Patent Description:
A typical LiDAR detection system includes a source of optical radiation, for example, a laser, which emits light into a region. An optical detection device, which can include one or more optical detectors and/or an array of optical detectors, receives reflected light from the region and converts the reflected light to electrical signals. A processing device processes the electrical signals to identify and generate information associated with one or more target objects in the region. This information can include, for example, bearing, range, velocity, and/or reflectivity information for each target object.

One very important application for LiDAR detection systems is in automobiles, in which object detections can facilitate various features, such as parking assistance features, cross traffic warning features, blind spot detection features, autonomous vehicle operation, and many other features. In automotive LiDAR detection systems, it is important to be able to detect both bright objects at close range and low-reflectivity objects at long range with the same system configuration.

<CIT> describes a LIDAR system with a pulsed frequency modulated laser, a micro-mirror optically coupled to the laser for scanning the emitted beam across a scene, and a photodiode detector. Documents <CIT> and <CIT> show, instead, examples of optical systems wherein the light sources and the photo-sensors are arranged on the opposite sides of a support basis.

According to a first aspect, an optical transceiver device for an automotive LiDAR detection system according to accompanying claim <NUM> is provided. According to a second aspect, an optical transceiver device for an automotive LiDAR detection system according to accompanying claim <NUM> is provided. Optional features of the first and second aspects are set out in the accompanying dependent claims.

In some exemplary embodiments, the transmission axis and the reception axis are substantially the same axis.

In some exemplary embodiments, the optical transceiver device further comprises a mask having at least one slit aligned with the opening of the substrate, such that the reflected light received by the detection element from the region passes through the slit. The mask can be formed at the first surface of the substrate. Alternatively, the mask can be formed at the second surface of the substrate.

In some exemplary embodiments, the optical transceiver device further comprises a bandpass filter, the light returning from the region impinging on the bandpass filter such that the light returning from the region is filtered by the bandpass filter. The bandpass filter can have a wavelength pass band which drifts with temperature, the bandpass filter being selected such that temperature drift of the pass band of the bandpass filter is determined according to temperature drift of a wavelength of the output light.

In some exemplary embodiments, the optical detection element comprises a silicon photomultiplier (SiPM) detector. In other exemplary embodiments, the optical detection element comprises a multi-pixel photon counter (MPPC) detector. In some exemplary embodiments, the optical transceiver device further comprises a mask having at least one slit aligned with the aperture of the substrate, such that the reflected light received by the detector from the region passes through the slit before it reaches the detector. The mask can be formed at the first surface of the substrate. Alternatively, the mask can be formed at the second surface of the substrate.

In some exemplary embodiments, the optical transceiver device further comprises a polarizing beam splitter in an optical path between the laser and the detector, both the output light and the input light at least partially passing through the polarizing beam splitter.

In some exemplary embodiments, the optical transceiver device further comprises a polarizing beam splitter in an optical path between the laser and the detector, at least one of the output light and the input light at least partially passing through the polarizing beam splitter.

In some exemplary embodiments, the optical transceiver device further comprises a
plurality of lasers fixed to a first surface of the substrate, the output light including a respective plurality of light beams generated by the plurality of lasers. In some exemplary embodiments, the optical transceiver device further comprises a scanning device for scanning the plurality of light beams over the region. The scanning device can comprise a scanning mirror. The scanning mirror can be a micro-electromechanical system (MEMS) scanning mirror.

In some exemplary embodiments, the optical detection element comprises an array of optical detectors. The optical detectors can comprise a silicon photomultiplier (SiPM). The optical detectors can comprise a multi-pixel photon counter (MPPC). The array of optical detectors can be a two-dimensional array.

The optical transceiver device can be part of an automotive LiDAR detection system. The LiDAR detection system can be a coaxial system.

The present disclosure is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of embodiments of the present disclosure, in which like reference numerals represent similar parts throughout the several views of the drawings.

Any reference to "embodiment(s)" or "aspect(s) of the invention" in this description not falling under the scope of the claims should be interpreted as illustrative example(s) for understanding the invention. The subject-matter described in relation to <FIG> (par. <NUM>-<NUM>) and <FIG> (par. <NUM>-<NUM>) does not fall within the scope of the claims.

The scanning LiDAR detection system described herein in detail can be of the type described in copending <CIT>, of the same assignee as the present application. According to the exemplary embodiments, the scanning LiDAR detection system of the present disclosure combines wide field of view with long detection range and high resolution. To achieve this in a biaxial system, i.e., a system in which the transmission optical axis is not the same as the reception optical axis, various features are combined in the system.

For example, the present system includes a high-sensitivity detector that can detect the relatively small number of photons reflected back from long range. Also, the detection device, i.e., detector array, of the present system is of relatively large size, thus providing an optical aperture collecting returning light from a relatively wide field of view. The detection system, i.e., detector array, of the present disclosure has relatively high bandwidth to allow capture of a relatively short-duration light pulse. In some particular exemplary embodiments, the waveform is a pulsed frequency-modulated continuous-wave (FMCW) signal having a pulse repetition frequency (PRF) of <NUM>-<NUM>. At <NUM>% duty cycle, the light pulse duration can be <NUM> - <NUM> ns, which is captured by the high-bandwidth detector array of the disclosure.

