Patent Publication Number: US-11662438-B2

Title: Optical scanning apparatus and lidar with extinction component

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 17/002,682, filed Aug. 25, 2020, which was a bypass continuation of International Application No. PCT/CN2020/082485, filed Mar. 31, 2020, and also claims the priority of Chinese patent application number CN 201910255918.3, filed Apr. 1, 2019, the entirety of each of which is hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present disclosure relate to the field of optics technology, and in particular to an optical scanning apparatus and a lidar device. 
     BACKGROUND 
     With the development of lidar technology, people have increasingly higher requirements on lidar detection performance. Solid-state lidar has aroused wide concern because of its advantages such as high system reliability, excellent detection performance, and easy control of cost. 
     The inventor has found that in solid-state lidars, micro-electromechanical systems (MEMS) are typically used for the core devices of scanning components. However, because MEMS themselves have reflection and scattering characteristics to the laser light signals, disordered stray light signals will occur inside the lidar. Because the receiving module of the lidar is extremely sensitive and tends to respond to these stray light signals, light signals reflected from the proximity of the lidar in the field of view submerge in the stray light signals. As such, the receiving module cannot distinguish the light signals reflected from the proximity of the lidar, and cannot effectively identify nearby objects, resulting in a larger detection blind area. 
     SUMMARY 
     In view of the above problems, the embodiments of the present disclosure provide an optical scanning apparatus and a lidar, which overcome the above problems or at least partially solve the above problems. 
     According to an aspect of an embodiment of the present disclosure, there is provided an optical scanning apparatus, the apparatus includes a reflector, a reflector substrate and an extinction component; the reflector is mounted on the reflector substrate, and the extinction component is arranged on the front of the reflector substrate. 
     The reflector is used to reflect incident light signals. 
     The extinction component is used to reduce the scattered light signals produced by the incident light signals on the reflector substrate. 
     According to another aspect of the embodiment of the present disclosure, there is provided an optical scanning apparatus. The apparatus includes a reflector, a connection frame, a reflector substrate and an extinction layer. The reflector and the reflector substrate are connected by the connection frame. The connection frame is provided with a coil. The front surface of the reflector substrate and the connection frame are provided with the extinction layer for reducing the stray light signals produced by the incident light signals on the connection frame and the reflector substrate. 
     According to another aspect of the embodiment of the present disclosure, there is provided a lidar, including the foregoing optical scanning apparatus. 
     For the optical scanning apparatus and the lidar described in the embodiments of the present disclosure, the optical scanning apparatus includes a reflector, a reflector substrate and an extinction component, wherein the reflector is mounted on the reflector substrate, and the reflector is used to reflect the incident light signals. In addition, the extinction component is arranged in front of the reflector substrate and the extinction component can reduce the incident light signals falling on the reflector substrate, thereby reducing the scattered light signals produced by the incident light signals on the reflector substrate. At the same time, the scattering coefficient on the surface of the extinction component is smaller than that of the front surface of the reflector substrate, thereby greatly reducing the scattered light signals inside the lidar and reducing the detection blind area caused by stray light signals, and thus greatly improving the receiving and detecting ability of the lidar. 
     The above description is only an overview of the technical solutions of the present disclosure. Specific implementations of this disclosure are provided below for the purpose of understanding the technical means of this disclosure more clearly and enabling implementation of the present disclosure according to the content of the specification, and making the abovementioned and other purposes, features and advantages of this disclosure more apparent. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       By reading the detailed description of the disclosed implementations below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only used to show the disclosed implementations, and are not considered as limitations to the present disclosure. And throughout the drawings, the same reference symbol indicates the same component. In the drawings: 
         FIG.  1    shows a structural diagram of a lidar; 
         FIG.  2    shows a structural diagram of an embodiment of an optical scanning apparatus of the present disclosure; 
         FIG.  3    shows a path of a major light signal generated in a lidar of an embodiment of the present disclosure; 
         FIG.  4    shows a schematic diagram of a reflector and a light spot of an incident light signal of an embodiment of an optical scanning apparatus of the present disclosure; 
         FIG.  5    shows a schematic diagram for determining a predetermined height set by a diaphragm of an optical scanning apparatus of the present disclosure; 
         FIG.  6    shows a structural diagram of another embodiment of an optical scanning apparatus of the present disclosure; 
         FIG.  7    shows a schematic diagram of a light path in an embodiment of a lidar of the present disclosure; 
         FIGS.  8 A and  8 B  respectively show structural diagrams of a front surface and a back surface of a diaphragm in an embodiment of an optical scanning apparatus of the present disclosure; 
     
    
    
     The reference numbers in the specific implementation are as follows:
           10 . Lidar;  11 . Transceiver component;  12 . Turn back mirror;  13 . Optical scanning apparatus;  14 . Base;  100 . Reflector;  200 . Reflector substrate;  300 . Extinction component;  400 . Extinction layer;  110 . Reflector;  120 . Connection frame;  121 . Coil;  130 . Reflector substrate;  140 . Outer connection bridge;  150 . Inner connection bridge;  160 . Diaphragm;  161 . Light shielding plate;  162 . Light pass aperture;  163 . Transitional interface;  164 . First slope;  165 . Second slope;  166 . Intersection line.       

