Patent Publication Number: US-2021190919-A1

Title: Detection system using optical scanning element with glass body and reflective member

Description:
FIELD OF THE TECHNOLOGY 
     The subject disclosure relates to object detection and more particularly to detection systems for vehicles. 
     BACKGROUND OF THE TECHNOLOGY 
     Vehicles benefit from having detection systems which seek information on a wide variety of information about the vehicle surroundings. Detection systems can be used for collision avoidance, self-driving, cruise control, and the like. Detection systems often seek information such as bearing, range, velocity, reflectivity, and image data on objects within the surrounding environment. LiDAR is one type of technology typically employed to help obtain information on the surroundings and provide the information to the driver or to a computer system within the vehicle. 
     In LiDAR systems in particular, it is important to combine very wide field of view with high resolution to ensure accurate information on the surroundings is obtained. This is often accomplished by providing a large number light transmitters and receivers. However, large transmitter/receiver arrays can add significantly to the cost of a detection system. Other LiDAR systems use scanning systems which employ rotating reflective parts to minimize the number of transmitters and receivers required. However, these systems can be bulky and/or can result in poor resolution at different areas within a scan pattern. 
     SUMMARY OF THE TECHNOLOGY 
     In light of the needs described above, in at least one aspect, the subject technology relates to a compact and cost effective vehicle detection system. More particularly, in at least one aspect, the subject technology relates to a LiDAR system which can accurately scan a wide field of view in both azimuth and elevation without requiring a large array of light transmitters and receivers. 
     In at least one aspect, the subject technology relates to a detection system for a vehicle in an environment. The system includes at least one LiDAR transmitter configured to transmit a light beam along an optical path and into the environment. The system includes a reflective mirror positioned along the optical path and configured to move to redirect the light beam to scan the environment in a first direction. The system includes an optical scanning element, the optical scanning element having a glass body in the shape of a rectangular prism and a reflective member within the glass body. The optical scanning element is positioned along the optical path and is configured to redirect the light beam and move around an axis to scan the environment in a second direction. The system includes at least one LiDAR receiver configured to receive a reflected light beam of a corresponding LiDAR transmitter, the reflected light beam returning from the environment. 
     In some embodiments, the first direction is an elevation direction and the second direction is an azimuth direction. The reflective member can form a cross section of the glass body. An exterior of the glass body can be formed by four transmissive faces. The transmissive faces can include a first pair of two transmissive faces on a first side of the reflective member and forming a first isosceles right triangular prism with the reflective member such that the reflective member is the hypotenuse. Further, the transmissive faces can include a second pair of two transmissive faces on a second side of the reflective member and forming a second isosceles right triangular prism with the reflective member such that the reflective member is the hypotenuse. Each transmissive face can be at a right angle to two of the transmissive faces. In some embodiments, the at least one LiDAR receiver is configured to receive the reflected light beam along the optical path. In some cases, the reflective mirror is configured to oscillate to redirect the light beam to scan the environment in the elevation direction and the optical scanning element is configured to rotate around the axis to scan the environment in an azimuth direction. 
     In at least one aspect, the subject technology relates to a detection system for a vehicle in an environment, the system including at least one LiDAR transmitter and receiver, a reflective mirror, and an optical scanning element. The LiDAR transmitter is configured to transmit a light beam along an optical path and into the environment. The reflective mirror redirects the light beam and is positioned along the optical path and configured to oscillate to scan the environment in an elevation direction. The optical scanning element has a glass body in the shape of a rectangular prism and is configured to redirect the light beam. The optical scanning element is positioned along the optical path. The optical scanning element is configured to rotate around an axis to scan the environment in an azimuth direction. The optical scanning element has a reflective member with two opposing reflective surfaces within the glass body, the glass body having four external transmissive faces including two faces on each side of the reflective member. The LiDAR receiver is configured to receive a reflected light beam of the LiDAR transmitter, the reflected light beam returning from the environment. 
     In some embodiments, the LiDAR receiver is configured to receive the reflected light beam along the optical path. The optical path can be straight in the azimuth direction between the at least one LiDAR transmitter, the reflective mirror, and the optical scanning element. The reflective mirror can be positioned between the at least one LiDAR transmitter and the optical scanning element along the optical path. In some embodiments, the reflective mirror is positioned between the LiDAR transmitter and the optical scanning element along the optical path. The optical path can include a first and second portion. In some cases, the first portion of the optical path between the LiDAR transmitter and the reflective mirror extends in a first direction along an azimuth plane. A second portion of the optical path between the reflective mirror and the optical scanning element can extend in a second direction along the azimuth plane, the second direction being orthogonal to the first direction. 