Additionally, it is known that ambient light, such as sunlight, can cause shot noise in the detection system. According to the present disclosure, the amount of ambient light, e.g., sunlight, impinging on the detection system is substantially reduced. Dynamic range is maximized such that both bright objects at short distance and low-reflectivity objects at long range can be detected with the same configuration.

Thus, the scanning LiDAR system of the disclosure reduces the amount of ambient light and the signal light from objects at short distance that can reach the detection system by means of spatial filtering matching the far field laser pattern. This enables the combination of a large sensitive detector, a narrow laser beam and high signal-to-noise ratio (SNR) at long range in daytime conditions.

According to the present disclosure, a fixed or moving mask is positioned in the focal plane of a receiver lens in the detection system, i.e., LiDAR sensor. The mask includes a set of slits and is aligned with the scan pattern of the transmitter. This enables the use of avalanche photodiode detectors (APDs) in the optical detector array. In alternative embodiments, silicon photomultipliers (SiPMs), also referred to as multi-pixel photon counters (MPPCs) can be used in the optical detector array. The SiPM array is an array of light-sensitive microcells, each in a binary single photon counting mode. Alternatively, APDs in the array are analog components, i.e., not operated in Geiger/photon counting mode. The array provides a very high gain over a large detector area combined with analog output and large bandwidth.

The LiDAR system of the present disclosure reduces ambient light by a factor of <NUM> to <NUM>, and typically by a factor of <NUM> to <NUM>. This results in increased SNR and increased range in daytime conditions. The system increases dynamic range due to focus change with respect to distance. The effective sensitivity of the APDs or SiPMs is increased, in the case of SiPMs, due to the non-linearity of the components. According to some exemplary embodiments, with the LiDAR system of the disclosure focused at infinity, the focal plane of the lens coincides with the slits in the mask. The focus shifts as the distance to a target object changes. At long range, the image plane will coincide with the focal plane of the lens, where the mask is placed. At closer range, the image plane will move away from the focal plane of the lens, i.e., further from the lens. This means that a significant amount of light will be blocked by the slit, and, therefore, the signal level at close range is substantially reduced, leading to increased dynamic range.

<FIG> includes a schematic functional block diagram of a scanning LiDAR system <NUM>, according to an example not part of the invention but useful for understanding it. Referring to <FIG>, system <NUM> includes a digital signal processor and controller (DSPC) <NUM>, which performs all of the control and signal processing required to carry out the LiDAR detection functionality described herein in detail. An optical source <NUM> operates under control of DSPC <NUM> via one or more control signals <NUM> to generate the one or more optical signals transmitted into a region <NUM> being analyzed. Among other functions, control signals <NUM> can provide the necessary control to perform wave shaping such as, in some exemplary embodiments, pulsed frequency-modulated continuous-wave (FMCW) modulation envelope control to produce the pulsed FMCW optical signal of some exemplary embodiments. Optical source <NUM> can include a single laser, or optical source <NUM> can include multiple lasers, which can be arranged in a one-dimensional or two-dimensional array. One or more optical signals <NUM> from source <NUM>, which can be the pulsed FMCW optical signal of some exemplary embodiments, impinge on scanning mirror <NUM>, which can be a microelectromechanical system (MEMS) scanning mirror. Scanning mirror <NUM> is rotatable about an axis <NUM> by an actuator <NUM>, which operates under control of one or more control signals <NUM> provided by DSPC <NUM> to control the rotation angle of scanning mirror <NUM>, such that the one or more output optical signals are scanned at various angles into region <NUM>. The output optical signals pass through a lens or glass plate <NUM>, which generates one or more collimated optical signals which are scanned across region <NUM>.

Returning optical signals <NUM> are received from region <NUM> at receive subsystem <NUM>. Receive subsystem <NUM> includes a lens <NUM> which receives and focuses light <NUM> returning from region <NUM>. According to exemplary embodiments, mask <NUM> is located at the focal plane of lens <NUM>, such that the returning light is focused at mask <NUM>. Light passing through mask <NUM> impinges on optical detector array <NUM>, which, in some exemplary embodiments, can include SiPM or MPPC photomultipliers. Detector array <NUM> converts the received optical signals to electrical signals, and a processor <NUM> generates digital signals based on the electrical signals and transmits the digital signals <NUM> to DSPC <NUM> for processing to develop target object identification, tracking and/or other operations. Reports of detections to one or more user interfaces or memory or other functions can be carried out via EO port <NUM>.

<FIG> include schematic functional diagrams illustrating portions of scanning LiDAR system <NUM> of <FIG>. <FIG> illustrate scanning of the transmitted optical signals into region <NUM> and reception of returning optical signals for a first angular direction of scanning of scanning mirror <NUM> about axis <NUM> and a second opposite angular scanning direction of scanning mirror <NUM> about axis <NUM>, respectively.

