Transmitting lens assembly, optical device and laser radar

Abstract

The invention provides an emission lens assembly, an optical device and a laser radar, and relates to the technical field of laser radars. The emission lens assembly comprises a double-convex cylindrical lens, a meniscus cylindrical lens and a plurality of micro-cylindrical lenses. The meniscus cylindrical lens is located in the light emitting direction of the double-convex cylindrical lens, and the meniscus cylindrical lens and the double-convex cylindrical lens are arranged in a spaced mode. At least one first light incident area is formed on a first light incident cambered surface of the meniscus cylinder lens, and the plurality of micro-cylinder lens arrays are distributed on the first light incident areas; laser beams emitted by the scanning laser light source enter the biconvex cylindrical lens, and the first light incident areas are in one-to-one correspondence with the laser beams; the double-convex cylindrical lens emits laser beams to the micro-cylindrical lenses in the first incident light areas in one-to-one correspondence, the micro-cylindrical lens on each first incident light area homogenizes the energy of the incident light beams and then emits the incident light beams to the meniscus cylindrical lens, and the meniscus cylindrical lens performs distortion correction on the incident light beams. According to the embodiment of the invention, the optical performance of the lens assembly can be emitted, so that the emitted laser beam has emission uniformity and stability.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to, but is not limited to, the technical field of laser radar, and particularly relates to a transmitting lens assembly, an optical device and a laser radar. BACKGROUND

[0002] A laser radar (LiDAR) system is a key component in modern remote sensing technology and is widely used in fields such as autonomous vehicles, unmanned aerial vehicles, and topographic mapping. Since the laser radar system measures the distance and speed of an object by emitting a laser pulse and receiving the reflected light, the performance of the laser radar system largely depends on the efficiency and accuracy of its optical components, especially the transmitting TX lens assembly at the transmitting end. In the prior art, the TX lens assembly usually faces several major challenges: first, the optical efficiency of the TX lens may be insufficient, resulting in excessive loss of emitted laser energy and thus affecting the ranging capability of the system; second, the optical design of the TX lens may not be sufficient to ensure uniform distribution of the laser beam; and third, the occurrence of bad points during the use of the laser chip can greatly affect the uniformity of the laser beam. Therefore, in the prior art, the optical performance of the TX lens assembly applied to the laser radar is poor. Based on this, how to provide a transmitting lens assembly applied to the laser radar to improve the optical performance is a technical problem to be solved. SUMMARY

[0003] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims. The embodiment of the present application provides a transmitting lens assembly, an optical device and a laser radar, which can improve the optical performance of the transmitting lens assembly applied to the laser radar, so that the emitted laser beam has emission uniformity and stability.

[0004] In a first aspect, the transmitting lens assembly according to the embodiment of the present application comprises: a lenticular lens; a meniscus lens, the meniscus lens being located in the light-emitting direction of the lenticular lens and being arranged at intervals with the lenticular lens; at least one first light-in area is formed on a first light-in arc surface of the meniscus lens, a plurality of micro-lens arrays, the plurality of micro-lens arrays being arrayed on each of the first light-in areas; wherein the laser beam emitted by the scanning laser light source is incident on the lenticular lens, the first light-in area corresponds to the scanning laser light source one by one; the lenticular lens emits the laser beam to the micro-lens in the corresponding first light-in area, and the micro-lens on each first light-in area emits the incident light beam energy after uniformization to the meniscus lens, and the meniscus lens corrects the distortion of the incident light beam.

[0005] Therefore, the above-mentioned embodiments of the present application have at least the following beneficial effects: the optical focusing can be realized by the lenticular lens and the meniscus lens, and the light beam energy homogenization of the light beam emitted by the lenticular lens can be realized by the micro-lens corresponding to the laser beam in the first light-in area of the meniscus lens, so that the uniformity of the energy of the light beam entering the meniscus lens can be improved, at this time, the lenticular lens can limit the field of view angle in the scanning direction, and the micro-lens can limit the field of view angle in the non-scanning direction, so that the light emitted by the meniscus lens can realize the homogenization of the light beam and the more concentrated energy. Therefore, compared with the related art, the embodiments of the present application can improve the optical performance of the transmitting lens assembly applied to the laser radar, so that the emitted laser beam has the emission uniformity and stability.

