CN111580115A

CN111580115A - Scanning device for laser radar and laser radar

Info

Publication number: CN111580115A
Application number: CN202010359099.XA
Authority: CN
Inventors: 顾亮; 韩筱敏; 曾昭明; 向少卿
Original assignee: Hesai Photonics Technology Co Ltd
Current assignee: Hesai Photonics Technology Co Ltd
Priority date: 2020-04-29
Filing date: 2020-04-29
Publication date: 2020-08-25

Abstract

The application provides a laser radar, includes: a scanning device; the scanning device includes: a laser array for emitting a light beam; an emission optical assembly collimating the light beam; a polygon mirror for reflecting the emission beam from the emission optical assembly to form a scanning beam; the laser array comprises a plurality of lasers arranged in multiple columns, and the lasers in adjacent columns are arranged in a staggered mode; a receiving optical assembly for converging the echo beam reflected by the polygon mirror; and a receiver for converting the echo beam from the receiving optical assembly into an electrical signal. The method and the device have the advantages that the vertical resolution of the laser radar and the quality of point cloud data are improved, and meanwhile, low cost and miniaturization are achieved.

Description

Scanning device for laser radar and laser radar

Technical Field

The application belongs to the technical field of radars, and particularly relates to a scanning device for a laser radar and the laser radar.

Background

The laser radar is a radar system that detects a characteristic amount such as a position and a velocity of a target by emitting a laser beam. The working principle of the laser radar is to transmit a detection signal (laser beam) to a target, then compare the received signal (target echo) reflected from the target with the transmitted signal, and after appropriate processing, obtain the relevant information of the target, such as the parameters of target distance, direction, height, speed, attitude, even shape, etc., thereby detecting, tracking and identifying the targets of automobiles, pedestrians, etc. The laser changes the electric pulse into optical pulse and emits it, the optical receiver restores the reflected optical pulse from the target into electric pulse, and the signal is transmitted to the display for display.

The laser radar has the characteristics of high resolution, strong active interference resistance, small volume, light weight, three-dimensional imaging and the like, and is suitable for various environmental scenes. The vertical resolution who improves lidar at present is general demand, and this scanning and the receiving channel that just requires on lidar's vertical direction increase, and common mechanical rotation formula lidar can increase the spatial configuration degree of difficulty of component through increasing scanning and receiving channel quantity in the vertical direction to make lidar's volume increase, the cost uprises, and therefore lidar can realize low-cost and miniaturization when improving vertical resolution is the main research direction.

The technical scheme in the prior art generally adopts a low-beam laser array to match with the rotation of a multi-surface rotating mirror for line expansion, and because the low-beam laser array is adopted, the inclination angles of all reflecting surfaces of the multi-surface rotating mirror are often set to be different for improving scanning beam; meanwhile, in order to improve the light emitting efficiency, the angles of the lasers need to be adjusted, and the problems of high installation and adjustment difficulty and the like exist.

The statements in the background section merely represent techniques known to the public and are not intended to represent prior art in the field.

Disclosure of Invention

The present application relates to a laser radar capable of achieving low cost and miniaturization while improving vertical resolution and point cloud data quality.

According to an aspect of the present application, the scanning apparatus for lidar includes: a laser array for generating an emission beam; a transmit optical assembly disposed downstream of the laser array in a beam propagation direction to receive and collimate the emitted beam; a polygon mirror disposed downstream of the emission optical assembly in a beam propagation direction, configured to reflect the emission beam collimated by the emission optical assembly to form a scanning beam; the laser array comprises a plurality of lasers arranged in multiple columns, and the lasers in adjacent columns are arranged in a staggered mode.

According to some embodiments of the application, the proximity distance of the plurality of lasers at the central region of the column is smaller than the proximity distance thereof at the two end regions of the column.

According to some embodiments of the present application, the plurality of lasers form a non-uniformly distributed array, and the plurality of lasers are adjacently spaced the same in the column, and the density of the lasers in the non-uniformly distributed array is greater at a central region of the array than at both end regions of the array.

According to some embodiments of the present application, the emission optical assembly comprises a telecentric lens system.

According to some embodiments of the present application, the telecentric lens system comprises: a three-piece gaussian lens comprising: a first lens comprising: one of a lenticular lens, a plano-convex lens, or a meniscus lens; a second lens comprising: one of a plano-concave lens, a biconcave lens, or a convex-concave lens; a third lens comprising: one of a plano-convex lens, a biconvex lens or a meniscus lens.

According to some embodiments of the present application, the telecentric lens system comprises: and the diaphragm is arranged on the upstream of the first lens in the light beam propagation direction and enables the emitted light beam to pass through.

According to some embodiments of the present application, the emission optical assembly further comprises a barrel provided as a partial cut edge.

According to some embodiments of the present application, the emitting optical assembly further comprises: the pressing rings are arranged at the front end and the rear end of the lens cone and are used for pressing the three Gaussian lenses; the spacing ring is arranged between the three Gaussian lenses and is used for spacing the Gaussian lenses and simultaneously matching with the pressing ring to press the three Gaussian lenses; wherein the pressing ring and the spacing ring are made of steel materials.

