System and method for photodiode-based detection

Abstract

A photodiode-based detection module may include at least one photodiode for detecting light. The photodiode-based detection module may further include a sensitivity damper configured to temporarily reduce the sensitivity of the at least one photodiode. The photodiode-based detection module may also include a controller configured to trigger the sensitivity damper to reduce the sensitivity of the at least one photodiode to below a nominal sensitivity threshold.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 883,231, filed August 6, 2019. The above-cited application is incorporated herein by reference in its entirety. Background Technology

[0003] I. Technical Field

[0004] This disclosure generally relates to lidar technology.

[0005] II. Background Information

[0006] With the advent of driver assistance systems and autonomous vehicles, automobiles need to be equipped with systems capable of reliably sensing and interpreting their surroundings, including identifying obstacles, hazards, objects, and other physical parameters that may affect vehicle navigation. To this end, a variety of different technologies have been proposed, including radar operating alone or in a redundant manner, lidar, and camera-based systems.

[0007] One consideration for driver assistance systems and autonomous vehicles is the system's ability to determine its surroundings under various conditions, including rain, fog, darkness, bright light, and snow. Light detection and ranging systems (LiDAR, also known as radar) are an example of technologies that work well under diverse conditions. This technology measures the distance to an object by illuminating it with light and measuring the reflected pulses with sensors. Lasers are an example of light sources that can be used in LiDAR systems. As with any sensing system, for LiDAR-based sensing systems to be fully adopted by the automotive industry, the system must provide reliable data to enable the detection of distant objects. However, the maximum illumination power of current LiDAR systems is limited by the need to ensure eye safety (i.e., to prevent them from damaging the human eye, which can occur when the projected light is absorbed by the cornea and lens of the eye, causing thermal damage to the retina).

[0008] The systems and methods disclosed herein are aimed at improving the performance of lidar systems while complying with eye safety regulations. Summary of the Invention

[0009] In one embodiment, the photodiode-based detection module may include at least one photodiode for detecting light. The photodiode-based detection module may further include a sensitivity damper configured to temporarily reduce the sensitivity of at least one photodiode. The photodiode-based detection module may also include a controller configured to trigger the sensitivity damper to reduce the sensitivity of the at least one photodiode to below a nominal sensitivity threshold.

[0010] In one embodiment, the electro-optic system may include at least one photodiode for detecting light. The electro-optic system may also include a sensitivity damper configured to temporarily reduce the sensitivity of at least one photodiode. The electro-optic system may further include a controller configured to trigger the sensitivity damper to reduce the sensitivity of the at least one photodiode to below a nominal sensitivity threshold.

[0011] In one embodiment, a method for controlling at least one photodiode of an electro-optic system may include reducing the sensitivity of the at least one photodiode to less than a nominal sensitivity threshold. The method may further include detecting reflections of light pulses from the field of view via the at least one photodiode.

[0012] The foregoing general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the scope of the claims. Attached Figure Description

[0013] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate various disclosed embodiments. In the drawings:

[0014] Figure 1A This is a diagram illustrating an exemplary lidar system consistent with the disclosed embodiments.

[0015] Figure 1B This is an image illustrating an exemplary output of a single scan cycle of a lidar system mounted on a vehicle, consistent with the disclosed embodiments.

[0016] Figure 1C This is another image illustrating a representation of a point cloud model determined from the output of a lidar system consistent with the disclosed embodiments.

[0017] Figure 2A , Figure 2B , Figure 2C , Figure 2D , Figure 2E , Figure 2F and Figure 2G This is a diagram illustrating different configurations of the projection unit according to some embodiments of the present disclosure.

[0018] Figure 3A , Figure 3B , Figure 3C and Figure 3D This is a diagram illustrating different configurations of scanning units according to some embodiments of the present disclosure.

[0019] Figure 4A , Figure 4B , Figure 4C , Figure 4D and Figure 4E This is a diagram illustrating different configurations of sensing units according to some embodiments of the present disclosure.

[0020] Figure 5A Includes four example diagrams illustrating the emission patterns in a single frame time for a single portion of the field of view.

[0021] Figure 5B Includes three example diagrams illustrating the emission patterns over a single frame time across the entire field of view.

[0022] Figure 5C It is a diagram illustrating the reflections of actual light emitted and received during a single frame of time over the entire field of view.

[0023] Figure 6A , Figure 6B and Figure 6C This is a diagram illustrating a first example implementation that is consistent with some embodiments of this disclosure.

[0024] Figure 6D This is a diagram illustrating a second example implementation that is consistent with some embodiments of this disclosure.

[0025] Figure 7 This is a diagram illustrating an exemplary lidar system consistent with the disclosed embodiments.

[0026] Figure 8A , Figure 8B and Figure 8C This is a diagram illustrating various exemplary detection modules consistent with the disclosed embodiments.

[0027] Figure 9 A graph illustrating the sensitivity of an exemplary photodiode over time, consistent with the disclosed embodiments, is shown.

[0028] Figure 10 A graph illustrating the sensitivity of an exemplary photodiode over time, consistent with the disclosed embodiments, is shown.

[0029] Figure 11 This is a flowchart illustrating an exemplary process for detecting the reflection of light pulses from the environment of a lidar system, consistent with the disclosed embodiments.

[0030] Figure 12 This is a flowchart illustrating an exemplary process for detecting the reflection of light pulses from the environment of a lidar system, consistent with the disclosed embodiments.

[0031] Figure 13 This is a flowchart illustrating an exemplary process for detecting the reflection of light pulses from the environment of a lidar system, consistent with the disclosed embodiments.

[0032] Figure 14 This is a flowchart illustrating an exemplary process for detecting the reflection of light pulses from the environment of a lidar system, consistent with the disclosed embodiments. Detailed Implementation

[0033] The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and the following description to denote the same or similar parts. While several illustrative embodiments are described herein, modifications, adaptations, and other implementations are possible. For example, components shown in the drawings may be replaced, added, or modified, and the illustrative methods described herein may be modified by replacing, reordering, removing, or adding steps to the disclosed methods. Therefore, the following detailed description is not limited to the disclosed embodiments and examples. Rather, the appropriate scope is defined by the appended claims.