[0006] According to some embodiments of the first aspect of the present application, the first light-out arc surface and the second light-in arc surface of the lenticular lens are both even aspheric surfaces.

[0007] According to some embodiments of the first aspect of the present application, the second light-out arc surface and the first light-in arc surface of the meniscus lens are both even aspheric surfaces.

[0008] According to some embodiments of the first aspect of the present application, the second light-in arc surface of the lenticular lens is provided with a plurality of second light-in areas, and each of the second light-in areas one-to-one corresponds to one of the scanning laser light sources; the lenticular lens is used for refracting the laser light beams incident on each of the second light-in areas to the corresponding first light-in area, wherein at least two of the first light-in areas partially overlap.

[0009] According to some embodiments of the first aspect of the present application, the total field of view angle in the scanning direction corresponding to the plurality of second light-in areas of the lenticular lens is greater than the total field of view angle in the non-scanning direction of each of the micro-lenses.

[0010] According to some embodiments of the first aspect of the present application, the curvature of the first light-in arc surface is determined according to the expansion direction of the micro-lens and the scanning direction field of view angle of the lenticular lens, wherein the scanning direction field of view angle is one-to-one corresponding to the first light-in area.

[0011] According to some embodiments of the first aspect of the present application, the ratio between the arc surface radii of the first light-in arc surface and the second light-out arc surface of the meniscus lens is 8:9; and / or; The ratio between the thickness of the meniscus lens and the thickness of the lenticular lens is 2:3.3; and / or; The ratio between the light source size of the scanning laser light source, the distance between the lenticular lens and the meniscus lens, and the thickness of the lenticular lens is 3.4:3.1:3.3.

[0012] In a second aspect, an optical device is provided, which includes the emission lens assembly of any of the first aspect.

[0013] In a third aspect, a lidar is provided, which includes: a scanning laser light source; The optical device of the second aspect, wherein the scanning laser light source is configured to provide a laser beam to the optical device. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of this specification that is made of the description of the application together with the embodiments of the present application to explain the technical scheme of the present application, and do not constitute a limitation on the technical scheme of the present application.

[0015] Figure 1 is a structural schematic diagram of an emission lens assembly according to an embodiment of the present application; Figure 2 is a schematic diagram of an optical path in a scanning direction of the emission lens assembly according to an embodiment of the present application; Figure 3 is a schematic diagram of an optical path in a non-scanning direction of the emission lens assembly according to an embodiment of the present application.

[0016] Reference signs: biconical cylindrical lens 100, meniscus cylindrical lens 200, microcylindrical lens 300. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not intended to limit the present application.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application, and are not intended to limit the present application. The terms "first", "second", "third", "fourth" and the like (if any) in the specification and the above drawings of the present application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0019] Moreover, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the

[0020] Laser radar (LiDAR) systems are key components in modern remote sensing technology, widely used in autonomous vehicles, drones, topographic mapping, and other fields. Since laser radar systems measure the distance and speed of objects by emitting laser pulses and receiving the reflected light, the performance of laser radar systems largely depends on the efficiency and accuracy of their optical components, especially the transmitting TX lens assembly. In the prior art, TX lens assemblies often face several major challenges: first, the optical efficiency of the TX lens may be insufficient, resulting in excessive loss of emitted laser energy and affecting the ranging ability of the system; second, the optical design of the TX lens may not be sufficient to ensure uniform distribution of the laser beam; and third, the presence of bad points during the use of the laser chip can greatly affect the uniformity of the laser beam. Therefore, in the prior art, the optical performance of TX lens assemblies applied to laser radars is poor. Based on this, how to provide a transmitting lens assembly applied to a laser radar to improve the optical performance is a technical problem to be solved. Therefore, the embodiments of the present application provide a transmitting lens assembly, an optical device, and a laser radar, which can improve the optical performance of the transmitting lens assembly applied to the laser radar, so that the emitted laser beam has emission uniformity and stability.