According to some embodiments of the present application, the polygon mirror has an axis and is rotatable around the axis, the polygon mirror includes an even number of reflecting surfaces enclosing a polygon for reflecting the emission beam and the scanning beam to form an echo beam after being reflected by the target, and the scanning device further includes a motor accommodated in a polygonal space enclosed by the reflecting surfaces.

According to some embodiments of the present application, the even number of the reflecting surfaces include two opposite reflecting surfaces having the same included angle with the axis, and two adjacent reflecting surfaces have the same included angle with the axis and have opposite signs.

According to some embodiments of the present application, an angle between the reflecting surface of the polygon mirror and the axis may be determined according to an interval of the plurality of lasers in the column.

According to some embodiments of the application, the interval of the plurality of lasers in the column corresponds to 0.5 degrees of the emission angle of the emission beam, the multi-surface rotating mirror is provided with four reflecting surfaces, wherein two reflecting surfaces and the included angle between the axes is 0.09 degrees, and the included angle between the other two reflecting surfaces and the axes is-0.09 degrees, so that the highest resolution ratio of 0.25 degrees can be realized in a certain view field range.

According to some embodiments of the present application, the polygon mirror further comprises an optical isolation portion for isolating the emission beam and the echo beam.

According to another aspect of the present application, there is also provided a lidar including: the scanning device as described above, wherein the reflecting surface of the polygon mirror of the scanning device is simultaneously used for receiving the echo beam of the laser radar; the receiving optical assembly receives and converges the echo light beam reflected by the multi-surface rotating mirror; a receiver that receives the echo beam from the receiving optical assembly and converts it into an electrical signal.

According to some embodiments of the present application, the receiver includes a detector array including a plurality of detectors arranged in a plurality of columns, the detectors of adjacent columns being staggered with respect to each other.

According to some embodiments of the present application, each detector in each column of detectors corresponds to an arrangement position of each laser in one of the columns of lasers, so that each detector is configured to receive an echo beam generated by the laser corresponding to the detector.

According to some embodiments of the present application, each of the reflective surfaces includes separate upper and lower portions, one of the upper and lower portions for receiving and reflecting the emitted beam and the other of the upper and lower portions for receiving and reflecting an echo beam of the lidar.

According to some embodiments of the present application, the detector comprises: APD, SPAD, or SiPM.

According to some embodiments of the present application, further comprising: the transmitting end turning mirror is arranged between the laser array and the transmitting optical assembly and used for deflecting the transmitting light beam; and the receiving end turning mirror is arranged between the receiver and the receiving optical assembly, is parallel to the transmitting end turning mirror along the vertical direction, and is used for deflecting the echo light beam.

According to some embodiments of the present application, a distance between the transmitting end turning mirror and the transmitting optical assembly is smaller than a distance between the receiving end turning mirror and the receiving optical assembly.

According to some embodiments, the present application provides a scanning apparatus for lidar, wherein the laser array may be 2 columns of lasers with 32 light emitting channels, capable of emitting high-line beam laser light simultaneously; the laser devices are arranged in a staggered mode in the vertical direction, and the arrangement mode increases the spatial arrangement density of the laser devices, so that denser point cloud data can be obtained; the telecentric lens system is matched with the staggered laser arrays, so that the light emitting efficiency of emitted light beams can be effectively improved under the condition of not adjusting the angles of the lasers, the installation and the adjustment are easy, and the quality of point cloud data is improved; utilize the polygon rotating mirror that has different inclination plane reflecting surfaces to expand the line to the transmission beam in vertical direction simultaneously, and confirm the inclination of each reflecting surface according to the interval of a plurality of lasers in the place is listed as, and improve the precision at inclination, make laser radar's point cloud data more regular, the uniformity is better, thereby can improve laser radar's vertical resolution and some cloud data quality, in addition, all set up the turning mirror at transmitting terminal and receiving terminal, can effectively reduce laser radar's volume, thereby realize low cost and miniaturization when improving laser radar's vertical resolution and some cloud data quality. The application also provides a laser radar with the scanning device, and low cost and miniaturization are realized while the vertical resolution and the point cloud data quality of the laser radar are improved.

Drawings

FIG. 1A is a schematic diagram of a scanning apparatus according to an exemplary embodiment of the present disclosure;

FIG. 1B is a schematic diagram of a laser array layout of a scanning apparatus according to an exemplary embodiment of the present application;

FIG. 1C is a schematic diagram of a laser array layout of a scanning apparatus according to another exemplary embodiment of the present application;

FIG. 2A is a schematic view of the emission optics assembly of a scanning device in an exemplary embodiment of the present application;

fig. 2B is a schematic view of a lens barrel structure of an emission optical assembly of a scanning device in an exemplary embodiment of the present application;

FIG. 3 is a schematic view of a polygon mirror of a scanning apparatus according to an exemplary embodiment of the present application;

FIG. 4A is a schematic diagram of a lidar in an exemplary embodiment of the present application;

FIG. 4B is a schematic diagram of a lidar in another exemplary embodiment of the present application;

FIG. 5A is a schematic diagram of a receive optical assembly of a lidar in an exemplary embodiment of the present application;

fig. 5B is a schematic view of a lens barrel structure of a receiving optical assembly of a lidar in an exemplary embodiment of the present application;

FIG. 6A is a schematic diagram of a receiver arrangement of a lidar in an exemplary embodiment of the present application;

fig. 6B is a light path diagram of the lidar in an exemplary embodiment of the present application.

