CN110850390A - Optical collimating device and laser radar - Google Patents

Optical collimating device and laser radar Download PDF

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Publication number
CN110850390A
CN110850390A CN201911179709.1A CN201911179709A CN110850390A CN 110850390 A CN110850390 A CN 110850390A CN 201911179709 A CN201911179709 A CN 201911179709A CN 110850390 A CN110850390 A CN 110850390A
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diffraction
optical element
diffractive optical
light source
laser light
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CN110850390B (en
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李璟
刘玉平
马如豹
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Guangdong Bozhilin Robot Co Ltd
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Guangdong Bozhilin Robot Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4818—Constructional features, e.g. arrangements of optical elements using optical fibres

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Semiconductor Lasers (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

The application provides an optical collimating device and a laser radar, and relates to the technical field of laser ranging. The optical collimating device comprises a laser light source and a diffractive optical element; the laser light source is positioned at the focus of the diffractive optical element and used for emitting light beams with different divergence angles; the diffraction surface of the diffraction optical element faces the laser light source, the diffraction surface is provided with a plurality of diffraction periodic structures, the diffraction periodic structures are grating structures with unequal intervals and repeated periods, the diffraction periodic structures are arranged along the horizontal central axis of the diffraction surface in a mirror image mode, each diffraction periodic structure is internally provided with a plurality of micro-nano structures with characteristic sizes, and the diffraction angle of each micro-nano structure is the same as the divergence angle of a light beam passing through each micro-nano structure. Therefore, a complex collimation light path consisting of a plurality of optical devices is not needed, and a single diffraction optical element collimates the light beam, so that the structural complexity of the light path is reduced, the processing and adjusting difficulty is reduced, and the cost is reduced.

Description

Optical collimating device and laser radar
Technical Field
The application relates to the technical field of laser ranging, in particular to an optical collimating device and a laser radar.
Background
With the development of laser technology, a laser radar becomes an important sensor for a robot in the aspects of obstacle avoidance, positioning, composition and the like, wherein an optical system in the laser radar directly influences the angle precision and the distance precision of measurement, and particularly, a collimating mirror used for a laser emission light path is particularly important for the divergence angle of emitted laser beams and the quality of light spots. The technical scheme adopted by the transmitting light path of the existing laser radar is as follows: the optical lens comprises a lens group scheme, a cylindrical lens group and lens scheme, an optical fiber coupling scheme, an off-axis reflector scheme and the like.
However, the emission light path schemes in the prior art all combine various optical components to finish light beam collimation, and have the problems of complex structure, high processing and assembling difficulty and high device and assembling cost.
Disclosure of Invention
In view of this, an object of the embodiments of the present application is to provide an optical collimating apparatus and a laser radar, so as to solve the problems in the prior art that a collimated light path has a complicated structure, is difficult to process and assemble, and has high device and assembly costs.
The embodiment of the application provides an optical collimating device, which comprises a laser light source and a diffraction optical element; the laser light source is positioned at the focal point of the diffractive optical element and used for emitting light beams with different divergence angles; the diffraction surface of the diffraction optical element faces the laser light source, a plurality of diffraction periodic structures are arranged on the diffraction surface, the diffraction periodic structures are grating structures with unequal intervals and repeated periods, the diffraction periodic structures are arranged along the horizontal central axis of the diffraction surface in a mirror image mode, a plurality of micro-nano structures with characteristic sizes are arranged in each diffraction periodic structure, and the diffraction angle of each micro-nano structure is the same as the divergence angle of a light beam passing through each micro-nano structure.
In the implementation mode, light paths of light beams with different divergence angles emitted by the laser light source are corrected based on the micro-nano structures in the plurality of diffraction period structures on the diffraction optical element, the light beams are collimated through one diffraction optical element, and collimation optical components with complex structures such as a combined lens are not needed, so that the complexity of the light path structure is reduced, the processing and adjusting difficulty is reduced, and the cost is reduced.
Optionally, the horizontal divergence angle of the light beam emitted by the laser light source is different from the vertical divergence angle.
