Objective lens system for laser radar and laser radar

Abstract

The present invention discloses an objective lens system for a laser radar, wherein the objective lens system includes a first optical element, a second optical element, a third optical element, a fourth optical element, a fifth optical element, a sixth optical element, a seventh optical element and an eighth optical element in sequence from the object side to the image side along the optical axis direction; the first optical element, the second optical element, the third optical element, the fourth optical element and the fifth optical element are a front group objective lens, and the sixth optical element, the seventh optical element and the eighth optical element are a rear group objective lens; the ratio of the focal length of the front group objective lens to the objective lens system is greater than 14.881 and less than 16.447, and the ratio of the focal length of the rear group objective lens to the objective lens system is greater than 0.926 and less than 1.024. The present invention, on the basis of configuring only eight optical elements, reasonably sets the focal lengths of the front group objective lens and the rear group objective lens, so that the objective lens system has a higher resolution and a simple structure.

Description

Technical Field

[0001] The present invention relates to the field of detection, and in particular to an objective lens system for a laser radar and a laser radar. Background Art

[0002] Lidar is a radar system that emits laser beams to detect the position, speed and other characteristic quantities of a target. Its working principle is to emit a detection signal (laser beam) to the target, and then compare the received signal reflected from the target (target echo) with the transmitted signal. After appropriate processing, relevant information about the target can be obtained, such as target distance, direction, height, speed, attitude, and even shape parameters, so as to detect, track and identify targets such as aircraft and missiles. It consists of a laser transmitter, an optical receiver, a turntable and an information processing system. The laser converts electrical pulses into light pulses and emits them. The optical receiver then converts the light pulses reflected from the target into electrical pulses and sends them to the display.

[0003] Although the current LiDAR solution of using MEMS for 2D scanning and acquiring echo signals point by point may be able to suppress ambient light better, it sacrifices a lot of energy and the speed of acquiring echo signals is very slow, resulting in a low frame rate of the point cloud map. Summary of the invention

[0004] The object of the present invention is to provide an objective lens system for a laser radar and a laser radar, which have high resolution and simple structure.

[0005] In order to achieve the above-mentioned objectives, in a first aspect, the present invention provides an objective system for a laser radar, wherein the objective system includes a first optical element, a second optical element, a third optical element, a fourth optical element, a fifth optical element, a sixth optical element, a seventh optical element and an eighth optical element in sequence from the object side to the image side along the optical axis direction; the first optical element, the second optical element, the fifth optical element, the sixth optical element, the seventh optical element and the eighth optical element all have a positive focal length, and the third optical element and the fourth optical element all have a negative focal length; the first optical element, the second optical element, the third optical element, the fourth optical element and the fifth optical element are a front group of objective lenses, and the sixth optical element, the seventh optical element and the eighth optical element are a rear group of objective lenses; the ratio of the focal length of the front group of objective lenses to the focal length of the objective lens system is greater than 14.881 and less than 16.447, and the ratio of the focal length of the rear group of objective lenses to the focal length of the objective lens system is greater than 0.926 and less than 1.024.

[0006] Preferably, the first optical element, the second optical element, the third optical element, the fourth optical element, the seventh optical element and the eighth optical element are all spherical lenses, the fifth optical element and the sixth optical element are both doublet lenses, and the objective system further comprises an aperture stop, which is located between the fifth optical element and the sixth optical element.

[0007] Preferably, the image side surface of the first optical element is convex, and the object side surface is concave; the image side surface of the second optical element is convex, and the object side surface is concave; the image side surface of the third optical element is convex, and the object side surface is concave; the image side surface of the fourth optical element is convex, and the object side surface is concave; the image side surface of the fifth optical element is concave, and the object side surface is convex; the image side surface of the sixth optical element is concave, and the object side surface is convex; the image side surface of the seventh optical element is concave, and the object side surface is convex; the image side surface of the eighth optical element is convex, and the object side surface is convex.

[0008] Preferably, the ratio of the focal length of the first optical element to the focal length of the front-group objective lens is greater than 0.33 and less than 0.35; the ratio of the focal length of the second optical element to the focal length of the front-group objective lens is greater than 0.306 and less than 0.324; the ratio of the focal length of the third optical element to the focal length of the front-group objective lens is greater than -0.089 and less than -0.083; the ratio of the focal length of the fourth optical element to the focal length of the front-group objective lens is greater than -1.681 and less than -1.583; the ratio of the focal length of the fifth optical element to the focal length of the front-group objective lens is greater than -1.856 and less than 0.203.