List of reference numerals

100 laser array

200 emitting optical assembly

300 multi-face rotating mirror

201 first lens

203 second lens

205 third lens element

207 space ring

209 space ring

211 pressing ring

213 drawtube

301 light-blocking part

402 transmitting end turning mirror

404 receiving end folding mirror

500 receive optical assembly

501 fourth lens

503 fifth lens

505 sixth lens

507 pressing ring

509 space ring

511 receiving lens barrel

600 receiver

601 detector

605 obstacle

Detailed Description

The following detailed description of the present application, taken in conjunction with the accompanying drawings and examples, is provided to enable the aspects of the present application and its advantages to be better understood. However, the specific embodiments and examples described below are for illustrative purposes only and are not limiting of the present application.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms "first," "second," "third," and "fourth," etc. in the description and claims of this application and in the accompanying drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

In view of this, the present application provides a laser radar and a scanning device thereof, wherein the laser array may be 2 rows of lasers with 32 light emitting channels, and may emit high-line beam laser simultaneously; the laser devices are arranged in a staggered mode in the vertical direction, and the arrangement mode increases the spatial arrangement density of the laser devices, so that denser point cloud data can be obtained; the telecentric lens system is matched with the staggered laser arrays, so that the light emitting efficiency of emitted light beams can be effectively improved under the condition of not adjusting the angles of the lasers, the installation and the adjustment are easy, and the quality of point cloud data is improved; utilize the polygon rotating mirror that has different inclination plane reflecting surfaces to expand the line to the transmission beam in vertical direction simultaneously, and confirm the inclination of each reflecting surface according to the interval of a plurality of lasers in the place is listed as, and improve the precision at inclination, make laser radar's point cloud data more regular, the uniformity is better, thereby can improve laser radar's vertical resolution and some cloud data quality, in addition, all set up the turning mirror at transmitting terminal and receiving terminal, can effectively reduce laser radar's volume, thereby realize low cost and miniaturization when improving laser radar's vertical resolution and some cloud data quality.

The present application will be described with reference to specific examples. The values of the process conditions taken in the following examples are illustrative and are not intended to limit the scope of the present application. For process parameters not specifically noted, reference may be made to conventional techniques. The detection method used in the following examples may be a detection method conventional in the art.

Fig. 1A is a schematic structural diagram of a scanning apparatus in an exemplary embodiment of the present application.

As shown in fig. 1A, according to an exemplary embodiment, a scanning apparatus for a laser radar includes: a laser array 100, a transmitting optical assembly 200, and a polygon mirror 300.

The laser array 100 is used to generate an emission beam to scan a target object. The laser array 100 may include a plurality of lasers 101. According to an example embodiment, the plurality of lasers 101 are arranged in columns at the same adjacent intervals, and the lasers in adjacent columns are arranged in a staggered manner, as shown in fig. 1B, the plurality of lasers 101 are arranged in a first column and a second column at equal intervals along a first direction, and the lasers in the first column and the second column are arranged in a staggered manner. For example, the first direction may be a vertical direction in fig. 1A and 1B. In addition, the invention is not limited thereto, and the plurality of lasers 101 may also be arranged in more columns, for example, three, four or more columns, and the lasers between the columns are staggered with each other in the first direction.

According to some embodiments, the plurality of lasers 101 are staggered, wherein each laser 101 of the second column corresponds to a gap location between each laser 101 of the first column. The arrangement mode increases the spatial arrangement density of the lasers, so that denser point cloud data can be acquired.

As shown in fig. 1A, the emission optical assembly 200 collimates the received emission beam to be incident on the polygon mirror 300. The emission optical assembly 200 may be a telecentric lens system, as described in detail below with reference to fig. 2A.

Referring to fig. 1A, the polygon mirror 300 may reflect the emission beam from the emission optical assembly 200 to form a scanning beam, which is emitted to the outside of the laser radar for detecting the target object, as described in detail in fig. 3 below.

According to some embodiments, the laser 101 comprises a semiconductor laser, wherein the semiconductor laser has a high luminous efficiency, a small volume, a light weight and a low price. Compared with the optical fiber laser, the semiconductor laser omits complex parts in the optical fiber laser, such as an optical fiber, a lens and the like, and has simpler structure and lower cost. In the present embodiment, the laser includes an edge-emitting semiconductor laser or a vertical cavity surface semiconductor laser. According to an embodiment, each semiconductor laser may emit laser light of the same wavelength. When the lasers 101 in the laser array 100 are arranged in a staggered manner in multiple rows as described above, the semiconductor lasers with single wavelength are used to emit light beams simultaneously, thereby reducing the manufacturing cost of the scanning device.