Referring to <FIG>, <FIG>, optical source <NUM> can include one or more linear arrays of lasers disposed along parallel axes. That is, each linear array of lasers includes a plurality of lasers disposed along a vertical axis, i.e., a y-axis. In the exemplary embodiment illustrated in <FIG>, two linear arrays are disposed along parallel axes in the y-axis direction. The axes are displaced along a horizontal axis, i.e., an x-axis. Also, the two linear laser arrays are displaced also in the vertical direction (y-axis) in order to generate different elevation angles. Alternatively, the linear laser arrays could be rotated around the x-axis in order to generate different elevation angles. Thus, as illustrated in <FIG>, the two parallel linear laser arrays create a two-dimensional array of laser outputs transmitted orthogonal to the x-y plane. In some particular exemplary embodiments, each of two linear arrays includes <NUM> lasers disposed along the y-axis, for a total of <NUM> lasers in the two-dimensional array. It will be understood that any number of lasers can be used, in accordance with the present embodiments. For example, in some particular exemplary embodiments, two linear arrays of <NUM> lasers, i.e., a total of <NUM> lasers, are used.

Continuing to refer to <FIG>, <FIG>, in some exemplary embodiments, the optical output signals from the laser array in source <NUM> are focused by a lens <NUM> onto MEMS scanning mirror <NUM>. The optical signals are reflected from scanning mirror <NUM> through glass plate or lens <NUM>, which generates the substantially mutually parallel collimated optical output signals <NUM>. Controlled rotation of scanning mirror <NUM> via actuator <NUM> and DSPC <NUM> scans the collimated optical output signals <NUM> over region <NUM>. Output signals or beams <NUM> constitute a fan of beams <NUM>, where each beam is collimated. In some particular exemplary embodiments, the fan angle can be <NUM>° to <NUM>°. In some alternative embodiments, beams <NUM> are substantially mutually parallel. Light <NUM> returning from region <NUM>, for example, light reflected from one or more target objects, is received at lens <NUM> of receive subsystem <NUM>. Lens <NUM> focuses the returning light <NUM> onto mask <NUM>, which is positioned in front of optical detector array <NUM>, which, as illustrated in <FIG>, can be, for example, a <NUM> x <NUM> array of APDs. As noted above the detectors in detector array <NUM> can also be SiPMs. Thus, in the particular illustrated exemplary embodiments, <NUM> x <NUM> SiPM detectors are arranged to provide a focal plane detector. Detector array <NUM> converts the received optical signals to electrical signals, and processor <NUM> generates digital signals based on the electrical signals and transmits the digital signals <NUM> to DSPC <NUM> for processing to develop target object identification, tracking and/or other operations. Reports of detections to one or more user interfaces or memory or other functions can be carried out via I/O port <NUM>.

Thus, as illustrated in <FIG>, in some particular exemplary embodiments, two arrays of <NUM> x <NUM> lasers are used to generate <NUM> individual laser beams, each beam with a nominal divergence of <<NUM>°. The vertical divergence of the group of <NUM> beams is nominally approximately <NUM>°. Scanning mirror <NUM> is controlled to scan across a nominal range of approximately <NUM>°, i.e., ± <NUM>° from its centered position. These angular limits are illustrated in <FIG> in the diagrams of the x-y plane. <FIG> illustrates the case in which the output optical signals <NUM> are scanned in a first direction (to the right in <FIG>) via angular rotation of scanning mirror <NUM> in a first angular direction, and <FIG> illustrates the case in which the output signals <NUM> are scanned in a second direction (to the right in <FIG>) via angular rotation of scanning mirror <NUM> in a second angular direction. The resulting returning optical signals are scanned across the columns of the <NUM> x <NUM> detector array <NUM> illuminating pixels in the array in a predetermined order determined by the scanning of the output optical signals <NUM> into region <NUM>, as illustrated in the schematic illustrations of pixel illumination scanning <NUM> and <NUM> in <FIG>, respectively. It will be understood that all of these parameters are exemplary nominal values. According to the present disclosure, any number of lasers can be used, having a group beam divergence of greater than or less than <NUM>°, and the angular scanning limits can be greater than or less than ± <NUM>° from the centered position of scanning mirror <NUM>.

According to the exemplary embodiments, since detector array has <NUM> detectors in the vertical (y) direction, only one vertical linear array, i.e., column, is turned on at a time. That is, detector array <NUM> is read out one column at a time, in synchronization with the laser scan. This time multiplexing provides a"rolling shutter" which limits the influence of environmental light, i.e., sunlight, since only one column of detectors is receiving at a time. Additionally, mask <NUM>, implemented in the form of a two-dimensional array of slits, is placed in front of detector array <NUM> to reduce further the amount of ambient light reaching detector array <NUM>.

<FIG> is a schematic diagram of receive subsystem <NUM>. Referring to <FIG>, and with reference to the foregoing detailed description of <FIG>, <FIG>, light <NUM> returning from region <NUM> impinges on lens <NUM>. Mask <NUM> is placed at the focal plane of lens <NUM>, such that light <NUM> is focused at mask <NUM>. Light passing through mask <NUM> is received at detector array <NUM>.