[0034] Terminology Definition

[0035] The disclosed embodiments may relate to optical systems. As used herein, the term "optical system" broadly includes any system for generating, detecting, and / or manipulating light. By way of example only, an optical system may include one or more optical components for generating, detecting, and / or manipulating light. Examples include light sources, lenses, mirrors, prisms, beam splitters, collimators, polarizing optics, optical modulators, optical switches, optical amplifiers, optical detectors, optical sensors, fiber optic components, and semiconductor optical components; while not all are necessary, each can be part of an optical system. In addition to one or more optical components, an optical system may also include other non-optical components, such as electronic components, mechanical components, chemical reaction components, and semiconductor components. Non-optical components may cooperate with the optical components of the optical system. For example, an optical system may include at least one processor for analyzing detected light.

[0036] Consistent with this disclosure, the optical system may be a lidar system. As used herein, the term "lidar system" broadly includes any system capable of determining parameter values ​​indicating the distance between a pair of tangible objects based on reflected light. In one embodiment, a lidar system may determine the distance between a pair of tangible objects based on the reflection of light emitted by the lidar system. As used herein, the term "determine distance" broadly includes generating an output indicating the distance between the pair of tangible objects. The determined distance may represent the physical dimension between the pair of tangible objects. By way of example only, the determined distance may include a flight distance line between the lidar system and another tangible object in the lidar system's field of view. In another embodiment, a lidar system may determine the relative velocity between a pair of tangible objects based on the reflection of light emitted by the lidar system. Examples of outputs indicating the distance between a pair of tangible objects include: the number of standard units of length between the tangible objects (e.g., meters, inches, kilometers, millimeters), the number of any units of length (e.g., the number of lengths of a lidar system), the ratio of the distance to another length (e.g., the ratio to the length of an object detected in the field of view of a lidar system), a time quantity (e.g., given in standard units, any unit, or ratio, such as the time it takes for light to travel between the tangible objects), one or more locations (e.g., specified using an agreed coordinate system, relative to a known location), and so on.

[0037] A lidar system can determine the distance between a pair of tangible objects based on reflected light. In one embodiment, the lidar system can process the detection results of a sensor, which produces time information indicating the time interval between the emission of a light signal and the time when the light signal is detected by the sensor. This time interval is sometimes referred to as the "time of flight" of the light signal. In one example, the light signal can be a short pulse whose rise and / or fall times can be detected upon reception. Using known information about the speed of light in the relevant medium (typically air), information about the time of flight of the light signal can be processed to provide the distance the light signal travels between emission and detection. In another embodiment, the lidar system can determine the distance based on frequency phase shifts (or multiple frequency phase shifts). Specifically, the lidar system can process information indicating one or more modulation phase shifts of the light signal (e.g., by solving a series of simultaneous equations to give a final measurement). For example, the emitted optical signal can be modulated with one or more constant frequencies. At least one phase shift of the modulation between the emitted signal and the detected reflection can indicate the distance the light travels between emission and detection. Modulation can be applied to continuous wave light signals, quasi-continuous wave light signals, or other types of emitted light signals. It is important to note that lidar systems can use additional information to determine distances, such as the location of the signal projection, the location information between detection locations (especially if they are far apart) (e.g., relative positions), and so on.

[0038] In some embodiments, a lidar system can be used to detect multiple objects in the environment in which the lidar system is located. The term "detecting objects in the environment of a lidar system" broadly includes generating information indicating objects that reflect light toward a detector associated with the lidar system. If the lidar system detects more than one object, the generated information about the different objects can be interconnected, such as a car driving on a road, a bird perched in a tree, a man touching a bicycle, or a truck moving toward a building. The dimensions of the environment in which the lidar system detects objects can vary depending on the implementation. For example, a lidar system can be used to detect multiple objects in the environment of a vehicle on which it is mounted, up to a horizontal distance of 100m (or 200m, 300m, etc.) and a vertical distance of up to 10m (or 25m, 50m, etc.). In another example, a lidar system can be used to detect multiple objects in the vehicle's environment or within a predefined horizontal range (e.g., 25°, 50°, 100°, 180°, etc.), up to a predefined vertical elevation (e.g., ±10°, ±20°, +40°–20°, ±90°, or 0°–90°).

[0039] As used herein, the term "detecting an object" can broadly refer to determining the presence of an object (e.g., the object may exist in a certain direction relative to the lidar system and / or another reference location, or the object may exist within a spatial volume). Additionally or alternatively, the term "detecting an object" can refer to determining the distance between an object and another location (e.g., the location of the lidar system, a location on the ground surface, or the location of another object). Additionally or alternatively, the term "object detection" may refer to identifying an object (e.g., classifying the type of an object, such as a car, plant, tree, road; distinguishing a specific object (e.g., the Washington Monument); determining a license plate number; determining the composition of an object (e.g., solid, liquid, transparent, translucent); determining the kinematic parameters of an object (e.g., whether it is moving, its speed, its direction of movement, the object's expansion). Additionally or alternatively, the term "object detection" may refer to generating a point cloud map, wherein each of one or more points in the point cloud map corresponds to a location in the object or a location on its face. In one embodiment, the data resolution associated with the point cloud map representation of the field of view may be associated with 0.1° x 0.1° or 0.3° x 0.3° of the field of view.