According to some embodiments, the left and right columns of lasers 101 may be non-uniformly arranged, such as where the center region of each column in the vertical direction is more dense than the two end regions, or it may be understood that the adjacent distance of the lasers at the center region is less than the adjacent distance of the lasers at the two end regions of the column. This arrangement allows better vertical resolution in the central region as compared to the two end regions, as shown in FIG. 1C. This arrangement is very advantageous in practical detection. Lidar, for example, is typically arranged on the roof of a vehicle for scanning the environment and objects around the vehicle. The point cloud and the information of the central region of the lidar field of view are particularly important, since they correspond to directly in front of, directly to the side of, and directly behind the vehicle, being the regions of major interest to the driver of the vehicle or to the control unit. For example, assuming that the horizontal plane is 0 °, the central region refers to a region where the angle between the emitted light beam and the horizontal plane is ± 5 ° in the vertical direction, and relatively sparse lasers can be disposed above and below the laser radar with a larger angle of view, such as the sky and the ground. By arranging more lasers in the central area in the vertical direction, the detection precision of the central area in the field of view of the laser radar can be improved.

According to another embodiment of the present invention, in each row of lasers, the lasers may be uniformly arranged, i.e. the spacing between adjacent lasers is the same; and adjacent columns of lasers, such as a first column and a second column of lasers, the spacing in the first column of lasers being different from the spacing in the second column of lasers such that the density of the lasers is greater at a central region of the array than at regions at both ends of the array.

According to some embodiments, the scanning device can obtain denser point cloud data through staggered arrangement of the laser in the vertical direction, and further improves the vertical resolution of the laser radar through the line expansion effect of the polygon mirror.

Fig. 2A is a schematic structural diagram of an emission optical assembly 200 of a scanning apparatus in an exemplary embodiment of the present application. The transmit optical assembly 200 is used to collimate the transmitted beam received from the laser array.

Referring to fig. 2A, according to some embodiments, emission optics assembly 200 includes a telecentric lens system that can emit a light beam at a large angle, such as 140 ° in the horizontal direction. The telecentric lens system can be selected from three Gaussian lenses, including a first lens 201, a second lens 203 and a third lens 205. The first lens element 201 may include a biconvex lens, a plano-convex lens, or a meniscus lens. The second lens 203 includes a plano-concave lens, and a biconcave lens, a convex-concave lens, or the like may be used. The third lens 205 includes a plano-convex lens, and may be a biconvex lens, a meniscus lens, or the like. The telecentric lens system sets a diaphragm upstream of the first lens 201 in the light beam traveling direction and passes the emission light beam, wherein the diaphragm may be an aperture diaphragm, and the diaphragm may or may not be set at the front focal position of the first lens 201, such as at a distance of 5mm upstream of the first lens 201 in the light beam traveling direction. Each lens of the lens group can be made of glass materials, the light emitting efficiency of emitted light beams can be effectively improved under the condition that the angles of the lasers are not adjusted by utilizing the telecentric lens system in cooperation with the staggered laser arrays, the adjustment is easy, and the quality of point cloud data is improved.

In addition, as shown in fig. 2A, the emitting optical assembly employs a fixing manner of a spacer ring and a pressing ring to avoid the adhesion of glue, wherein the pressing ring 211 is disposed at the front end and the rear end of the emitting optical assembly for pressing the first lens 201 and the third lens 205.

Spacers

207 and 209 are disposed between the first lens 201 and the second lens 203 and between the second lens 203 and the third lens 205, respectively. The pressing ring 211 and the spacing ring 207/209 can be made of steel materials, the expansion coefficient of the steel materials is closer to that of glass, the thermal stability of the transmitting optical assembly can be improved, and the manufacturing cost of the laser radar can be reduced by adopting aluminum alloy materials. By adopting the fixing mode of the space ring and the pressing ring, the optical performance of the transmitting optical assembly can be ensured, the risk of fragmentation of each lens under the high-temperature condition can be effectively reduced, and the reliability of the laser radar is improved. In addition, the barrel 213 may be provided with a partial cut-out, as shown in fig. 2B, with its side wall partially cut away. The lens barrel 213 having the partial trimming structure can improve the light extraction efficiency of the laser radar at a partial light emission angle.

According to a preferred embodiment of the present invention, the scanning device may further include a reinforcing cylindrical lens disposed downstream of the emission optical assembly in the optical path thereof, for deflecting the portion of the emission beam collimated by the emission optical assembly, for reinforcing the emission beam irradiating the short-distance target object. Specifically, the emission beam passes through the reinforcing cylindrical lens after exiting from the emission optical assembly, then is emitted to the polygon mirror, and is continuously rotated to scan the emission beam to the surrounding environment through the polygon mirror. By adopting the reinforcing cylindrical lens, the laser pulse signal in a short-distance area such as 0-4m can be enhanced so as to eliminate a short-distance blind area.