     DETAILED DESCRIPTION 
     Embodiments of the technical solutions of the present disclosure will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly explain the technical solutions of the present disclosure, and therefore are only used as examples, and shall not be used to limit the protection scope of the present disclosure. 
     Referring to  FIG.  1   , which shows a lidar  10  including at least one transceiver component  11 , at least one turn back mirror  12 , an optical scanning apparatus  13  and a control component (not shown in the figures). The transceiver component  11  and the turn back mirror  12  are arranged in one-to-one correspondence. 
     Take a transceiver component  11  and a corresponding turn back mirror  12  for example. The transceiver component  11  transmits transmitted light signals to the turn back mirror  12 , and the turn back mirror  12  reflects the transmitted light signals to the optical scanning apparatus  13 , and the optical scanning apparatus  13  receives the transmitted light signals reflected by the turn back mirror  12  and then transmits them outwards for scanning. Objects in the detection area reflect the outward transmitted light signals, and return the reflected light signals. Part of the reflected light signals having the same light path and the opposite direction as the transmitted light signals are coaxially transmitted to the optical scanning apparatus  13 . The optical scanning apparatus  13  deflects the received reflected light signals and then transmits them to the turn back mirror  12 , and the turn back mirror  12  reflects the reflected light signals to the transceiver component  11 . The light paths of the transmitted light signals and the corresponding reflected light signals pass through a group of transceiver component  11  and turn back mirror  12  arranged correspondingly, and are scanned and received by the optical scanning apparatus  13  to form a field of view. The control component is configured to drive and control the transceiver component  11  and the optical scanning apparatus  13 . 
     The lidar  10  may include one group of transceiver component  11  and turn back mirror  12 , and may include a plurality of groups of transceiver component  11  and turn back mirror  12  arranged in correspondence. A plurality of groups of the transceiver components  11  and the turn back mirror  12  are arranged in sequence, and their light paths are at different angles with the optical scanning apparatus  13 , i.e., a plurality of transmitted light signals are transmitted to the optical scanning apparatus  13  at different angles, reflected by the optical scanning apparatus  13  and then transmitted outwards and scan different spatial regions, and the plurality of reflected light signals are coaxially returned and received by the corresponding transceiver components  11 . Multiple fields of view that do not completely overlap in space are formed. And after being scanned and received by the optical scanning apparatus  13 , multiple fields of view are formed, thereby expanding the overall field of view of the lidar  10 . As shown in  FIG.  1   , the lidar  10  further includes a housing assembly, including a top cover (not shown in the figure) and a base  14 . The base  14  is provided with six groups of transceiver components  11  and turn back mirrors  12  arranged correspondingly. The six transceiver components  11  are sequentially arranged and fixed on the base  14 , and the front end of each transceiver component  11  is correspondingly provided with a turn back mirror  12 , there is a total of six turn back mirrors. The optical scanning apparatus  13  is fixed to the base  14  by a mounting bracket. It can be seen from the foregoing that the lidar  10  can form six fields of view arranged in sequence in the horizontal direction. After splicing, the horizontal field of view of the lidar is greatly expanded, for example, the horizontal field of view can reach 120°, which improves the detecting ability of the lidar. 
     Each transceiver component  11  includes a transmitting module, a beam splitting module and a receiving module. The transmitted light signals transmitted by the transmitting module pass through the beam splitting module and then are transmitted outwards, the coaxially reflected light signals enter the transceiver component  11  and are deflected by the beam splitting module and then received by the receiving module. The foregoing control component is used to drive the transmitting module and the receiving module, and is also used to perform signal processing and transmission on the reflected light signals received by the receiving module. 