<FIG> includes a schematic diagram of mask <NUM>. Mask <NUM> includes an optically opaque portion <NUM> and a plurality of optically transparent horizontal slits 142a-142p. It is noted that the use of <NUM> slits is consistent with the particular illustrative exemplary embodiment described herein in which light source <NUM> includes two linear arrays of <NUM> lasers each. It will be understood that where a different laser configuration or quantity is used, mask <NUM> would include a different number of slits <NUM>. For example, in the case in which source <NUM> includes two linear arrays of <NUM> lasers, mask <NUM> would include <NUM> slits <NUM>.

Referring to <FIG>, it is noted that alternating slits <NUM> are associated with the same linear laser array in source <NUM>. That is, specifically, each of alternating slits 142a through <NUM> is associated with returning light generated by a respective one of the eight lasers in one of the vertical linear arrays of lasers in source <NUM>, and each of alternating slits 142i through 142p is associated with returning light generated by a respective one of the eight lasers in the other of the vertical linear arrays of lasers in source <NUM>. In accordance with some exemplary embodiments, the linear arrays of lasers of source <NUM> are offset vertically with respect to each other. As a result, the alternating groups of slits 142a-<NUM> and 142i-142r are offset vertically with respect to each other on mask <NUM>, such that returning light associated with each laser is in alignment with its corresponding slit.

Mask <NUM> can be made of one of various possible materials, such as plastic, metal, metal foil, or other material. Slits <NUM> can be formed in mask <NUM> by laser. In other embodiments, opaque portion <NUM> and slits <NUM> can be formed by photolithographic processes. For example, the opaque portion <NUM> can be formed of an optically sensitive opaque material, and slits <NUM> can be formed by selective exposure of the optically sensitive opaque material, e.g., through a patterned mask, followed by appropriate developing and further processing to generate the transparent slits <NUM>.

<FIG> includes a schematic elevational view of a portion of detector array <NUM>. Referring to <FIG>, eight rows of four detectors 126a are illustrated. That is, <NUM> of the <NUM> detectors 126a in detector array <NUM> are illustrated for clarity of illustration and description. As described above, according to the present disclosure, each of detectors 126a can be an APD or SiPM. <FIG> also illustrates the received pulses of light <NUM> returning from region after being focused by lens <NUM> and passing through slits <NUM> in mask <NUM>. These received pulses appear in <FIG> as broken lines along array <NUM> of detectors 126a. Specifically, broken lines 152a through <NUM> illustrate pulses of returning light <NUM> impinging on array <NUM> after passing through slits 142a through <NUM>, respectively, of mask <NUM>. Similarly, broken lines 152i through 152p illustrate pulses of returning light <NUM> impinging on array <NUM> after passing through slits 142i through 142p, respectively, of mask <NUM>. Thus, referring to <FIG>, because of the vertical, y-axis offset between the linear arrays of lasers in source <NUM>, each detector 126a of array <NUM> receives and processes light from a plurality of lasers, e.g., two lasers as illustrated in <FIG>, the light passing through a respective plurality of slits <NUM>, e.g., two slits, in mask <NUM>.

Thus, according to the present disclosure, in some exemplary embodiments, mask <NUM> having 2N horizontal slits is placed in front of detector array <NUM> of detectors 126a, the array <NUM> having N detectors 126a in the vertical, i.e., y, direction. Mask <NUM> is aligned with the scan pattern of 2N horizontally alternately scanning laser beams. Continuing to refer to <FIG>, in some particular exemplary embodiments, slits <NUM> could be as small as the diffraction limit allows, i.e., I X f-number ~ Ipm. In some embodiments, the width of slits <NUM> can be ~<NUM>, due to alignment tolerances. With two O. Imm slits <NUM> per Imm2 detector element 126a, ambient light is reduced by a nominal factor of <NUM>, but a factor of ~<NUM> is also possible.

According to the exemplary embodiments, array <NUM> is an array of APDs or SiPMs, which provide certain advantages and improvements. For example, the large size and short response time of the detector elements 126a provide array <NUM> with a large detection area. This in turn enables a large light-collecting aperture of the receiving subsystem lens. The increased light provides better signal -to-noise ratio (SNR) and longer range. Also, with mask <NUM> in focus, but detector array <NUM> out of focus, local saturation of detector elements 126a is avoided. This results in increased dynamic range and further increased performance in high levels of ambient light.

According to the exemplary embodiments, with mask <NUM> in the focal plane of lens <NUM>, all signal light passes through slits <NUM> in mask <NUM> at long distances. Without mask <NUM>, the optical signal intensity would vary inversely with the square of the distance. Therefore, at short range, signal intensity would be extremely high, which can cause a drop in system dynamic range. With mask <NUM> inserted as described herein in detail, only a small fraction of the returning light at short distances passes through slits <NUM>, which eliminates the reduction in dynamic range caused by light returning from short-range target objects.