In the implementation mode, the light beam with the different horizontal divergence angle and vertical divergence angle can form the elliptical laser spot with high energy concentration degree in the far field, and laser ranging is facilitated.
Optionally, the line width of the feature size is in the same order as the operating wavelength of the light beam emitted by the laser light source.
In the implementation mode, when the line width of the characteristic dimension is the same magnitude as the working wavelength of the light beam emitted by the laser light source, the light beam can be accurately corrected locally based on the micro-nano structure of the characteristic dimension.
Optionally, the diffractive optical element has a horizontal diffraction angle of αHVertical diffraction angle of αVHas a horizontal diffraction period of dH＝kλ/sin(αH) With a vertical diffraction period of dV＝kλ/sin(αv) Wherein λ is an operating wavelength of the laser light source, and k is a main diffraction order of a diffraction surface of the diffractive optical element.
In the above implementation, by defining the horizontal diffraction period and the vertical diffraction period of the diffractive optical element, the diffraction angle of the diffractive optical element is made to be the same as the divergence angle of the laser light source, and the refraction angle of the light beam emitted from the diffractive optical element is zero, thereby achieving the light beam collimation.
Optionally, the diffractive optical element has a horizontal diffraction angle of αHVertical diffraction angle of αVThe horizontal caliber of the position is DH＝f*tan(αH) Vertical caliber of DV＝f*tan(αV) Wherein f is the focal length of the diffractive optical element.
In the implementation mode, the divergence angle, the diffraction period and other aspects of the emission light path are comprehensively considered, and the structural parameters of the diffractive optical element such as the aperture size, the focal length and the like are finally determined, so that the light beam can be more accurately collimated.
Optionally, the diffractive optical element is a multilayer diffractive optical element.
In the implementation mode, based on the advantages of no heat, light weight and small size and high diffraction efficiency of the multilayer diffraction optical element, the collimation effect of the optical collimation device is improved, and the overall volume of the optical collimation device is reduced.
Optionally, the micro-nano structure is a relief step structure, each diffraction periodic structure is composed of a plurality of relief step structures, and the width of each relief step is the characteristic size.
In the implementation mode, the beams with different divergence angles can be subjected to diffraction at different angles through the structural accuracy of the relief step structure, so that the collimation accuracy is improved.
Optionally, the diffractive optical element presents a unique focal plane on which the laser light source is located.
In the above implementation, by placing the laser light source on the only focal plane of the diffractive optical element, it is advantageous to perform angle adjustment on the light incident to the diffractive optical element.
The embodiment of the application also provides a laser radar which comprises the optical collimating device in any mode.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is a schematic structural diagram of an optical alignment apparatus according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram illustrating positions and optical paths of a laser light source and a diffractive optical element according to an embodiment of the present disclosure;
fig. 3 is a schematic diagram of a diffraction surface structure according to an embodiment of the present disclosure.
Icon: 10-an optical collimating means; 11-a laser light source; 12-a diffractive optical element; 121-a diffractive periodic structure; 1211-micro nano structure.
Detailed Description
The technical solution in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
The applicant researches and discovers that the technical scheme adopted by the emission light path of the laser radar at present comprises a lens group scheme, a cylindrical lens group and lens scheme, an optical fiber coupling scheme, an off-axis reflector scheme and the like.
The lens group scheme mainly comprises two realization modes of a global surface lens and 1 aspheric lens, wherein the global surface lens has a large number of lenses, and the number of the lenses is at least 3; on one hand, the energy utilization rate of the emitted laser beam is influenced, on the other hand, the difficulty of adjusting the lens group is increased, and the accumulated error of the adjustment is increased. The aspheric lens mode has the problems that the processing precision of the aspheric surface shape is not high, and the scheme of the cylindrical lens group and the lens can improve the roundness of the emitted laser beam, but the number of the lenses is at least 3, the overall structure is more complex, the spot quality and the divergence angle of the emitted laser beam are basically the same as the scheme of the lens group, and the collimation of the emitted laser beam is relatively poor.
