High-precision 2D lidar scanning with a rotatable concave mirror and a beam steering device

Abstract

Light detection and ranging LiDAR scanning system (300A-F), which includes: a first light source (220) configured to provide one or more first light pulses (212A); and one or more beam steering devices (100, 100'; 900) optically coupled to the first light source, each beam steering device comprising a rotatable concave reflector (112; 920) and a light beam steering device (102), wherein the light beam directing device is at least partially arranged in the rotatable concave reflector, wherein the combination of the light beam directing device and the rotatable concave reflector, when moving relative to each other, is configured to: directing one or more first light pulses both vertically and horizontally to illuminate an object within a field of view, receive one or more first returning light pulses, wherein the one or more first returning light pulses are generated based on the directed first light pulses illuminating an object within the field of view, and redirect one or more of the first returning light pulses to one or more optical receiving systems (1160, 1162, 1164) located in the LiDAR scanning system.

Description

FIELD OF DISCLOSURE

[0001] The present disclosure relates generally to light detection and ranging (LiDAR), and more particularly to a system for scanning successive light pulses to illuminate objects in a field of view and coaxially collecting the scattered light from each light pulse to delineate the objects in the field of view. BACKGROUND TO THE DISCLOSURE

[0002] To reduce the size of LiDAR systems, efforts are being made to implement on-chip microelectromechanical systems (MEMS) that direct light pulses to illuminate objects within a field of view. Such on-chip solutions reduce the size of the LiDAR system. However, these on-chip MEMS designs typically provide an optical aperture cross-section of a few (less than 5) millimeters or less, making it difficult to distinguish a light pulse reflected from objects at a greater distance (e.g., at 100 meters) from background noise signals. An optical aperture cross-section has been found to increase the signal-to-noise ratio for light. However, a typical LiDAR system can be bulky and expensive due to its system configurations. These systems may not be easily integrated into a vehicle and / or may be prohibitively expensive to do so.Therefore, a high-precision LiDAR system with reduced dimensions and costs is desired.

[0003] A device for the optical detection of objects, particularly in front of vehicles within a surveillance sector, is shown in DE 197 57 848 A1. The device includes a scanner having a transmitter that generates a collimated beam of pulses of electromagnetic radiation, and a radiation receiver that receives pulses reflected from the surveillance sector. The scanner moves the beam in rotation about a rotation axis. Several plane mirrors are arranged in the beam's rotation area so that, during one rotation, they reflect the beam one after the other in several pivoting planes into the surveillance sector. The device also has an evaluation unit that determines relative spatial coordinates of objects in the pivoting areas from the angle and transit time of the pulses. The plane mirrors are each aligned with the rotating beam so that they reflect the beam in several pivoting planes with a non-parallel scanning direction.

[0004] One of the challenges in a high-precision LiDAR system is to reduce the size of the LiDAR systems while increasing the cross-sectional coverage of the optical aperture. SUMMARY OF DISCLOSURE

[0005] The invention is defined by the independent claims. Optional embodiments are set forth in the dependent claims.

[0006] The following is a simplified summary of one or more examples to provide a basic understanding of the disclosure. This summary is not a comprehensive overview of all examples considered and is not intended to identify key or critical elements of all examples, nor to describe the scope of any or all examples. Its purpose is to present some concepts of one or more examples in simplified form in preparation for the more detailed description set forth below.

[0007] In accordance with some embodiments, an optical laser ranging and speed measurement (LiDAR) system is provided. The system includes a first light source configured to deliver one or more first light pulses. The system also includes one or more beam steering devices optically coupled to the first light source. Each beam steering device includes a rotatable concave reflector and a light beam steering device disposed at a location such that the light pulses directed by the rotatable concave reflector or the light beam steering device can be further directed in a different direction by the light beam steering device or the rotatable concave reflector.The combination of the light beam steering device and the rotatable concave reflector, when moving relative to each other, steers the one or more first light pulses both vertically and horizontally to illuminate an object within a field of view; receives one or more first return light pulses, the one or more first return light pulses being generated based on the steered first light pulses illuminating an object within the field of view; and redirects one or more first return light pulses to one or more return light detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a better understanding of the various aspects described, reference is made to the following description in conjunction with the following figures, in which like numbers refer to corresponding parts in the figures. Fig. shows a variety of coaxial LiDAR systems mounted on a vehicle. Fig. shows an exemplary beam steering device with a polyhedron located within the concave reflector. Fig. shows an exemplary beam steering device with an oscillating mirror that replaces the concave reflector. Fig. shows a binocular LiDAR system. Fig. shows a coaxial LiDAR system with a converging lens. Fig. shows a coaxial LiDAR system with a converging mirror. Fig. shows a dual coaxial LiDAR system. Fig. shows an exemplary beam steering device that directs the transmitted light in a direction between the positive x-axis and the positive z-axis and collects the scattered light. Fig. shows an exemplary beam steering device that directs transmitted light in a direction between the negative x-axis and the positive z-axis and collects the scattered light. Fig. shows an exemplary beam steering device that directs transmitted light more toward the edge of the positive horizontal region of the field of view and detects scattered light from that direction. Fig. and Fig. show interlaced plots for the angular distribution over the horizontal and vertical directions for a dual coaxial LiDAR system. Fig. shows a heat map corresponding to the detection aperture widths along the xz-plane at y = 0 across the horizontal and vertical directions for a dual coaxial LiDAR system. Fig. shows an example process of LiDAR scan detection. Fig. show various views of another embodiment of the beam steering device, in accordance with the examples of the disclosure. Fig. show various exemplary configurations for generating a collimated illumination laser beam, consistent with the examples of the disclosure. Fig. shows exemplary configurations of a beam steering device for increasing the receiving aperture and for detecting returning light pulses from different facets, in accordance with the examples of the disclosure. Fig. show exemplary configurations of receiving optical systems, consistent with the examples of the disclosure. Fig. show exemplary detector elements for light collection using an optically sensitive device, in accordance with the examples of the disclosure. Fig. show exemplary configurations for combining light pulses through different facets using free-space optics or a combination of fiber bundle and / or power group, in accordance with the examples of the disclosure. Fig. show various configurations of multiple facets of exemplary polyhedra with curved and flat surfaces, consistent with the examples of the disclosure. Fig. shows an exemplary configuration of a LiDAR system for determining the time of flight of a light pulse, in accordance with the examples of the disclosure. Fig. shows a reference pulse and a received return light pulse, in accordance with the examples of the disclosure. Fig. shows another embodiment of a beam steering device with an oscillating mirror, in accordance with the examples of the disclosure. Fig. shows an exemplary flowchart for a method for determining the transit time of one or more laser pulses, in accordance with the examples of the disclosure. DETAILED DESCRIPTION

[0009] The following detailed description, taken in conjunction with the accompanying drawings, is intended to describe various configurations and is not the only configuration in which the concepts described herein may be practiced. The detailed description includes specific details to provide a thorough understanding of various concepts. However, it will be apparent to one skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order not to obscure these concepts.

[0010] Examples of LiDAR scanning systems will now be presented using various elements of devices and methods. These devices and methods are described in the following detailed description and represented in the accompanying drawings by various blocks, components, circuits, steps, procedures, algorithms, etc. (collectively, "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0011] The present disclosure describes a 2D scanning high-precision LiDAR system using a combination of rotatable concave reflector and light beam steering devices. The LiDAR system includes a beam steering device with a polyhedral reflector located within the concave reflector aligned about a central axis. The concave reflector is configured to rotate about the central axis. The polyhedral is configured to rotate about a pivot point in a direction at an angle (e.g., 90 degrees) to the central axis. The respective instantaneous positions of the concave reflector and the polyhedral direct light pulses to illuminate objects in a field of view while detecting scattered light from the light pulses scattered by the objects. Each transmitted light pulse is substantially coaxial or parallel to the detected scattered light from the corresponding light pulse.The LiDAR system includes a microcontroller to calculate the distance to the objects based on the time differences between each transmitted light pulse and the detected light from the corresponding light pulse scattered by the objects. The present disclosure further describes interlaced subimages to achieve a higher-resolution image. This technique involves scanning range points to one or more objects across successive horizontal and vertical directions to construct one or more subimages. The vertical and / or horizontal positions of the scan points for successively acquired subimages are slightly offset, which collectively results in a higher density of scan points. The higher density of scan points results in a higher resolution of the LiDAR system.

[0012] Although the examples described in the disclosure are for integration into a vehicle, other applications are contemplated. For example, the central laser delivery system and multiple LiDAR systems may be incorporated or integrated into robots, installed at multiple locations within a building for security monitoring, or at traffic intersections or specific road locations for traffic monitoring, etc.

[0013] Fig. shows a plurality of LiDAR scanning systems 300A-300F mounted on a vehicle 150. The LiDAR scanning systems 300A-300F may be 2D scanning LiDAR systems. Each LiDAR scanning system 300A-300F detects and calculates the distance to objects within a field of view corresponding to positions on and around the vehicle 150. For example, the LiDAR scanning systems 300A disposed at the front of the vehicle 150 detect the adjacent vehicle 150' (and / or other objects) using light pulses that are detected substantially coaxially or parallel to the respective light pulse. The range (e.g., the distance) to the adjacent vehicle 150' is determined by the time difference in which each light pulse is transmitted and the scattered light from the corresponding light pulse is detected.

[0014] As in the example in Fig. , the plurality of LiDAR scanning systems 300A-300F are distributed around the vehicle 150 to cover the field of view between each coaxial LiDAR system. For example, the field of view may be configured so that the LiDAR scanning system 300F can capture the centerline 154 on one side of the vehicle 150 and the LiDAR scanning system 300C can capture the lane divider 152 on the other side of the vehicle 150. In some cases, the field of view of one or more of the plurality of LiDAR scanning systems 300A-300F may overlap. For example, the field of view of the LiDAR scanning system 300B may overlap that of the LiDAR scanning system 300A. Overlapping the field of view may provide greater scanning density. Likewise, the field of view of the 300A LiDAR scanning systems may overlap with that of the 300F LiDAR scanning systems.Each of the 300A-300F LiDAR scanning systems may include a beam steering device capable of directing light pulses both vertically and horizontally to transmit them to a field of view for scanning objects. Controlling the light pulses enables continuous scanning of points on one or more objects within the field of view.

[0015] It should be noted that the sizes of the LiDAR scanning systems 300A-300F in Fig. can be relatively small. This means that each corresponding LiDAR scanning system (e.g., the 300A-300F systems) can occupy a space no larger than, for example, 1 cubic foot (28316.8 cubic centimeters) or 1 / 4 of a cubic foot (7079.21 cubic centimeters).