[0009] Preferably, the ratio of the focal length of the sixth optical element to the focal length of the rear objective lens is greater than -31.779 and less than -29.928; the ratio of the focal length of the seventh optical element to the focal length of the rear objective lens is greater than 3.013 and less than 3.199; the ratio of the focal length of the eighth optical element to the focal length of the rear objective lens is greater than -1.970 and less than -1.856.

[0010] Preferably, the refractive index of the first optical element, the second optical element, the third optical element, the fourth optical element, the seventh optical element and the eighth optical element is 1.92, and the dispersion coefficient of the first optical element, the second optical element, the third optical element, the fourth optical element, the seventh optical element and the eighth optical element is 20.9.

[0011] Preferably, the fifth optical element is formed by bonding a first bonded lens and a second bonded lens, and the sixth optical element is formed by bonding a third bonded lens and a fourth bonded lens; the refractive index of the first bonded lens is 1.51, the refractive index of the second bonded lens is 1.92, the refractive index of the third bonded lens is 1.90, and the refractive index of the fourth bonded lens is 1.52; the dispersion coefficient of the first bonded lens is 63.4, the dispersion coefficient of the second bonded lens is 20.9, the dispersion coefficient of the third bonded lens is 37.1, and the dispersion coefficient of the fourth bonded lens is 59.0.

[0012] Preferably, the distance between the geometric center of the image side optical axis of the first optical element and the geometric center of the object side optical axis of the second optical element is 0.100 mm, the distance between the geometric center of the image side optical axis of the second optical element and the geometric center of the object side optical axis of the third optical element is 0.100 mm, the distance between the geometric center of the image side optical axis of the third optical element and the geometric center of the object side optical axis of the fourth optical element is 5.653 mm, the distance between the geometric center of the image side optical axis of the fourth optical element and the geometric center of the object side optical axis of the fifth optical element is 3.335 mm, and the distance between the geometric center of the image side optical axis of the fifth optical element is 0.100 mm. The distance between the geometric center of the axis and the geometric center of the object side optical axis of the aperture is 0.100 mm, the distance between the geometric center of the image side optical axis of the aperture and the geometric center of the object side optical axis of the sixth optical element is 6.667 mm, the distance between the geometric center of the image side optical axis of the sixth optical element and the geometric center of the object side optical axis of the seventh optical element is 0.100 mm, the distance between the geometric center of the image side optical axis of the seventh optical element and the geometric center of the object side optical axis of the eighth optical element is 0.100 mm, and the distance between the geometric center of the image side optical axis of the eighth optical element and the geometric center of the imaging surface is 16.00 mm.

[0013] Preferably, the ratio of the focal length to the clear aperture of the objective lens system is 1.4, the field of view angle is 56 degrees, and the adapted wavelength of the objective lens system is 905 nanometers.

[0014] In a second aspect, the present invention further provides a laser radar, comprising an array detector and the objective system for the laser radar of the first aspect, wherein the array detector is used to focus the image formed by the objective system.

[0015] Compared with the prior art, the present invention, on the basis of configuring only eight optical elements, reasonably sets the focal length of the front group objective lens and the focal length of the rear group objective lens, so that the objective lens system has higher resolution and simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural diagram of an objective lens system for a laser radar according to an embodiment of the present invention.

[0017] Figure 2 This is a light path diagram of an objective lens system used for a laser radar according to an embodiment of the present invention.

[0018] Figure 3 This is a spatial frequency MTF diagram of the objective lens system used for laser radar according to an embodiment of the present invention.

[0019] Figure 4 This is a field curvature diagram of an objective lens system used for a laser radar according to an embodiment of the present invention.

[0020] Figure 5 This is a distortion curve diagram of the objective lens system used for laser radar according to an embodiment of the present invention.

[0021] Figure 6 This is a relative illumination diagram of an objective lens system used for a laser radar according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to explain the technical content, structural features and achieved effects of the present invention in detail, the following is a detailed description in conjunction with the implementation methods and the accompanying drawings.