The optical fiber coupling scheme is to guide out the laser beam of the laser by using an optical fiber coupling mode, and although the quality and the roundness of a light spot for emitting the laser beam are good, the coupling efficiency is not high, and the detection distance is directly influenced.
The main problem with the off-axis mirror solution is that the difficulty of machining and adjusting can be high, thus requiring high manufacturing process and increasing manufacturing costs.
In order to solve the above problem, the embodiment of the present application provides an optical collimating device 10, which implements angle modulation and spatial modulation on a divergent laser light source to form a transmitting light path for collimating a laser beam to exit a laser radar. The light path has a simple structure, and no redundant other optical elements are used for shaping the light path, so that the problems of structural complexity and difficulty in installation and adjustment are solved.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an optical collimating device according to an embodiment of the present application, where V denotes a vertical directionDirection, H denotes horizontal direction, αHα being the water diffraction angle of the diffractive optical element 12VThe vertical diffraction angle of the diffractive optical element 12, the arrow direction indicating the beam propagation direction.
The optical collimating device 10 comprises a laser light source 11 and a diffractive optical element 12, which form an emission light path of the optical collimating device 10, wherein the diffractive optical element 12 is used for performing angle modulation and spatial modulation on a light beam emitted by the laser light source 11 to obtain a high-quality parallel laser beam.
The laser light source 11 is an electric light source that emits light under the action of excited state particles, and is a coherent light source, and the optical collimating device 10 of the present embodiment uses the electric light source as a light source device because of its high brightness, good color, low energy consumption, long service life, and small volume. Further, the laser light source 11 in the present embodiment may be a solid laser light source, a gas laser light source, a liquid laser light source, a semiconductor laser light source, or the like, and the present embodiment may select an LD repetitive pulse laser.
Specifically, the laser light source 11 in this embodiment is a single laser to obtain multiple light beams with a large divergence angle and different divergence angles, and may be a surface light source, where the size of the surface light source in the horizontal direction is different from the size of the surface light source in the vertical direction, and the size difference between the horizontal direction divergence angle and the vertical direction divergence angle of the laser light source 11 is large, so as to form a high-quality elliptical light spot.
The divergence angle of the light beam is determined by the size of the surface light source of the laser light source 11, so that the ratio of the divergence angle of the light beam emitted from the emission light path in the horizontal direction to the divergence angle of the light beam in the vertical direction and the ratio of the size of the surface light source of the laser light source 11 in the horizontal direction to the size of the light beam in the vertical direction are the same value, that is, the divergence angles of the emission light path in the horizontal direction and the vertical direction are different, so that the laser beam emitted from the emission light path forms an elliptical laser spot with high energy concentration degree in a far field.
Referring to fig. 2, fig. 2 is a schematic diagram of the positions and optical paths of a laser light source and a diffractive optical element according to an embodiment of the present disclosure, where α is a diffraction angle, PP' is a focal plane of the diffractive optical element 12, Q is a focal point of the diffractive optical element 12, and a, b, and c are paraxial parallel upper rays, paraxial parallel lower rays, and paraxial parallel lower rays incident from a diffractive surface, respectively.
Alternatively, when setting the relative positional relationship between the laser light source 11 and the diffractive optical element 12, the focal plane of the diffractive optical element 12 may be determined first, and then the laser light source 11 may be set in front of the diffractive optical element 12 by exchanging the positions of the diffractive optical element 12 and the laser light source 11 according to the principle that the optical path is reversible, the laser light source 11 may be placed on the best focal plane of the diffractive optical element 12 with the diffraction plane thereof being close to the laser light source 11 side and the emission center of the laser light source 11 coinciding with the focal point of the diffractive optical element 12 to control the incident angle of the light beam emitted by the laser light source 11 on the diffractive optical element 12.
As an optional implementation manner, the diffractive optical element 12 in this embodiment is a multilayer diffractive optical element, which has the advantages of no heat, light weight, high diffraction efficiency, and the like, and can more accurately complete the optical path adjustment of the light beam under the condition of a small volume.