[0021] Reference is made below to Figures 1 to 3 The transmitting lens assembly of the embodiments of the present application is described, wherein, Figure 1 The arrow in the above formula indicates that the advancing direction of the light beam is from the lenticular lens to the meniscus lens, Figure 2 And Figure 3 In the above formula, a, b, and c respectively represent different scanning laser light sources. The illumination ranges of a, b, and c can be the same or different, and the illumination angles of a, b, and c towards the lenticular lens are different from each other. The area enclosed by the line segments of the same type is the light beam direction of the same type of scanning laser light source.

[0022] In a first aspect, the transmitting lens assembly according to the embodiments of the present application comprises: a lenticular lens 100; a meniscus lens 200, the meniscus lens 200 is located in the light emitting direction of the lenticular lens 100 and is arranged at intervals with the lenticular lens 100; at least one first light inlet area is formed on the first light inlet arc surface of the meniscus lens 200, a plurality of micro-lens columns 300, the plurality of micro-lens columns 300 are arrayed on each first light-in area; Wherein, the laser beams emitted by the scanning laser light source are incident on the lenticular lens 100, and each first light-in area corresponds to a scanning laser light source; the lenticular lens 100 emits the laser beams to the micro-lens columns 300 in the corresponding first light-in area; the micro-lens columns 300 on each first light-in area emit the incident light beams after uniformization to the meniscus lens 200, and the meniscus lens 200 corrects the distortion of the incident light beams.

[0023] Therefore, the optical focusing can be realized by the lenticular lens 100 and the meniscus lens 200, and the micro-lens columns 300 corresponding to the laser beams are arranged in the first light-in area of the meniscus lens 200, the micro-lens columns 300 can uniformize the light beams emitted by the lenticular lens 100, so that the uniformity of the energy of the light beams entering the meniscus lens 200 can be improved, at this time, the lenticular lens 100 can limit the field of view angle in the scanning direction, and the micro-lens columns 300 can limit the field of view angle in the non-scanning direction, so that the light beams emitted by the meniscus lens 200 can be uniformized and the energy is more concentrated. Therefore, the optical performance of the transmitting lens assembly applied to the laser radar can be improved, and the emitted laser beams have uniformity and stability.

[0024] The first light-out arc surface and the second light-in arc surface of the lenticular lens 100 are both convex cylindrical lenses, the cross section is in the shape of a “convex lens” (convex on both sides), and the cross section along the axial direction (non-refractive direction) is rectangular or straight. The lenticular lens 100 has curvature only in one direction (refractive direction), and the other direction (non-refractive direction) is flat or straight, and the effect on the incident light beams has “one-dimensionality”.

[0025] The surface of the meniscus lens 200 is composed of a convex second light-out arc surface and a concave first light-in arc surface, and the centers of curvature of the two arc surfaces are located on the same side of the lens. It has a certain length in one direction (i.e. axial direction), and has a certain radius of curvature in the other direction (perpendicular to the axial direction), for specific refraction and focusing of light.

[0026] The number of scanning laser light sources supported by the lenticular lens 100 is not limited in the embodiment of the application, and can be selectively set by those skilled in the art according to actual needs. Different scanning laser light sources have different second light-in areas incident on the second light-in arc surface of the lenticular lens 100. Each second light-in area does not overlap. The first light-in area and the second light-in area are arranged one by one. The lenticular lens 100 is used to determine the field of view angle of the scanning laser light source in the scanning direction, such as Figure 2As shown, when the laser light beams from the scanning laser light source a, the scanning laser light source b, and the scanning laser light source c in different areas are incident on their respective corresponding second light incident areas, the laser light beams in different areas are refracted after passing through the double convex lens 100. At this time, different scanning laser light sources correspond to different field angles, and the field angles formed by the three different scanning laser light sources are superimposed to form the total field angle in the scanning direction.