     In some embodiments, the optical scanning element is configured to rotate continuously during a scanning cycle. The optical scanning element can be configured to oscillate at a predetermined cycle time. In some embodiments, the reflective mirror is configured to oscillate to scan the environment in the elevation direction at a first frequency and the optical scanning element is configured to rotate to scan the environment in the azimuth direction at a second frequency. The first frequency can be greater than the second frequency. In some cases first frequency is over twenty times greater than the second frequency. 
     In some embodiments, the transmissive faces of the glass body include first and second pairs of transmissive faces. The first pair of two transmissive faces is on a first side of the reflective member, forming a first isosceles right triangular prism with the reflective member such that the reflective member is the hypotenuse. The second pair of two transmissive faces is on a second side of the reflective member, forming a second isosceles right triangular prism with the reflective member such that the reflective member is the hypotenuse. The first transmissive face can form a right angle with a second transmissive face. The second transmissive face can form a right angle with a third transmissive face. The third transmissive face can form a right angle with a fourth transmissive face. The fourth transmissive face can form a right angle with the first transmissive face. The reflective member can form a cross section of the glass body. 
     In at least one aspect, the subject technology relates to a detection system for a vehicle in an environment. The system includes a LiDAR transmitter configured to transmit a light beam along an optical path and into the environment. The system includes an optical scanning element having a glass body in the shape of a rectangular prism and a reflective member within the glass body. The optical scanning element is configured to redirect the light beam. The optical scanning element is positioned along the optical path and is configured to move around an axis to scan the environment. A LiDAR receiver is configured to receive a reflected light beam of a corresponding LiDAR transmitter, the reflected light beam returning from the environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those having ordinary skill in the art to which the disclosed system pertains will more readily understand how to make and use the same, reference may be had to the following drawings. 
         FIG. 1  is an overhead block diagram of a detection system for a vehicle in accordance with the subject technology. 
         FIG. 2 a    is a rear perspective view of a detection system for a vehicle in accordance with the subject technology. 
         FIG. 2 b    is a zoomed in view of an area of  FIG. 2   a.    
         FIGS. 2 c -2 d    are front perspective views of the detection system of  FIG. 2 a      
         FIG. 3  is a front perspective view of a detection system for a vehicle in accordance with the subject technology. 
         FIG. 4 a    is a front perspective view of an optical scanning element for a detection system in accordance with the subject technology. 
         FIG. 4 b    is a bottom perspective view of the optical scanning element of  FIG. 4   a.    
         FIGS. 5 a -5 e    are overhead schematic views the detection system of  FIG. 3  showing an exemplary scan range in the azimuth direction. 
         FIGS. 6 a -6 c    are side schematic views of the detection system of  FIG. 3  showing an exemplary scan range in the elevation direction. 
     
    
    
     DETAILED DESCRIPTION 
     The subject technology overcomes many of the prior art problems associated with vehicle detection systems. In brief summary, the subject technology provides a detection system utilizing an optical scanning element. The advantages, and other features of the systems and methods disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred embodiments taken in conjunction with the drawings which set forth representative embodiments of the subject technology. Like reference numerals are used herein to denote like parts. Further, words denoting orientation such as “upper”, “lower”, “distal”, and “proximate” are merely used to help describe the location of components with respect to one another. For example, an “upper” surface of a part is merely meant to describe a surface that is separate from the “lower” surface of that same part. No words denoting orientation are used to describe an absolute orientation (i.e. where an “upper” part must always be vertically above). 
     Referring now to  FIG. 1 , a detection system  100  for a vehicle in accordance with the subject technology is shown. The detection system  100  can be mounted on or within a vehicle (not distinctly shown) and can be used generally to gather information and generate data on the surrounding environment. The detection system  100  employs LiDAR, detecting objects using typical LiDAR components, as are known in the art, in conjunction with other components discussed herein. Thus, while certain components of the detection system  100  are discussed herein which relate to the subject technology, it should be understood that the detection system can include other LiDAR components as are known in the art. 