     The above-mentioned optical scanning apparatus  13  may be micro-electro mechanical systems (MEMS for short) or other galvanometer systems. Referring to  FIG.  4   , since the reflector  100  of the optical scanning apparatus is very small in volume, the light spots of the transmitted light signals and the reflected light signals falling on the optical scanning apparatus tend to be larger than the working surface of the optical scanning apparatus. That is to say, the mirror surface of the reflector  100  of the optical scanning apparatus, especially the light spot of the reflected light signal is larger. Part of the light signals with light spots exceeding the reflector  100  falls on the reflector substrate  200 , the reflector substrate  200  reflects or scatters the light signals, and the scattered light signal is different from its original light path direction to become a stray light signal. The stray light signal is received by the transceiver component  11 , which causes the receiving module of the transceiver component  11  to respond to the stray light signal, and thus makes the receiving module premature saturated and unable to quickly respond to the light signal returned from the proximity of the lidar in the field of view. The receiving module cannot distinguish the light signal reflected from the proximity of the lidar in the field of view, and cannot effectively identify the near object, resulting in a larger detection blind area. 
     In view of the above technical problems,  FIG.  2    shows a structural schematic diagram of an optical scanning apparatus provided by an embodiment. The optical scanning apparatus includes a reflector  100 , a reflector substrate  200  and an extinction component  300 . The reflector  100  is mounted on the reflector substrate  200 ; the extinction component  300  is arranged in front of the reflector substrate  200 . The reflector  100  is used to reflect the incident light (i.e. incident light signal). The extinction component  300  is used to reduce the scattered light produced by the incident light (i.e. incident light signal) on the reflector substrate  200 . 
     Note that,  FIG.  3    shows a path of a major light signal generated in a lidar. Wherein, the laser collimation system (i.e., transmitting module) is a laser transmitting system with a smaller beam divergence angle. It consists of a laser light source and a collimation optical system. Optionally, the laser light source may include, but not be limited to, solid-state laser light sources, gas laser light sources, semiconductor laser light sources, liquid laser light sources, chemical laser light sources, fiber laser light sources and free-electron laser light source lamps. Optionally, collimated optical systems may include, but are not limited to, spherical lens optical system combinations, cylindrical lens optical system combinations, aspherical lens optical system combinations, fold-back type hybrid optical system combinations, and gradient index(GRIN) composite optical system combinations, etc. Usually, the laser collimation system (i.e., transmitting module) of the lidar transmits the transmitted light signal, and the transmitted light signal reaches the target object through the optical scanning apparatus. This part of the transmitted light signal is reflected by the target object and returned to the receiving system (i.e., receiving module) of the lidar. In addition, some light signals cause scattering inside the optical scanning apparatus. The incident light (i.e., incident light signal) can be either one or more of the transmitted light signal transmitted to the optical scanning apparatus and the reflected light signal received by the optical scanning apparatus. As mentioned above, when the incident light signals (transmitted light signals or reflected light signals) enter the optical scanning apparatus, most of the incident light signals are concentrated on the reflector  200  and reflected to the target object, but the part of the incident light signals with light spots exceeding the reflector  100  is scattered by the reflector substrate  200  and exhibits like an Nth cosine scattering characteristic distribution. The scattered light is captured by the receiving system (i.e., the receiving module), causing the receiving system (i.e., the receiving module) to form a signal response of the internal scattering (i.e., stray light signals), so that the receiving system (i.e., the receiving module) is premature saturated, unable to respond to returned light signals (i.e., the reflected light signals) from the proximity of the lidar, so that the returned light signals (i.e., the reflected light signals) are submerged in the signals produced by the internal stray lights (i.e., stray light signals), resulting in a detection blind area. 
     Specifically, the above optical scanning apparatus includes a reflector  100 , a reflector substrate  200  and an extinction component  300 . Wherein, the reflector  100  is mounted on the reflector substrate  200 ; the extinction component  300  is arranged in front of the reflector substrate  200 . Optionally, the extinction component  300  may be attached to the front surface of the reflector substrate  200 , or may be arranged at a certain distance in front of the reflector substrate  200 , which is not limited in this embodiment. When the light signals (transmitted light signals or reflected light signals) enter the optical scanning apparatus, since the extinction component  300  is arranged in front of the reflector  200 , most of the incident light signals (i.e., transmitted light signals or reflected light signals) enter the reflector  100  and are then reflected, a small part of the incident light signals first passes through the extinction component  300 , which can reduce or even approximately eliminate part of the incident light signals that don&#39;t fall on the reflector  100 , thereby greatly reducing the incident light signals that would fall on the reflector substrate  200 , thus greatly reducing the scattered light reflected by the reflector substrate  200  from the incident light signal. 