Fig. 3 is a schematic view of a polygon mirror of a scanning apparatus according to an exemplary embodiment of the present application. The polygon mirror 300 is used to reflect the emission beam from the emission optical assembly 200 to form a scanning beam.

Referring to fig. 3, according to an exemplary embodiment of the present application, the polygon mirror 300 includes a reflection surface that may reflect a transmission beam incident on the polygon mirror 300 to form a scanning beam, and may reflect an echo beam formed by a target object after receiving the scanning beam to a receiver of a laser radar. Two reflective surfaces 301-1 and 301-2 are shown in FIG. 3, near the outside of the drawing plane. In addition, as shown in fig. 3, the polygon mirror includes at least two pairs of reflection surfaces, the reflection surfaces are used for expanding the multi-line scanning beam in the vertical direction, the inclination angles of two opposite reflection surfaces in the reflection surfaces are the same, and the inclination angles of two adjacent reflection surfaces are different, wherein the inclination angle refers to the included angle between the reflection surface and the bottom surface of the polygon mirror, and the vertical resolution of the laser radar is improved by the continuous rotation of the polygon mirror. The polygon mirror 300 may further be provided at the center thereof with a light-shielding portion 301 for shielding the emission beam and the echo beam, so that crosstalk between the scanning beam and the echo beam can be reduced. As shown in fig. 3, the light-blocking part 301 may be a light-blocking plate. Additionally or alternatively, the light-blocking portion 301 may include a light-blocking paint or other type of light-blocking tape.

As shown in fig. 3, in the present embodiment, the polygon mirror 300 is a four-sided mirror, and the polygon mirror 300 is driven by a motor to perform rotational scanning. The polygon mirror 300 has two opposite reflective surfaces with the same inclination angle, for example 90.09 °, and two opposite reflective surfaces with the same inclination angle, for example 89.91 °. The included angle between the reflecting surfaces of the polygon mirror 300 and the axis AX can be determined according to the interval of the plurality of lasers in the row, for example, the interval of the plurality of lasers in the row corresponds to the emission angle of the emitted light beam of 0.5 °, the included angle between two reflecting surfaces and the axis is 0.09 °, and the included angle between the other two reflecting surfaces and the axis is-0.09 °, so as to achieve the resolution of 0.25 ° at the maximum in a certain field range.

Further according to an embodiment of the present invention, the scanning apparatus may further include a motor configured to drive the polygon mirror 300 to rotate about the axis AX thereof. The motor is, for example, included in a polygonal space surrounded by a plurality of reflecting surfaces, and drives the polygon mirror 300 to rotate. In addition, through the arrangement mode, the height of the scanning device is basically the same as that of the reflecting surface, so that the height of the scanning device can be effectively reduced, the integral volume of the laser radar is reduced, and the laser radar is smaller and more compact in structure. The polygon mirror 300 can rotate around its axis AX at a constant speed of 360 degrees, or can swing back and forth within a certain range, or its movement speed can be non-constant movement, but follows a preset movement curve.

According to a preferred embodiment of the present invention, the polygon mirror 300 is a four-sided mirror, wherein two opposite reflecting surfaces have the same angle with the main axis AX, and two adjacent reflecting surfaces have the same absolute value but opposite sign with respect to the main axis AX. Preferably, two of the four-sided rotating mirror opposite to each other have an angle of 0.09 ° with the main axis AX, and the other two have an angle of-0.09 ° with the main axis AX. As shown in fig. 3, two adjacent turning mirror reflecting surfaces are shown, namely a left turning mirror reflecting surface 302-1 and a right turning mirror reflecting surface 302-2, wherein the left turning mirror reflecting surface 302-1 (and the turning mirror reflecting surface opposite thereto) forms an angle of 89.91 ° with the bottom surface of the multi-surface turning mirror 300, and the right turning mirror reflecting surface 302-2 (and the turning mirror reflecting surface opposite thereto) forms an angle of 90.09 ° with the bottom surface of the multi-surface turning mirror 300.

Preferably, repeated comparison experiments for multiple times show that the included angle between the reflecting surface of the rotating mirror and the main shaft is set to have proper precision, such as the precision of +/-0.009 degrees, so that the point cloud data of the laser radar is more regular, and the data consistency is better. Continuing with the previous embodiment, the actual angle between the left turning mirror surface 302-1 and the bottom surface may be between 89.901 ° and 89.919 °; the actual angle of the right turning mirror reflective surface 302-2 to the bottom surface may be between 90.081 ° and 90.099 °. In this way, when the polygon mirror 300 rotates by 90 ° about the axis AX every time, the adjacent two reflection surfaces of the polygon mirror shift the scanning area of the laser radar transceiver unit in the vertical angle. When two adjacent reflecting surfaces of the rotating mirror are spliced to obtain a scanning area, a scanning image with encrypted scanning lines in the vertical direction can be obtained, so that the encryption of partial scanning lines in the area is realized under the condition of not increasing the emission units, and the scanning efficiency is improved.