[0016] Fig. shows an exemplary beam steering device 100 with a light beam steering device (e.g., a polyhedron 102) disposed within the concave reflector 112. As shown in Fig. In some embodiments, the concave reflector 112 is aligned coaxially with a first axis 106 (e.g., substantially concentrically). The concave reflector 112 may include one or more reflective surfaces (e.g., flat-surface mirrors) on the concave side surrounding an aperture 118. The aperture 118 of the concave reflector 112 is aligned coaxially with the first axis 106 (e.g., substantially concentrically). In the example in Fig. the mirrors are angled inwards to form a hexagonal shell of the concave reflector 112. In the example in Fig. The hexagonal aperture 118 of the concave reflector 112 may have a width of two and a half centimeters (one inch) across the opposite sides of the (e.g., hexagonal) aperture 118, and the reflective surfaces (e.g., mirrors) of the concave reflector 112 may be angled at 45° from the hexagonal aperture 118 with a length of 6.22 centimeters (2.45 inches) (along the angled mirrors). In some embodiments, the reflective surfaces (e.g., mirrors) of the concave reflector 112 range from 0.5 centimeters to 10 centimeters (0.2 inches to 4 inches). In some embodiments, the reflective surfaces of the concave reflector 112 may be curved. In some examples, the curved surfaces protrude outward (e.g., convex), which can be used to increase the field of view of the beam steering device 100. In some examples, the curved surfaces protrude inward (e.g., concave).

[0017] As shown in Fig. The polyhedron 102 may be disposed within the concave reflector 112. The polyhedron 102 includes a pivot point 120 that is coaxial with (e.g., substantially concentric with) a second axis 104 that is perpendicular to the first axis 106. The polyhedron 102 further includes at least one reflective surface (e.g., a mirror) disposed on one side of the polyhedron 102 to redirect the light between the aperture 118 of the concave reflector 112 and at least one reflective surface (e.g., a mirror) of the concave reflector 112. For example, light pulses transmitted through the aperture 118 onto a reflective surface of the polyhedron 102 may be redirected or directed onto a reflective surface of the concave reflector 112. They may be further redirected or directed toward the field of view. In the example in Fig. The polyhedron 102 is a cube with six facets. In some examples, the two opposite facets with the pivot point 120 have no reflective surfaces (e.g., mirrors), and the remaining four facets have reflective surfaces (e.g., mirrors) facing outwards. In the example in Fig. The cube has an edge length of approximately 3.10 centimeters (1.22 inches).

[0018] It should be noted that polyhedron 102 may have six facets, not all of which are orthogonal. For example, in some embodiments, polyhedron 102 may have asymmetric facets that may balance the vertical and horizontal scanning direction between sub-images and / or alter an interlaced scanning pattern. In some examples, polyhedron 102 is a rhombohedron. It should also be noted that polyhedron 102 may have fewer than six facets. For example, in some embodiments, polyhedron 102 is a pentahedron. In such an embodiment, polyhedron 102 may be a triangular prism with the pivot point located at two opposing triangular facets and one or more reflective surfaces (e.g., mirrors) located at the rectangular facets. It should also be noted that polyhedron 102 may have more than six facets.For example, the polyhedron 102 may be a hexahedron, a heptahedron, an octahedron, etc. In some embodiments, the facets of the polyhedron 102 are curved. In some examples, the curved facets protrude outward (e.g., convex), which can be used to increase the field of view of the beam steering device 100. In some examples, the curved facets protrude inward (e.g., concave), which can reduce the field of view and shape the profile of the exiting laser beam.

[0019] In some embodiments, the beam steering device 100 includes one or more motors (not shown) operatively coupled to the concave reflector 112 and the polyhedron 102. In this example, one or more motors may be configured to rotate the concave reflector 112 counterclockwise (as viewed in the -z direction) about the first axis 106 at a first rotational speed 116, as shown in Fig. One or more motors may also be configured to rotate the polyhedron 102 counterclockwise (as viewed in the +y direction) about the pivot point 120, i.e., about the second axis 104, at a second rotational speed 114. In some embodiments, a rotation controller is configured to control the first rotational speed 116 of the concave reflector 112 and the second rotational speed 114 of the polyhedron 102. In some cases, the rotation controller is electrically coupled to one or more motors to independently control the first rotational speed 116 of the concave reflector 112 and the second rotational speed 114 of the polyhedron 102. In some embodiments, the first rotational speed 116 of the concave reflector 112 is different from the second rotational speed 114 of the polyhedron 102.For example, the second rotational speed 114 of the polyhedron 102 may be faster than the first rotational speed 116 of the concave reflector 112. In the example in . Fig. the second rotational speed 114 of the polyhedron 102 may be set to 500 revolutions per second (rpm), whereas the first rotational speed 116 of the concave reflector 112 may be set to 10 rpm.

[0020] In some embodiments, the second rotational speed 114 of the polyhedron 102 may be slower than the first rotational speed 116 of the concave reflector 112.

[0021] In some embodiments, the instantaneous positions of the rotating polyhedron 102 relative to the rotating concave reflector 112 for each scanned point in a scan activated by the beam steering device 100 are such that the beam steering device 100 can direct or steer light pulses toward an object and collect returning light pulses from the object along a substantially similar beam path. With reference to Fig. The instantaneous positions of the rotating polyhedron 102 can be measured with respect to the positive z-axis. The angle of the polyhedron 102 is positive when measured counterclockwise along the y-axis. The instantaneous positions of the rotating concave reflector 112 can be measured with respect to the negative y-axis. The angle of the concave reflector 112 is positive when measured clockwise along the z-axis.

[0022] It should be noted that other mechanisms may be employed to achieve the same effect as the rotation of the concave reflector 112 and / or the rotation of the polyhedron 102. For example, as shown in Fig. , the concave reflector 112 may be replaced by an oscillating mirror 112A that oscillates along the axis 129. Thus, rotations of the polyhedron 102 coupled to the oscillating mirror 112A to scan successive light pulses may provide a similar control mechanism to illuminate objects in a field of view and collect the light returning from each light pulse coaxially or parallel to the illuminating light pulses so that objects in the field of view can be delineated. In another example, the polyhedron 102 may be driven by an actuator that oscillates the polyhedron along an axis. In some examples, the oscillating mirror 112A may oscillate about a first axis, and the polyhedron 102 may be disposed adjacent to the oscillating mirror 112A, as shown in the Fig. . The polyhedron 102 may include a pivot point coaxially aligned with a second axis. The second axis may be arranged at an angle (for example, 90 degrees or 75 degrees) to the first axis. At least one mirror may be arranged on a facet of the polyhedron 102 to reflect light pulses between the aperture and the concave reflector 112. One or more motors or actuators may be operatively coupled to the oscillating mirror 112A and the polyhedron 102. One or more motors or actuators may be configured to rotate (shown as 128A) or oscillate (shown as 128B) the oscillating mirror 112A about the first axis at a first frequency and to rotate (shown as 125A) or oscillate (shown as 125B) the rotatable polyhedron about the second axis at a second frequency.

[0023] In the example in Fig. Light pulses 307A received from a light source are directed through aperture 118 toward polyhedron 102, generating redirected light pulses 307B by redirecting or reflecting light pulses 307A. Light pulses 307B are directed toward a mirror on concave reflector 112. Concave reflector 112, in turn, generates directed light pulses 312A by redirecting or reflecting directed light pulses 307B. Directed light pulses 312A are directed toward the field of view to illuminate objects within the field of view. Directed light pulses 312A illuminate the objects, scattering the light pulses in one or more directions. Some of the scattered light pulses return to beam steering device 100 as the first returning light pulses 207A. As shown in Fig. In some examples, the first returning light pulses 207A to the beam steering device 100 may return (coaxially) along substantially the same optical path as the steered light pulses 312A. Each of the first returning light pulses 207A may be redirected or reflected by the concave reflector 112 to generate redirected returning light pulses 209. The redirected returning light pulses 209 are directed toward the polyhedron 102, which in turn redirects and reflects the light pulses to generate redirected returning light pulses 214A. Redirected returning light pulses 214A are redirected through the aperture 118 to a light detector.

[0024] Fig. shows a binocular LiDAR system 200. In some examples, the binocular LiDAR system 200 transmits light pulses generated by a light source through a first aperture 210A along the illumination beam path 210C to objects within the field of view. The transmitted light pulses reach the objects and are scattered and distributed in one or more directions. Some of the scattered light pulses return to a light detector along the detection beam path 210D through a second aperture 210B. The geometry of the binocular LiDAR system 200 determines the detection range, which is determined by the overlapping region between the exemplary illumination beam path 210C and the detection beam path 210D, as illustrated in Fig. . Therefore, scattered light pulses in certain regions along the beam path of the binocular LiDAR system 200 cannot return through the second aperture 210B. In some embodiments, the illumination beam path 210C and the detection beam path 210D are substantially parallel (e.g., at a small angle). As a result, the detection range can be wide. For example, as shown in Fig. The detection area on the right side can have no boundary. The advantage of the binocular LiDAR system is that the illumination optics and the detection optics are spatially separated within the LiDAR scanning system, making it easier to avoid light interference in the detection module caused by light scattering in the illumination optics.

[0025] Fig. shows a coaxial LiDAR scanning system 250 with a converging lens 224. In some embodiments, the coaxial LiDAR scanning system 250 includes a light source 220, a reflecting mirror 222, a converging lens 224, a mask 226 with an aperture, a light detector 230, and a beam steering device 100. As shown in Fig. Incident light pulses 212A generated by a light source 220 are directed onto the reflection mirror 222, which deflects or reflects the incident light pulses 212A to generate the deflected light pulses 212B. The deflected light pulses 212B are guided along the optical axis 211 to the beam steering device 100. The beam steering device 100 can then steer the deflected light pulses 212B similarly as described above to generate steered light pulses 212C for illuminating objects in the FOV, wherein the direction of 212C, shown in Fig. , only shows the time at which the steering direction is parallel to the direction of 212B. At other times, the direction of 212C in the FOV may be in other directions. In the example in Fig. The reflection mirror 222 is a nearly 100% reflective mirror arranged on the optical axis 211, which is located along the optical path of both the deflected light pulses 212B and the deflected returning light pulses 214. It should be noted that the reflection mirror 222 should be sufficiently small so as not to obstruct or interfere with the deflected returning light pulses 214.

[0026] In the example of Fig. the beam steering device 100 can be the coaxial beam steering device 100 of Fig. In some examples, the beam steering device 100 may be a dual coaxial device that implements two substantially parallel light pulses directed toward one or more objects in a field of view. The beam steering device 100 may be configured to direct the redirected light pulses 212B in vertical and horizontal directions toward the generated redirected light pulses 212C, while collecting the returning light pulses 212D along substantially the same optical path as the redirected light pulses 212C. The beam steering device 100 redirects the returning light pulses 212D to generate the redirected returning light pulses 214 in the opposite direction of 212B.Thus, the beam path of the returning light pulses 212D to the deflected returning light pulses 214 overlaps the illumination beam path of the deflected light pulses 212B to the directed light pulses 212C, and therefore increases the effective detection range.

[0027] With reference to Fig. The converging lens 224 of the coaxial LiDAR scanning system 250 is configured to collect deflected returning light pulses 214 along the optical axis 211 and direct the deflected returning light pulses 214 through the aperture of the mask 226 to the light detector 230. The converging lens 224 may be made of any transparent material, such as any high-refractive-index glass, plastic, or the like. As shown in Fig. The converging lens 224 may be substantially concentric with the optical axis 211. It should be noted that in some embodiments, the converging lens 224 is arranged so as not to be concentric with the optical axis 210.