[0040] Consistent with this disclosure, the term "object" broadly includes a finite composition of matter from which at least a portion reflects light. For example, an object can be at least partially solid (e.g., a car, a tree); at least partially liquid (e.g., a puddle on a road, rainwater); at least partially gaseous (e.g., smoke, a cloud); composed of a variety of distinct particles (e.g., a sandstorm, fog, a spray); and its size can be one or more magnitudes, such as about 1 millimeter (mm), about 5 mm, about 10 mm, about 50 mm, about 100 mm, about 500 mm, about 1 meter (m), about 5 m, about 10 m, about 50 m, about 100 m, etc. Smaller or larger objects, and any size between those examples, can also be detected. It should be noted that, for various reasons, a lidar system may detect only a portion of an object. For example, in some cases, light may only be reflected from some sides of an object (e.g., only the side facing the lidar system will be detected); in other cases, light may only be projected onto a portion of the object (e.g., a laser beam projected onto a road or building); in other cases, the object may be partially blocked by another object between the lidar system and the object being detected; in still other cases, the lidar sensor may only detect light reflected from a portion of the object, for example, because ambient light or other interference interferes with the detection of some portions of the object.

[0041] Consistent with this disclosure, a lidar system can be configured to detect objects by scanning the environment of the lidar system. The term "scanning the environment of the lidar system" broadly includes illuminating the field of view or a portion of the field of view of the lidar system. In one example, scanning the environment of the lidar system can be achieved by moving or pivoting a light deflector to deflect light in different directions toward different portions of the field of view. In another example, scanning the environment of the lidar system can be achieved by changing the positioning (i.e., position and / or orientation) of a sensor relative to the field of view. In yet another example, scanning the environment of the lidar system can be achieved by changing the positioning (i.e., position and / or orientation) of a light source relative to the field of view. In yet another example, scanning the environment of the lidar system can be achieved by changing the position of at least one light source and at least one sensor to move rigidly relative to the field of view (i.e., the relative distance and orientation of at least one sensor to at least one light source are maintained).

[0042] As used herein, the term "field of view (FOV) of a lidar system" can broadly encompass the range of the observable environment in which the lidar system can detect objects. It is important to note that the FOV of a lidar system can be affected by various conditions, such as, but not limited to: the orientation of the lidar system (e.g., the direction of the lidar system's optical axis); the position of the lidar system relative to the environment (e.g., distance above the ground and adjacent terrain and obstacles); the operating parameters of the lidar system (e.g., transmit power, calculation settings, defined operating angles), etc. The FOV of a lidar system can be defined, for example, by solid angle (e.g., using...). The angle θ is defined as follows: And θ is, for example, an angle defined in a vertical plane relative to the axis of symmetry of the lidar system and / or its field of view. In one example, the field of view can also be defined within a certain range (e.g., up to 200m).

[0043] Similarly, the term "instantaneous field of view" can broadly encompass the range of the observable environment in which a lidar system can detect objects at any given moment. For example, for a scanning lidar system, the instantaneous field of view is narrower than the entire FOV of the lidar system, and it can be moved within the FOV of the lidar system to enable detection in other parts of the FOV. Movement of the instantaneous field of view within the FOV of the lidar system can be achieved by moving optical deflectors (either on the lidar system itself or externally) to deflect the beam toward and / or away from the lidar system in different directions. In one embodiment, the lidar system can be configured to scan a scene within the environment in which the lidar system is operating. As used herein, the term "scene" can broadly encompass some or all objects within the lidar system's field of view, in their relative positions and in their current state, during the duration of the lidar system's operation. For example, a scene may include ground elements (e.g., ground surface, roads, grass, sidewalks, road markings), sky, man-made objects (e.g., vehicles, buildings, signs), vegetation, people, animals, light projection elements (e.g., flashlights, the sun, other lidar systems), and so on.

[0044] The disclosed embodiments may involve obtaining information used in generating a reconstructed 3D model. Examples of types of reconstructed 3D models that can be used include point cloud models and polygon meshes (e.g., triangular meshes). The terms "point cloud" and "point cloud model" are well known in the art and should be interpreted as including a set of data points spatially located in a coordinate system (i.e., having identifiable locations in a space described by the corresponding coordinate system). The term "point cloud point" refers to a point in space (which may be dimensionless or a tiny cellular space, such as 1 cm). 3A point cloud model can be described using a set of coordinates (e.g., (X, Y, Z), (r, <, θ)). As an example only, a point cloud model can store additional information for some or all of its points (e.g., color information for points generated from camera images). Similarly, any other type of reconstructed 3D model can store additional information for some or all of its objects. Likewise, the terms "polygonal mesh" and "triangle mesh" are well-known in the art and should be interpreted as including a set of vertices, edges, and faces that define the shape of one or more 3D objects (e.g., polyhedral objects). These faces can include one or more of the following: triangles (triangle mesh), quadrilaterals, or other simple convex polygons, as this simplifies rendering. These faces can also include more general concave polygons or polygons with holes. Polygonal meshes can be represented using different techniques, such as: vertex-to-vertex meshes, face-to-vertex meshes, wing-edge meshes, and rendering dynamic meshes. Different parts of a polygonal mesh (e.g., vertices, faces, edges) are located in space, either directly or relative to each other, in a coordinate system (i.e., have identifiable positions in the space described by the corresponding coordinate system). The generation of the reconstructed 3D model can be achieved using any standard, specialized, and / or novel photogrammetric techniques, many of which are known in the art. It should be noted that lidar systems can generate other types of environmental models.

[0045] Consistent with the disclosed embodiments, a lidar system may include at least one projection unit having a light source configured to project light. As used herein, the term "light source" broadly refers to any device configured to emit light. In one embodiment, the light source may be a laser, such as a solid-state laser, a laser diode, a high-power laser, or alternative light sources (such as light-emitting diode (LED) based sources). Furthermore, as shown throughout the figures, light source 112 may emit light in different formats, such as light pulses, continuous wave (CW), quasi-CW, etc. For example, one type of light source that can be used is a vertical-cavity surface-emitting laser (VCSEL). Another type of light source that can be used is an external cavity diode laser (ECDL). In some examples, the light source may include a laser diode configured to emit light with wavelengths between approximately 650 nm and 1150 nm. Alternatively, the light source may include a laser diode configured to emit light with wavelengths between approximately 800 nm and approximately 1000 nm, approximately 850 nm and approximately 950 nm, or approximately 1300 nm and approximately 1600 nm. Unless otherwise stated, the term "approximately" with respect to numerical values ​​is defined as having a variation of up to 5% relative to the stated value. Additional details regarding the projection unit and at least one light source are referenced below. Figures 2A to 2C describe.