     In this embodiment, the optical scanning apparatus includes a reflector, a reflector substrate and an extinction component, wherein the reflector is mounted on the reflector substrate, and the reflector is used to reflect the incident light signals. In addition, the extinction component is arranged in front of the reflector substrate and the extinction component can reduce the incident light signals falling on the reflector substrate, thereby reducing the scattered lights produced by the incident light signals on the reflector substrate. At the same time, the scattering coefficient of the surface of the extinction component is smaller than that of the front surface of the reflector substrate, thereby greatly reducing the scattered lights (i.e., stray light signal) inside the lidar and reducing the detection blind area caused by stray light signals, and thus greatly improving the receiving and detecting ability of the lidar. 
     Optionally, with continued reference to  FIG.  2   , on the basis of the above embodiment, the extinction component  300  can be a diaphragm, and the diaphragm is arranged on the front of the reflector  100 , and the light pass aperture of the diaphragm is aligned with the reflector  100 . 
     Specifically, since the diaphragm is arranged on the front of the reflector  100 , i.e. on the incident side, before the incident light signal enters the reflector  100 , the incident light signal is first selected by the diaphragm. Since the light pass aperture of the diaphragm is aligned with the reflector  100 , the part of the incident light signals falling into the light pass aperture of the diaphragm can reach the reflector  100 , and the rest part of the incident light signals falling on the diaphragm can be prevented from falling on the reflector substrate  200  by the function of the diaphragm. 
     In this embodiment, through disposing the diaphragm on the front of the reflector and aligning the light pass aperture of the diaphragm with the reflector, the light signals falling on the reflector substrate are greatly reduced, thereby reducing the scattered light produced by the incident light signal on the reflector substrate, so that the scattered light (i.e., stray light signal) inside the optical scanning apparatus is greatly reduced, which greatly reduces the detection blind area caused by the stray light signal and greatly improves the receiving and detecting abilities of the lidar. 
     Optionally, the surface scattering coefficient of the above-mentioned diaphragm is smaller than the scattering coefficient of the front surface of the reflector substrate  200 . By setting the surface scattering coefficient of the diaphragm to be smaller than the scattering coefficient of the front surface of the reflector substrate  200 , compared with the degree of scattering of the incident light signal by the reflector substrate  200 , it can greatly reduce the scattering of the incident light signal falling on the diaphragm, and then greatly reduce the scattered light, so that the scattered light inside the lidar (i.e., stray light signal) is greatly reduced, and the detection blind area caused by the stray light signal is reduced, which greatly improves the receiving and detecting abilities of the lidar. 
     Optionally, a light absorbing film or a light reflecting film may be attached to the diaphragm to reduce the scattering coefficient of the surface of the diaphragm. Generally, an object has three responses of incident, reflected and scattered to a light signal. Due to conservation of energy, the scattering characteristics can be reduced by increasing absorption and reflection. Therefore, by attaching a light absorbing film to the surface of the diaphragm, more incident light signals can be absorbed, thereby greatly reducing scattered light; or by attaching a light reflecting film to the surface of the diaphragm, more light signals can be reflected. Since the reflection can be directional, the light signal can be reflected to a direction that does not affect the receiving system, thereby greatly reducing scattered light. In this embodiment, the light absorbing film is attached to the diaphragm to increase the absorption of the incident light signal to reduce scattering, or the light reflecting film is attached to the diaphragm to enhance the reflection of the incident light signal to reduce scattering, thereby reducing the scattering coefficient on the surface of the diaphragm and reducing the detection blind area caused by stray light, which greatly improves the receiving and detecting abilities of the lidar. 
     Optionally, the thickness of the above diaphragm is less than the preset thickness threshold, which is determined by that the diaphragm does not block the incident light signal reflected by the reflector. 