In some embodiments, in addition to horizontal scanning as described above in detail, scanning can also be carried out vertically. The vertical scanning can be performed in order to increase vertical resolution. <FIG> includes a schematic functional block diagram of a scanning LiDAR system <NUM> A, in which horizontal and vertical scanning are performed, according to exemplary embodiments. <FIG> includes a schematic diagram of receive subsystem 118A in scanning LiDAR system <NUM> A of <FIG>, in which horizontal and vertical scanning are performed, according to exemplary embodiments. Referring to <FIG> and <FIG>, elements that are substantially the same as those in <FIG>, <FIG>, <FIG> and <FIG> are identified by the same reference numerals. Referring to <FIG> and <FIG>, in this embodiment, actuator 112A, in addition to initiating and controlling horizontal scanning of scanning mirror 110A about vertical axis <NUM>, initiates and controls vertical scanning of scanning mirror 110A about horizontal axis 114A. In this alternative embodiment, mask <NUM> is also moved vertically alternately up and down in synchronization with the vertical scanning of scanning mirror <NUM> A, as indicated by arrow <NUM> in <FIG>. Vertical movement of mask <NUM> is initiated by a mechanical actuation device, such as a piezoelectric actuator <NUM>, in synchronization with scanning of scanning mirror <NUM> A, such that alignment of slits <NUM> of mask <NUM> with returning light <NUM> is maintained. This synchronization is accomplished via interface <NUM> with DSPC <NUM>.

<FIG> is a schematic diagram illustrating the pattern of light beams scanned over detector array <NUM>, in the case in which vertical and horizontal scanning are used. Referring to <FIG>, in some embodiments, as illustrated by the scan pattern, at the end of each horizontal scan line, scanning mirror 110A is rotated one step vertically. At the same time, mask <NUM> is moved vertically to ensure alignment of slits <NUM> in mask <NUM>. This process of horizontal scan lines separated by vertical scanning increments results in the serpentine pattern of light beams impinging on detector array <NUM>, as illustrated in <FIG>.

In the foregoing detailed description, scanning LiDAR systems <NUM>, <NUM> A of the exemplary embodiments are shown as having biaxial configurations. That is, systems <NUM>, 100A are illustrated and described as having separate output (transmission) axes and input (reception) axes. Output signals <NUM> are transmitted into region <NUM> along a first axis, and returning light signals <NUM> are received from region <NUM> along a second axis different than the first axis. The present disclosure is also applicable to coaxial system configurations in which the input and output axes are substantially the same.

<FIG> and <FIG> include schematic diagrams illustrating portions of a scanning LiDAR system <NUM> in which a coaxial configuration is implemented, according to some exemplary embodiments. <FIG> illustrates a single coaxial configuration, and <FIG> illustrates multiple coaxial configurations in parallel. Referring to <FIG> and <FIG>, a laser light source <NUM> integrated on or in a substrate <NUM> generates an output beam of light. The output beam is reflected by a polarizing beam splitting cube <NUM> such that output signals <NUM> are transmitted into region <NUM>. Returning light signals <NUM> from region <NUM> are transmitted through beam splitting cube <NUM>, through an opening <NUM> in substrate <NUM>. The light may pass through an optional bandpass filter <NUM>, which further reduces the ambient light. In some exemplary embodiments, bandpass filter <NUM> is characterized by a drift in its wavelength pass band which is dependent on temperature. Laser light source <NUM> can also have a temperature-dependent drift in wavelength of its output. In some exemplary embodiments, the temperature drift of laser light source <NUM> and that of bandpass filter <NUM> are matched, such that temperature effects on operation of the overall system are substantially reduced.

<FIG> include schematic diagrams illustrating portions of scanning LiDAR systems 300A and 300B, respectively, in which a coaxial configuration is implemented, according to some exemplary embodiments. The primary difference between systems 300A, 300B of <FIG> is that, in system <NUM> A, mask <NUM> is under substrate <NUM>, and, in system 300B, mask <NUM> is at the top side of substrate <NUM>. In both systems 300A and 300B, incoming light from polarizing beam splitting cube <NUM> passes through slits <NUM> in mask <NUM> and impinges on APD or SiPM detector <NUM>. In the embodiments of <FIG>, lens <NUM> generates the substantially mutually parallel collimated optical output signals <NUM> A. Controlled rotation of the scanning mirror scans the substantially mutually parallel collimated optical output signals <NUM> A over the region being analyzed.

<FIG> includes a schematic diagram illustrating any of systems <NUM>, 300A, 300B, illustrating the size relationship between the opening <NUM> or slit <NUM> and the pupil of the laser source <NUM>. As in the embodiments described in detail above, in the embodiment of <FIG>, lens <NUM> generates the collimated optical output signals <NUM> A. Controlled rotation of the scanning mirror scans the collimated optical output signals <NUM> A over the region being analyzed. Optical output signals or beams 323A constitute a fan of beams <NUM> A, where each beam is collimated. In some particular exemplary embodiments, the fan angle can be <NUM>° to <NUM>°. In some alternative embodiments, beams 323A are substantially mutually parallel.

It should be noted that polarizing beam splitting cube <NUM> in the embodiments described above in detail in connection with <FIG>, <FIG>, <FIG> and <FIG> need not be a cube. In alternative embodiments, polarizing beam splitting cube <NUM> can be replaced with a polarizing beam splitting plate tilted at an appropriate angle with respect to the optical paths of the respective systems.