[0046] Consistent with the disclosed embodiments, a lidar system may include at least one scanning unit having at least one light deflector configured to deflect light from a light source in order to scan a field of view. The term "light deflector" broadly includes any mechanism or module configured to deflect light off its original path; for example, mirrors, prisms, controllable lenses, mechanical mirrors, mechanically scanned polygons, active diffraction (e.g., controllable LCDs), Risley prisms, non-mechanical electric beam steering (such as that manufactured by Vscent), polarization gratings (such as those provided by Boulder Non-Linear Systems), optical phased arrays (OPAs), and so on. In one embodiment, a light deflector may include multiple optical components, such as at least one reflective element (e.g., a mirror), at least one refractive element (e.g., a prism, a lens), and so on. In one example, the light deflector may be movable to deflect light to different angles (e.g., discrete angles, or over a continuous span of degrees). The optical deflector can be optionally controllable in different ways (e.g., deflecting to an angle α, changing the deflection angle by Δα, moving a component of the optical deflector by M millimeters, changing the speed of the deflection angle change). Furthermore, the optical deflector can optionally be operated to change the deflection angle within a single plane (e.g., the θ coordinate). The optical deflector can optionally be operated to operate in two non-parallel planes (e.g., θ and θ). The deflection angle can be changed within the coordinate system. Alternatively or additionally, the optical deflector may be optionally operable to change the deflection angle between predetermined settings (e.g., along a predefined scan path) or otherwise. Regarding the use of optical deflectors in LiDAR systems, it should be noted that optical deflectors can be used in the outbound direction (also known as the transmit direction or TX) to deflect light from a light source to at least a portion of the field of view. However, optical deflectors can also be used in the inbound direction (also known as the receive direction or RX) to deflect light from at least a portion of the field of view to one or more optical sensors. See below for reference. Figures 3A to 3C Additional details are described regarding the scanning unit and at least one optical deflector.

[0047] The disclosed embodiments may involve pivoting an optical deflector to scan a field of view. As used herein, the term "pivot" broadly includes the rotation of an object (especially a solid object) about one or more axes of rotation while substantially keeping the center of rotation fixed. In one embodiment, pivoting an optical deflector may include rotation of the optical deflector about a fixed axis (e.g., a shaft), but it is not necessarily so. For example, in some MEMS mirror implementations, the MEMS mirror can be moved by actuating multiple benders attached to the mirror, which may undergo some spatial translation in addition to rotation. However, such a mirror may be designed to rotate about a substantially fixed axis and is therefore considered pivoting in accordance with this disclosure. In other embodiments, some types of optical deflectors (e.g., non-mechanical electro-optical beam steering, OPA) do not require any moving parts or internal motion to change the deflection angle of the deflected light. It should be noted that any discussion of moving or pivoting an optical deflector also applies, with necessary modifications, to controlling the optical deflector to alter its deflection behavior. For example, controlling a light deflector can cause a change in the deflection angle of a light beam arriving from at least one direction.

[0048] The disclosed embodiments may involve receiving reflections associated with a portion of the field of view corresponding to a single instantaneous position of the optical deflector. As used herein, the term "instantaneous position of the optical deflector" (also referred to as "state of the optical deflector") broadly refers to the location or position in space of at least one controlled component of the optical deflector at an instantaneous point in time or over a short time span. In one embodiment, the instantaneous position of the optical deflector may be measured relative to a reference frame. The reference frame may be related to at least one fixed point in the lidar system. Alternatively, for example, the reference frame may be related to at least one fixed point in the scene. In some embodiments, the instantaneous position of the optical deflector may include some movement of one or more components of the optical deflector (e.g., mirrors, prisms), typically to a limited degree of maximum variation relative to the scanning of the field of view. For example, scanning the entire field of view of a lidar system may include changing the deflection of light over a span of 30°, and the instantaneous position of at least one optical deflector may include an angular displacement of the optical deflector within 0.05°. In other embodiments, the term "instantaneous position of the optical deflector" may refer to the position of the optical deflector during the acquisition of light, which is processed to provide data for a single point in a point cloud (or another type of 3D model) generated by the LiDAR system. In some embodiments, the instantaneous position of the optical deflector may correspond to a fixed position or orientation, wherein the deflector pauses at that fixed position or orientation for a short period of time during illumination of a specific sub-region of the LiDAR field of view. In other cases, the instantaneous position of the optical deflector may correspond to a position / orientation along a range of scanned positions / orientations of the optical deflector, which the optical deflector passes through as part of a continuous or semi-continuous scan of the LiDAR field of view. In some embodiments, the optical deflector may be moved such that it is located at multiple different instantaneous positions during a scan cycle of the LiDAR FOV. In other words, the deflector may be moved through a series of different instantaneous positions / orientations during the time period in which the scan cycle occurs, and the deflector may arrive at each different instantaneous position / orientation at different times during the scan cycle.