[0023] like Figure 1 to Figure 2 As shown, an embodiment of the present invention provides an objective lens system for a laser radar, wherein the objective lens system includes a first optical element 1, a second optical element 2, a third optical element 3, a fourth optical element 4, a fifth optical element 5, a sixth optical element 6, a seventh optical element 7 and an eighth optical element 8 in sequence from the object side to the image side along the optical axis direction; the first optical element 1, the second optical element 2, the fifth optical element 5, the sixth optical element 6, the seventh optical element 7 and the eighth optical element 8 all have a positive focal length, and the third optical element 3 and the fourth optical element 4 all have a negative focal length; the first optical element 1, the second optical element 2, the third optical element 3, the fourth optical element 4 and the fifth optical element 5 are a front group objective lens, and the sixth optical element 6, the seventh optical element 7 and the eighth optical element 8 are a rear group objective lens; the ratio of the focal length of the front group objective lens to the focal length of the objective lens system is greater than 14.881 and less than 16.447, and the ratio of the focal length of the rear group objective lens to the focal length of the objective lens system is greater than 0.926 and less than 1.024.

[0024] Specifically, the ratio of the focal length of the front group objective lens to the focal length of the objective lens system is preferably 15.664, and the ratio of the focal length of the rear group objective lens to the focal length of the objective lens system is preferably 0.975.

[0025] The embodiment of the present invention configures only eight optical elements and reasonably sets the focal length of the front objective lens group and the focal length of the rear objective lens group, so that the objective lens system has a higher resolution and a simple structure.

[0026] In the embodiment of the present invention, the first optical element 1, the second optical element 2, the third optical element 3, the fourth optical element 4, the seventh optical element 7 and the eighth optical element 8 are all spherical lenses, and the fifth optical element 5 and the sixth optical element 6 are both double-cemented lenses. The embodiment of the present invention adopts spherical lenses, which can effectively save costs.

[0027] In the embodiment of the present invention, the ratio of the focal length of the first optical element 1 to the focal length of the front objective lens is greater than 0.33 and less than 0.35; the ratio of the focal length of the second optical element 2 to the focal length of the front objective lens is greater than 0.306 and less than 0.324; the ratio of the focal length of the third optical element 3 to the focal length of the front objective lens is greater than -0.089 and less than -0.083; the ratio of the focal length of the fourth optical element 4 to the focal length of the front objective lens is greater than -1.681 and less than -1.583; the ratio of the focal length of the fifth optical element 5 to the focal length of the front objective lens is greater than 0.191 and less than 0.203.

[0028] Specifically, the ratio of the focal length of the first optical element 1 to the focal length of the front group objective lens is preferably 0.34; the ratio of the focal length of the second optical element 2 to the focal length of the front group objective lens is preferably 0.315; the ratio of the focal length of the third optical element 3 to the focal length of the front group objective lens is preferably -0.086; the ratio of the focal length of the fourth optical element 4 to the focal length of the front group objective lens is preferably -1.632; the ratio of the focal length of the fifth optical element 5 to the focal length of the front group objective lens is preferably 0.197.

[0029] In the embodiment of the present invention, the ratio of the focal length of the sixth optical element 6 to the focal length of the rear objective lens is greater than -31.779 and less than -29.928; the ratio of the focal length of the seventh optical element 7 to the focal length of the rear objective lens is greater than 3.013 and less than 3.199; the ratio of the focal length of the eighth optical element 8 to the focal length of the rear objective lens is greater than -1.970 and less than -1.856.

[0030] Specifically, the ratio of the focal length of the sixth optical element 6 to the focal length of the rear objective lens is preferably -30.854; the ratio of the focal length of the seventh optical element 7 to the focal length of the rear objective lens is preferably 3.106; the ratio of the focal length of the eighth optical element 8 to the focal length of the rear objective lens is preferably -1.913.

[0031] In the embodiment of the present invention, the objective lens system further comprises an aperture 9, wherein the aperture 9 is located between the fifth optical element 5 and the sixth optical element 6, and the aperture 9 divides the objective lens system into the front objective lens group and the rear objective lens group.

[0032] In the embodiment of the present invention, the refractive index of the first optical element 1, the second optical element 2, the third optical element 3, the fourth optical element 4, the seventh optical element 7 and the eighth optical element 8 are all 1.92, and the dispersion coefficient of the first optical element 1, the second optical element 2, the third optical element 3, the fourth optical element 4, the seventh optical element 7 and the eighth optical element 8 are all 20.9.