The multi-surface rotating mirror with the reflecting surfaces with different inclination angles is used for expanding the emitted light beams in the vertical direction, the inclination angles of the reflecting surfaces are determined according to the intervals of the plurality of lasers in the columns, the precision of the inclination angles is improved, point cloud data of the laser radar are more regular and better in consistency, and therefore the vertical resolution and the point cloud data quality of the laser radar can be improved.

It will be appreciated by those skilled in the art that when hexagonal, octagonal or more polygonal shaped turning mirrors are used in the present embodiment, the same angle between two opposing reflective surfaces and the bottom surface is the same, and the angle between two adjacent reflective surfaces and the bottom surface is different.

More preferably, the angular difference between adjacent reflecting surfaces can be determined by one skilled in the art according to actual conditions and needs. For example, for a hexagonal rotating mirror, there are three pairs of rotating mirror surfaces, where an angle between a pair of reflecting surfaces and the main axis AX is set to be 0.09 °, and an angle between a pair of reflecting surfaces and the main axis AX is set to be 0 °; the angle between the pair of reflecting surfaces and the main axis AX is-0.09 deg.

The polygon mirror 300 may include two, three, five or more reflecting surfaces. Wherein the polygon mirror 300 has an even number of reflecting surfaces enclosing a polygon for changing an angle of the emitted light beam incident thereon, wherein each of the reflecting surfaces includes an upper portion SU and a lower portion SL separated by a light blocking portion 301, according to a preferred embodiment of the present invention. The polygon mirror 300 is schematically shown in fig. 3 to have four reflecting surfaces, enclosing a square. Those skilled in the art will readily appreciate that the present invention is not limited thereto, and the number of the reflecting surfaces 111 may be 6, 8, and more, and the polygon may be a regular polygon or a non-regular polygon, which are within the scope of the present invention.

In addition, as shown in fig. 3, the upper portion SU and the lower portion SL of each reflecting surface of the polygon mirror 300 may be used to individually emit light beams or receive echo light beams, respectively, according to an embodiment of the present invention. While the lower SL is shown in fig. 3 for emitting the beam and the upper SU for receiving the echo beam, the present invention is not limited thereto, and the lower SL may be arranged for receiving the echo beam and the upper SU for emitting the beam. These are all within the scope of the present invention.

Fig. 4A illustrates a lidar according to an exemplary embodiment of the present application. The lidar according to this embodiment may comprise the scanning device, the receiving optical assembly 500 and the receiver 600 described above.

As shown in fig. 4A, according to some embodiments, the receiving optical assembly 500 may include three gauss lenses to converge the echo beams reflected by the polygon mirror. After being reflected by one of the reflecting surfaces of the polygon mirror 300, the reflected echoes are incident on the receiving optical assembly 500, and the receiver 600 is located at the focal plane of the receiving optical assembly 500, so that the receiving optical assembly 500 can converge the echoes to the receiver 600. In this embodiment, the lidar optical system employs a paraxial structure with an upper part and a lower part, where the receiver 600 is disposed on the upper half part and the laser 100 is disposed on the lower half part. In other embodiments, the laser 100 is disposed on the transmitting side of the laser radar, and the receiver 600 is disposed on the lower half of the laser radar, as shown in fig. 4B.

Referring to fig. 4A, according to some embodiments, a receiver 600 converts an echo beam from a receive optical assembly 500 into an electrical signal.

In addition, as shown in fig. 4A, the lidar further includes a transmitting end turning mirror 402 and a receiving end turning mirror 404. An emission-side turning mirror 402 is disposed between the laser array 100 and the emission optical assembly 200 for deflecting the emission beam. The receiving end turning mirror 404 is disposed between the receiver 600 and the receiving optical assembly 500, and is used for deflecting the echo light beam. The arrangement of the folding mirror can increase the space utilization rate, reduce the size, realize the miniaturization of the laser radar and reduce the influence of stray light. In addition, the light shielding plate 301 is omitted in fig. 4A for simplicity, but those skilled in the art will readily understand that the light shielding plate 301 may be included.

Fig. 5A is a schematic structural diagram of a receiving optical assembly of a lidar in an exemplary embodiment of the present application.

Referring to fig. 5A, according to an exemplary embodiment of the present application, the receiving optical assembly 500 is used for converging a plurality of echo beams reflected by a target, and three gaussian lens elements including a fourth lens 501, a fifth lens 503 and a sixth lens 505 may be used. The fourth lens element can be a plano-convex lens element, or a biconvex lens element or a meniscus lens element, the fifth lens element can be a biconcave lens element, or a plano-concave lens element or a meniscus lens element, and the sixth lens element can be a plano-convex lens element, or a biconvex lens element or a meniscus lens element. The lens can be made of glass material.