     The detection system  100  includes at least one LiDAR transmitter  102  configured to transmit a light beam  104  along an optical path  106 . The LiDAR transmitters  102  are emitters of optical radiation such as laser diodes configured to generate pulsed lasers or light beams  104  for reflection off objects within the environment (not distinctly shown, but generally around the detection system and associated vehicle). The light beams  104  transmitted by the LiDAR transmitters  102  can be infrared, and/or near infrared light, for example, to avoid distracting or otherwise effecting the visibility of other drivers. After reflecting off an object within the environment, the light beam returns along the optical path  106  for receipt by at least one LiDAR receiver  108 , the LiDAR receiver  108  being an optical detection device. Note that the detection system  100  requires only a single LiDAR transmitter and LiDAR receiver. However, in some cases, multiple LiDAR transmitters and receivers may be included to improve resolution. When multiple LiDAR transmitters and receivers are included, they can be arranged in a column or array to transmit and receive the light beams  104 , respectively. A processing module, which can include memory and a processor for carrying out instructions, then processes and stores data related to the range and position of objects within the environment based on the received signals. 
     The optical path  106  of the light beams is shared by the LiDAR transmitters  102  and LiDAR receivers  108 . At the end of the optical path  106 , a beam splitter  110  is employed to account for the offset LiDAR transmitters  102  and receivers  108 . The beam splitter  110  is a polarized beam splitter which redirects the initially transmitter light beams  104  along the optical path  106 , while allowing returning light beams to pass therethrough for receipt by the LiDAR receivers  108 . A collimating lens  112  focuses the transmitted light beams  104 , which are then directed to a reflective mirror  114 . During a scanning cycle, the reflective mirror  114  moves such that the orientation of its reflective surface  116  changes with respect to the elevation direction (i.e. changing the deflection angle along the “y” axis). Therefore, through movement, such as an oscillation of the reflective surface, the reflective mirror  114  redirects the ultimate path of the light beams  104  in the elevation direction. From the reflective mirror  114 , the light beams  104  are redirected to an optical scanning element  118 . While the properties of the optical scanning element  118  are discussed in greater detail below, the optical scanning element  118  includes a reflective surface within a glass body in the shape of a rectangular prism. During a scanning cycle, the optical scanning element  118  is configured to move around an axis to redirect the light beam  104  for scanning the environment. The optical scanning element  118  can be affixed to rotate around the “y” axis to scan the azimuth direction (i.e. changing field of view along the x-z plane) and can continuously rotate in full, 360 degree, rotations during the scanning cycle, or can oscillate at a predetermined cycle time. Movement of both the reflective mirror  114  and optical scanning element  118  can be accomplished by coupling them to respective actuators, not distinctly shown. 
     The reflected light beams then return around substantially the same optical path  106 , being redirected by the optical scanning element  118  to the reflective mirror  114  before being redirected through the collimating lens  112 . The optical path  106  then splits at the beam splitter  110 , and the returning light beams pass through the beam splitter  110  and return to the optical receivers  108 . Thus, the transmitted light beams  104  and returning light beams share the same optical path  106  through the lens  112 , making the LiDAR transmitters  102  and receivers  108  coaxial. In some cases, the positioning of the LiDAR transmitters  102  and receivers  108  can also be reversed, or otherwise positioned to provide a coaxial system. The system  100  can also include a processing module  120 , which can be a processor connected to memory and configured to carry out instructions, the processing module  120  being configured to control all aspects of the detection process and to store and process any generated detection data. 
     Referring now to  FIGS. 2 a -2 b   , rear perspective views of an exemplary arrangement of components of a detection system  200  in accordance with the subject technology are shown. While the arrangement of the detection system  200  is slightly different than that of  FIG. 1 , it should be understood that the components of the detection system  200  can function similarly to the detection system  100 , except as otherwise shown and described herein. 
     A support structure  202  is shown upon which the other components of the detection system  200  can be affixed. Note, other structural mechanisms attaching the components to the support structure  202  are omitted for ease of reference. The support structure  202  also serves as an outer housing, shielding internal components of the system  200 . The system  200  includes components for a co-axial LiDAR system  204 , as best seen in  FIG. 2 b   . The LiDAR system  204  includes LiDAR transmitters  206  transmitting light beams through a beam splitter  210  and LiDAR receivers  208  receiving light beams from the beam splitter  210 . The beam splitter  210  is a pinhole-type beam splitter, which is generally cheaper than a polarizing beam splitter, such as the beam splitter  110 . The beam splitter  210  includes a central aperture  212  through which transmitted light beams can pass similar to a pinhole telescope. Returning light beams reflect off a reflective surface  214  and are sent through a slit  216  before receipt by the LiDAR receivers  208 . The slit  216  functions to block out unwanted sunlight, or other interfering light, that may enter the detection system  200 , in accordance with similar devices, as are known in the art. Transmitted and returning light beams also pass through a collimating lens  218  that is proximate the other LiDAR system  204  components. 
