical lens and laser radar provided by the present application are described in detail above. This paper applies specific examples to describe the principles and implementation modes of the present application. The above description of the embodiments is only used to help understand the method of the present application and its core idea. It should be pointed out that for ordinary skilled persons in the technical field, without departing from the principles of the present application, the present application can be improved and modified in many ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. An optical lens characterized in that, The optical lens comprises five lenses, which are sequentially arranged along the optical axis from the object side to the image side, and comprise: a first lens having a negative focal power, the object side surface of which is convex, and the image side surface of which is concave; a second lens having a positive focal power, the object side surface of which is convex; a third lens having a negative focal power, the object side surface of which is convex, and the image side surface of which is concave; a fourth lens having a positive focal power, the object side surface of which is concave, and the image side surface of which is convex; a fifth lens having a positive focal power, the object side surface of which is convex, and the image side surface of which is concave; a stop arranged between the second lens and the third lens; at least one of the first lens to the fifth lens is an aspheric lens, and the object side surface and the image side surface of the fifth lens are aspheric surfaces; and the following conditional expression is satisfied: 1.7≤TTL / EFL≤2.04, wherein TTL represents the distance on the optical axis from the center of the object side surface of the first lens to the imaging surface of the optical lens, and EFL represents the effective focal length of the optical lens; |(R 31 -d2) / R 22 |≤0.1, R 22 denotes the radius of curvature of the image side of the second lens, R 31 denotes the radius of curvature of the object side of the third lens, d2 denotes the separation distance between the image side of the second lens and the object side of the third lens; 0.7≤|f 45 EFL|≤0.9, where 1 / f 45 =1 / f4+1 / f5, f4 denotes the focal length of the fourth lens, f5 denotes the focal length of the fifth lens, f 45 denotes the combined focal length of the fourth and fifth lenses, and EFL denotes the effective focal length of the optical lens.

2. The optical lens of claim 1, wherein, Also satisfies the following conditional expression: 1.1 ≤ |f 12 EFL| ≤ 2.4, where 1 / f 12 = 1 / f1 + 1 / f2, f1 denotes the focal length of the first lens, f2 denotes the focal length of the second lens, f 12 denotes the combined focal length of the first lens and the second lens, and EFL denotes the effective focal length of the optical lens.

3. The optical lens of claim 1, wherein, Also, the following conditional expression is satisfied: 1.9 ≤ |f 12 / f 45 ≤ 2.7, where 1 / f 12 = 1 / f1 + 1 / f2, f1 denotes the focal length of the first lens, f2 denotes the focal length of the second lens, f 12 denotes the combined focal length of the first lens and the second lens, 1 / f 45 = 1 / f4 + 1 / f5, f4 denotes the focal length of the fourth lens, f5 denotes the focal length of the fifth lens, f 45 denotes the combined focal length of the fourth lens and the fifth lens.

4. The optical lens of claim 1, wherein, Also, the following conditional expression is satisfied: |f3 / f 12 |≥1.2, where 1 / f 12 =1 / f1+1 / f2, f1 denotes the focal length of the first lens, f2 denotes the focal length of the second lens, f 12 denotes the combined focal length of the first lens and the second lens, and f3 denotes the focal length of the third lens.

5. The optical lens of claim 1, wherein, the following conditional expression is also satisfied: 0.45≤EPD / TTL≤0.6, wherein EPD represents the entrance pupil diameter of the optical lens, and TTL represents the distance on the optical axis from the center of the object side surface of the first lens to the imaging surface of the optical lens.

6. The optical lens of claim 1, wherein, the following conditional expression is also satisfied: BFL / TTL≥0.15, wherein BFL represents the distance on the optical axis from the center of the image side surface of the fifth lens to the imaging surface of the optical lens, and TTL represents the distance on the optical axis from the center of the object side surface of the first lens to the imaging surface of the optical lens.

7. The optical lens of claim 1, wherein, and the following conditional expression is also satisfied: dn / dt(2) + dn / dt(4) ≥ -5 x 10 -6 dn / dt(2) + dn / dt(4) ≥ -5 x 10-4 / °C, dn / dt(2) represents the coefficient of the change in the refractive index of the material of the second lens with temperature, dn / dt(4) represents the coefficient of the change in the refractive index of the material of the fourth lens with temperature, and dn / dt(2) is negative and dn / dt(4) is negative, n representing the refractive index of the material of the lens and t representing the temperature.

8. A lidar, comprising: The application further provides an optical system comprising the optical lens. The optical system comprises: a receiving end for collecting light returned from the outside, which comprises a receiving lens and a photoelectric device, the receiving lens converging the collected light to the photoelectric device, and the receiving lens being the optical lens according to any one of claims 1 to 7; 9. The lidar of claim 8, wherein, a transmitting end comprising a light source and a projecting lens, the projecting lens being used for projecting the light emitted by the light source, and the projecting lens being the optical lens according to any one of claims 1 to 7.

10. The lidar of claim 8, wherein, When the light source is a dot array light source, the light source is arranged at a position deviating from the focal plane of the projecting lens, so that the light projected by the projecting lens is uniformly distributed in a surface array; or when the light source is a dot array light source, the optical system further comprises a light homogenizing device arranged on the light emitting side of the projecting lens, which is used for uniformly distributing the light projected by the projecting lens in a surface array after the light passes through the light homogenizing device. The projecting lens is an optical lens obtained by reducing the size of the receiving lens according to a predetermined ratio.

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