[0028] As shown in Fig. In some examples, the light detector 230 is arranged substantially concentrically with the optical axis 211. The light detector 230 may be a photodiode, an avalanche photodiode, or the like. In some embodiments, as in the enlarged diagram of the light detector 230 shown in Fig. , the light detector 230 may include a reflective surface 231 (e.g., a reflective mirror) facing the opposite side of the light incident surface 232. The reflective surface 231 may redirect (e.g., reflect) light back toward the absorption region of the light detector 230, thereby increasing detection efficiency and sensitivity. In some embodiments, the mask 226 may be part of the light detector 230. Generally, the mask 226 filters the redirected returning light pulses 214 near the light detector 230 that are obliquely inclined to the optical path (e.g., optical path along the optical axis 211), so that only light pulses substantially parallel to the optical axis 211 can reach the light detector 230.

[0029] In the example in Fig. The light source 220 may be a laser light source. In some examples, the laser light generated by the light source 220 may have a wavelength in the visible spectrum. In some examples, the laser light may have a wavelength in the infrared spectrum. In some examples, the laser light may have a wavelength in the ultraviolet spectrum.

[0030] Fig. shows a coaxial LiDAR scanning system 250' with a converging mirror 221. In some embodiments, the coaxial LiDAR scanning system 250' includes a light source 220, a converging mirror 221, a mask 226 with an aperture, a light detector 230, and a beam steering device 100. As shown in Fig. , incident light pulses 212A generated by a light source 220 are directed by an aperture of the converging mirror 221 along an optical axis 211 to the beam steering device 100. The beam steering device 100 directs (e.g., redirects and reflects) the incident light pulses 212A to generate the directed light pulses 212C for illuminating an object. The object may scatter the directed light pulses 212C. A portion of the scattered light pulses return to the beam steering device 100 as returning light pulses 212D. The returning light pulses 212D are directed along a trajectory substantially similar to or parallel to the trajectory of the directed light pulses 212C.The beam steering device 100 can then align the returning light pulses 212D to produce redirected returning light pulses 214 that are in a direction coaxial with the optical axis 211 toward the converging mirror 221, which redirects (e.g., reflects) the redirected returning light pulses 214 through the aperture of the mask 226 toward the light detector 230.

[0031] In some embodiments, as described, the converging mirror 221 of the coaxial LiDAR scanning system 250 is configured to collect the redirected returning light pulses 214 along the optical axis 211 and redirect the redirected returning light pulses 214 through the aperture of the mask 226 to the light detector 230. In the example in Fig. The converging mirror 221 may be a nearly 100% reflective mirror disposed on or near the optical axis 211, which is along the optical path of both the steered light pulses 212C and the redirected returning light pulses 214. The converging mirror 221 causes the redirected returning light pulses 214 to be focused onto the light detector 230. It should be noted that in some embodiments, the converging mirror 221 may be disposed so that it is not concentric with the optical axis 211. The converging mirror 221 may be made of any substrate (e.g., glass, plastic, metal, etc.) with a reflective mirror finish. In some examples, an antioxidant layer is applied to the reflective mirror layer to hermetically isolate the reflective layer from the air. This prevents oxygen and other corrosive agents (e.g.,corrosive gases or liquids) attack the reflecting parts of the surface of the converging mirror 221.

[0032] In the example in Fig. the beam steering device 100 can be the coaxial beam steering device 100 of Fig. In some embodiments, the beam steering device 100 may be a dual coaxial device that implements two substantially parallel light pulses directed at one or more objects in a field of view. The beam steering device 100 may be configured to steer the incident light pulses 212A in vertical and horizontal directions to generate the steered light pulses 212C, while collecting the returning light pulses 212D along substantially the same optical path as the steered light pulses 212C. For example, as shown in Fig. , the beam path of the returning light pulses 212D may be substantially parallel to at least a portion of the beam path of the steered light pulses 212C. Thus, the beam path of the returning light pulses from 212D overlaps the beam path of the steered light pulses 212C.

[0033] As shown in Fig. , in some embodiments, the light detector 230 is arranged substantially concentrically with the reflected optical axis 211'. In some embodiments, the reflected optical axis 211' extends from the converging mirror 221 (e.g., the center of the aperture of the converging mirror 221) through the focal point of the converging mirror 221. The reflected optical axis 211' may form an angle with the optical axis 211 that is substantially parallel to the optical path of the steered light pulses 212C and the redirected returning light pulses 214. The light detector 230 may be a photodiode, an avalanche photodiode, or the like. In some embodiments, similar to those shown in Fig. , the light detector 230 may include a reflective surface (e.g., a reflective mirror) facing the opposite side of the light incident surface. The reflective surface may redirect (e.g., reflect) light toward the absorption region of the light detector 230, thereby increasing detection efficiency and sensitivity. In some embodiments, the mask 226 may be part of the light detector 230.

[0034] In the example in Fig. The light source 220 may be a laser light source. In some examples, the laser light generated by the light source 220 may have a wavelength in the visible spectrum. In some examples, the laser light may have a wavelength in the infrared spectrum. In some examples, the laser light may have a wavelength in the ultraviolet spectrum.

[0035] Fig. shows a dual coaxial LiDAR scanning system 300. As shown in Fig. , the dual coaxial LiDAR scanning system 300 may include a light source 220, a reflection mirror 222, a partial reflection mirror 322, a first converging lens 224A, a second converging lens 224B, a first mask 226A with an aperture, a second mask 226B with an aperture, a first light detector 230A, a second light detector 230B, and a dual beam steering device 100'. As shown in Fig. , incident light pulses 212A generated by a light source 220 are directed onto the partial reflection mirror 322, which reflects a first portion of the incident light pulses 212A to generate the redirected light pulses 212B. Based on the redirected light pulses 212B, the polyhedron 102 generates the redirected light pulses 212C, which in turn are redirected by the concave reflector 112 to generate steered light pulses 312A. The steered light pulses 312A can be directed onto the objects in the FOV through the aperture 118 of the beam steering device 100'. In the example in Fig. The partial reflection mirror 322 is a 50% reflection mirror arranged along the first optical axis 311A. The partial reflection mirror 322 can be configured to reflect, for example, 50% of the incident light along the first optical axis 311A. In some embodiments, the partial reflection mirror 322 can be configured to reflect more than 50% of the incident light along the first optical axis 311A. In some embodiments, the partial reflection mirror 322 can be configured to reflect less than 50% of the incident light along the first optical axis 311A. It should be noted that the partial reflection mirror 322 should be sufficiently small so as not to block a significant portion of the first returning light pulses 207A.

[0036] As shown in Fig. , another portion of the incident light pulses 212A passes through the partial reflection mirror 322 and becomes a second portion of the incident light pulses 212A. The second portion of the incident light pulses 212A can be deflected onto the reflection mirror 222, which deflects the second portion of the incident light pulses 212A to generate the deflected light pulses 213B. Based on the deflected light pulses 213B, the polyhedron 102 generates the deflected light pulses 213C, which in turn are deflected by the concave reflector 112 to generate the deflected light pulses 312B. The deflected light pulses 312B can be directed along a second optical axis 311B through the aperture 118 of the beam steering device 100. In the example in Fig. The reflection mirror 222 may be a nearly 100% reflective mirror arranged on the second optical axis 311B. It should be noted that the reflection mirror 222 should be sufficiently small so as not to block a significant portion of the returning light pulses 207B. It should also be noted that during Fig. shows that the two parts of the incident light pulses 212A are generated by the light source 220, two separate and independent light sources can be used to generate the two parts of the incident light pulses 212A separately.

[0037] The double jet steering device 100', shown in Fig. , the coaxial beam steering device 100 may be as shown in Fig. One difference in this example is that the beam steering device 100' is configured to steer two beams of light pulses (e.g., the first steered light pulses 312A and the second steered light pulses 312B) to illuminate one or more objects in a field of view. For example, the beam steering device 100' may be configured to steer the first steered light pulses 312A and the second steered light pulses 312B in the vertical and horizontal directions while collecting the first returning light pulses 207A and the second returning light pulses 207B. The first returning light pulses 207A and the second returning light pulses 207B may have beam paths that are substantially equal to or parallel to the beam paths of the first steered light pulses 312A and the second steered light pulses 312B, respectively.Thus, the optical paths of the first returning light pulses 207A and the second returning light pulses 207B overlap with the optical paths of the first steered light pulses 312A and the second steered light pulses 312B, respectively. In some embodiments, the dual coaxial LiDAR scanning system 300 may also include a power controller (not shown) configured to dynamically control the power of the light source 220. The power control of the light source 220 may be based on the cross-sectional area of ​​an aperture associated with the returning light pulses 207A-B. The power control of the light source 220 may compensate for aperture variations within the field of view.

[0038] In the example in Fig. The dual beam steering device 100' may be generally asymmetric in the xz plane. Thus, the geometry of the optical components for generating the first steered light pulses 312A may be asymmetric at any time to that for generating the second steered light pulses 312B. Similarly, the geometry of the optical components for aligning the first returning light pulses 207A may be asymmetric at any time to that for aligning the second returning light pulses 207B. This allows the beam path of the first steered light pulses 312A to be scanned in a different area and pattern than that of the second steered light pulses 312B.

[0039] With reference to Fig. , the first returning light pulses 207A and the second returning light pulses 207B can be directed by the dual beam steering device 100' through the aperture 118 onto the first converging lens 224A and the second converging lens 224B, similarly as described above. Similarly as described above, the first and second returning light pulses 207A and 207B are redirected by the polyhedron 102 and the concave reflector 112 to generate the first and second returning light pulses 214A and 214B, respectively. In some embodiments, the first collection lens 224A of the coaxial LiDAR scanning system 300 is configured to collect the redirected returning light pulses 214A along the optical axis 311A ​​and redirect the redirected returning light pulses 214A through the aperture of the first mask 226A to the first light detector 230A.Similarly, the second converging lens 224B of the coaxial LiDAR scanning system 300 is configured to converge the second redirected returning light pulses 214B along the second optical axis 311B and direct the second redirected returning light pulses 214B through the aperture of the second mask 226B to the second light detector 230B. Both the first converging lens 224A and the second converging lens 224B may be made of any transparent material, such as high-refractive-index glass, plastic, or the like. In the embodiment shown in FIG. Fig. In the example shown, the first converging lens 224A is not concentric with the first optical axis 311A ​​and the second converging lens 224B is not concentric with the second optical axis 311B. It should be noted that in some embodiments, one or both of the first converging lens 224A and the second converging lens 224B may be concentric with the first optical axis 311A ​​and the second optical axis 311B, respectively.

[0040] As shown in Fig. In some examples, the first light detector 230A may be located at or near the focus area of ​​the first converging lens 224A. Similarly, the second light detector 230B may be located at or near the focus area of ​​the second converging lens 224B. This allows the first redirected returning light pulses 214A to be focused on the first light detector 230A and the second redirected returning light pulses 214B to be focused on the second light detector 230B. One or both of the first light detector 230A and the second light detector 230B may be a photodiode, an avalanche photodiode, or the like. In some embodiments, similar to the light detector 230 described above, the first light detector 230A or the second light detector 230B may have a reflective surface (e.g., a reflective mirror) facing the opposite side of the light incident surface.The light incidence surface can redirect (e.g., reflect) light to the absorption region of the first light detector 230A or the second light detector 230B, respectively. This can improve the efficiencies and sensitivity of the first and second light detectors 230A and 230B. In some embodiments, the first mask 226A can be part of the first light detector 230A. In some embodiments, the second mask 226B can be part of the second light detector 230B.