Referring to fig. 5A, the receiving optical assembly 500 is also configured to be fixed by the pressing ring 507 and the spacer 509, similar to the transmitting optical assembly. Pressing rings 507 are arranged at the front end and the rear end of the receiving optical assembly and used for pressing the fourth lens, the fifth lens and the sixth lens, each space ring 509 is arranged between the fourth lens and the fifth lens, the pressing rings and the space rings are made of steel materials, the expansion coefficient of the pressing rings and the space rings is closer to that of glass, the thermal stability of the transmitting optical assembly is improved, and aluminum alloy materials can be adopted, so that the use cost is reduced; the fixing mode of the space ring and the pressing ring can ensure the optical performance of the receiving optical assembly, effectively reduce the risk of fragmentation of each lens under the conditions of high temperature and low temperature, improve the overall reliability of the laser radar, and the lens barrel 511 can be partially cut off, as shown in fig. 5B, and the side wall of the lens barrel is partially cut off. The lens barrel 511 having the partial cut-off structure can improve the reception efficiency of the laser radar at partial angles.

Fig. 6A is a schematic diagram of a receiver arrangement of a lidar in an exemplary embodiment of the present application.

Referring to fig. 6A, according to an exemplary embodiment, a receiver 600 converts an echo beam from a receive optical assembly into an electrical signal. The receiver 600 comprises at least a first and a second column of detectors arranged in a second direction, for example two columns 601 of 32 light emitting channels. And the two columns of detectors are staggered with respect to each other. The second direction is, for example, parallel to the first direction.

Referring to fig. 6B, in some embodiments, a row of detectors 601 corresponds to a row of lasers 101 in a one-to-one arrangement position, and are respectively configured to receive echo beams generated after laser beams emitted by the row of lasers are subjected to diffuse reflection by a target object. For example, one laser in the laser array emits beam 1, exits via the transmit optics and polygon mirror to the obstruction 605, and is diffusely reflected back to the receive optics for reception by the detector 601 in fig. 6B. Similarly, the other rows of detectors respectively correspond to the arrangement positions of the corresponding rows of lasers one by one and are used for receiving the echo beams generated by the rows of lasers. The detector may be an APD or SPAD or SiPM.

The operation principle of the lidar in the exemplary embodiment of the present application will be described in detail below.

According to an exemplary embodiment of the present application, the laser array 100 is disposed at the transmitting end of the lower half portion, the receiver 600 is disposed at the receiving end of the upper half portion, and the laser array 100 and the receiver 600 are integrally fixed in the optical transceiver module in the optical system of the lidar, as shown in fig. 4A. In other embodiments, the transmitting laser 100 is disposed in the upper half of the lidar optical system, and the receiver 600 is disposed at the receiving end of the lower half, as shown in fig. 4B.

Laser array 100 produces many emission beams, carries out the deflection to many emission beams through transmitting terminal turning mirror 402, and transmission optical subassembly 200 incides many emission beams after collimating on polygon mirror 300, drives the inside rotor rotation of polygon mirror 300 through the motor to realize the scanning of polygon mirror on the horizontal direction. The scanning beam forms diffuse reflection after reaching the target, the echo beam passes through the receiving optical assembly 500, the receiving end turning mirror 404 is incident on the receiver 600, and various information of the target is obtained after signal processing. Wherein the receiving end turning mirror 404 is disposed parallel to the transmitting end turning mirror along a first direction for deflecting the echo beam.

The arrangement of the transmitting end turning mirror 402 and the receiving end turning mirror 404 can increase the space utilization rate, reduce the volume, realize miniaturization and reduce the influence of stray light; the transmitting end folding mirror and the receiving end folding mirror are fixed to be arranged in a vertically staggered mode, the transmitting end folding mirror is arranged at the lower end of the receiving end folding mirror, the distance between the transmitting end folding mirror and the transmitting optical assembly is smaller than the distance between the receiving end folding mirror and the receiving optical assembly, and therefore the energy of the transmitted light beams can be maximized.

As can be seen from the above embodiments, the scanning apparatus for lidar and the lidar provided by the present application have one or more of the following advantages.

According to some embodiments, the laser array of the scanning device provided by the present application may be 2 rows of lasers with 32 light emitting channels, and implement a high beam, where the lasers in the left and right rows are arranged in a staggered manner in the vertical direction, and the lasers in the second row correspond to the spacing positions of the lasers in the first row. The arrangement mode increases the spatial arrangement density of the lasers, so that denser point cloud data can be obtained.

According to some embodiments, lasers with staggered emission optical components in the scanning device are matched with the telecentric lens system to emit light, and are matched with the edge cutting lens barrel, so that the light emitting efficiency can be improved, the vertical resolution is ensured, and the quality of point cloud data is improved. In addition, the pressing ring and the spacing ring for fixing can effectively reduce the risk of the fragmentation of each lens under the conditions of high temperature and low temperature, and improve the overall reliability of the laser radar scanning device while ensuring the optical performance.

According to some embodiments, the emission light beam of the laser radar is shot into the polygon mirror, the inclination angles of two adjacent reflecting surfaces of the polygon mirror are different, and the polygon mirror with the reflecting surfaces with different inclination angles can play a role of expanding lines when rotating and scanning, so that the vertical resolution of the laser radar is improved. By setting a higher-precision inclination angle, the point cloud data of the laser radar is more regular, and the data consistency of all points is better. Meanwhile, the method replaces the method of improving the quality of point cloud data through angle adjustment of each laser, solves the problems of complex installation and adjustment, high technical difficulty, high cost and the like, and realizes low cost and miniaturization of the laser radar.