     Specifically, the thickness of the above diaphragm needs to be less than the preset thickness threshold. If the thickness of the diaphragm is too thick, it will interfere with the incident light signal and affect the receiving performance of the receiving system. Therefore, the thickness of the diaphragm can be less than the thickness threshold by setting the thickness threshold, thus ensuring that the diaphragm will not block the incident light signal reflected by the reflector due to the excessive thickness. Specifically, the thickness of the above diaphragm should be as small as possible to minimize the impact on the incident light signal. 
     Optionally, on the basis of the above embodiments, the area of the light pass aperture of the diaphragm is greater than or equal to the area of the reflector  100 . 
     Specifically, the area of the light pass aperture of the diaphragm can be greater than or equal to the area of the reflector  100 , the area of the light pass aperture can be slightly greater than the area of the reflector  100 , and can also equal to the area of the reflector  100 . Through setting the area of the light pass aperture of the diaphragm greater than or equal to the area of the reflector, it is ensured that the incident light signal can fall on the reflector as much as possible, while at the same time reducing the scattering of the incident light signal by the reflector substrate as much as possible, thereby ensuring the response of the optical scanning apparatus to the light signal and reducing the detection blind area caused by the stray light, so that the receiving and detecting ability of the lidar is greatly improved. 
     Optionally, on the basis of the above embodiments, the diaphragm is provided at the front of the reflector  100  in accordance with a predetermined setting height; the setting height is determined according to the maximum incident angle of the incident light signal and the radius difference between the diaphragm and the reflector. 
     Specifically, when the incident light signals is transmitted toward the reflector  100 , there will be an angle with the plane of the reflector and the incident light signals, and when the angle is too large, it may not be able to enter the reflector  100  and falls on the reflector substrate  200 . In order to ensure that the incident light signal transmitted toward the reflector is blocked by the diaphragm as little as possible, the setting height of the diaphragm can be determined according to the maximum incident angle of the incident light signal, the radius difference between the diaphragm and the reflector  100 . It can be seen in  FIG.  5   , d is the difference between the radius of the diaphragm and the radius of the reflector  100 , a is the maximum incidence angle of the incident light signal, and h is the setting height of the diaphragm, wherein the height value is the distance between the front surface of the diaphragm and the reflector  100 . Optionally, the setting height of the diaphragm can be determined by the formula or a variation of the formula. 
     In this embodiment, the diaphragm is arranged on the front of the reflector according to the predetermined setting height, since the setting height is determined by the maximum incidence angle of the incident light signal and the radius difference between the diaphragm and the reflector, it can ensure that the incident light signal passes through the light pass aperture of the diaphragm as much as possible and is transmitted towards the reflector, so that the incident light signal can be reflected to the greatest extent, thereby improving the light utilization rate and the detecting ability of the lidar. 
     Optionally, on the basis of the foregoing embodiments, an extinction layer  400  may be attached to the front surface of the reflector substrate  200 , and the extinction layer  400  is used to reduce the scattering of the incident light signal by the reflector substrate  200 . Specifically, since the diaphragm is unable to eliminate the incident light signal irradiated on the reflector substrate  200  completely, the extinction layer  400  can also be attached on the front surface of the reflector substrate  200 . The extinction layer can further reduce the scattering of the incident light signal by the reflector substrate  200 . Optionally, the extinction layer  400  may be a light reflecting layer or a light absorbing layer. When the extinction layer  400  is a light reflecting layer, it can reduce the scattering characteristics by increasing the reflection characteristics to the incident light signal; when the extinction layer  400  is a light absorbing layer, it can reduce the scattering characteristics by increasing the absorption characteristics to the incident light signal. Therefore, the scattering of the reflector substrate to the incident light signal can be further reduced, and the detection blind area caused by stray light can be reduced, so that the receiving detecting ability of the lidar is greatly improved. 