     After transmitted light beams pass through the collimating lens  218 , the transmitted light beams pass through an additional collimating lens  220 , and are redirected, by a folding mirror  222 , through an additional collimating lens  224 . The transmitted light beams then strike the reflective surface of a scanning mirror  226 . The scanning mirror  226  can be a MEMs device which oscillates around an axis to control redirection of the transmitted light beams in the elevation direction (i.e. along the y-axis). The transmitted light beams pass through an additional collimating lens  228  towards an optical scanning element  234  (shown in  FIG. 2 c   ). Returning light beams follow the same optical path as the transmitted beams in returning to the LiDAR system  204  for receipt by the LiDAR receivers  208 . Notably, various components, such as the collimating lenses  218 ,  220 ,  222 ,  228  and folding mirror  222  are included only to show one exemplary arrangement of components a detection system in accordance with the subject technology. It should be understood that more of fewer of these components, or other standard optical components within a detection and/or LiDAR system, can be used, or said components may be arranged in a different orientation and arrangement. The exemplary components shown herein are not absolutely necessary to implement the subject technology. 
     Referring now to  FIGS. 2 c -2 d   , the system  200  is shown from a front perspective.  FIG. 2 d    is similar to  FIG. 2 c    except that a printed circuit board  230  and glass housing  232  are shown. The printed circuited board  230  is located behind the support structure  202  and can include circuitry or the like for carrying out the control and processing functions of the detection system. The protective glass housing  230  surrounds the optical scanning element  234  and collimating lens  228 , connecting to the support structure  202  to form a secure housing. 
     After passing through the collimating lens  228 , the transmitted light beams pass through and/or reflect off the optical scanning element  234 . The optical scanning element  234  is connected to an actuator  236  configured to rotate the optical scanning element. The actuator  236  can be, for example, a brushless stator coupled to the support structure  202 . The optical scanning element  234  can then be connected to the support structure  202  via coupling to a bearing or bushing  238 . 
     In the arrangement of the system  200 , the optical path between the LiDAR transmitter  206  and the reflective mirror  226  would be in one direction with respect to the azimuth plane (i.e. the x-z plane), while the optical path between the reflective mirror  226  and optical scanning element  234  is at substantially a right angle to the optical path between the LiDAR transmitter  206  and the reflective mirror  226 , with respect to the azimuth plane. Thus, in this embodiment, the LiDAR transmitter  206  and optical scanning element  234  are offset along the azimuth plane. 
     Referring now to  FIG. 3 , a front perspective view of components of a detection system  300  in accordance with the subject technology is shown. It should be understood that the components of the detection system  300  can function similarly to those of the other detection systems herein, except as otherwise shown and described herein. The specific components of the LiDAR system within the detection system  300  are omitted from  FIG. 3 . The optical path between the LiDAR system and the reflective mirror  302  can run through collimating lens  320 , with the LiDAR system, reflective mirror  302 , and optical scanning element  304  positioned in alignment with respect to the azimuth plane (although not necessarily at a shared elevation), providing a compact system while still allowing for a significant scanning range in the azimuth and elevation directions. As with other detection systems shown and described herein, after reflecting off the reflective mirror  302 , which can oscillate to change the field of view of the system in the elevation direction, the light beams interact with the optical scanning element  304  before entering the surrounding environment. 
     Referring now to  FIGS. 4 a -4 b   , the details of the optical scanning element  304  are shown and described in further detail. The optical scanning element  304  has a glass body in the shape of a rectangular prism with an exterior defined by four outer glass faces  306   a,    306   b,    306   c,    306   d  (generally  306 ) forming the prism sides which extend between the glass faces  310   a,    310   b  (generally  310 ) which form the prism ends. In general, the faces  306  sit at right angles to one another. The outer faces  306  are generally transmissive, allowing light to pass therethrough, and allowing light to pass through the glass body of the optical element  304 , while redirecting the light as discussed in more detail below. A flat rectangular reflective member  312  with opposing reflective surfaces  308   a,    308   b  forms a diagonal cross section of the optical element  304 . The reflective member  312  extends the length of the optical scanning element  304  between the ends  310 , running parallel to the outer faces  306 . In particular, two of the transmissive faces  306   b,    306   c  are on a first side  308   a  of the reflective member  312 , light passing through those transmissive faces  306   b,    306   c  interacting with the first side  308   a.  In effect, the sides  306   b,    306   c  form an isosceles right triangular prism with the first side  308   a  of the reflective member  312  and with the reflective member  312  being the hypotenuse. Similarly other two transmissive faces  306   a,    306   d  are on a second side  308   b  of the reflective member  312 , allowing light passing through to interact with the second side  308   b  of the reflective member  312 . The transmissive faces  306   a,    306   d  likewise form an isosceles right triangular prism with the second side  308   b  of the reflective member  312  and with the reflective member  312  being the hypotenuse. 