<FIG> includes a schematic diagram illustrating a portion of a scanning LiDAR system <NUM> in which a coaxial configuration is implemented, according to some exemplary embodiments. System <NUM> differs from systems <NUM>, <NUM> A and 300B in that, in system <NUM>, no beam splitting cube is included. Instead, laser light source <NUM> provides output light <NUM> in a vertical direction into region <NUM> through an optical element such as birefringent crystal <NUM> and lens <NUM>. Returning light <NUM> passes through lens <NUM> and birefringent crystal <NUM> such that the returning light is shifted to pass through apertures <NUM> in substrate <NUM> toward the detector array. Birefringent crystal <NUM> affects the two polarization directions of the light differently. One is laterally shifted, and the other is not shifted. Hence, birefringent crystal <NUM> acts as a polarizing beam splitter. Birefringent crystal <NUM> can be made of a material such as calcite, or other similar material.

According to exemplary embodiments, a coaxial scanning LiDAR system, such as coaxial systems <NUM>, 300A, 300B and <NUM> illustrated in <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, can be implemented using a selected configuration which may include one or more lasers, polarizing beam splitters, apertures or slits, filters and detectors in combination. For example, configurations can vary depending on the laser and aperture or opening subassembly and/or the detector type and configuration. In some embodiments, the laser or lasers can be discrete lasers. In other embodiments, one or more arrays of multiple lasers can be used. Similarly, in the case of detectors, one or more discrete detectors, such as APDs or SiPMs, can be used. In other embodiments, one or more arrays of detectors, such as arrays of APDs or SiPMs, can be used.

<FIG> include schematic cross-sectional diagrams which illustrate two configurations of coaxial scanning LiDAR systems <NUM> and <NUM>, respectively, in which discrete lasers and discrete detectors are used, according to some exemplary embodiments. Referring to <FIG>, a laser light source <NUM> is integrated on or over a substrate <NUM>, with a layer of inert spacing material <NUM>, made of, for example, printed circuit board (PCB) material, epoxy, metal or similar material, mounted therebetween. Laser light source <NUM> generates an output beam of light <NUM>, which impinges on a beam splitting cube <NUM>, such that output signals <NUM> are transmitted into region <NUM>. Returning light signals from region <NUM> are transmitted through beam splitting cube <NUM>, through a slit <NUM> in mask <NUM> and then through opening <NUM> in substrate <NUM>. It should be noted that beam splitting cube <NUM> can be a polarizing beam splitting cube. It should also be noted that, as with the embodiments described above, beam splitting cube <NUM>, or polarizing beam splitting cube <NUM>, need not be a cube. It may be a beam splitting plate or polarizing beam splitting plate tilted at an appropriate angle with respect to the optical path(s). Light beams <NUM> from slit <NUM> pass through opening <NUM> in substrate <NUM> and are detected by detector <NUM>, which is mounted to the bottom side of substrate <NUM>. In some exemplary embodiments, detector <NUM> is a surface mount device mounted to the bottom surface of substrate <NUM>. It should be noted that, in some exemplary embodiments, laser light source <NUM> is one of an array of laser light sources disposed in parallel along an axis directed substantially normal to the page of <FIG>. Similarly, polarizing or non-polarizing beam splitting cube or plate <NUM> can be a single long cube or plate, or multiple cubes or plates, extending along the same axis normal to the page. Similarly, detector <NUM> can be a single long detector or array of detectors, or multiple detectors or arrays of detectors, extending along the same axis normal to the page. In some exemplary embodiments, detector(s) or array(s) of detectors <NUM> can be SiPM or MPPC detectors.

Referring to <FIG>, a laser light source <NUM> is integrated on or over a substrate <NUM>, with a layer of inert spacing material <NUM>, made of, for example, printed circuit board (PCB) material, epoxy, or other similar material, mounted therebetween. Laser light source <NUM> generates an output beam of light <NUM>, which impinges on a beam splitting cube <NUM>, such that output signals <NUM> are transmitted into region <NUM>. Returning light signals from region <NUM> are transmitted through beam splitting cube <NUM>, through a slit <NUM> in mask <NUM>. It should be noted that beam splitting cube <NUM> can be a polarizing beam splitting cube. It should also be noted that, as with the embodiments described above, beam splitting cube <NUM>, or polarizing beam splitting cube <NUM>, need not be a cube. It may be a beam splitting plate or polarizing beam splitting plate tilted at an appropriate angle with respect to the optical path(s). Light beams <NUM> from slit <NUM> are detected by detector <NUM>, which is mounted to the top side or surface of second substrate <NUM>. First substrate <NUM> and second substrate <NUM> are mechanically supported and properly located with respect to each other by a mounting/spacing support layer <NUM>. Mounting/spacing support layer <NUM> can be made of, for example, a layer of inert spacing material, made of, for example, printed circuit board (PCB) material, epoxy, metal, or other similar material. The physical configuration of mounting/spacing support layer <NUM>, i.e., dimensions, location, etc., are selected to provide appropriate support and stability among components such as laser light source <NUM>, beam splitting cube <NUM>, first substrate <NUM>, second substrate <NUM>, mask <NUM> and slit <NUM>, such that the performance requirements of system <NUM> are met.