[0049] Consistent with the disclosed embodiments, a lidar system may include at least one sensing unit having at least one sensor configured to detect reflections from objects in the field of view. The term "sensor" broadly includes any device, element, or system capable of measuring characteristics of electromagnetic waves (e.g., power, frequency, phase, pulse timing, pulse duration) and generating an output associated with the measured characteristics. In some embodiments, at least one sensor may include multiple detectors comprising multiple detection elements. At least one sensor may include one or more types of optical sensors. It should be noted that at least one sensor may include multiple sensors of the same type, which may differ in other characteristics (e.g., sensitivity, size). Other types of sensors may also be used. Combinations of several types of sensors may be used for various reasons, such as to improve detection over a range span (especially in the near range); to improve the dynamic range of the sensor; to improve the time response of the sensor; and to improve detection under varying environmental conditions (e.g., atmospheric temperature, rain, etc.). In one embodiment, at least one sensor includes a SiPM (Silicon Photomultiplier), a solid-state single-photon sensing device constructed from an array of avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs), used as a detection element on a common silicon substrate. In one example, the typical distance between SPADs can be between approximately 10 μm and approximately 50 μm, where each SPAD can have a recovery time between approximately 20 ns and approximately 100 ns. Similar photomultipliers from other non-silicon materials can also be used. Although SiPM devices operate in a digital / switching mode, SiPMs are analog devices because all the microcells can be read out in parallel, enabling them to generate signals with a dynamic range from single photons to tens of thousands of photons detected by different SPADs. It is important to note that outputs from different types of sensors (e.g., SPADs, APDs, SiPMs, PIN diodes, photodetectors) can be combined into a single output that can be processed by the processor of a lidar system. See below for reference. Figures 4A to 4C Describe additional details regarding the sensing unit and at least one sensor.

[0050] Consistent with the disclosed embodiments, a lidar system may include or communicate with at least one processor configured to perform various functions. The at least one processor may constitute any physical device having circuitry that performs logical operations on one or more inputs. For example, the at least one processor may include one or more integrated circuits (ICs), including application-specific integrated circuits (ASICs), microchips, microcontrollers, microprocessors, all or part of a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), or other circuitry suitable for executing instructions or performing logical operations. Instructions executed by the at least one processor may, for example, be preloaded into memory integrated with or embedded in the controller, or may be stored in separate memory. Memory may include random access memory (RAM), read-only memory (ROM), hard disk, optical disk, magnetic media, flash memory, other permanent, fixed, or volatile memory, or any other mechanism capable of storing instructions. In some embodiments, the memory is configured to store information representing data about objects in the environment of the lidar system. In some embodiments, the at least one processor may include more than one processor. Each processor may have a similar configuration, or the processors may have different configurations that are electrically connected or disconnected from each other. For example, the processors may be separate circuitry or integrated into a single circuit. When using more than one processor, the processors can be configured to operate independently or collaboratively. Processors can be coupled electrically, magnetically, optically, acoustically, mechanically, or through other means that allow them to interact. See below for reference. Figures 5A to 5C Describe additional details of the processing unit and at least one processor.

[0051] System Overview

[0052] Figure 1AA lidar system 100 is illustrated, comprising a projection unit 102, a scanning unit 104, a sensing unit 106, and a processing unit 108. The lidar system 100 may be mountable on a vehicle 110. Consistent with embodiments of this disclosure, the projection unit 102 may include at least one light source 112, the scanning unit 104 may include at least one light deflector 114, the sensing unit 106 may include at least one sensor 116, and the processing unit 108 may include at least one processor 118. In one embodiment, the at least one processor 118 may be configured to coordinate the operation of at least one light source 112 with the movement of at least one light deflector 114 to scan a field of view 120. During a scanning cycle, each instantaneous position of the at least one light deflector 114 may be associated with a specific portion 122 of the field of view 120. Furthermore, the lidar system 100 may include at least one optional optical window 124 for guiding light projected toward the field of view 120 and / or receiving light reflected from objects in the field of view 120. The optional optical window 124 can be used for various purposes, such as collimating projected light and focusing reflected light. In one embodiment, the optional optical window 124 can be an opening, a flat window, a lens, or any other type of optical window.

[0053] Consistent with this disclosure, the lidar system 100 can be used in autonomous or semi-autonomous road vehicles (e.g., cars, buses, vans, trucks, and any other land vehicles). Autonomous road vehicles equipped with the lidar system 100 can scan their environment and drive to their destination without human input. Similarly, the lidar system 100 can also be used in autonomous / semi-autonomous aircraft (e.g., UAVs, unmanned aerial vehicles, quadcopters, and any other aerial vehicles or devices); or autonomous or semi-autonomous watercraft (e.g., boats, ships, submarines, or any other vessels). Autonomous aircraft and watercraft equipped with the lidar system 100 can scan their environment and navigate to their destination autonomously or with the aid of a remote operator. According to one embodiment, a vehicle 110 (road vehicle, aircraft, or watercraft) can use the lidar system 100 to help detect and scan the environment in which the vehicle 110 is operating.

[0054] It should be noted that the lidar system 100 or any of its components can be used with any of the example embodiments and methods disclosed herein. Furthermore, while some aspects of the lidar system 100 are described relative to an exemplary vehicle-based lidar platform, the lidar system 100, any of its components, or any processing described herein can be applied to lidar systems of other platform types.

[0055] In some embodiments, the lidar system 100 may include one or more scanning units 104 for scanning the environment surrounding the vehicle 110. The lidar system 100 may be attached to or mounted to any part of the vehicle 110. The sensing unit 106 may receive reflections from the surrounding environment of the vehicle 110 and transmit reflection signals indicating light reflected from objects in the field of view 120 to the processing unit 108. Consistent with this disclosure, the scanning units 104 may be mounted to or incorporated into bumpers, fenders, side panels, spoilers, roofs, headlight assemblies, taillight assemblies, rearview mirror assemblies, hoods, trunks, or any other suitable part of the vehicle 110 capable of accommodating at least a portion of the lidar system. In some cases, the lidar system 100 may capture a complete surround view of the environment of the vehicle 110. Therefore, the lidar system 100 may have a 360-degree horizontal field of view. In one example, such as Figure 1A As shown, the lidar system 100 may include a single scanning unit 104 mounted on the roof of the vehicle 110. Alternatively, the lidar system 100 may include multiple scanning units (e.g., two, three, four, or more scanning units 104), each having a field of view such that the overall horizontal field of view is covered by a 360-degree scan around the vehicle 110. Those skilled in the art will recognize that the lidar system 100 may include any number of scanning units 104 arranged in any manner, each having a field of view of 80° to 120° or less, depending on the number of units employed. Furthermore, a 360-degree horizontal field of view can also be achieved by mounting multiple lidar systems 100 on the vehicle 110, each with a single scanning unit 104. However, it should be noted that one or more lidar systems 100 need not provide a complete 360° field of view, and a narrower field of view can be useful in some situations. For example, vehicle 110 may require a first lidar system 100 with a 75° field of view looking forward, and possibly a second lidar system 100 with a similar field of view looking backward (optionally with a lower detection range). It should also be noted that different vertical field of view angles can also be achieved.