The diffraction surface of the diffractive optical element 12 faces the laser light source 11, the diffraction surface is provided with a plurality of diffraction periodic structures 121, the plurality of diffraction periodic structures 121 are grating structures with unequal intervals and repeated periods, each diffraction periodic structure 121 is internally provided with a plurality of micro-nano structures 1211 with characteristic sizes, the direction of a light beam incident to the diffractive optical element 12 is changed through the micro-nano structures 1211 to form a convergent light beam, the convergent light beam is focused on a focal point at a certain distance from the diffractive optical element 12, and paraxial parallel light of the incident light beam is focused on a focal plane outside the focal point of the diffractive optical element 12 after passing through the diffractive optical element 12. It will be appreciated that in order to obtain a high quality spot, the diffractive optical element 12 does not have multiple paraxial foci, and only a single focal plane.
The line width of the characteristic dimension should be the same order of magnitude as the operating wavelength of the light beam emitted from the laser light source 11, so that the diffractive optical element 12 can accurately collimate the light beam. Specifically, according to the diffraction theory in wave optics, a diffraction phenomenon occurs after the light wave passes through the diffraction surface having the micro-nano structure 1211, and the propagation direction of the light wave is changed.
Specifically, when the arrangement of the diffractive periodic structure 121 is performed, the diffractive optical element 12 has a horizontal diffraction angle of αHVertical diffraction angle of αVHas a horizontal diffraction period of dH＝kλ/(sin(αH)+sin(βH) Has a vertical diffraction period of d)V＝kλ/(sin(αV)+sin(βV) α) among themHnAnd αVmDiffraction angles in the horizontal direction and the vertical direction on the diffraction plane of the diffractive optical element 12, λ is the operating wavelength of the laser light source 11, βHAnd βVThe refraction angles in the horizontal direction and the vertical direction after the light beam passes through the diffraction surface of the diffractive optical element 12, respectively, and k is the main diffraction order of the diffraction surface of the diffractive optical element 12.
Furthermore, in order to form a collimated laser beam by passing the laser light source 11 having a large divergence angle through the diffractive optical element 12, two conditions must be satisfied at the same time, (1) the diffraction angle of the diffractive optical element 12 is the same as the divergence angle of the laser light source 11, and (2) the refraction angle β is required for the collimation of the laser beamH＝βV0, therefore, the diffraction angle α of the diffractive optical element 12HEqual to the horizontal divergence angle of the laser light source 11, the diffraction angle α of the diffractive optical element 12VEqual to the vertical divergence angle of the laser light source 11, the diffractive optical element 12 has a horizontal diffraction angle of α at the main diffraction order k and the beam wavelength λ being known quantitiesHVertical diffraction angle of αVHas a horizontal diffraction period of dH＝kλ/sin(αH) With a vertical diffraction period of dV＝kλ/sin(αv)。
The principle of the above steps is to make the diffraction angle of the diffractive optical element 12 the same as the divergence angle of the laser light source 11 and the refraction angle of the light beam emitted from the diffractive optical element 12 zero by defining the horizontal diffraction period and the vertical diffraction period of the diffractive optical element 12, thereby achieving the beam collimation.
The embodiment optimizes the space coordinate position and the characteristic dimension in the diffraction period of the diffractive optical element 12 through design, and performs light path correction on light beams with different divergence angles emitted by the laser light source 11 based on the micro-nano structure in the plurality of diffraction period structures on the single diffractive optical element 12 to collimate the light beams, thereby realizing light beam collimation through one diffractive optical element 12 without adopting collimating optical components with complicated structures such as a combined lens and the like, thereby reducing the complexity of the light path structure, reducing the processing and debugging difficulty, lowering the cost and simultaneously improving the light utilization efficiency.
The micro-nano structure 1211 in the diffraction period structure 121 refers to an artificially designed functional structure having a characteristic dimension of a micro or nano scale and arranged in a specific manner. With the development of the third-generation optical imaging technology to integration, light weight and ultra-large caliber, the traditional catadioptric optical system faces a plurality of bottlenecks, and the micro-nano structure optical element has the characteristics of light weight, high design freedom, flexible structure and the like, and shows remarkable advantages in the imaging field.