[0027] The embodiments of the present application do not limit the spacing distance between the meniscus lens 200 and the biconvex lens 100. The radius of the front surface of the meniscus lens 200 is set in a one-to-one correspondence with the spacing. In some embodiments, the radius (R) of the front surface of the meniscus lens 200 and the spacing between the meniscus lens 200 and the biconvex lens 100 can be adjusted according to the distortion correction amount of the light emitted by the meniscus lens 200 to determine whether the distortion correction amount and the lens size of the meniscus lens 200 are met (such as the front surface radius and spacing of the meniscus lens 200). Different spacings correspond to different Rs, and the smaller the spacing, the smaller the size of the meniscus lens 200. In practical applications, the optical path of the meniscus lens 200 and the biconvex lens 100 can be simulated to select the radius and spacing of the meniscus lens 200 that meet the distortion correction amount and lens size requirements. Among them, the R of the rear surface of the meniscus lens 200 is determined according to the thickness of the lens. The meniscus lens 200 in the embodiment of the present application is a lens of equal thickness. Therefore, the R of the rear surface of the meniscus lens 200 is equal to the R of the front surface + thickness.

[0028] The embodiments of the present application can be applied to intelligent driving systems that assist cars in automatic parking, obstacle avoidance for robots and drones, and short-distance literacy scenarios.

[0029] The embodiment of the present application does not limit the spacing between the micro-cylindrical lenses 300. Multiple micro-cylindrical lenses 300 can split the light beam emitted by the lenticular lens 100 into sub-beams corresponding one to one with the micro-cylindrical lenses 300. The micro-cylindrical lenses 300 are arranged continuously. The smaller the aperture of the micro-cylindrical lens 300, the more sub-beams are split, and the more uniform the light output. Therefore, after determining the size of the meniscus lens 200 and the spacing between the meniscus lens 200 and the lenticular lens 100, the aperture of the micro-cylindrical lens 300 can be determined through simulation, thereby ensuring that the emission lens assembly of the embodiment of the present application can meet the uniformity of the output light.

[0030] It is understandable that the first light-emitting arc surface and the second light-incident arc surface of the lenticular lens 100 are both even-order aspherical surfaces.

[0031] By setting the first light-emitting arc surface and the second light-entering arc surface as even-order aspheric surfaces, the aberration between the light rays in the scanning direction can be reduced, thereby improving the stability of the optical performance.

[0032] It can be understood that the second light-out arc surface and the first light-in arc surface of the meniscus cylindrical lens 200 are both even aspheric surfaces.

[0033] The second light-in arc surface is the arc surface on the side of the light incidence direction, and the first light-out arc surface is the arc surface on the side of the light emission direction.

[0034] By setting the second light-out arc surface and the first light-in arc surface as even aspheric surfaces, the aberration between the light rays in the non-scanning direction can be reduced, and the stability of the optical performance can be further improved.

[0035] It can be understood that the second light-in arc surface of the lenticular cylindrical lens 100 is provided with a plurality of second light-in regions, and each second light-in region one-to-one corresponds to a laser beam; the lenticular cylindrical lens 100 is used to refract the laser beams incident on each second light-in region to the corresponding first light-in region, wherein at least two first light-in regions partially overlap.

[0036] By setting a plurality of second light-in regions on the lenticular cylindrical lens 100, the laser beams of the scanning laser light source with different illumination angles can be supported to be incident, and at the same time, by refracting each laser beam into different first light-in regions by the lenticular cylindrical lens 100, the light efficiency can be improved.