[0056] Figure 1BThis is an image illustrating an exemplary output from a single scan cycle of a LiDAR system 100 mounted on a vehicle 110, consistent with the disclosed embodiments. In this example, scanning unit 104 is incorporated into the right front light assembly of vehicle 110. Each gray dot in the image corresponds to a location in the environment surrounding vehicle 110, determined from reflections detected by sensing unit 106. In addition to location, each gray dot may also be associated with different types of information, such as intensity (e.g., how much light returns from that location), reflectivity, proximity to other points, etc. In one embodiment, LiDAR system 100 may generate multiple point cloud data entries based on detected reflections over multiple scan cycles of the field of view, enabling, for example, the determination of a point cloud model of the environment surrounding vehicle 110.

[0057] Figure 1C This is an image showing a representation of a point cloud model determined from the output of the lidar system 100. Consistent with the disclosed embodiments, an surround view image can be generated from the point cloud model by processing point cloud data entries of the generated environment surrounding the vehicle 110. In one embodiment, the point cloud model can be provided to a feature extraction module that processes the point cloud information to identify multiple features. Each feature may include data about different aspects of the point cloud and / or objects (e.g., cars, trees, people, roads) in the environment surrounding the vehicle 110. Features may have the same resolution as the point cloud model (i.e., the same number of data points, optionally arranged in a 2D array of similar size), or they may have different resolutions. Features may be stored in any kind of data structure (e.g., raster, vector, 2D array, 1D array). Furthermore, virtual features (such as a representation of the vehicle 110, boundary lines, or bounding boxes separating regions or objects in the image, e.g., as shown in the image) can also be used. Figure 1B The symbols depicted in the image, as well as icons representing one or more identified objects, can be overlaid on the representation of the point cloud model to form the final surround view image. For example, the symbol for vehicle 110 can be overlaid on the center of the surround view image.

[0058] Projection unit

[0059] Figures 2A to 2G Various configurations of the projection unit 102 and its role in the lidar system 100 are described. Specifically, Figure 2A This is a schematic diagram of a projection unit 102 with a single light source; Figure 2B This is a schematic diagram of multiple projection units 102 of multiple light sources having a common light deflector 114 for aiming; Figure 2C This is a schematic diagram of a projection unit 102 having a main light source and an auxiliary light source 112; Figure 2DThis is a schematic diagram illustrating an asymmetric deflector used in some configurations of the projection unit 102; Figure 2E This is a schematic diagram of the first configuration of a non-scanning lidar system. Figure 2F This is a schematic diagram of the second configuration of the non-scanning lidar system; and Figure 2G This is a schematic diagram of a lidar system that scans in the outward direction but not in the inward direction. Those skilled in the art will recognize that the depicted configuration of the projection unit 102 can have many variations and modifications.

[0060] Figure 2A An example of a bi-static configuration of a lidar system 100 is illustrated, where the projection unit 102 includes a single light source 112. The term "bi-static configuration" broadly refers to a lidar system configuration in which the projected light leaving the lidar system and the reflected light entering the lidar system travel through substantially different optical paths. In some embodiments, the bi-static configuration of the lidar system 100 may include separating the optical paths by using entirely different optical components, by using parallel but not completely separated optical components, or by using the same optical components (which may include, for example, windows, lenses, mirrors, beam splitters, etc.) for only a portion of the optical path. Figure 2A In the depicted example, the transceiver separation configuration includes a configuration where outgoing and incoming light pass through a single optical window 124; however, the scanning unit 104 includes two optical deflectors, a first optical deflector 114A for outgoing light and a second optical deflector 114B for incoming light (incoming light in a lidar system includes emitted light reflected from objects in the scene and may also include ambient light arriving from other sources). Figure 2E and Figure 2G In the illustrated examples, the transceiver separation configuration includes a configuration in which outgoing light passes through a first optical window 124A and incoming light passes through a second optical window 124B. In all the example configurations described above, the incoming and outgoing optical paths are different.

[0061] In this embodiment, all components of the lidar system 100 may be contained within a single housing 200, or may be partitioned among multiple housings. As shown, the projection unit 102 is associated with a single light source 112 comprising a laser diode 202A (or one or more laser diodes coupled together) configured to emit light (projection light 204). In a non-limiting example, the light projected by the light source 112 may have a wavelength between approximately 800 nm and 950 nm, an average power between approximately 50 mW and approximately 500 mW, a peak power between approximately 50 W and approximately 200 W, and a pulse width between approximately 2 ns and approximately 100 ns. Furthermore, the light source 112 may optionally be associated with an optical component 202B for manipulating the light emitted by the laser diode 202A (e.g., for collimation, focusing, etc.). It should be noted that other types of light sources 112 may be used, and this disclosure is not limited to laser diodes. Furthermore, the light source 112 may emit light in different formats, such as light pulses, frequency modulation, continuous wave (CW), quasi-CW, or any other form corresponding to the specific light source employed. The projection format and other parameters can be changed from time to time by the light source based on various factors such as instructions from the processing unit 108. The projected light is projected toward an outward deflector 114A, which serves as a steering element for guiding the projected light within the field of view 120. In this example, the scanning unit 104 also includes a pivotable return deflector 114B that guides photons (reflected light 206) reflected from the object 208 within the field of view 120 toward the sensor 116. The reflected light is detected by the sensor 116, and information about the object (e.g., distance to object 212) is determined by the processing unit 108.