     Referring again to  FIG. 3 , an actuator  314  is affixed to the optical scanning element  304  to cause it to oscillate or rotate around the vertical axis, changing the glass face  306  and reflective surface  308  interfacing with the transmitted light beams to change the field of view of the detection system  300  in the azimuth direction. As the transmitted and returning light passes through the moving optical scanning element  304 , the glass body of the optical scanning element  304  redirects light and the reflective member  312  completely reflects light which contacts its surface. 
     Referring now to  FIGS. 5 a   - 6   c,  schematic diagrams of an exemplary detection system  500  are shown, which can include components at a similar positioning and alignment of the detection system  300 .  FIGS. 5 a -5 e    show a scanning pattern of the system  500  over an azimuth sweep, while  FIGS. 6 a -6 c    show a scanning pattern over an elevation sweep. It should be understood that the detection system  500  can include other components of the detection systems as shown in described herein and the components shown in the detection system  500  are exemplary only, to illustrate a typical scan pattern in accordance with the subject technology. 
       FIGS. 5 a -5 e    are an overhead view of the scanning pattern of the detection system  500 , showing the full range of a scanning pattern in the azimuth direction. In the arrangement shown, the reflective mirror  502 , optical scanning element  504 , and the LiDAR system  506  (including LiDAR transmitters and receivers, as well as other necessary LiDAR components) are arranged in substantially a straight line in the azimuth plane (understanding there might be a slight offset of some LiDAR system  506  components, for example, as shown when the beam splitter  110  of  FIG. 1  is used). In particular, the optical path  508  forms a straight line between the LiDAR transmitters of the LiDAR system  506 , the reflective mirror  502 , and the optical scanning element  504 . A first collimating lens  510  is included between the LiDAR system  506  and the reflective mirror  502  and a second collimating lens  512  is included between the reflective mirror  502  and the optical scanning element  504 . A third collimating lens  520  is also located between the reflective mirror  502  and a folding mirror  518 , as seen in  FIGS. 6 a   - 6   c.  The configuration of the system  500 , with an optical path  508  straight along the azimuth plane between the LiDAR system  506 , reflective mirror  502 , and optical scanning element  504  (i.e. with the LiDAR transmitters straight behind the optical scanning element  504  in the x-z plane) allows for a large, 270 degree field of view in the azimuth direction. 
     For explanatory purposes, it is described that the reflective member  514  of the optical scanning element  504  is at 0 degrees of rotation as shown in  FIG. 5 c   , that representing a scan at the boresight of the field of view in azimuth. Therefore,  FIG. 5 a    shows the limits of the field of view in azimuth in one direction, where the reflective member  514  is at an angle of −65 degrees. This allows for the field of view to reach −135 degrees with respect to the boresight as the transmitted and returning light beams  516  reflect off the angled surface of the reflective member  514 . Note that while a greater field of view is achievable by the components of the system  500 , the components themselves may start to block the field of view of the system  500  at larger angles.  FIG. 5 b    shows the reflective member at an angle of −35 degrees, with the transmitted and returning light beams  516  continuing to reflect off a surface of the reflective member  514 . At the position shown in  FIG. 5 c   , the system  500  is scanning directly ahead. The optical element  504  has rotated such that the flat reflective faces of the reflective member  514  are parallel to the direction of the transmitted and returning light beams  516 . In this position, the glass body of the optical scanning element  504  helps redirect light around the reflective member  514  so that it does not interfere with the transmission and receipt of light beams  516 . 
       FIG. 5 d    shows the scanning pattern as the optical scanning element  504  turns in the other direction (i.e. shown at the opposite angle of  FIG. 5 b   ). In  FIG. 5 d   , the reflective member  514  is at an angle of 35 degrees and the transmitted and returning light beams  516  scan the other side of the vehicle, as compared to  FIG. 5 b   . Likewise,  FIG. 5 e    shows the opposite scan angle of  FIG. 5 a   , with the reflective member  514  at a 65 degree angle, allowing the detection system  500  to scan at 135 degrees in the azimuth direction. As such, a 270 degree scan in the azimuth direction occurs between as the optical scanning element  504  rotates between the positions shown in  FIGS. 5 a    and  5   e.    