     Referring to  FIG.  6   ,  FIG.  6    shows a structural diagram of an optical scanning apparatus provided by another embodiment. The optical scanning apparatus includes a reflector  110 , a connection frame  120  and a reflector substrate  130 . The reflector substrate  130  is stationary relative to a mounting bracket, the reflector  110  vibrates relative to the reflector substrate  130  to realize scanning. The connection frame  120  connects the reflector  110  and the reflector substrate  130 . An outer connection bridge  140  connects the reflector substrate  130  and the connection frame  120 . An inner connection bridge  150  connects the connection frame  120  and the reflector  110 . The number of the outer connection bridge  140  can be two and the two outer connection bridges  140  are on the second axis. The number of the inner connection bridge  150  can also be two, and the two inner connection bridges  150  are on the first axis. The reflector  110  vibrates relative to the first axis and the second axis. The connection frame  120  is provided with a coil  121 , the coil  121  is applied with electromagnetic force to vibrate, thereby driving the reflector  110  to vibrate. It should be noted that the coil  121  may be provided on the back surface of the connection frame  120  or on the front surface of the connection frame  120 . Since the area of the reflector substrate  130  is smaller, the circuits on the back surface of the reflector substrate  130  are arranged densely. In order to save space on the back surface of the reflector substrate  130 , the coil  121  can be arranged on the front surface of the connection frame  120 , as long as the coil  121  does not block the light signal through in and out of the reflector  110 . 
     Optionally, both of the front surface of the reflector substrate  130  and the front surface of the connection frame  120  are provided with an extinction layer. The extinction layer is used to reduce the scattering of the incident light signals by the reflector substrate  130  and the connection frame  120 . The front surface of the reflector substrate  130  is a metallic reflection plane, and most of the incident light signals (such as the transmitted light signal and the reflected light signal) are transmitted to the front surface of the reflector  110 . The incident light signal has an edge portion thereof, which exceeds the reflector  110  and falls on the reflector substrate  130 . After being reflected by the reflector substrate  130 , the incident light signal deviates from its preset transmission trajectory. For example, a preset transmission trajectory of the transmitted light signal may be to transmit the signal toward the reflector at a designed incident angle, and to reflect the signal by the reflector  110  and then transmit it outwards at a designed angle. Also for example, a preset transmission trajectory of the reflected light signal may be to transmit the signal toward the reflector  110  at an angle which enables it to be coaxial with the transmitted light signal, and to reflect the signal by the reflector  110  and then transmit it to a corresponding turn back mirror  12 . 
     Incident light signals that deviate from the preset transmission trajectory form stray light signals inside the lidar, resulting in a larger detection blind area. Similarly, the front surface of the connection frame  120  is a metal coil  121 , the surface of the coil  121  is uneven and has many small grooves distributed thereon. After the incident light signal falls on the connection frame  120 , it is reflected a plurality of times in the grooves and also deviates from the preset transmission trajectory of the incident light signal, forming a large number of stray light signals. Therefore, extinction layers arranged on the front surfaces of the connection frame  120  and the reflector substrate  130  can result in absorption of the incident light signal transmitted to the reflector substrate  130  and the connection frame  120 . As such, scattering on the surfaces of the connection frame  120  and the reflector substrate  130  can be alleviated; and further reducing the generation of stray light signals. 
     Optionally, the optical scanning apparatus further includes a diaphragm  160 , which is arranged on the front of the reflector  110 , the connection frame  120 , and the reflector substrate  130 . The diaphragm  160  is used to limit the incident light signal and to limit part of the incident light signals with light spots falling outside the reflector  110 , such as it is transmitted to the connection frame  120  and the reflector substrate  130 . The diaphragm  160  reduces the disordered stray light signals formed after the incident light signals reflect or scatter on the connection frame  120  and the reflector substrate  130 , and also reduces the detection blind area caused by the stray light signals, thereby greatly improving receiving and detecting ability of the lidar. 