[0033] In the embodiment of the present invention, the fifth optical element 5 is formed by bonding a first cemented lens 51 and a second cemented lens 52, and the sixth optical element 6 is formed by bonding a third cemented lens 61 and a fourth cemented lens 62; the refractive index of the first cemented lens 51 is 1.51, the refractive index of the second cemented lens 52 is 1.92, the refractive index of the third cemented lens 61 is 1.90, and the refractive index of the fourth cemented lens 62 is 1.52; the dispersion coefficient of the first cemented lens 51 is 63.4, the dispersion coefficient of the second cemented lens 52 is 20.9, the dispersion coefficient of the third cemented lens 61 is 37.1, and the dispersion coefficient of the fourth cemented lens 62 is 59.0. The embodiment of the present invention adopts cemented lenses to obtain short focal length, large magnification and good imaging quality.

[0034] In the embodiment of the present invention, the image side surface of the first optical element 1 is convex, and the object side surface is concave; the image side surface of the second optical element 2 is convex, and the object side surface is concave; the image side surface of the third optical element 3 is convex, and the object side surface is concave; the image side surface of the fourth optical element 4 is convex, and the object side surface is concave; the image side surface of the fifth optical element 5 is concave, and the object side surface is convex; the image side surface of the sixth optical element 6 is concave, and the object side surface is convex; the image side surface of the seventh optical element 7 is concave, and the object side surface is convex; the image side surface of the eighth optical element 8 is convex, and the object side surface is convex. The fifth optical element 5 is formed by gluing a first glued lens 51 and a second glued lens 52, wherein the image side surface of the first glued lens 51 is concave and the object side surface is concave; the image side surface of the second glued lens 52 is convex and the object side surface is convex; the sixth optical element 6 is formed by gluing a third glued lens 61 and a fourth glued lens 62, wherein the image side surface of the third glued lens 61 is concave and the object side surface is concave; the image side surface of the fourth glued lens 62 is convex and the object side surface is convex.

[0035] Specifically, in the embodiment of the present invention, the radius of curvature of the object side of the first optical element 1 is 38.4709 mm, the radius of curvature of the image side of the first optical element 1 is 69.5068 mm, the distance from the geometric center of the optical axis of the object side of the first optical element 1 to the geometric center of the optical axis of the image side (i.e., the thickness of the first optical element 1) is 4.710 mm, the radius of curvature of the object side of the second optical element 2 is 24.7663 mm, the radius of curvature of the image side of the second optical element 2 is 34.0385 mm, the distance from the geometric center of the optical axis of the object side of the second optical element 2 to the geometric center of the optical axis of the image side (i.e., the thickness of the second optical element 2) is 4.384 mm, and the radius of curvature of the object side of the third optical element 3 is 16 .995mm, the radius of curvature of the image side of the third optical element 3 is 89.976mm, the distance from the geometric center of the optical axis of the object side of the third optical element 3 to the geometric center of the optical axis of the image side (i.e. the thickness of the third optical element 3) is 1.000mm, the radius of curvature of the object side of the fourth optical element 4 is 23.217mm, the radius of curvature of the image side of the fourth optical element 4 is 21.448mm, the distance from the geometric center of the optical axis of the object side of the fourth optical element 4 to the geometric center of the optical axis of the image side (i.e. the thickness of the fourth optical element 4) is 1.000mm, the fifth optical element 5 is formed by gluing a first glued lens 51 and a second glued lens 52, and the radius of curvature of the object side of the first glued lens 51 is -25.07mm. 7mm, the curvature radius of the image side surface of the first cemented lens 51 and the curvature radius of the object side surface of the second cemented lens 52 are the same, both of which are 97.8975mm, the curvature radius of the image side surface of the second cemented lens 52 is -26.253mm, the distance from the geometric center of the optical axis of the object side surface of the first cemented lens 51 to the geometric center of the optical axis of its image side surface (i.e. the thickness of the first cemented lens 51) is 1.000mm, the distance from the geometric center of the optical axis of the object side surface of the second cemented lens 52 to the geometric center of the optical axis of its image side surface (i.e. the thickness of the second cemented lens 52) is 2.865mm, the curvature radius of the aperture 9 is infinite, and the sixth optical element 6 is formed by cementing the third cemented lens 61 and the fourth cemented lens 62. The radius of curvature of the object side surface of the third cemented lens 61 is -30.0027mm, the radius of curvature of the image side surface of the third cemented lens 61 is the same as the radius of curvature of the object side surface of the fourth cemented lens 62, both of which are 45.5993mm, the radius of curvature of the image side surface of the fourth cemented lens 62 is -17.1466mm, the distance from the geometric center of the optical axis of the object side surface of the third cemented lens 61 to the geometric center of the optical axis of its image side surface (i.e. the thickness of the third cemented lens 61) is 1.000mm, the distance from the geometric center of the optical axis of the object side surface of the fourth cemented lens 62 to the geometric center of the optical axis of its image side surface (i.e. the thickness of the fourth cemented lens 62) is 7.295mm, and the radius of curvature of the object side surface of the seventh optical element 7 is -59.02378mm, the curvature radius of the image side surface of the seventh optical element 7 is -26.5978mm, the distance between the geometric center of the optical axis of the object side surface of the seventh optical element 7 and the geometric center of the optical axis of the image side surface (i.e. the thickness of the seventh optical element 7) is 4.139mm, the curvature radius of the object side surface of the eighth optical element 8 is 30.20668mm, the curvature radius of the image side surface of the eighth optical element 8 is -369.5884mm, and the distance between the geometric center of the optical axis of the object side surface of the eighth optical element 8 and the geometric center of the optical axis of the image side surface (i.e. the thickness of the eighth optical element 8) is 6.453mm.