Further, the micro-nano structure 1211 is a relief step structure, each diffraction period structure 121 is composed of a plurality of relief step structures, and the width of a single relief step structure is a line width of a characteristic dimension.
Alternatively, the number of the relief step structures in each of the diffraction periodic structures 121 may be 2, 4, 6, 8, 16, or the like, and in the present embodiment, in terms of the energy utilization efficiency of the emission light path, the minimum feature size manufacturing accuracy and manufacturing cost of the diffractive optical element 12, or the like, the number of the relief step structures may be set to 8, and the feature sizes of the diffractive optical element 12 in the horizontal direction and the numerical direction of the diffraction surface are dH/8 and dV/8. In this arrangement of the diffractive optical element 12, the diffraction efficiency of the diffractive optical element 12 can be 95% or more.
As an alternative implementation, in addition to the feature size, the aperture of each micro-nano structure 1211 is also one of the important parameters, and the aperture is the effective diameter of the primary mirror or lens of the optical system. The aperture is a main index of the light condensing ability of the optical system. The larger the aperture of the optical system, the larger the light flux.
Specifically, the aperture size of the micro-nano structure 1211 in the horizontal direction in the diffractive optical element 12 may be DH＝f*tan(αH) The caliber in the vertical direction can be DV＝f*tan(αV) Where f is the focal length of the diffractive optical element 12.
Referring to fig. 3, fig. 3 is a schematic diagram of a diffraction surface structure according to an embodiment of the present disclosure. In the diffraction surface of the exemplary diffractive optical element 12, grating structures (diffraction periods) with unequal pitches and repeated periods are arranged in the X (horizontal) and Y (vertical) directions, and the sizes of the diffraction periods are d in the X, Y directionhnAnd dvmN is more than or equal to 1 and less than or equal to N, and M is more than or equal to 1 and less than or equal to M. In addition, the spatial coordinate position of each diffraction period is (n, m), the spatial positions of the diffraction periods are arranged symmetrically in a mirror image manner along the central axis of the diffraction surface, the sizes of the diffraction periods with mirror images are completely the same, each diffraction period structure 121 is further composed of a plurality of micro-nano structures 1211 with micron-scale characteristic dimensions, and the line width of the characteristic dimension is the minimum processing unit of the diffraction surface.
By finding dHAnd dVCan calculate the diffraction period d of the diffractive optical element 12 in the X directionHn＝kλ/sin(αH) And the diffraction period d in the Y directionVm＝kλ/sin(αv) Wherein, αHAnd αVDiffraction angles in the X-direction and Y-direction on the diffractive optical element 12, respectively, said βHAnd βVThe refraction angles in the X direction and the Y direction after the light beam passes through the diffractive optical element 12, respectively. When the number of the micro-nano structures 1211 of each diffraction period structure 121 is 8, the characteristic dimensions of the diffractive optical element 12 in the X direction and the Y direction are dHn/8 and dVm/8。
The aperture of each micro-nano structure 1211 for the diffractive optical element 12 can be determined according to DHAnd DVAnd calculating by a formula.
Alternatively, the thickness h of the diffractive optical element 12 in this embodiment may be, but is not limited to, about one tenth of the effective aperture.
Therefore, the focal length f of the diffractive optical element 12 is proportional to the aperture of the micro-nano structure 1211, and the focal length f of the diffractive optical element 12 is inversely proportional to the divergence angle of the light beam emitted from the emission optical path.
The embodiment of the present application may further provide a laser radar, where the laser radar includes the above optical collimating device 10.
Optionally, the laser radar can be applied to robot equipment such as an indoor building robot and the like to realize accurate automatic positioning in a complex environment.
It should be understood that the optical collimating apparatus 10 can be applied to any other device requiring the complexity of the optical path structure, the cost of the device, the installation and adjustment complexity, and the volume of the device, besides the lidar.