     The diaphragm  160  includes a light shielding plate  161  and a light pass aperture  162 . The light pass aperture  162  is configured to allow the light signals transmitted to the reflector  110  and the light signals reflected by the reflector to pass through. The light shielding plate  161  is used to block the light signals at the edge of the normal light path and to reduce the stray light signals produced by the light signals transmitted to the connection frame  120  and the reflector substrate  130 . Since the incident light signals transmitted to the reflector  110  include the transmitted light signal and the reflected light signal, if the light pass aperture  162  is set very small, it can effectively block the light signal, so that the incident light signals are all transmitted to the reflector  110 . It is even possible that the size of the light spot of the incident light signal is smaller than the size of the mirror plane of the reflector  110 , and there is no incident light signal transmitted to the connection frame  120  and the reflector substrate  130  at all. Nevertheless, this will also reduce the transmitted light signal and reflected light signal used for detection, so that the lidar cannot effectively detect areas at a long distance, which reduces the ranging ability of the lidar. Therefore, the shape of the light pass aperture  162  is designed to not block the light signal transmitted to the reflector  110  and the light signal reflected by the reflector, which not only ensures that the ranging ability of the lidar is not affected, but also reduces the stray light signal and improves the receiving and detecting ability. As shown in  FIGS.  8 A and  8 B , the shape of the light pass aperture  162  may be trapezoid. When the diaphragm is installed in the lidar shown in  FIG.  1   , the longer side of the trapezoid of the light pass aperture  162  is arranged above, and the shorter side of the trapezoid is arranged below, the light pass aperture  162  is arranged inverted trapezoidal. Since the light paths of the transmitted light signal and the reflected light signal among the transceiver module  11  and turn back mirror  12  and the optical scanning apparatus  13  are coaxial, i.e., they are spatially overlapping and are only located in opposite directions; the following only uses the transmitted light signal as an example for explanation. As shown in  FIG.  7   , since the transmitted light signal is reflected by the turn back mirror  12  and then is transmitted inclined upward to the reflector  110  of the optical scanning apparatus  13 , the transmitted light signal reflected by the reflector  110  also exits inclined upward to transmit outwards. Due to the compact internal structure of the lidar, the distance between the turn back mirrors  12  is relatively shorter, and the angle between the transmitted light signals transmitted to the reflector  110  after being reflected by two outermost turn back mirror  12  is smaller. In addition, the reflector  110  of the optical scanning apparatus  13  is constantly vibrating, and the angle between the two outermost beams of the transmitted light signals among the transmitted light signals reflected by the reflector  110  becomes significantly larger. From this, it can be seen that the angle between the transmitted light signals transmitted from the bottom up to the reflector  110  is smaller, and the angle between the transmitted light signals that exit in an inclined upward direction from the reflector  110  is larger. Therefore, the light pass aperture  162  of the diaphragm  160  is set to be shorter on the lower side and longer on the upper side. As such, the diaphragm  160  can effectively block the light signals at the edge of the normal light path, and reduce the stray light signals produced by the light signals transmitted to the connection frame  120  and the reflector substrate  130 . In addition, the diaphragm  160  can allow the transmitted light signals and the reflected light signals to transmit to the reflector  110  of the optical scanning apparatus  13  as much as possible, in order to ensure the ranging capability of the lidar. 
     As shown in  FIG.  8 A , a transitional interface  163  in the shape of a circle is arranged at the light pass aperture  162  of the diaphragm  160 , and is arranged on the front surface of the diaphragm  160 . In view of the foregoing, the transmitted light signal travels upwards to the reflector  110  from below, and exits from the reflector  110  in an inclined upward direction. The reflected light signal and the transmitted light signal travel in the same light path, but in opposite directions. Therefore, by providing a transitional interface  163  in the shape of a circle on one side of the light pass aperture  162 , which side faces the front surface of diaphragm  160 , it is possible to alleviate the problem of unnecessary blocking of the light signal caused by the thickness of the light shielding plate  161 . Accordingly, unnecessary blocking of the transmitted light signal and the reflected light signal is alleviated, and the ranging ability of the lidar is guaranteed. The shape of the transitional interface  163  may be consistent with the direction of the light signal transmitted to the reflector  110  and transmitted from the reflector  110 . 
     In addition, the diaphragm  160  is provided on the front of the reflector  110  at a preset height. In order to reduce the transmitted light signal and the reflected light signal blocked by the diaphragm  160  as much as possible while meeting the above-mentioned requirements for the size of the light spot of the incident light signal, the diaphragm  160  may be attached directly to the optical scanning apparatus  13 , as shown in  FIG.  7   . For example, the diaphragm  160  is directly attached to the connection frame  120  and the reflector substrate  130 , as long as the reflector  110  can be exposed. However, the connection frame  120  and the reflector  110  are driven to vibrate, and the diaphragm  160  cannot be arranged directly on the connection frame  120  and the reflector substrate  130 ; therefore, the diaphragm  160  is fixed on the front of the reflector  110  at a preset height. The diaphragm  160  is arranged as close as possible to the optical scanning apparatus  13 , as long as the diaphragm does not affect the vibration of the connection frame  120  and the reflector  110 . A transitional interface  163  in the shape of a circle is provided on one side of the light pass aperture  162 , which side facing the front surface of the diaphragm  160 . The transitional interface  163  gradually extends backward as it approaches one end of the light pass aperture  162 . The light pass aperture  162  is located behind the plane where the front surface of the light shielding plate  161  is located, enabling the light pass aperture  162  of the diaphragm  160  to be closer to the optical scanning apparatus with improved performance. 