[0041] In the example in Fig. The light source 220 may be a laser light source. In some examples, the laser light generated by the light source 220 may have a wavelength in the visible spectrum. In some examples, the laser light may have a wavelength in the infrared spectrum. In some examples, the laser light may have a wavelength in the ultraviolet spectrum.

[0042] As shown in Fig. , in some examples, the dual coaxial LiDAR scanning system 300 includes a microprocessor 306 electrically coupled to a computer-readable storage / memory 304, the light source 220, the first light detector 230A, the second light detector 230B, and one or more motors 302. The microprocessor in the dual coaxial LiDAR scanning system 300 may process software. Software may include, for example, instructions, instruction sets, code, code segments, program code, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, and others, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0043] In some embodiments, the microprocessor 306 may be configured to determine a distance to one or more objects in the field of view. As shown in Fig. , the microprocessor 306 includes a timer / clock module 308 and a calculator 310 configured to calculate the distance to one or more objects for each corresponding light pulse based on a time difference between the transmission of the steered light pulses 312A and the detection of the first returning light pulses 207A.

[0044] The timer / clock module 308 is configured to mark each transmitted or received light pulse with a timestamp. The timestamp is an encrypted date and time. Examples of timestamps include "month-dayyear@hour:min:sec," "month-day-year@hour:min:sec," "year-dd-month@hour:min:sec," "1234567890 (Unix time)," etc. In some embodiments, the transmission of the steered light pulse triggers the timer / clock module 308 to mark a steered light pulse with a timestamp. The timer / clock module 308 may further couple a steered light pulse with a corresponding returning light pulse and determine the time difference based on the timestamps.

[0045] The calculator 310 is configured to calculate the distance to one or more objects from the time difference. In some examples, to determine the distance to an object, the calculator 310 may multiply the time difference by the speed of light divided by 2 (assuming a symmetrical light path). For example, if a time difference is 0.8 microseconds, the calculator 310 calculates that the distance to an object is approximately 120 meters (e.g., (0.8*10 -6 )*(2.9979*10 8 ) / 2). After calculating the distance, the computer 310 can store the values ​​in a computer-readable storage device 304.

[0046] Computer-readable storage / memory 304 is electronically coupled to microprocessor 306 and may provide storage for identifiers associated with steered light pulses transmitted to the FOV, identifiers associated with returning light pulses, timestamps, range determinations, etc. In some examples, each pulse (e.g., a steered light pulse transmitted to the FOV and / or a returning light pulse) may be assigned an identifier that uniquely identifies the respective pulse. Identifying the pulses enables the determination of the time differences between the corresponding transmitted and returned light pulses.

[0047] In some embodiments, the microprocessor 306 may optionally include a rotation controller 312. The rotation controller 312 is configured to control the first rotational speed of the concave reflector 112 and the second rotational speed of the polyhedron 102. The rotation controller 312 is electronically coupled to one or more motors 302 that are operatively coupled to the concave reflector 112 and the polyhedron 102. In some examples, the rotation controller 312 may vary the first rotational speed of the concave reflector 112 and the second rotational speed of the polyhedron 102 by changing the drive current to the one or more motors 302.

[0048] In some embodiments, the rotation controller 312 is configured to superimpose a random perturbation on a control parameter such that the first rotational speed of the concave reflector 112 and / or the second rotational speed of the polyhedron 102 increases proportionally with the random perturbation. The random perturbation of the first rotational speed of the concave reflector 112 and / or the second rotational speed of the polyhedron 102 causes the horizontal and vertical scan angles associated with the light pulses transmitted by the beam steering device 100' to be randomly distributed when the light pulses are substantially periodic (e.g., have equal intervals). This facilitates more random acquisition within a sub-image. In some examples, the rotation controller 312 may set the first rotational speed of the concave reflector 112 to 10 rpm and the second rotational speed of the polyhedron 102 to 500 rpm.

[0049] The rotation controller 312 may also add a perturbation of ±1 rpm to one or both of the first rotational speeds of the concave reflector 112 and the second rotational speed of the polyhedron 102. In some cases, the perturbation may be the same and in other cases, different.

[0050] The one or more motors are operatively coupled to the concave reflector 112 and the polyhedron 102. In some examples, a first motor may rotate the concave reflector 112, while a second motor may rotate the polyhedron 102. In some examples, a single motor coupled to one or more gears may rotate the concave reflector 112 and the polyhedron 102. In the example in Fig. The one or more motors 302 may be configured to rotate the concave reflector 112 about the first axis 106 at a first rotational speed and to rotate the polyhedron 102 about the second axis 104 at a second rotational speed. In some embodiments, the first and second rotational speeds are controlled independently of each other.

[0051] Fig. shows that the first steered light pulses 312A and the second steered light pulses 312B are aligned along the positive z-axis. The positions of the polyhedron 102 and the concave reflector 112, as shown in Fig. for generating the first steered light pulses 312A and the second steered light pulses 312B aligned along the positive z-axis can be defined as the target position. The beam steering device 100 can steer the steered light pulses in any desired direction of the field of view and collect the returning light pulses from any desired direction of the field of view when the polyhedron 102 and the concave reflector 112 rotate at specific angles. Fig. shows an exemplary beam steering device 100 that directs directed light pulses in a direction between the positive x-axis and the positive z-axis and collects the returning light pulses therefrom. In some examples, as shown in Fig. , the current position of the rotating polyhedron 102 with respect to the target position is +15° and the current position of the rotating concave reflector 112 is in the target position. As shown in Fig. , the light pulses 307A are directed through the aperture 118 of the beam steering device 100 and redirected (e.g., reflected) by the polyhedron 102 to generate the redirected light pulses 307B. The redirection may occur at or near the point 402 and direct the redirected light pulses 307B toward the concave reflector 112.

[0052] The redirected light pulses 307B are further redirected (e.g., reflected) by a reflective surface (e.g., mirror) of the concave reflector 112 to generate the first redirected light pulses 312A. The redirection may occur at or near the point 404 and direct the first redirected light pulses 312A toward one or more objects in the direction between the positive x-axis and the positive z-axis in the field of view. The first redirected light pulses 312A illuminate the objects, and the first returning light pulses 207A return along a beam path that is substantially coaxial or parallel to the first redirected light pulses 312A. In the example in Fig. The first returning light pulses 207A overlap with the first steered light pulses 312A. For example, the first steered light pulse 312A illuminates an object at an angle of approximately 30° to the horizontal (e.g., at a 30° angle between the positive z-axis and the direction of the transmitted light pulses 312A), and the exemplary beam steering device 100 collects the first returning light pulses 207A at an angle of approximately 30° to the horizontal. Similar to those described above, the first returning light pulses 207A can be redirected by the polyhedron 102 and the concave reflector 112 to generate the returning light pulses 214A.

[0053] Fig. shows an exemplary beam steering device 100 that directs steered light pulses to the FOV and collects the returning light pulses from a direction between the negative x-axis and the positive z-axis. In some examples, as shown in Fig. the current position of the rotating polyhedron 102 with respect to the target position is -5° (or 355°) and the current position of the rotating concave reflector 112 is in the target position. As shown in Fig. , the light pulses 307A are directed through the aperture 118 of the beam steering device 100 and redirected (e.g., reflected) by the polyhedron 102 to generate the redirected light pulses 307B. The redirection may occur at or near point 402 and redirect the redirected light pulses 307B toward the concave reflector 112. The redirected light pulses 307B are further redirected (e.g., reflected) by a reflective surface (e.g., mirror) of the concave reflector 112 to generate the first redirected light pulse 312A. The redirection may occur at or near point 404 and redirect the first redirected light pulses 312A toward one or more objects in the direction between the negative x-axis and the positive z-axis in the field of view.The first steered light pulses 312A illuminate the objects, and the first returning light pulses 207A return along a beam path that is substantially coaxial or parallel to the first steered light pulses 312A. In the example in . Fig. The first returning light pulses 207A overlap with the first steered light pulses 312A, with the first steered light pulses 312A illuminating an object at an angle of approximately -10° to the horizontal (e.g., at a -10° angle between the positive z-axis and the direction of the first steered light pulses 312A), and the exemplary beam steering device 100 collects the first returning light pulses 207A at an angle of approximately -10° to the horizontal. Similar to those described above, the first returning light pulses 207A may be redirected by the polyhedron 102 and the concave reflector 112 to generate the returning light pulses 214A.

[0054] In some embodiments, the beam steering device 100 can be configured to send light pulses more toward the edge of a field of view and collect recurring light pulses from that direction. Fig. shows an exemplary beam steering device 100 that directs steered light pulses in a direction closer to the edge of the positive horizontal region of the field of view and collects returning light from that direction. As shown in Fig. , the current position of the rotating polyhedron 102 with respect to the target position is 15° and the current position of the rotating concave reflector 112 with respect to the target position is 30°. As shown in Fig. , the light pulses 307A are directed through the aperture 118 of the beam steering device 100 and redirected (e.g., reflected) by the polyhedron 102 to generate the redirected light pulses 307B at or near the point 402. The redirection may redirect the redirected light pulses 307B to the concave reflector 112. The redirected light pulses 307B are further redirected (e.g., reflected) by a reflective surface (e.g., mirror) of the concave reflector 112 to generate first redirected light pulses 312A at or near the point 404. The redirection may redirect the redirected light pulses 312A toward one or more objects in a direction more toward the edge of the field of view. The first steered light pulses 312A illuminate the objects and the first returning light pulses 207A return along a beam path that is substantially coaxial or parallel to the first steered light pulses 312A. In the example in Fig. the first returning light pulses 207A overlap with the first steered light pulses 312A. For example, the first steered light pulses 312A illuminate an object at an angle of approximately 40° toward the positive x-direction (e.g., at a 40° angle between the positive z-axis and the projection of the steered light pulses 312A on the XZ plane) and approximately -7° toward the y-direction (e.g., at 7° in the negative y-direction between the z-axis and the projection of the steered light pulses 312A on the YZ plane), and the example beam steering device 100 collects first returning light pulses 207A at an angle of approximately 40° to the positive x-direction and approximately -7° to the y-direction. Similar to those described above, the first returning light pulses 207A may be redirected by the polyhedron 102 and the concave reflector 112 to produce the returning light pulses 214A.

[0055] In some embodiments, to further increase the scanning area, concave lenses or cylindrical lenses may be placed in the beam path of the steered light pulses 312A and / or the second steered light pulses 312B as they are transmitted from the beam steering device 100. With this configuration, the horizontal and / or vertical scanning area may be further increased. In some examples, including convex lenses, the light angle may also be increased, which may reduce resolution.