It should be noted that, in some exemplary embodiments, laser light source <NUM> is one of an array of laser light sources disposed in parallel along an axis directed substantially normal to the page of <FIG>. Similarly, polarizing or non-polarizing beam splitting cube or plate <NUM> can be a single long cube or plate, or multiple cubes or plates, extending along the same axis normal to the page. Similarly, detector <NUM> can be a single long detector or array of detectors, or multiple detectors or arrays of detectors, extending along the same axis normal to the page. In some exemplary embodiments, detector(s) or array(s) of detectors <NUM> can be SiPM or MPPC detectors.

<FIG> includes a schematic cross-sectional diagram which illustrates a configuration of a coaxial scanning LiDAR system <NUM>, according to an example not part of the invention but useful for understanding it. <FIG> includes a schematic top view of the coaxial scanning LiDAR system <NUM> of <FIG>. Referring to <FIG> and <FIG>, system <NUM> includes two laser light sources or arrays of laser light sources 804A, 804B on opposite sides of a first substrate or board <NUM>. Laser light sources 804A-<NUM> through 804A-<NUM> generate output beams of light 807A, which impinge on a beam splitting cube <NUM>, such that output signals 823A are transmitted into region <NUM>. Returning light signals from region <NUM> are transmitted through beam splitting cube <NUM>, through a slit 842A in mask 824A. It should be noted that beam splitting cube <NUM> can be a polarizing beam splitting cube. It should also be noted that, as with the embodiments described above, beam splitting cube <NUM>, or polarizing beam splitting cube <NUM>, need not be a cube. It may be a beam splitting plate or polarizing beam splitting plate tilted at an appropriate angle with respect to the optical path(s). Light beams 825A from slit <NUM> A are detected by detectors <NUM> A- <NUM> through <NUM> A- <NUM>, which are mounted to the top side or surface of second substrate <NUM>. In some exemplary embodiments, detector(s) or array(s) of detectors 826A and 826R can be SiPM or MPPC detectors.

Similarly, laser light sources 804B-<NUM> through 804B-<NUM> (not seen on back surface of first substrate <NUM>) generate output beams of light 807B, which impinge on a beam splitting cube or plate <NUM>, such that output signals 823B are transmitted into region <NUM>. Returning light signals from region <NUM> are transmitted through beam splitting cube <NUM>, through a slit 842BA in mask 824B. Light beams 825B from slit 842B are detected by detectors 826B-<NUM> through 826B-<NUM>, which are mounted to the top side or surface of second substrate <NUM>.

First substrate <NUM> and second substrate <NUM> are mechanically supported and properly located with respect to each other by a mounting/spacing support layer <NUM>. Mounting/spacing support layer <NUM> can be made of, for example, a layer of inert spacing material, made of, for example, printed circuit board (PCB) material, epoxy, metal, or other similar material. The physical configuration of mounting/spacing support layer <NUM>, i.e., dimensions, location, etc., are selected to provide appropriate support and stability among components such as laser light sources 804A and 804B, beam splitting cube or plate <NUM>, first substrate <NUM>, second substrate <NUM>, masks 824A and 824B, slits 842A and 842B, such that the performance requirements of system <NUM> are met.

Is should be noted that the exemplary embodiment of <FIG> and <FIG> includes eleven (<NUM>) detectors on the top side of substrate <NUM> and ten (<NUM>) detectors on the bottom side of substrate <NUM>. It will be understood that these quantities are selected as exemplary illustrations only. Other quantities of detectors can be used.

<FIG> and <FIG> include schematic top views of a portion of a scanning LiDAR system, using multiplexing of lasers in a plurality of multi-laser array devices 901A, 901B, 901C, 901D and a respective plurality of detector arrays 926A, 926B, 926C, 926D, under a respective plurality of beam splitting cubes or plates 902A, 902B, 902C, 902D. In some exemplary embodiments, detector(s) or array(s) of detectors 926A, 926B, 926C, 926D can be SiPM or MPPC detectors. It is noted that, in the exemplary embodiments, all of multi-laser array devices 901A, 901B, 901C, 901D are the same. Accordingly, for ease and clarity of description and for avoidance of unnecessary redundancy, only one of the devices will be described. Multi-laser array device <NUM> A includes multiple, e.g., four (<NUM>), laser light sources 904A, 904B, 904C, 904D. The activation of each laser light source 904A, 904B, 904C, 904D is controlled by a respective activation power and timing/control circuit 905A, 905B, 905C, 905D. In some exemplary embodiments, activation of laser light sources <NUM> is controlled in a time-multiplexed fashion such that only a single laser light source <NUM> in each multi-laser array device <NUM> is active at a time. As a result, only a single corresponding detector <NUM> is actively receiving signal at a time. At the instant illustrated in <FIG>, each first laser light source 904A is active, as indicated by the laser light beam output from all four laser light sources 904A. At some instant later in time, as illustrated in <FIG>, each fourth laser light source 904D is active, as indicated by the laser light beam output from all four laser light sources 904D. This laser multiplexing approach to activation of the laser light sources is applicable to any of the embodiments described herein.