[0036] In some other embodiments, the structures of the image-side surface and the object-side surface of the first optical element 1, the second optical element 2, the third optical element 3, the fourth optical element 4, the fifth optical element 5, the sixth optical element 6, the seventh optical element 7 and the eighth optical element 8 can be other structures, as long as the first optical element 1, the second optical element 2, the fifth optical element 5, the sixth optical element 6, the seventh optical element 7 and the eighth optical element 8 all have a positive focal length, and the third optical element 3 and the fourth optical element 4 all have a negative focal length and meet the focal length requirements.

[0037] In the embodiment of the present invention, the distance between the geometric center of the image side optical axis of the first optical element 1 and the geometric center of the object side optical axis of the second optical element 2 (i.e., the spacing between the first optical element 1 and the second optical element 2) is 0.100 mm, the distance between the geometric center of the image side optical axis of the second optical element 2 and the geometric center of the object side optical axis of the third optical element 3 (i.e., the spacing between the second optical element 2 and the third optical element 3) is 0.100 mm, the distance between the geometric center of the image side optical axis of the third optical element 3 and the geometric center of the object side optical axis of the fourth optical element 4 (i.e., the spacing between the third optical element 3 and the fourth optical element 4) is 5.653 mm, the distance between the geometric center of the image side optical axis of the fourth optical element 4 and the geometric center of the object side optical axis of the fifth optical element 5 (i.e., the spacing between the fourth optical element 4 and the fifth optical element 5) is 3.335 mm, and the distance between the geometric center of the image side optical axis of the fifth optical element 5 is 0.100 mm. The distance between the geometric center of the image side optical axis of the aperture 9 and the geometric center of the object side optical axis of the sixth optical element 6 (i.e. the distance between the aperture 9 and the sixth optical element 6) is 6.667 mm, the distance between the geometric center of the image side optical axis of the sixth optical element 6 and the geometric center of the object side optical axis of the seventh optical element 7 (i.e. the distance between the sixth optical element 6 and the seventh optical element 7) is 0.100 mm, the distance between the geometric center of the image side optical axis of the seventh optical element 7 and the geometric center of the object side optical axis of the eighth optical element 8 (i.e. the distance between the seventh optical element 7 and the eighth optical element 8) is 0.100 mm, and the distance between the geometric center of the image side optical axis of the eighth optical element 8 and the geometric center of the imaging plane 10 (i.e. the distance between the eighth optical element 8 and the imaging plane 10) is 16 mm.

[0038] In the embodiment of the present invention, the ratio F / # of the focal length and the aperture of the objective lens system is 1.4, the field of view FOV is 56 degrees, and the adaptive wavelength of the objective lens system is 905 nanometers. A smaller F / # value indicates that the light spot itself has better convergence and high brightness, so the energy is smaller and no energy is wasted.