[0056] Fig. and Fig. show interlaced plots for the angular distribution over the horizontal and vertical directions for a dual coaxial LiDAR scanning system 300 ( Fig. ). Diagrams 600A-B of the Fig. show results of a simulation in which the dual coaxial LiDAR scanning system 300 is configured to collect data in approximately 50 milliseconds. The diagrams show a combination of three consecutive sub-images that form one frame, which corresponds to approximately 20 frames per second (fps). To build the first sub-image 604, the dual coaxial LiDAR scanning system 300 sequentially scans one or more objects across the field of view in both the horizontal and vertical directions at periodic intervals. In doing so, the laser light beam (the light beam spot at or near point 404, as shown in the Fig. shown) is deflected by the reflective surface (e.g. a mirror) of the concave reflector 112 (as shown in the Fig. shown), moves across the mirror at one of the facets of the polyhedron 102, so that the light beam spot moves from one edge of the mirror to the other. To construct the second sub-image 606, the dual coaxial LiDAR scanning system 300 scans one or more objects sequentially across the field of view at periodic intervals, except this time the scanning in the horizontal and vertical directions is slightly offset from the scanning used to generate the first sub-image 604. At this scan offset, the light beam moves across the mirror at one of the facets of the polyhedron 102, so that the light beam spot moves from one mirror edge to the other.To construct the third sub-image 608, the dual coaxial LiDAR scanning system 300 sequentially scans one or more objects across the field of view at periodic intervals, except for the time when scanning in the horizontal and vertical directions occurs slightly offset from the scanning for generating the first sub-image 604 and the scanning for generating the second sub-image 606. The first sub-image 604, the second sub-image 606, and the third sub-image 608 are interlaced to construct a single image with a higher density of scan values, corresponding to higher resolution. The single image also represents the motion correction for both the motion of the LiDAR scanning system and the motion of the detected object.

[0057] As shown in Fig. , grid points from the image generated by the steered light pulses 312A form a pattern covering a range of approximately -10° and 40° in the x-direction and -30° and 30° in the y-direction. Similarly, grid points of the image generated by the steered light pulses 312B form a pattern covering a range of approximately -40° and 10° in the x-direction and -30° and 30° in the y-direction. In the area of ​​the dual coaxial LiDAR scanning system 300, there is an overlay region 602 between the first steered light pulses 312A and the second steered light pulses 312B. The overlay provides denser data scanning in the center of the field of view (e.g., approximately between -10° and 10° in the x-direction and -30° and 30° in the y-direction). This results in higher resolution in the overlapping region 602.

[0058] The shape of the rasterized image pattern, shown in the Fig. , is based on the geometry of the dual beam steering device 100' (e.g., the geometry of the polyhedron 102 and the concave reflector 112). Factors that obstruct the beam path can contribute to the overall rasterized image pattern, as shown in the Fig. . For example, with reference to Fig. In some cases, the first steered light pulses 312A may miss the concave reflector 112 by a certain angle, which determines an end of the scanning range of the dual beam steering device 100'.

[0059] These may correspond to the horizontal peripheral area. Overall, in some embodiments, the dual beam steering device 100' may steer the scanning range of the first steered light pulses 312A between approximately -10° and 40° in the x-direction and approximately -30° and 30° in the y-direction. Similarly, the scanning range of the dual beam steering device 100' may steer the second steered light pulses 312B between approximately -40° and 10° in the x-direction and -30° and 30° in the y-direction.

[0060] Fig. shows an enlarged portion of a frame diagram for the angular distribution over the horizontal and vertical directions for a dual coaxial LiDAR scanning system 300. Fig. thus more clearly shows the combination of three consecutive partial images (e.g., the first partial image 604, the second partial image 606, and the third partial image 608). If, as described above, perturbations are added to the rotational speed of the polyhedron 102 and / or the concave reflector 112, the angular distribution across the horizontal and vertical directions can be arbitrary.

[0061] In some examples, the partial images and / or images in the Fig. in three dimensions to form a “point cloud”. For example, in Fig. The positions in two dimensions illustrate the light scattering on an object. In some examples, the computer 310 of the microprocessor 306 (in Fig. ) provide the third dimension (e.g., a distance at corresponding horizontal and vertical angles). Thus, the shape of the objects around the LiDAR scanning system 300 can be reconstructed (e.g., by analyzing the "point cloud" using data analysis algorithms).

[0062] In some examples, objects within the field of view may move or translate during scanning to build an image or sub-image. For example, in some cases, the time span of the light pulses in an image may be considerably short (e.g., less than 1 millisecond), meaning that the objects, including the dual coaxial LiDAR scanning system 300A and the objects in the field of view, do not move significantly. In such cases, the scan points in the point cloud in the image are collected substantially simultaneously. However, in some cases, the time span may be relatively long (e.g., 20 to 50 milliseconds), which is sufficient time for one or more objects to move a measurable distance. For example, an object moving at approximately 18 meters per second (65 miles per hour) may move approximately 0.6 meters (2 feet) in 20 milliseconds.Thus, the position of each point in the point cloud of the image can be compensated by the LiDAR's own motion and the detected speed of the moving object in the field of view.

[0063] To account for such object movements, the dual coaxial LiDAR scanning system 300 can determine the scan rate from one or more sub-images, determine a relative velocity of the one or more objects, and compensate for the scan rate and relative velocity when forming a point cloud of points in three dimensions by compensating for the aggregate distance. Note that data collected over arbitrary time intervals can be aggregated into a point cloud image. Therefore, the density of the point cloud can be denser or less dense than that described above.

[0064] Fig. shows a heat map 700 corresponding to the detection aperture areas of a dual coaxial LiDAR system with certain system parameter values, wherein the collected cross-sectional areas of the first redirected return light pulses 214A and the second redirected return light pulses 214B, shown in the Fig. , both in Fig. and overlap in the center of the FOV. Thus, the area of ​​the detection aperture changes with the angle of the polyhedron 102 and the angle of the concave reflector 112. For example, the cross-sectional area of ​​the first deflected returning light pulses from 214A, shown in Fig. , smaller than the cross-sectional area of ​​the first deflected returning light pulses of 214A, shown in the Fig. . Thus, the intensity of the collected light corresponding to the configuration of the polyhedron 102 and the concave reflector 112 with the angles shown in Fig. are lower than those shown in Fig. for the same intensity of the first directed light pulses 312A and the same reflectance and distance from the object in the field of view.

[0065] In the example in Fig. The central region of the heat map 700, corresponding to approximately -10°~10° in the x-direction and -30°~30° in the y-direction, has a high detection aperture. This region forms an hourglass shape due to the dual beam paths overlapping in approximately the same region. The regions located approximately between -35° and -30° in the x-direction and approximately between -5° and 5° in the y-direction, as well as approximately between 30° and 35° in the x-direction and approximately between -5° and 5° in the y-direction, have a low detection aperture, which is caused by the oblique angles on the concave reflector 112.

[0066] In some embodiments, the power of the incident light pulses 212 from a light source 220 (shown in the Fig. ) may vary based on the detection aperture. Varying the strength of the incident light pulses 212 may compensate for the size variation of the detection aperture of the first redirected return light pulses 214A and the second redirected return light pulses 214B across the vertical and horizontal directions in the field of view.

[0067] Fig. illustrates an exemplary process 800 for LiDAR scan detection in accordance with the examples of the disclosure. The process 800 may be performed by a system mounted on or located within a vehicle, such as the various systems described in Fig. and the systems depicted in Figures 9A-9D, 10A-10B and 11 as described in detail below. As shown in Fig. At block 802, a first light source of a LiDAR scanning system may provide one or more first light pulses. In the examples described herein, the first light source may be a laser light source. It should be noted that the first light source may be incandescent light, fluorescent light, and the like. Furthermore, the first light source may have one or more wavelengths in the visible spectrum, one or more wavelengths in the infrared spectrum, or one or more wavelengths in the ultraviolet spectrum.

[0068] At block 804, a beam steering device of the LiDAR scanning system may steer the first light pulses to illuminate an object along a beam path. The beam steering device may be the coaxial beam steering device 100 configured to transmit a single beam of light pulses (e.g., light pulses 312A, as shown in Fig. , or the dual coaxial beam steering device 100' configured to transmit dual beams of light pulses (e.g., light pulses 312A and 312B, as shown in Fig. ). During successive scans, the rotation of a light beam steering device (e.g., polyhedron 102) and a concave reflector (e.g., concave reflector 112) may cause the reflective facets of the light beam steering device and the concave reflector that are in the path of the light pulses to change over time. The steering angle of the light pulses by the beam steering device may be calculated using the rotational positions of the light beam steering device and the concave reflector. It should be noted that for some embodiments, the rotational positions of the light beam steering device and the concave reflector may cause the light source to emit a light pulse.

[0069] At block 806, in some examples, the beam steering device (e.g., beam steering device 100 or dual beam steering device 100') may collect and redirect returning light pulses (e.g., the first returning light pulses 207A generated based on the first steered light pulses 312A that illuminated the object). The collected returning light pulses may be aligned coaxially or parallel to the optical path. The returning light pulses may be redirected toward the receiving optical systems by the concave reflector and the light beam steering device. When the beam steering device is used, in some examples, the steered light pulses and the returning light pulses may be coaxially aligned. Furthermore, the beam steering device may transmit the steered light pulses while collecting the returning light pulses in parallel or substantially simultaneously.For example, the time it takes for a transmitted, steered light pulse to illuminate an object and return along the same beam path is more or less directly related to the positions of the light beam steering device (e.g., polyhedron 102) and the concave reflector. For example, the travel time of a light pulse for an object approximately 150 meters away is approximately 1 microsecond. This corresponds to approximately a 0.18° rotation of the light beam steering device (e.g., polyhedron 102 rotating at 500 rpm).

[0070] At block 808, an optical receiving system including a light convergence device may further direct the redirected, returning light pulses to a light detector (e.g., the first light detector 230A shown in Fig. ). In some examples, the light convergence device may be a converging lens 224 ( Fig. or a converging mirror 221 ( Fig. ).

[0071] At block 810, a microcontroller / processor may calculate (e.g., determine) the distance from the LiDAR scanning system to the object based on a time difference between transmitting the steered light pulses and detecting the corresponding returning light pulses. The travel time for a light pulse traveling along the beam path is proportional to the distance the light pulse travels to illuminate an object. Generally, this travel time for a light pulse to illuminate the object is approximately half the time it takes for the light pulse to be detected.

[0072] At optional block 812, the microcontroller may generate one or more sub-images based on the aggregation of distances to one or more objects over consecutive or continuous horizontal and vertical scans (e.g., first sub-image 604, second sub-image 606, third sub-image 608, Fig. For example, a coaxial LiDAR scanning system or the dual coaxial LiDAR system (e.g., system 300) may sequentially scan the same object or objects at periodic intervals across a field of view in both the horizontal and vertical directions. The field of view being sampled (e.g., scanned) may be aggregated according to a first subpattern similar to the first sub-image 604, explained in Fig. . The dual coaxial LiDAR system may, in turn, scan sequentially over the same field of view at one or more periodic intervals, except that the horizontal and vertical directions are slightly offset from the first sub-image 604. The field of view being sampled (e.g., scanned) may be aggregated according to a second sub-pattern, similar to the second sub-image 606 in the Fig. . The dual coaxial LiDAR system may, in turn, scan the same field of view sequentially at one or more periodic intervals, except that the horizontal and vertical directions of the first sub-image 604 and the second sub-image 606 are slightly offset. The field of view being sampled (e.g., scanned) may be aggregated according to a third sub-pattern, similar to the third sub-image 608 in the Fig. .