[0062] In this figure, the LiDAR system 100 is connected to the host 210. Consistent with this disclosure, the term "host" refers to any computing environment that can interface with the LiDAR system 100; it can be a vehicle system (e.g., part of vehicle 110), a testing system, a safety system, a surveillance system, a traffic control system, a city modeling system, or any system that monitors its surrounding environment. Such a computing environment may include at least one processor and / or may be connected to the LiDAR system 100 via a cloud. In some embodiments, the host 210 may also include an interface to external devices, such as cameras and sensors configured to measure different characteristics of the host 210 (e.g., acceleration, steering wheel deflection, reverse driving, etc.). Consistent with this disclosure, the LiDAR system 100 may be fixed to a stationary object associated with the host 210 (e.g., a building, a tripod) or to a portable system associated with the host 210 (e.g., a laptop computer, a movie camera). Consistent with this disclosure, the LiDAR system 100 may be connected to the host 210 to provide the host 210 with the output of the LiDAR system 100 (e.g., a 3D model, a reflectivity image). Specifically, host 210 can use LiDAR system 100 to help detect and scan its environment or any other environment. Furthermore, host 210 can integrate, synchronize, or otherwise use the output of LiDAR system 100 with the output of other sensing systems (e.g., cameras, microphones, radar systems). In one example, LiDAR system 100 can be used by a security system.

[0063] The lidar system 100 may also include a bus 212 (or other communication mechanism) for interconnecting subsystems and components, used for transmitting information within the lidar system 100. Optionally, the bus 212 (or another communication mechanism) may be used to interconnect the lidar system 100 with the host 210. Figure 2A In the example, processing unit 108 includes two processors 118 to coordinate the operation of projection unit 102, scanning unit 104, and sensing unit 106, at least in part, based on information received from internal feedback of lidar system 100. In other words, processing unit 108 can be configured to dynamically operate lidar system 100 in a closed loop. A closed-loop system is characterized by having feedback from at least one element and updating one or more parameters based on the received feedback. Furthermore, the closed-loop system can receive feedback and update its own operation at least in part based on that feedback. A dynamic system or element is one that can be updated during operation.

[0064] According to some embodiments, the environment surrounding the scanning lidar system 100 may include illuminating the field of view 120 with light pulses. The light pulses may have parameters such as pulse duration, pulse dispersion, wavelength, instantaneous power, photon density at different distances from the light source 112, average power, pulse power intensity, pulse width, pulse repetition rate, pulse sequence, pulse duty cycle, wavelength, phase, polarization, etc. The environment surrounding the scanning lidar system 100 may also include detecting and characterizing various aspects of reflected light. Characteristics of the reflected light may include, for example, time of flight (i.e., the time from emission to detection), instantaneous power (e.g., power characteristics), average power of the entire return pulse, and photon distribution / signal during the return pulse period. By comparing the characteristics of the light pulse with the characteristics of the corresponding reflection, the distance to the object 212 and possible physical characteristics (such as reflection intensity) can be estimated. A complete scan of the field of view 120 can be achieved by repeating this process on multiple adjacent portions 122 in a predefined pattern (e.g., grating, lissajous, or other patterns). As discussed in more detail below, in some cases, the lidar system 100 can direct light to only some portions 122 of the field of view 120 in each scan cycle. These portions may be adjacent to each other, but not necessarily.

[0065] In another embodiment, the lidar system 100 may include a network interface 214 for communicating with a host 210 (e.g., a vehicle controller). Communication between the lidar system 100 and the host 210 is indicated by dashed arrows. In one embodiment, the network interface 214 may include an Integrated Services Digital Network (ISDN) card, a cable modem, a satellite modem, or a modem that provides data communication connectivity to a corresponding type of telephone line. As another example, the network interface 214 may include a local area network (LAN) card to provide data communication connectivity to a compatible LAN. In another embodiment, the network interface 214 may include an Ethernet port connected to an RF receiver and transmitter and / or an optical (e.g., infrared) receiver and transmitter. The specific design and implementation of the network interface 214 depends on the communication networks(s) on which the lidar system 100 and the host 210 will operate. For example, the network interface 214 may be used to provide the output of the lidar system 100 to an external system, such as a 3D model, operating parameters of the lidar system 100, etc. In other embodiments, the communication unit may be used, for example, to receive instructions from an external system, to receive information about the environment being inspected, to receive information from another sensor, and so on.

[0066] Figure 2BAn example of a monostatic configuration of a lidar system 100 including multiple projection units 102 is illustrated. The term "monostatic configuration" broadly refers to a lidar system configuration in which projected light emitted from the lidar system and reflected light entering the lidar system travel through substantially similar optical paths. In one example, the outgoing and incoming beams may share at least one optical component through which both the outgoing and incoming beams pass. In another example, the outgoing light radiation may pass through an optical window (not shown), and the incoming light radiation may pass through the same optical window. The monostatic configuration may include a configuration in which scanning unit 104 includes a single light deflector 114 that directs the projected light toward a field of view 120 and the reflected light toward a sensor 116. As shown, both the projected light 204 and the reflected light 206 strike the asymmetric deflector 216. The term "asymmetric deflector" refers to any optical device having two sides capable of deflecting a beam of light striking it from a second side in a direction different from the direction of the beam it deflects from one side. In one example, the asymmetric deflector does not deflect the projected light 204, but instead deflects the reflected light 206 toward the sensor 116. One example of an asymmetric deflector may include a polarizing beam splitter. In another example, the asymmetric deflector 216 may include an optical isolator that allows light to pass through in only one direction. An illustration of the asymmetric deflector 216 is shown in [image of a diagram]. Figure 2D As shown in the figure. Consistent with this disclosure, the transceiver configuration of the lidar system 100 may include an asymmetric deflector to prevent reflected light from hitting the light source 112 and to direct all reflected light toward the sensor 116, thereby increasing detection sensitivity.