[0039] Figure 3 : This is a spatial frequency MTF index diagram of the objective lens system of an embodiment of the present invention. The MTF (Modulation Transfer Function) index is a more accurate and scientific evaluation standard for objective lenses. Figure 3 In the figure, the ordinate is contrast, the closer it is to 1, the better the imaging quality of the objective system; the abscissa represents resolution, in units of line pairs per millimeter. In general, the objective lens requires the contrast of each field of view to be above 0.3, and Figure 3 It can be seen that the contrast of most of the viewing fields in the embodiments of the present application is greater than 0.5, which indicates that the imaging quality is relatively high.

[0040] Figure 4 It is a field curvature diagram of the objective lens system of an embodiment of the present invention, where the abscissa is the field curvature value and the ordinate is the field angle; Figure 5 : is the distortion curve diagram of the objective lens system in this embodiment, the horizontal axis is the distortion amount, and the vertical axis is the field of view angle. Figure 4 and Figure 5 It can be seen that the absolute value of the field curvature of the objective lens system in this embodiment is within 0.25 mm, and the distortion is within 0.2%. The field curvature and distortion are both excellent, ensuring uniform imaging clarity and high imaging quality across the entire screen.

[0041] Figure 6 : is a relative illumination diagram of the objective lens system of this embodiment. The relative illumination is mainly used to describe the spectrum of the relative energy intensity change of the final image formed by the objective lens system on the imaging surface 10 as the field of view changes. Figure 6 It can be seen that the energy uniformity of the image finally formed by the objective lens system is very high. When the objective lens system is applied to the laser radar, this will be beneficial to the consistent perception intensity of the center and the edge during the detection process of the laser radar.

[0042] In the embodiment of the present invention, the focal length of the objective lens system and the aperture of the diaphragm 9 are reasonably designed to improve the brightness of the objective lens system. At the same time, through the reasonable lens structure design and the parameter design of each lens, it is ensured that the field curvature and distortion of the lens are very excellent, the energy distribution of the entire picture is uniform, and the imaging quality is high. In addition, in the embodiment of the present invention, the tolerance redundancy of the objective lens system is large. Specifically, the thickness of each optical element can fluctuate within the range of ±0.04mm, the spacing between the optical elements can fluctuate within the range of ±0.04mm, the curvature radius of the optical element can fluctuate within the range of 3 Newton rings, and the matching clearance between the optical element and the lens barrel can reach 0.04mm, which improves the success rate of assembly. The structural design of the objective lens system is very reasonable.

[0043] The embodiment of the present invention further provides a laser radar, including an array detector and the above-mentioned objective lens system for the laser radar, wherein the array detector is used to focus the image formed by the objective lens system. Specifically, the imaging surface 10 of the objective lens system corresponds to the array detector, that is, the objective lens system is imaged on the array detector, and the detector array pixel size used in the embodiment of the present application is 100um, and the corresponding design resolution is 5 line pairs per millimeter. This embodiment is based on the array detector, and the overall imaging quality of the objective lens system is high.

[0044] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. An objective lens system for laser radar, Features: The objective lens system comprises a first optical element, a second optical element, a third optical element, a fourth optical element, a fifth optical element, a sixth optical element, a seventh optical element and an eighth optical element in order from the object side to the image side along the optical axis; the first optical element, the second optical element, the fifth optical element, the sixth optical element, the seventh optical element and the eighth optical element all have positive focal lengths, and the third optical element and the fourth optical element all have negative focal lengths; The first optical element, the second optical element, the third optical element, the fourth optical element and the fifth optical element are a front group objective lens, and the sixth optical element, the seventh optical element and the eighth optical element are a rear group objective lens; the ratio of the focal length of the front group objective lens to the focal length of the objective lens system is greater than 14.881 and less than 16.447, and the ratio of the focal length of the rear group objective lens to the focal length of the objective lens system is greater than 0.926 and less than 1.

024.

2. The objective lens system for laser radar according to claim 1, Features: The first optical element, the second optical element, the third optical element, the fourth optical element, the seventh optical element and the eighth optical element are all spherical lenses, the fifth optical element and the sixth optical element are both doublet lenses, and the objective lens system further includes an aperture stop, which is located between the fifth optical element and the sixth optical element.