[0073] At optional block 814, the microcontroller can interlace one or more sub-images to construct a higher resolution image. For example, as shown in Fig. , the LiDAR system can interweave the first sub-image 604, the second sub-image 606, and the third sub-image 608 to construct an image with a higher density of scan values. A higher density of scan values ​​(of non-overlapping scan points) corresponds to a higher resolution. It should be noted that many of the scan points in the overlapping region 602 ( Fig. of a dual coaxial LiDAR system (e.g., System 300) may have a higher density. Therefore, the resolution in the overlapping region 602 is higher, shown in Fig. .

[0074] The beam steering devices 100 and 100', as shown in Fig. , comprise a polyhedron 102 having six facets. As explained, a polyhedron can have any number of facets (e.g., more than six or fewer than six). Fig. show various views of another exemplary embodiment of a beam steering device 900. The beam steering device 900 may include a polyhedron with more than six facets. The beam steering device 900 may be used to perform one or more steps of the process 800 and / or 1900 (e.g., steering light pulses in blocks 1904 and 1910 shown in Fig. ). Fig. shows a perspective view of the beam steering device 900; Fig. shows a side view of the beam steering device 900 along the positive y-axis direction; Fig. shows a rear view of the beam steering device 900 along the positive z-axis direction; and Fig. shows a side view of the beam steering device 900 along the positive x-axis direction. With reference to Fig. A polyhedron 910 may include a plurality (e.g., 18) of side facets parallel to the y-axis of the polyhedron 910. In some embodiments, the polyhedron 910 may be centered at and rotate about or along the y-axis. That is, the y-axis may be the axis of rotation of the polyhedron 910. In some embodiments, each of the plurality of side facets may be polished and function similarly to a reflective surface (e.g., a mirror surface) to transmit and collect laser light.

[0075] With reference to Fig. The beam steering device 900 may also include a concave reflector 920. The concave reflector 920 may include a plurality of (e.g., four) flat or curved reflective surfaces (e.g., mirrors). In some embodiments, each of the flat or curved mirrors of the concave reflector 920 may have a polygonal shape (e.g., trapezoidal shape) or any other desired shape. In some embodiments, each of the flat or curved mirrors may have corners and / or bottom edges cut or trimmed to allow the incident laser light to pass through the concave reflector 920. For example, corners and / or bottom edges cut into the concave reflector 920 are Fig. In some embodiments, similar to the concave reflector 112 shown in Fig. , the concave reflector 920 can rotate about or along the z-axis, the rotation speed being independent of that of the polyhedron 910. With reference to Fig. , at a current position of the rotating polyhedron 910 and the rotating concave reflector 920, in the xz-plane at an angle 935 (e.g., at an angle between the focused one or more light pulses 930 and the negative z-direction), a focused beam of one or more light pulses 930 can be directed towards the facet 940 of the polyhedron 910.

[0076] Fig. shows an embodiment of a configuration for generating a collimated illumination laser beam comprising one or more light pulses. As shown in Fig. , a light source 1010 may direct one or more light pulses onto an optical lens 1020. In some embodiments, the optical lens 1020 and the light source 1010 may be configured to be a predetermined distance apart to form an illuminating laser beam (e.g., a Gaussian beam) with a predetermined divergence angle. The illuminating laser beam may be directed onto a facet of the polyhedron 910. The light source 1010 may be a fiber laser, a semiconductor laser, or other type of laser light source. Alternatively, other collimating optics, such as an aspheric lens, compound lens, reflected spherical surface, reflected parabolic surface, or the like, may be used to generate the collimated laser beam.In some embodiments, the concave reflector 920 can be configured to have geometry parameter values ​​such that, at a particular rotation angle, the illuminating laser beam can be blocked or partially blocked by one or more reflective surfaces (e.g., mirrors) of the concave reflector 920. As discussed above, in the concave reflector 920, a portion of the bottom edges of one or more trapezoidal mirrors (e.g., cutout region 1030) can be cut off or exposed to allow the laser beam from a light source to pass through, as shown in FIG. Fig. .

[0077] Fig. shows another embodiment of a configuration for generating a focused, illuminating laser beam comprising one or more light pulses. In this configuration, one or more light pulses can be generated by a light source (not shown in Fig. , such as by fiber lasers, semiconductor lasers, or other types of laser sources. The one or more light pulses may be emitted by an optical fiber 1042 and directed by a mirror 1040 onto a facet of the polyhedron 910. The configuration of the light delivery, shown in Fig. allows the optics (e.g., fibers, mirrors) to be placed inside the concave reflector 920, thereby eliminating the need to eliminate or reduce the edges of the concave reflector 920 (e.g., eliminating the cutout 1030 as shown in Fig. or reducing the size of the clipping area 1030).

[0078] With reference to the Fig. In some embodiments, the relative position and / or angle of an applied laser beam (e.g., a laser beam applied by the optical fiber 1042 and the mirror 1040) to the rotation axis of the reflective surfaces (e.g., polygon mirrors) of the polyhedron 910 can be configured such that the effective LiDAR scan rate (e.g., the horizontal and vertical coverage angles) achieves the desired coverage values. In one example, the position and / or angle of the laser beam reaching one of the facets of the polygon mirrors of the polyhedron 910 is configured such that an angle 965 (shown in Fig. approximately 59° from the vertical direction (e.g. negative z-direction in Fig. to achieve approximately 100° of horizontal field of view and 25° of vertical field of view.

[0079] In some embodiments of light delivery configurations, the laser beam reaching the side facet of the polyhedron 910 may have different Gaussian beam parameters, such as beam waist widths and beam divergence angles, in the y-axis direction and the direction within the xz-plane. By using one or more aspherical lenses or cylindrical lenses between the laser light source and a side facet of the polyhedron 910, different Gaussian beam parameters can be achieved. In some embodiments, it is desirable and advantageous to configure the lenses or other components of the LiDAR system such that the beam waist width at the location where the laser beam reaches the side facet of the polyhedron 910 is very narrow. In a typical embodiment, a beam waist width of 0.45 mm with an approximately 0.06° divergence angle can be achieved. A narrow or small laser beam waist width (e.g.,0.2 mm) can reduce the percentage of polyhedral rotation positions where, relative to all polyhedral rotation positions reached by the light beam, a portion of the light beam reaches two side facets simultaneously (e.g., a laser beam spot reaches two facets that share a common edge). A light beam reaching two side facets simultaneously may be undesirable, as this can complicate signal analysis.

[0080] If the beam waist of the Gaussian beam is narrow in one direction, its beam divergence angle may become larger in that direction, which may be undesirable for certain embodiments. For example, for a Gaussian beam with a waist width of 0.2 mm, the divergence angle may be approximately 0.14°. To reduce the beam divergence angle, in some examples, the polyhedron 910 may have curved facets with curved surfaces. In some embodiments, a curved surface may be used for the side facets of the polyhedron 910, as shown in Fig. .

[0081] Fig. shows several facets 1510A-C of an exemplary polyhedron 910 with curved surfaces. In Fig. The solid lines show three of the multiple side facets of the polyhedron 910 when flat surfaces are used. The dashed lines show the curved surfaces that can modify the Gaussian beam to reduce the beam divergence angle. Although Fig. While FIG. 1 illustrates curved surfaces as convex surfaces, those skilled in the art will recognize that concave surfaces may also be used in some embodiments. In another embodiment, curved surfaces may also be used for the reflective surfaces (e.g., mirrors) of the concave reflector 920 (shown in FIGS. Fig. to modify the Gaussian beam.

[0082] In some embodiments, the portion of the polyhedron that reflects the illuminating laser beam can be configured to have one set of parameters (flat or curved surface, diameter, number of facets), while the remaining portion of the polyhedron that collects the returning light can be configured to have a different set of parameters. Fig. shows a top view of such an embodiment, where the portion of polyhedron 910 that reflects the illuminating or transmitting laser beam has curved surfaces (e.g., facets 1520A-C) and a larger diameter, while the remaining portion of the polyhedron that collects the returning light has flat surfaces of smaller diameter (e.g., facets 1522A-C). Both portions of polyhedron 910 may have the same number (e.g., eighteen) of facets. Fig. shows the side view of this embodiment of the polyhedron 910, which includes the facets 1520A-N with curved surfaces for reflecting the illuminating or transmitting laser beam and the facets 1522A-N with flat surfaces for collecting the returning light.

[0083] Fig. shows a top view of another embodiment of the polyhedron 910. As shown in Fig. , the portion of the polyhedron that reflects the illuminating laser beam may have a first number (e.g., eighteen) of facets (e.g., facets 1540A-D) with curved surfaces and a larger diameter, while the portion that collects the returning light may have a second number (e.g., six) of facets (e.g., facets 1542A-B) with flat surfaces and a smaller diameter. Fig. shows the side view of this embodiment of the polyhedron 910, which includes facets 1540A-N with curved surfaces for reflecting the illuminating or transmitting laser beam and facets 1542A-M with flat surfaces for collecting the returning light.

[0084] With reference to the rear Fig. , as discussed above, a beam of one or more collimated light pulses 930 can be directed onto a facet 940 of the polyhedron 910 at an angle of 935 in the xz-plane. The angle 935 can be configured such that the angle between the direction of the light pulses 930 of the illuminating laser beam and a direction of the returning light incident on the detector 960 of the returning light is 2N times the spanning angle of a side of the polyhedron 910. A spanning angle is the angle between the two radii extending from the center of the polyhedron 910 to two adjacent edges of a facet. For an 18-facet polyhedron, the spanning angle is 20° (i.e., 360° / 18 = 20°). In the exemplary embodiment in the Fig. For the 18-facet polygon with a rake angle of 20°, “N” can have the value 1 and the angle 935 can have the value 40°. As shown in Fig. , the one or more deflected light pulses 942 generated (e.g., reflected) by facet 940 are directed onto a mirror 945 of the concave reflector 920 and, in turn, reflected by mirror 945 and deflected onto the field of view as directed light pulses 948.

[0085] With reference to Fig. After the one or more steered light pulses 948 reach an object in the field of view, they may be reflected or scattered in multiple directions, and a portion of the returning light pulses 950 may be reflected back and collected by the mirror 945. If the object is relatively far (e.g., farther than 1 meter) from the LiDAR system, the returning light pulses 950 may be approximated as a collimated beam and are in a direction substantially parallel to the original direction of the steered light pulses 948, but in the opposite direction. The returning light pulses 950 may be redirected by the mirror 945 and propagate in the opposite direction from the redirected light pulses 942 to the polyhedron 910.