     Referring now to  FIGS. 6 a   - 6   c,  while the azimuth scan occurs, as shown in  FIGS. 5 a -5 e   , an elevation scan also occurs. The azimuth scan is controlled by rotation of the optical scanning element  504 , while the elevation scan is controlled by oscillation of the reflective mirror  502 , although it should be understood that these roles could be reversed in other embodiments. Although the positions of the LiDAR system  506 , reflective mirror  502 , and optical scanning element  504  are aligned in the azimuth plane, the LiDAR system  506  is at a different elevation (i.e. different position along the y axis) from the reflective mirror  502  and the optical scanning element  504  which are centered at the same elevation. The folding mirror  518  makes this positioning possible, as it is placed directly above the scanning mirror  502  to redirect transmitted light beams  516  from the LiDAR system  506  through the lens  520  and to the scanning mirror  502 . Thus, the LiDAR system  506  can be placed directly behind the scanning mirror  502  in the azimuth direction and the light beams still reflect off the scanning mirror  502  to the optical scanning element  504 . 
     For explanatory purposes,  FIG. 6 b    will be described as having a reflective mirror  502  at an angle of 0 degrees, representing a scan angle at the same elevation as the boresight of the detection system  500 .  FIG. 6 a    depicts a scan position where the reflective mirror has oscillated to an angle of −15 degrees to obtain a maximum scan angle upwards in the elevation direction, while  FIG. 6 c    depicts a scan position where the reflective mirror  502  has oscillated to an angle of 15 degrees to obtain a maximum scan angle downwards in the elevation direction. While a greater scan range in the elevation direction is possible, the exemplary range of the system  500  has been shown to be effective for capturing the desirable information for a vehicle detection system at a high resolution. Therefore,  FIGS. 6 a -6 c    present an exemplary effective elevation scan range which can be achieved by oscillating the reflective mirror  502  between angles of −15 and 15 degrees. 
     The elevation scan is carried out simultaneously to the azimuth scan, and both scans can have different frequencies. More particularly, the optical scanning element  504  can be configured to have a particular scanning frequency, or to have a particular scanning frequency as compared to the scanning frequency of the reflective mirror  502  to optimize resolution of the detection system  500 . Typically, the elevation scan will be at a much quicker frequency than the azimuth scan. In some cases, the scan frequency of the reflective mirror  502  in the elevation direction can be over twenty times greater than the scan frequency of the optical scanning element  504  in the azimuth direction. In other cases, the optical scanning element  504  can rotate at 300 rotations per minute (two azimuth sweeps per rotation), producing a cycle frequency of 10 Hz and the reflective mirror  502  can oscillate at 454 microseconds per cycle period, producing a cycle frequency of 2.2 kHz. The LiDAR transmitters can operate at a pulse repetition frequency of 216 kHz in order to achieve an angular resolution better than 1 degree in both azimuth and elevation. It should be understood that these possibilities are exemplary only, and while the aforementioned examples have been found to be advantageous and provide good resolution, other configurations could also be used. Further, increasing elevation resolution is also possible by increasing the rotation speed of the optical scanning element  504  and accumulating data over successive azimuth scan cycles. 
     The detection systems shown and described herein are able to achieve a wide field of view and high resolution scanning in both the azimuth and elevation direction. This is achieved while using a low cost system that can scan with as few as a single LiDAR transmitter and receiver, the wide field of view being achieved through the implementation of a moving reflective mirror, moving optical scanning element, and other components as needed. Further, the components of the detection systems can be provided in a compact arrangement, minimizing the space occupied by the detection systems, since so few LiDAR transmitters and receivers are required. As such, the detection systems of the subject technology can provide a high level of detail about the surrounding environment to a vehicle operator, or to automated driving functions within the vehicle or the like, while keeping costs down. 
     It will be appreciated by those of ordinary skill in the pertinent art that the functions of several elements may, in alternative embodiments, be carried out by fewer elements or a single element. Similarly, in some embodiments, any functional element may perform fewer, or different, operations than those described with respect to the illustrated embodiment. Also, functional elements (e.g. processors, circuitry, and the like) shown as distinct for purposes of illustration may be incorporated within other functional elements in a particular implementation. 
     While the subject technology has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the subject technology without departing from the spirit or scope of the subject technology. For example, each claim may depend from any or all claims in a multiple dependent manner even though such has not been originally claimed.