It should be understood that the above examples are only for clearly illustrating the present application and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of this invention may be made without departing from the spirit or scope of the invention.

Claims

1. A scanning apparatus for a lidar comprising:

a laser array for generating an emission beam;

a transmit optical assembly disposed downstream of the laser array in a beam propagation direction to receive and collimate the emitted beam;

a polygon mirror disposed downstream of the emission optical assembly in a beam propagation direction, configured to reflect the emission beam collimated by the emission optical assembly to form a scanning beam;

the laser array comprises a plurality of lasers arranged in multiple columns, and the lasers in adjacent columns are arranged in a staggered mode.

2. A scanning device according to claim 1, wherein the proximity distance of the plurality of lasers at the central region of the column is smaller than the proximity distance thereof at the two end regions of the column.

3. A scanning device according to claim 1, wherein the plurality of lasers form a non-uniformly distributed array in which the density of the lasers is greater at a central region of the array than at both end regions of the array, and the plurality of lasers are adjacent at the same distance in the column.

4. A scanning device according to claim 1, wherein the emission optical assembly comprises a telecentric lens system.

5. The scanning device of claim 4, wherein the telecentric lens system comprises: a three-piece gaussian lens comprising:

a first lens comprising: one of a lenticular lens, a plano-convex lens, or a meniscus lens;

a second lens comprising: one of a plano-concave lens, a biconcave lens, or a convex-concave lens;

a third lens comprising: one of a plano-convex lens, a biconvex lens or a meniscus lens.

6. The scanning device of claim 5, wherein the telecentric lens system comprises: and a diaphragm disposed upstream of the first lens in a beam propagation direction, the diaphragm passing the emission beam therethrough.

7. The scanning device according to claim 1,

the emission optical assembly further includes a barrel provided as a partial cut edge.

8. The scanning device of claim 7, wherein the emission optics assembly further comprises:

the pressing rings are arranged at the front end and the rear end of the lens cone and are used for pressing the three Gaussian lenses;

and the spacing ring is arranged between the three Gaussian lenses and is used for spacing the Gaussian lenses and simultaneously matching with the pressing ring to press the three Gaussian lenses.

9. The scanning device of claim 1, wherein the polygon mirror has an axis and is rotatable around the axis, the polygon mirror includes an even number of reflecting surfaces enclosing a polygon for reflecting the emitted light beam and the reflected echo light beam formed by the reflected scanning light beam reflected by the target, and the scanning device further includes a motor accommodated in a space of the polygon enclosed by the reflecting surfaces.

10. A scanning device according to claim 9, wherein two of the even number of reflecting surfaces are at the same angle to the axis, and two adjacent reflecting surfaces are at the same angle to the axis and have the same absolute value and opposite signs.

11. The lidar of claim 9, wherein an angle between the reflective surface of the polygon and the axis is determined based on a spacing of the plurality of lasers in the column.

12. The lidar of claim 11, wherein the plurality of lasers are spaced apart in the column by an angle corresponding to 0.5 ° of exit of the emitted beam, and wherein the polygon has four reflective surfaces, two of which are at an angle of 0.09 ° to the axis, and two of which are at an angle of-0.09 ° to the axis, to achieve a resolution of up to 0.25 ° over a field of view.

13. A scanning device according to any of claims 9-12, wherein the polygon mirror further comprises an optical isolation portion for isolating the emission beam and the echo beam.

14. A lidar, comprising:

the scanning device of any one of claims 1-13, wherein a reflective surface of a polygon mirror of the scanning device is simultaneously used to receive an echo beam of a lidar;

the receiving optical assembly receives and converges the echo light beam reflected by the multi-surface rotating mirror;

a receiver that receives the echo beam from the receiving optical assembly and converts it into an electrical signal.

15. The lidar of claim 14, wherein the receiver comprises a detector array including a plurality of detectors arranged in a plurality of columns, the detectors of adjacent columns being staggered relative to each other.

16. The lidar of claim 15, wherein each detector in each column corresponds to a position of the laser in one of the columns, such that each detector is configured to receive an echo beam from the laser corresponding thereto.

17. The lidar of claim 16, wherein each reflective surface comprises separate upper and lower portions, one of the upper and lower portions for receiving and reflecting the transmitted beam and the other of the upper and lower portions for receiving and reflecting the return beam.

18. The lidar of claim 15, wherein the detector comprises: APD, SPAD, or SiPM.

19. The lidar of claim 14, further comprising:

the transmitting end turning mirror is arranged between the laser array and the transmitting optical assembly and used for deflecting the transmitting light beam; and

and the receiving end turning mirror is arranged between the receiver and the receiving optical assembly, is parallel to the transmitting end turning mirror along the vertical direction, and is used for deflecting the echo light beams.

20. The lidar of claim 19, wherein a distance between the transmitting end turning mirror and the transmitting optical assembly is less than a distance between the receiving end turning mirror and the receiving optical assembly.