     As the light pass aperture  162  of the diaphragm  160  approaches the optical scanning apparatus  13  in a backward direction, the back surface of the light shielding plate  161  approaching the light pass aperture  162  protrudes rearward, and the space between the light shielding plate  161  and the connection frame  120  and the reflector substrate  130  decreases. As can be seen from the foregoing, the connection frame  120  and the reflector  110  are driven to vibrate, and the back surface of the light shielding plate  161  is too close to the connection frame  120 . When the connection frame  120  vibrates, it will be interfered by the light shielding plate  161 , causing a hinder to the normal work of the connection frame  120  and the reflector  110 . The back surface of the diaphragm  160  is provided with a space for the vibration of the reflector  110  and the connection frame  120 . The back surface of the light shielding plate  161  is provided with a plurality of slopes that gradually extend outward from the light pass aperture  162 , and the ends of each slope that are away from the light pass aperture  162  gradually extend towards the front surface. The lidar mentioned above may include six groups of transceiver components  11  and correspondingly arranged turn back mirrors  12 , i.e., light paths of six transmitted light signals and corresponding light paths of reflected light signals may be arranged along the first axis direction. In order to allow the six paths of transmitted light signals and corresponding reflected light signals arranged along the first axis direction to pass through, the light pass aperture  162  has a diameter in the direction of the first axis larger than diameters in other directions. Therefore, the light shielding plates  161  on both sides of the light pass aperture  162  perpendicular or approximately perpendicular to the first axis direction have less influence on the connection frame  120 . By contrast, the light shielding plates  161  on the upper and lower sides of the light pass aperture  162  parallel or approximately parallel to the first axis direction have a greater influence on the connection frame  120 . A plurality of slopes provided on the back surface of the light shielding plate  161  can gradually extend in directions perpendicular to the first axis, from their centers to two sides, towards the front surface. As shown in  FIG.  8 B , the back surface of the light shielding plate  161  is provided with a first slope  164  and a second slope  165 , and an intersection line  166  between the first slope  164  and the second slope  165  is parallel to the first axis. The light shielding plate  161  at the intersection line  166  is the rearmost, and extends from the intersection line  166  to both sides perpendicular to the first axis direction respectively, and the ends of the first slope  164  and the second slope  165  farther away from the intersection line  166  are closer to the front. As a result, space between the light shielding plate  161  on the upper and lower sides of the light pass aperture  162  and the connection frame  120  is increased, and the problem of the influence of the light shielding plate  161  on the vibration of the connection frame  120  is solved. 
     In one embodiment, a lidar is also provided, which includes any one of the optical scanning apparatuses in the foregoing embodiments. The technical principles and technical effects involved in the lidar are the same as in the above-mentioned optical scanning apparatuses, and will not be repeated here. 
     It should be noted that, unless otherwise stated, the technical terms or scientific terms used in the embodiments of the present disclosure shall be interpreted with the common meanings understood by those skilled in the art to which the embodiments of the present disclosure belong. 
     In the description of the embodiments of this invention, the azimuth or positional relationships indicated by the technical terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner” “outer”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential” etc. are the azimuth or positional relationships based on the drawings, and are used only to facilitate the description of the embodiments of the present disclosure and simplify the description, rather than to indicate or imply the referred apparatus or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of the present disclosure. 
     In addition, the technical terms “first”, “second” etc. are for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. In the description of the embodiments of the present disclosure, the meaning of “plurality” is more than two, unless otherwise specifically limited. 
     In the description of the embodiments of the present invention, unless otherwise clearly specified and defined, the technical terms “mounted”, “connection”, “connected”, “fixed” and other terms should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected, or it can be indirectly connected through intermediaries, or it can be the internal communication of two elements or interaction relationship of two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the present disclosure can be understood according to specific situations. 
     In the description of the embodiments of the present invention, unless otherwise clearly specified and defined, the first feature is “above” or “below” the second feature, which may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediary. Moreover, the first feature is “on”, “above” and “over” the second feature, which may be that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher than the second feature in level. The first feature is “down”, “below”, and “under” the second feature, which may be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less than the second feature in level. 
     Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that the technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure and should be covered in the scope of the claims and the description of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any way. This disclosure is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.