[0037] The present application does not limit how the first light-in region is distributed, and the person skilled in the art can selectively set according to actual needs.

[0038] It can be understood that the total field of view angle of the scanning direction corresponding to the plurality of second light-in regions of the lenticular cylindrical lens 100 is greater than the total field of view angle of the non-scanning direction of each micro-lens 300.

[0039] It can be understood that the curvature of the first light-in arc surface is determined according to the expansion direction of the micro-lens 300 and the scanning direction field of view angle of the lenticular cylindrical lens 100, wherein the scanning direction field of view angle is one-to-one corresponding to the first light-in region.

[0040] Since the micro-lens 300 is arranged on the first light-in arc surface, and the expansion direction of the micro-lens 300 changes with the curvature on the first light-in arc surface, at this time, the movement of the light beam can be simulated in the process of adjusting the curvature of the first light-in arc surface, so as to determine the performance of the light beam, and select the curvature of the first light-in arc surface that meets the performance.

[0041] It can be understood that the ratio between the arc radii of the first light-in arc surface and the second light-out arc surface of the meniscus cylindrical lens 200 is 8:9; and / or; The ratio between the thickness of the meniscus cylindrical lens 200 and the thickness of the lenticular cylindrical lens 100 is 2:3.3; and / or; The ratio between the light source size, the interval between the lenticular lens 100 and the meniscus lens 200, and the thickness of the lenticular lens 100 is 3.4:3.1:3.3.

[0042] The person skilled in the art can select one or more of the following conditions according to actual needs: the ratio between the arc surface radius of the first light-in arc surface of the meniscus lens 200 and the arc surface radius of the second light-out arc surface of the meniscus lens 200 is 8:9, the ratio between the thickness of the meniscus lens 200 and the thickness of the lenticular lens 100 is 2:3.3, and the ratio between the light source size, the interval between the lenticular lens 100 and the meniscus lens 200, and the thickness of the lenticular lens 100 is 3.4:3.1:3.3, to obtain the emission lens assembly of the embodiments of the present application.

[0043] For example, referring to FIG. 6, the lens group has a field of view FOV of 112°*70°, the scanning direction field of view is 112°, and the non-scanning direction field of view is 70°. Figure 2 The lenticular lens 100 controls the FOV in the scanning direction, and the FOV in the scanning direction is related to the light source size of the incident scanning light source. The FOV in the scanning direction of the lens group is determined by the focal length of the lenticular lens 100 and the light source size. The lenticular lens 100 is optimized by using this feature. For example, the light source size of the light source in the scanning direction is 3.4 mm, and the initial structure focal length is 2.3 mm. Then, by optimizing the parameters of the lenticular lens 100, the light sources in different regions on the light source chip are combined into a 112° field of view after passing through the lenticular lens 100 and forming a sub-beam out of the different laser beams. At this time, the size of the lenticular lens 100 is determined to be 6*6 mm, and the thickness is 3.3 mm.

[0044] For example, referring to FIG. 6, the lens group has a field of view FOV of 112°*70°, the scanning direction field of view is 112°, and the non-scanning direction field of view is 70°. Figure 3 The first light-in arc surface of the meniscus lens 200 is arranged with micro-lenticular lenses 300 along the curved direction. The aperture of the micro-lenticular lens 300 is 100 um. The light beams are divided into a plurality of sub-beams by the array of micro-lenticular lenses 300, so that each sub-beam has a FOV greater than 70° and the energy is uniformly distributed after passing through the micro-lenticular lens 300, and then is superimposed to realize homogenization in the non-scanning direction and meet the field of view requirement. The interval between the meniscus lens 200 and the lenticular lens 100 is 3.1 mm. In order to correct the beam distortion, the R of the first light-in arc surface of the lenticular lens 100 is 16 mm, the R of the second light-out arc surface is 18 mm, and the thickness is 2 mm. At this time, the light path of the emission lens assembly in the non-scanning direction is as shown in FIG. 7. Figure 3 The FOV control in the non-scanning direction and the beam homogenization are realized by the meniscus lens 200.