In summary, the embodiment of the present application provides an optical collimating apparatus and a laser radar, where the apparatus includes a laser light source and a diffractive optical element; the laser light source is positioned at the focal point of the diffractive optical element and used for emitting light beams with different divergence angles; the diffraction surface of the diffraction optical element faces the laser light source, a plurality of diffraction periodic structures are arranged on the diffraction surface, the diffraction periodic structures are grating structures with unequal intervals and repeated periods, the diffraction periodic structures are arranged along the horizontal central axis of the diffraction surface in a mirror image mode, a plurality of micro-nano structures with characteristic sizes are arranged in each diffraction periodic structure, and the diffraction angle of each micro-nano structure is the same as the divergence angle of a light beam passing through each micro-nano structure.
In the implementation mode, light paths of light beams with different divergence angles emitted by the laser light source are corrected based on the micro-nano structures in the plurality of diffraction period structures on the diffraction optical element, the light beams are collimated through one diffraction optical element, and collimation optical components with complex structures such as a combined lens are not needed, so that the complexity of the light path structure is reduced, the processing and adjusting difficulty is reduced, and the cost is reduced.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus may be implemented in other manners. The apparatus embodiments described above are merely illustrative, and for example, the block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of devices according to various embodiments of the present application. In this regard, each block in the block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams, and combinations of blocks in the block diagrams, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, functional modules in the embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims (10)

1. An optical collimating apparatus, comprising a laser light source and a diffractive optical element;
the laser light source is positioned at the focal point of the diffractive optical element and used for emitting light beams with different divergence angles;
the diffraction surface of the diffraction optical element faces the laser light source, a plurality of diffraction periodic structures are arranged on the diffraction surface, the diffraction periodic structures are grating structures with unequal intervals and repeated periods, the diffraction periodic structures are arranged along the horizontal central axis of the diffraction surface in a mirror image mode, a plurality of micro-nano structures with characteristic sizes are arranged in each diffraction periodic structure, and the diffraction angle of each micro-nano structure is the same as the divergence angle of a light beam passing through each micro-nano structure.
2. The apparatus of claim 1, wherein the laser light source emits a beam of light having a horizontal divergence angle that is different from a vertical divergence angle.
3. The apparatus of claim 1, wherein the feature size has a linewidth on the same order of magnitude as an operating wavelength of a beam of light emitted by the laser light source.
4. The apparatus of claim 1, wherein the diffractive optical element has a horizontal diffraction angle of αHVertical diffraction angle of αVHas a horizontal diffraction period of dH＝kλ/sin(αH) With a vertical diffraction period of dV＝kλ/sin(αv) Wherein λ is an operating wavelength of the laser light source, and k is a main diffraction order of a diffraction surface of the diffractive optical element.
5. The apparatus of claim 4, wherein the diffractive optical element has a horizontal diffraction angle of αHVertical diffraction angle of αVThe horizontal caliber of the position is DH＝f*tan(αH) Vertical caliber of DV＝f*tan(αV) Wherein f is the focal length of the diffractive optical element.
6. The apparatus of claim 1, wherein the diffractive optical element is a multilayer diffractive optical element.
7. The apparatus of claim 6, wherein the micro-nano structure is a relief step structure, each diffraction periodic structure is composed of a plurality of relief step structures, and the width of each relief step is the characteristic dimension.
8. The apparatus of claim 7, wherein each diffraction period consists of 8 of the relief step structures.
9. The apparatus of claim 1, wherein the diffractive optical element presents a unique focal plane, and the laser light source is located on the unique focal plane.
10. Lidar characterized in that it comprises an optical collimating device according to any of claims 1 to 9.
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CN111337900A (en) * 2020-03-27 2020-06-26 广东博智林机器人有限公司 Laser radar ranging system and laser radar
CN111398937A (en) * 2020-04-07 2020-07-10 广东博智林机器人有限公司 Optical performance adjusting device and optical performance adjusting method
CN112987018A (en) * 2021-02-08 2021-06-18 中国科学院光电技术研究所 Laser imaging optical system for realizing large-gaze field detection by using planar micro-nano structure lens
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