<FIG> includes a schematic perspective view which illustrates a configuration of a coaxial scanning LiDAR system <NUM>. <FIG> includes a schematic cross-sectional view of the coaxial scanning LiDAR system <NUM> of <FIG>, according to some exemplary embodiments. <FIG> includes a schematic top view of the coaxial scanning LiDAR system <NUM> of <FIG>, according to some exemplary embodiments. Referring to <FIG>, system <NUM> includes laser light sources or arrays of laser light sources <NUM> on a first substrate or board <NUM>. Laser light sources <NUM> generate output beams of light which impinge on a beam splitting plate <NUM>, such that output signals are transmitted into region <NUM>. Returning light signals from region <NUM> are transmitted through beam splitting cube <NUM>, through opening <NUM> in mechanical support structure <NUM>, and through a slit <NUM> in mask <NUM> attached to a surface of mechanical support structure <NUM>. It should be noted that beam splitting plate <NUM> can be a polarizing beam splitting plate. Light beams are detected by detectors <NUM>, which are mounted to the top side or surface of second substrate <NUM>. In some exemplary embodiments, detector(s) or array(s) of detectors <NUM> can be SiPM or MPPC detectors.

First substrate <NUM> and second substrate <NUM> are mechanically supported and properly located with respect to each other by a mechanical support structure <NUM>. Mechanical support structure <NUM> can be made of, for example, a layer of inert spacing material, made of, for example, printed circuit board (PCB) material, epoxy, metal, or other similar material. The physical configuration of mechanical support structure <NUM>, i.e., dimensions, location, etc., are selected to provide appropriate support and stability among components such as laser light sources <NUM>, beam splitting plate <NUM>, first substrate <NUM>, second substrate <NUM>, mask(s) <NUM>, slits <NUM>, such that the performance requirements of system <NUM> are met.

<FIG> includes a schematic perspective view of an automobile <NUM>, equipped with one or more scanning LiDAR systems <NUM>, <NUM> A, described herein in detail. Referring to <FIG>, it should be noted that, although only a single scanning LiDAR system <NUM>, <NUM> A is illustrated, it will be understood that multiple LiDAR systems <NUM>, 100A according to the exemplary embodiments can be used in automobile <NUM>. Also, for simplicity of illustration, scanning LiDAR system <NUM>, 100A is illustrated as being mounted on or in the front section of automobile <NUM> It will also be understood that one or more scanning LiDAR systems <NUM>, 100A can be mounted at various locations on automobile <NUM>. Also, it will be understood that LiDAR system <NUM>, 100A can be replaced with any of the LiDAR systems described herein. That is, the description of <FIG> is applicable to an automobile equipped with any of the embodiments described herein.

<FIG> includes a schematic top view of automobile <NUM> equipped with two scanning LiDAR systems <NUM>, <NUM> A, as described above in detail. In the particular embodiments illustrated in <FIG>, a first LiDAR system <NUM>, 100A is connected via a bus <NUM>, which in some embodiments can be a standard automotive controller area network (CAN) bus, to a first CAN bus electronic control unit (ECU) <NUM> A. Detections generated by the LiDAR processing described herein in detail in LiDAR system <NUM>, <NUM> A can be reported to ECU <NUM> A, which processes the detections and can provide detection alerts via CAN bus <NUM>. Similarly, in some exemplary embodiments, a second LiDAR scanning system <NUM>, 100A is connected via CAN bus <NUM> to a second CAN bus electronic control unit (ECU) 558B. Detections generated by the LiDAR processing described herein in detail in LiDAR system <NUM>, <NUM> A can be reported to ECU 558B, which processes the detections and can provide detection alerts via CAN bus <NUM>. It should be noted that this configuration is exemplary only, and that many other automobile LiDAR configurations within automobile <NUM> can be implemented. For example, a single ECU can be used instead of multiple ECUs. Also, the separate ECUs can be omitted altogether. Also, it will be understood that LiDAR system <NUM>, 100A can be replaced with any of the LiDAR systems described herein. That is, the description of <FIG> is applicable to an automobile equipped with any of the embodiments described herein.

It is noted that the present disclosure describes one or more scanning LiDAR systems installed in an automobile. It will be understood that the embodiments of scanning LiDAR systems of the disclosure are applicable to any kind of vehicle, e.g., bus, train, etc. Also, the scanning LiDAR systems of the present disclosure need not be associated with any kind of vehicle.

Claim 1:
An optical transceiver device for an automotive LiDAR detection system (<NUM>), comprising:
a substrate (<NUM>);
a laser (<NUM>) fixed to a first surface of the substrate, the laser generating output light for transmission along a transmission axis into a region; and
an optical detection element (<NUM>) fixed to a second surface of the substrate (<NUM>) opposite the first surface, the optical detection element receiving input light reflected from the region along a reception axis through an opening (<NUM>) in the substrate (<NUM>) between the first and second surfaces of the substrate (<NUM>), the transmission axis and the reception axis being substantially parallel.