[0086] Fig. shows exemplary configurations of a beam steering device 1100 for effectively enlarging the receiving aperture and for detecting returning light pulses from different facets. With reference to Fig. the one or more returning light pulses 950, which are in Fig. shown, (e.g., the light pulses that the LiDAR system collects from light pulses scattered or reflected by the object in the field of view) correspond to the returning light pulses 1110 shown in Fig. For example, the returning light pulses 1110 may reach a reflective surface (e.g., mirror 1130) of the concave reflector 920. After the initial reflection by the mirror 1130 of the concave reflector 920, the returning light pulses 1110 may be redirected toward the polyhedron 910. In some embodiments, the one or more returning light pulses 1110 may be scattered and extend across the entire surface in directions perpendicular to the beam propagation. As a result, a significant portion or all of the surface of the mirror 1130 may receive the one or more returning light pulses 1110 (except for the portion blocked by the shadow of the polyhedron 910). Therefore, the one or more returning light pulses 1110 may be reflected by the mirror 1130 to generate pulses of multiple light sections directed to different facets of the polyhedron 910. For example, as shown in Fig. , a portion of the returning light pulses 1120 propagating toward the polyhedron 910 may reach the facet 1140 (e.g., the same facet 940 shown in Fig. and can be reflected / deflected by facet 1140 as light pulses 1150; another portion of the returning light pulses 1122, propagating toward polyhedron 910, can reach another facet 1142 and be reflected / deflected by facet 1142 as light pulses 1152; yet another portion of the returning light pulses 1124, propagating toward polyhedron 910, can reach another facet 1144 and be reflected / deflected by facet 1144 as light pulses 1154.

[0087] With reference to Fig. In some embodiments, the rays reflected / deflected by different facets of polyhedron 910 may be collected by different optical receiving systems (e.g., systems 1160, 1162, and 1164). For example, a first optical receiving system 1160 may be disposed in the path of light pulses 1150; a second optical receiving system 1162 may be disposed in the path of light pulses 1152, and so on.

[0088] Fig. show exemplary configurations of optical receiving systems. With reference to Fig. an optical receiving system may include a refractive optical lens 1210 (shown in Fig. or an optical compound lens 1220 comprising a plurality of optical elements (shown in Fig. or a compound focusing optic 1230 comprising a parabolic or spherical mirror and a refractive optical lens (shown in Fig. ). The refractive optical lenses shown in Fig. , can be spherical or aspherical lenses or a combination of both. Each of the optical receiving systems shown in Fig. , can focus the substantially parallel incident light onto a detector element 1240, regardless of whether the pulses of incident light have slightly tilted and diverging angles. Although three exemplary embodiments in the Fig. listed, it should be noted that other configurations of optical receiving systems can be used and serve the same purpose.

[0089] The detector element 1240, shown in Fig. , may comprise an optically sensitive device capable of detecting optical signals and converting them into electrical signals. Fig. shows an exemplary embodiment of the detector element 1240 for direct light collection, which uses an optically sensitive device 1320. As shown in Fig. , light pulses may propagate through an optional window 1310 and reach the optically sensitive device 1320, which converts the optical signals into electrical signals. The electrical signals may be further processed by electrical switching elements on the electrical circuit board 1330 and converted into digital data for further processing. In some examples, the optically sensitive device 1320 may include a refractive index matching material disposed on the surface of the optically sensitive device 1320. For example, the optically sensitive device 1320 may include indium gallium arsenide material, whose refractive index does not match that of air. Therefore, the refractive index matching material is disposed on the surface of the optically sensitive device 1320 to reduce or eliminate the mismatch.

[0090] Fig. shows another exemplary embodiment of the detector element 1240 for light collection, which uses an optical fiber 1350. As shown in Fig. , the light pulses received by the optically sensitive device 1370 may first be focused by an optically sensitive device 1340 onto one end of an optical fiber 1350. The optical fiber 1350 may be a multi-mode fiber, a single-mode fiber, or a double-mode fiber, where the light entering the inner cladding fiber is slowly absorbed into the small core. In one embodiment, the light pulses exiting the other end of the optical fiber 1350 may be converged by an optical device 1360 to the optically sensitive device 1370, which may convert the optical signals into electrical signals.The optical device 1360 that converges the light signal coming from the optical fiber 1350 can be an optical lens, a spherical or aspherical mirror, or a direct coupling to the optically sensitive device 1370, with refractive index matching material optionally disposed on the surface of the device 1370 to improve the amount of light received by the optically sensitive device 1370. The electrical signals can be further processed by electrical switching elements on the circuit board 1380. In this embodiment, the electrical devices (e.g., the electrical circuit board 1380) and / or the optically sensitive device 1370 can be located remotely from the beam steering device 1100 (e.g., more than 0.1 meters, more than 1 meter, or even more than 5 meters), as shown in FIG. Fig. , so that the size of the beam steering device 1100 can be reduced. For example, unlike the light exiting the end of the optical fiber 1350, the beam steering device 1100 can be configured to be physically smaller.

[0091] With reference back to Fig. In another embodiment, the optical receiving system 1160 may be arranged in the optical path of the light pulses 1150. In another embodiment, the optical receiving system 1164 may be arranged in the optical path of the light pulses 1154. In yet another embodiment, two or more optical receiving systems (e.g., both 1160 and 1162, or all 1160, 1162, and 1164) may coexist in the LiDAR system. In one embodiment, each of these optical receiving systems may be independent of each other, each having its own optically sensitive device. In another embodiment, some or all of these optical receiving systems may share an optically sensitive device.

[0092] Fig. show exemplary configurations for the combination of redirected returning light pulses from different facets using free-space optics or a combination of fiber bundles and / or power couplers. As shown in Fig. , in some embodiments, an optically sensitive device (e.g., device 1420) may be shared by multiple optical receiving systems. In such embodiments, the light pulses from beams coming from different directions may be redirected by multiple mirrors and focusing optics (e.g., optics 1410, 1412, and 1414) to the same optically sensitive device 1420. For example, the light pulses 1150 may be focused by the focusing optics 1410 and subsequently become pulses of focused light 1450 and travel to the optically sensitive device 1420. Similarly, pulses from the light pulses 1152 may be redirected and focused by the optics 1412 and subsequently become pulses of focused light beam 1452 and travel to the optically sensitive device 1420.Pulses of 1154 can be redirected and focused by the optics 1414 and subsequently become a focused light beam 1454 and reach the optically sensitive device 1420.

[0093] Fig. shows another embodiment in which an optically sensitive device 1440 is shared by multiple optical receiving systems. In this embodiment, pulses of each light coming from different directions can be focused by an optical convergence device (not shown in Fig. . Subsequently, each of the focused light beams from each of the three optical fiber channels 1430, 1432, or 1434 can be coupled into a receiving end. These three optical fiber channels can be combined into one optical fiber channel, for example, using a three-to-one optical combiner (e.g., a backward-propagating optical fiber bundle). Subsequently, the light pulses transmitted from a transmitting end of the combined optical fiber channel can be directed to a shared optically sensitive device 1440. In some embodiments, optical combiners may not be used, and the light pulses transmitted from the transmitting end of the optical fiber bundle (e.g., a bundle of three optical fibers) can be focused directly onto a shared optically sensitive device.

[0094] Fig. shows another embodiment of a beam steering device 1800 with an oscillating mirror. As shown in Fig. , instead of an existing polyhedron 910 (shown in Fig. ), the beam steering device 1800 comprises a single or multi-facet oscillating mirror 1810. In a multi-facet mirror, the adjacent facets may be at an angle similar to that of the adjacent facets of the polyhedron 910, shown in Fig. (e.g., 20°). The mirror 1810 may oscillate along an axis 1820 that is parallel to or along the y-axis, so that the pulses of a light beam illuminating one or more facets of the mirror 1810 may be directed in different directions along the xz-plane. It should be noted that, similar to the embodiments in the Fig. described, in a polyhedron, the portion of the oscillation mirror 1810 that reflects the light pulses may be curved and / or have a different size than the portion of the oscillation mirror 1810 that collects the returning light pulses.

[0095] With reference back to Fig. In some embodiments, in order to accurately determine the time of flight of a pulse (e.g., the time it takes from the transmission of the pulse from the LiDAR system to the scattering / reflection by an object in the FOV and the reception by the detector of the LiDAR system), the time when the pulse is transmitted from the LiDAR system must be determined. Fig. shows an optical beam steering device 1610, a light source 1620, and an optically sensitive device 1630. The optical beam steering device 1610 may be similar or identical to the beam steering device 100 shown in Fig. the device 900 shown in Fig. ; the light source 1620 may be similar or the same as the light source 220 shown in Fig. the light source 1010, shown in Fig. and the optically sensitive device 1630 may be similar or the same as that shown in Fig. As discussed above, an optically sensitive device may include a light detection module to detect and convert received light signals.

[0096] With reference to Fig. In one embodiment, the light source 1620 generates one or more light pulses based on an electrical trigger signal, which can come from either an external signal source or an internally generated signal source. In some embodiments, the time period between the generation of the electrical trigger signal and the transmission of one or more light pulses from the light source 1620 can be considered and / or calibrated as a constant from pulse to pulse (e.g., with negligible fluctuations). This electrical trigger signal can be transmitted to the optically sensitive device 1630 via an electrical connection 1640 (e.g., a cable) and used to determine the reference time of a light pulse.

[0097] In some embodiments, an optical fiber 1650 may be used to direct a portion of one or more light pulses emitted by light source 1620. An optical splitter may be used to split a light pulse and obtain a portion of the light pulse as a reference signal. This portion may be any percentage of the total light pulse, such as 10%, 1%, 0.1%, or 0.0001%, or any desired percentage. This portion of the light pulse may be directed by optical fiber 1650 to optically sensitive device 1630 and used to determine the reference time of the light pulse emitted by light source 1620.

[0098] In some embodiments, a reference pulse generating device 1660 may be arranged with an optical beam steering device 1610 to receive a portion of a light pulse as a reference signal and redirect the portion to an optically sensitive device 1630 after the light pulse has been transmitted from the light source 1620. This portion may be any percentage of the total light pulse, such as 10%, 1%, 0.1%, or 0.0001%, or any desired percentage. One skilled in the art may recognize that the reference pulse generating device 1660 shown in Fig. , is only an illustration; and any optics may be used that can receive a portion of one or more light pulses as reference signals and redirect them to the optically sensitive device 1630. For example, the reference pulse generating device 1660 may be a partial reflection device that reflects a portion of the light pulses to the optically sensitive device.

[0099] In the previous embodiments described with respect to Fig. discussed, the reference signal (e.g., a reference light pulse) can be detected by the optically sensitive device 1630. With reference to Fig. the reference signal is shown as reference pulse 1710. Fig. also shows a returning light pulse 1720. The returning light pulse (e.g., a pulse reflected / scattered by an object in the FOV and received by the optically sensitive device 1630) is depicted as pulse 1720. Pulse 1720 may have a different intensity and pulse width than the reference pulse 1710. In some embodiments, pulses 1710 and 1720 may have a similar shape profile. In one embodiment, the reference pulse 1710 may be used as a template to match the received returning pulse 1720 to accurately determine the time difference (or TOF) between the returning pulse and the reference pulse. Based on the TOF, the distance of the object in the field of view may be determined.

[0100] Fig. shows an exemplary flowchart for methods for determining the travel time of one or more light pulses for generating a 3D image using a LiDAR scanning system (e.g. different systems, shown in the Fig. ). With reference to Fig.At block 1902, one or more light pulses (e.g., short laser light pulses with a pulse width of approximately 0.01 nanoseconds to 5 nanoseconds, or light pulses with a pulse width of 5 nanoseconds to 30 nanoseconds or longer) may be generated from a light source of the LiDAR scanning system. At block 1904, a beam steering device may steer or scan the one or more light pulses across the field of view in both horizontal and vertical directions. At block 1906, one or more light pulses, or a portion thereof, illuminate or reach an object and are scattered or reflected in one or more directions. In some embodiments, a portion of the scattered or reflected light pulses may return to the LiDAR scanning system and reach a detection aperture of a detector of the LiDAR scanning system.