[0045] Based on the aboveFigure 2 and Figure 3 The light performance test is performed on the example of the above-mentioned optical device, the uniformity of the light spot in the middle angular space is 53%, the window efficiency is 69%, the uniformity of the light spot in the edge angular space is 33%, and the window efficiency is 59%.

[0046] It can be understood that the optical device according to the embodiment of the present application comprises any one of the above-mentioned transmitting lens assemblies.

[0047] It can be understood that the laser radar according to the embodiment of the present application comprises: a scanning laser light source; the optical device as described above, the scanning laser light source is configured to provide a laser beam to the optical device.

[0048] The above is a specific description of the preferred embodiment of the present application, but the present application is not limited to the above-mentioned embodiments, those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the present application, and these equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A transmitting lens assembly, characterized in that: include: Biconvex cylindrical lens; A meniscus lens is located in the light-emitting direction of the biconvex lens and is spaced apart from the biconvex lens; at least one first light-entering area is formed on the first light-entering arc surface of the meniscus lens, a plurality of micro-cylindrical lenses, wherein the plurality of micro-cylindrical lens arrays are distributed on each of the first light incident areas; Among them, the laser beam emitted by the scanning laser light source enters the double convex cylindrical lens, and the first light incident area corresponds one-to-one to the scanning laser light source; the double convex cylindrical lens emits the laser beam to the micro-cylindrical lens in the one-to-one corresponding first light incident area, and the micro-cylindrical lens on each first light incident area homogenizes the energy of the incident beam and then emits it to the meniscus cylindrical lens, and the meniscus cylindrical lens corrects the distortion of the incident beam.

2. The transmitting lens assembly according to claim 1, characterized in that: The first light-emitting arc surface and the second light-incident arc surface of the double convex cylindrical lens are both even-order aspherical surfaces.

3. The transmitting lens assembly according to claim 1 or 2, characterized in that: The second light-emitting arc surface and the first light-entering arc surface of the meniscus lens are both even-order aspherical surfaces.

4. The transmitting lens assembly according to claim 1, wherein: The second incident light arc surface of the double convex cylindrical lens is provided with a plurality of second light incident areas, and each second light incident area corresponds one-to-one to one of the scanning laser light sources; the double convex cylindrical lens is used to refract the laser light beam incident from each second light incident area to the corresponding first light incident area, wherein at least two of the first light incident areas partially overlap.

5. The transmitting lens assembly according to claim 4, characterized in that: The total field angle in the scanning direction corresponding to the plurality of second light incident areas of the double convex cylindrical lens is greater than the total field angle in the non-scanning direction of each of the micro cylindrical lenses.

6. The transmitting lens assembly according to claim 1, characterized in that: The curvature of the first light incident arc surface is determined according to the expansion direction of the micro-cylindrical lens and the scanning direction field angle of the double convex cylindrical lens, wherein the scanning direction field angle is set in a one-to-one correspondence with the first light incident area.

7. The transmitting lens assembly according to claim 1, characterized in that: The ratio between the arc radius of the first light incident arc surface and the second light exit arc surface of the meniscus lens is 8:9; and / or; The ratio between the thickness of the meniscus lens and the thickness of the double convex lens is 2:3.3; and / or; The ratio among the light source size of the scanning laser light source, the distance between the double convex cylindrical lens and the meniscus cylindrical lens, and the thickness of the double convex cylindrical lens is 3.4:3.1:3.

3.

8. An optical device, characterized in that: Comprising the transmitting lens assembly according to any one of claims 1 to 7.

9. A laser radar, characterized in that: include: Scanning laser light source; The optical device according to claim 8, wherein the scanning laser light source is used to provide a laser beam to the optical device.

Images