3. The objective lens system for laser radar according to claim 1, Features: The image side surface of the first optical element is convex, and the object side surface is concave; the image side surface of the second optical element is convex, and the object side surface is concave; the image side surface of the third optical element is convex, and the object side surface is concave; the image side surface of the fourth optical element is convex, and the object side surface is concave; the image side surface of the fifth optical element is concave, and the object side surface is convex; the image side surface of the sixth optical element is concave, and the object side surface is convex; the image side surface of the seventh optical element is concave, and the object side surface is convex; the image side surface of the eighth optical element is convex, and the object side surface is convex.

4. The objective lens system for laser radar according to claim 1, Features: The ratio of the focal length of the first optical element to the focal length of the front-group objective lens is greater than 0.33 and less than 0.35; the ratio of the focal length of the second optical element to the focal length of the front-group objective lens is greater than 0.306 and less than 0.324; the ratio of the focal length of the third optical element to the focal length of the front-group objective lens is greater than -0.089 and less than -0.083; the ratio of the focal length of the fourth optical element to the focal length of the front-group objective lens is greater than -1.681 and less than -1.583; the ratio of the focal length of the fifth optical element to the focal length of the front-group objective lens is greater than -1.856 and less than 0.

203.

5. The objective lens system for laser radar according to claim 1, Features: The ratio of the focal length of the sixth optical element to the focal length of the rear objective lens is greater than -31.779 and less than -29.928; the ratio of the focal length of the seventh optical element to the focal length of the rear objective lens is greater than 3.013 and less than 3.199; the ratio of the focal length of the eighth optical element to the focal length of the rear objective lens is greater than -1.970 and less than -1.

856.

6. The objective lens system for laser radar according to claim 1, Features: The refractive indexes of the first optical element, the second optical element, the third optical element, the fourth optical element, the seventh optical element and the eighth optical element are all 1.92, and the dispersion coefficients of the first optical element, the second optical element, the third optical element, the fourth optical element, the seventh optical element and the eighth optical element are all 20.

9.

7. The objective lens system for laser radar according to claim 2, Features: The fifth optical element is formed by bonding the first cemented lens and the second cemented lens, and the sixth optical element is formed by bonding the third cemented lens and the fourth cemented lens; the refractive index of the first cemented lens is 1.51, the refractive index of the second cemented lens is 1.92, the refractive index of the third cemented lens is 1.90, and the refractive index of the fourth cemented lens is 1.52; the dispersion coefficient of the first cemented lens is 63.4, the dispersion coefficient of the second cemented lens is 20.9, the dispersion coefficient of the third cemented lens is 37.1, and the dispersion coefficient of the fourth cemented lens is 59.

0.

8. The objective lens system for laser radar as claimed in claim 2, Features: The distance between the geometric center of the image side optical axis of the first optical element and the geometric center of the object side optical axis of the second optical element is 0.100 mm, the distance between the geometric center of the image side optical axis of the second optical element and the geometric center of the object side optical axis of the third optical element is 0.100 mm, the distance between the geometric center of the image side optical axis of the third optical element and the geometric center of the object side optical axis of the fourth optical element is 5.653 mm, the distance between the geometric center of the image side optical axis of the fourth optical element and the geometric center of the object side optical axis of the fifth optical element is 3.335 mm, and the distance between the geometric center of the image side optical axis of the fifth optical element is 0.100 mm. The distance between the geometric center of the image side optical axis of the aperture and the geometric center of the object side optical axis of the sixth optical element is 6.667 mm, the distance between the geometric center of the image side optical axis of the sixth optical element and the geometric center of the object side optical axis of the seventh optical element is 0.100 mm, the distance between the geometric center of the image side optical axis of the seventh optical element and the geometric center of the object side optical axis of the eighth optical element is 0.100 mm, and the distance between the geometric center of the image side optical axis of the eighth optical element and the geometric center of the imaging surface is 16.00 mm.

9. The objective lens system for laser radar according to claim 1, It is characterized in that The ratio of the focal length to the clear aperture of the objective lens system is 1.4, the field angle is 56 degrees, and the adapted wavelength of the objective lens system is 905 nanometers.

10. A laser radar, Features: It comprises an array detector and an objective lens system for a laser radar as described in any one of claims 1 to 9, wherein the array detector is used to focus an image formed by the objective lens system.

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