[0101] At block 1910, the one or more returning light pulses may be steered or redirected in a direction substantially opposite to the steering direction and substantially parallel to the light pulses transmitted from the LiDAR scanning system. At block 1912, the one or more redirected returning light pulses may be focused onto a light detector of an optical receiving system. At block 1914, the light detector converts photons of the redirected returning light pulses that reach the light detector into one or more electrical signals. At block 1916, one or more electrical output signals generated by the light detector may be amplified by a predetermined factor using an amplification circuit or device. At block 1920, the one or more amplified electrical signals may be sampled and converted into a digital value at a predetermined scan rate.In some embodiments, the digitized signal data may be collected within a time period of the expected maximum TOF corresponding to the farthest object in the field of view. At block 1922, the digitized signal data may be analyzed to determine the TOF of one or more returning light pulses and the distance from the LiDAR scanning system to the reflection or scattering points of the objects.

[0102] It is assumed that the specific order or hierarchy of blocks in the presented processes and / or flowcharts illustrates exemplary approaches. Based on design preferences, it is assumed that the specific order or hierarchy of blocks in the processes and / or flowcharts can be rearranged. Furthermore, some blocks may be combined or omitted. The accompanying method requires that elements of the various blocks be presented in a scanning order and does not imply that it is limited to the specific presented order or hierarchy.

[0103] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to one skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be construed to the fullest extent consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless expressly stated, but rather "one or more." The word "exemplary" is used herein to mean "serving as an example, instance, or representation." Any aspect described herein as "exemplary" need not necessarily be construed as preferred or advantageous over other aspects.Unless specifically stated otherwise, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, and may include multiples of A, multiples of B, or multiples of C. In particular, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," "one or more of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and B, A and C, B and C, or A and B and B.All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are now known or later become known are expressly incorporated herein by reference and are intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be disclosed to the public, regardless of whether such disclosure is explicitly recited in the claims. The words "module," "mechanism," "element," "device," and the like shall not be substituted for the word "means." As such, no element of the statement shall be construed under 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase "means for."

Claims

[1] Light detection and ranging, LiDAR scanning system (300A-F), which includes: a first light source (220) configured to provide one or more first light pulses (212A); and one or more beam steering devices (100, 100'; 900) optically coupled to the first light source, each beam steering device comprising a rotatable concave reflector (112; 920) and a light beam steering device (102), wherein the light beam directing device is at least partially arranged in the rotatable concave reflector, wherein the combination of the light beam directing device and the rotatable concave reflector, when moving relative to each other, is configured to: directing one or more first light pulses both vertically and horizontally to illuminate an object within a field of view, receive one or more first returning light pulses, wherein the one or more first returning light pulses are generated based on the directed first light pulses illuminating an object within the field of view, and redirect one or more of the first returning light pulses to one or more optical receiving systems (1160, 1162, 1164) located in the LiDAR scanning system. [2] The system of claim 1, wherein the rotatable concave reflector comprises a plurality of polygonal-shaped mirrors, the polygonal-shaped mirrors including flat or curved surfaces. [3] The system of claim 2, wherein the polygonal-shaped mirrors include cutouts associated with one or more edges and corners, the cutouts enabling delivery of the one or more first light pulses to the light beam steering device. [4] The system of claim 1, wherein the light beam directing device is a rotatable polyhedron (102) rotatable along an axis at an angle to the axis of rotation of the rotatable concave reflector. [5] The system of claim 4, wherein the angle between the axis along which the rotatable polyhedron is rotatable and the axis of rotation of the rotatable concave reflector is 90°. [6] The system of claim 4, wherein the rotatable polyhedron comprises a plurality of facets capable of reflecting or redirecting light pulses. [7] The system of claim 1, wherein the light beam directing device is a single- or multi-surface oscillating mirror capable of oscillating along an axis at an angle to the rotation axis of the rotatable concave reflector. [8] The system of claim 7, wherein the angle between the axis along which the single- or multi-surface oscillating mirror can oscillate and the axis of rotation of the rotatable concave reflector is 90°. [9] The system of claim 7, wherein the single- or multi-faceted oscillating mirror comprises one or more facets capable of reflecting or redirecting light pulses. [10] The system of claim 1, wherein the light beam directing device includes flat or curved surfaces. [11] The system of claim 1, further comprising: an oscillating mirror (112A) replacing the rotatable concave reflector, wherein the oscillating mirror oscillates about a first axis (106) and wherein the light beam steering device has a pivot point coaxially aligned with a second axis, the second axis (104) being at an angle to the first axis; and one or more motors (302) or actuators operatively coupled to the oscillating mirror and the light beam steering device, the one or more motors or actuators configured to oscillate the oscillating mirror about the first axis at a first speed and rotate the light beam steering device about the second axis at a second speed. [12] The system of claim 11, wherein the angle between the first axis and the second axis is 90°. [13] The system of claim 1, wherein the one or more first returning light pulses are substantially parallel to the directed first light pulses illuminating the object within the field of view. [14] The system of claim 1, wherein the rotatable concave reflector comprises one or more mirrors configured to: to generate a plurality of first deflected returning light pulses; and to redirect the first deflected returning light pulses to one or more facets of the light beam steering device. [15] The system of claim 14, wherein the light beam steering device is configured to: generate a plurality of second, redirected, returning light pulses based on the first, redirected, returning light pulses using the one or more facets of the light beam directing device; and redirect the plurality of second redirected returning light pulses to the one or more optical receiving systems. [16] The system of claim 15, wherein at least one of the plurality of second redirected, returning light pulses is generated using the same facet of the light beam steering device as the facet that steers the first light pulses. [17] The system of claim 15, wherein at least one of the plurality of second redirected, returning light pulses is generated using a facet of the light beam steering device that is different from the facet that directs the first light pulses. [18] The system of claim 15, wherein the portion of the light beam steering device that generates the plurality of second redirected returning light pulses has one or more of: different flatness, different dimensions, different number of facets from the portion that directs the one or more first light pulses to illuminate an object within a field of view. [19] The system of claim 1, further comprising: optical fibers (1350) and a beam collimation device, wherein the first light source is optically coupled to the one or more beam steering devices using the optical fibers and the beam collimation device to enable delivery of the one or more of the first light pulses to the light beam steering device. [20] The system of claim 1, wherein the first light source is further configured to provide one or more second light pulses directed toward the beam steering device, wherein the beam steering device is configured to direct the first light pulses both vertically and horizontally along a first beam path and to direct the one or more second light pulses both vertically and horizontally along a second beam path, and wherein the beam steering device is further configured to receive one or more second returning light pulses simultaneously with receiving the first returning light pulses, the second returning light pulses being generated based on the steered second light pulses illuminating a second direction in the second beam path. [21] The system of claim 20, further comprising: a power controller configured to dynamically control the power of the first light pulses according to a cross-sectional area of ​​an aperture associated with the first returning light pulses. [22] The system of claim 20, further comprising a partial reflection mirror configured to generate the second light pulses using the first light source. [23] The system of claim 1, wherein each of the one or more optical receiving systems is configured to focus the redirected returning light pulses to a focal point. [24] The system of claim 23, wherein each of the optical receiving systems comprises at least one of the following: a refractive optical lens; a parabolic mirror; a concave mirror; an optical compound lens (1220) including a plurality of optical elements; and a compound focusing optics (1230) with a parabolic mirror and a refractive optical lens. [25] The system of claim 23, wherein at least one of the one or more optical receiving systems comprises an optically sensitive device (1370) capable of detecting optical signals and converting optical signals into electrical signals. [26] The system of claim 25, wherein the optically sensitive device comprises at least one of the following: an optical detection device (1630) configured to convert an optical signal into an electrical signal; and an optical fiber (1350) configured to redirect the redirected returning light pulses to an optical detection device that converts an optical signal into an electrical signal. [27] The system of claim 25, wherein the optically sensitive device is shared by the one or more optical receiving systems. [28] The system of claim 27, further comprising at least one of the following: a first combination of one or more focusing optics (1410, 1412, 1414) and one or more mirrors; and a second combination of at least one of a fiber bundle (1430, 1432, 1434) and a power coupler, wherein the first and second combinations are both configured to redirect the redirected returning light pulses to the optically sensitive device (1440). [29] The system of claim 25, further comprising a refractive index matching material disposed on a surface of the optically sensitive device. [30] The system of claim 23, wherein the first light source is configured to generate the one or more first light pulses based on an electrical trigger signal, the electrical trigger signal enabling determining a reference time associated with the one or more steered first light pulses transmitted by the LiDAR scanning system. [31] The system of claim 23, further comprising: a reference pulse generating device (1660) configured to receive and redirect one or more reference light pulses, wherein the one or more reference light pulses include a portion of the one or more first light pulses; and an optically sensitive device (1630) configured to detect the redirected reference light pulses, wherein the redirected reference light pulses enable determining a reference time associated with the one or more controlled first light pulses transmitted by the LiDAR scanning system. [32] The system of claim 31, wherein the reference pulse generating device is a partial reflection device that reflects a portion of the first light pulses to the optically sensitive device. [33] The system of claim 31, wherein the reference pulse generating device is an optical splitter that splits a portion of the first light pulses and redirects a portion of the first light pulses to the optically sensitive device. [34] The system of claim 31, further comprising: one or more processors (306) electrically coupled to the optically sensitive device, wherein one or more processors are configured to determine the time of flight based on a match between the redirected reference light pulses and the redirected, returning light pulses. [35] The system of claim 1, further comprising a second light source, wherein the one or more receiving optical systems comprise a first receiving optical system and a second receiving optical system, wherein the second light source and the second receiving optical system are arranged on a different side of the light beam steering device than the first light source and the first receiving optical system, such that oscillation or rotation of the light beam steering device facilitates steering the second light pulses generated by the second light source in a different direction in the field of view than those generated by the first light source. [36] A method for performing a LiDAR scan using a LiDAR scanning system (300A-F), comprising: Providing, by a first light source (220), one or more first light pulses (307A); Performing, by one or more beam steering devices (100, 100'; 900) optically coupled to the first light source, each beam steering device comprising a rotatable concave reflector (112; 920) and a light beam steering device (102) disposed at least partially within the rotatable concave reflector, the combination of the light beam steering device and the rotatable concave reflector, when moving with respect to each other: direct the one or more first light pulses both vertically and horizontally to illuminate an object within a field of view, receive one or more first returning light pulses, wherein the one or more first returning light pulses are generated based on the directed first light pulses illuminating an object within the field of view, and redirect the one or more first returning light pulses to a receiving optical device in the system. [37] The method of claim 36, further comprising: Forming one or more points of a point cloud based on a calculation of the distance of the object that scatters or reflects the directed first light pulses at one or more combinations of horizontal and vertical angles; Generating a partial image based on the aggregation of the one or more points corresponding to the directed first light pulses, wherein the directed first light pulses are directed at least once in both the horizontal and vertical directions; and Combining one or more partial images into one image, where the image represents the motion correction of both the movement of the LiDAR scanning system and the movement of the objects.

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