[0067] exist Figure 2B In one embodiment, the lidar system 100 includes three projection units 102, each projection unit 102 having a single light source 112 aimed at a common optical deflector 114. In one embodiment, multiple light sources 112 (including two or more light sources) can project light having substantially the same wavelength, and each light source 112 is generally associated with a different region of the field of view (shown as 120A, 120B, and 120C in the figures). This allows for scanning a wider field of view than can be achieved using the light sources 112. In another embodiment, multiple light sources 112 can project light with different wavelengths, and all light sources 112 can be directed to the same (or overlapping) portion of the field of view 120.

[0068] Figure 2CAn example of a lidar system 100 is illustrated, in which projection unit 102 includes a main light source 112A and an auxiliary light source 112B. The main light source 112A can project light with wavelengths longer than those sensitive to the human eye to optimize SNR and detection range. For example, the main light source 112A can project light with wavelengths between approximately 750 nm and 1100 nm. Conversely, the auxiliary light source 112B can project light with wavelengths visible to the human eye. For example, the auxiliary light source 112B can project light with wavelengths between approximately 400 nm and 700 nm. In one embodiment, the auxiliary light source 112B can project light along substantially the same optical path as the light projected by the main light source 112A. The two light sources can be time-synchronized and can project light emission together or in an interleaved mode. An interleaved mode means that the light sources are not activated simultaneously, which can mitigate mutual interference. Those skilled in the art will readily see that other combinations of wavelength ranges and activation schedules can also be achieved.

[0069] Consistent with some embodiments, the auxiliary light source 112B can cause blinking in the human eye if it gets too close to the lidar's optical output port. This ensures an eye-safe mechanism that is not feasible with typical laser sources utilizing the near-infrared spectrum. In another embodiment, the auxiliary light source 112B can be used for calibration and reliability at service points, somewhat similar to headlight calibration relative to vehicle 110 using a special reflector / pattern at a certain height above the ground. Operators at service points can check lidar calibration by simply visually inspecting the scanned pattern on a characteristic target, such as a test pattern board at a specified distance from lidar system 100. Furthermore, the auxiliary light source 112B can provide a means of demonstrating operational confidence that the lidar is working for the end user. For example, the system can be configured to allow a person to place their hand in front of the light deflector 114 to test its operation.

[0070] The auxiliary light source 112B may also have invisible components that can serve as a backup system in the event of a failure of the main light source 112A. This feature is useful for fail-safe devices with higher functional safety levels. Assuming the auxiliary light source 112B can be visible, and also due to cost and complexity reasons, it can be associated with lower power compared to the main light source 112A. Therefore, in the event of a failure of the main light source 112A, the system functionality will revert to the functionality and capabilities of the auxiliary light source 112B. Although the capabilities of the auxiliary light source 112B may be inferior to those of the main light source 112A, the lidar system 100 can be designed in a manner that enables the vehicle 110 to safely reach its destination.

[0071] Figure 2DAn asymmetric deflector 216, which may be part of a lidar system 100, is illustrated. In the example shown, the asymmetric deflector 216 includes a reflective surface 218 (such as a emitting mirror) and a unidirectional deflector 220. While not necessarily so, the asymmetric deflector 216 may optionally be a deflector in a transceiver configuration. The asymmetric deflector 216 can be used in a transceiver configuration of the lidar system 100 to allow a common optical path for transmitting and receiving light via at least one deflector 114, such as... Figure 2B and Figure 2C The diagram is shown in the figure. However, typical asymmetric deflectors (such as beam splitters) are characterized by energy loss, especially in the receive path, which may be more sensitive to power loss than the transmit path.

[0072] like Figure 2D As depicted, the lidar system 100 may include an asymmetric deflector 216 located in the transmission path, which includes a unidirectional deflector 220 for separating the transmitted optical signal and the received optical signal. Optionally, the unidirectional deflector 220 may be substantially transparent to the transmitted light and substantially reflective to the received light. The transmitted light is generated by the projection unit 102 and can travel through the unidirectional deflector 220 to the scanning unit 104, which deflects it toward the optical exit. The received light reaches at least one deflection element 114 through the optical entrance, which deflects the reflected signal away from the light source and toward the separation path toward the sensing unit 106. Optionally, the asymmetric deflector 216 may be combined with a polarized light source 112, which is linearly polarized using the same polarization axis as the unidirectional deflector 220. It is worth noting that the cross-section of the transmitted beam is much smaller than the cross-section of the reflected signal. Therefore, the lidar system 100 may include one or more optical components (e.g., lenses, collimators) for focusing or otherwise manipulating the emitted polarized beam into the dimension of the asymmetric deflector 216. In one embodiment, the unidirectional deflector 220 may be a polarization beam splitter that is almost transparent to the polarized beam.

[0073] Consistent with some embodiments, the lidar system 100 may also include optics 222 (e.g., a quarter-wave plate delayer) for modifying the polarization of the emitted light. For example, optics 222 may modify the linear polarization of the emitted beam to circular polarization. Light reflected back to system 100 from the field of view will pass through deflector 114 back to optics 222, which will then be subjected to circular polarization with inverted chirality relative to the emitted light. Optics 222 then converts the received inverted chiral polarized light into linear polarization that is not on the same axis as the linear polarization of polarization beam splitter 216. As noted above, due to optical dispersion of the beam across the distance to the target, the received light patch is larger than the emitted light patch.

[0074] Some of the received light will strike a one-way deflector 220, which will reflect the light toward the sensing unit 106 with some power loss. However, another portion of the received light spot will fall onto a reflective surface 218 surrounding the one-way deflector 220 (e.g., a polarization beamsplitter slit). The reflective surface 218 will reflect the light toward the sensing unit 106 with essentially zero power loss. The one-way deflector 220 will reflect the light, composed of various polarization axes and directions, that will eventually reach the detector. Optionally, the sensing unit 106 may include a sensor 116 that is agnostic to laser polarization and is primarily sensitive to the amount of incident photons within a certain wavelength range.

[0075] It is important to note that the proposed asymmetric deflector 216 offers superior performance compared to a simple mirror with a through-hole. In a mirror with a hole, all reflected light reaching the hole is lost to the detector. However, in deflector 216, the unidirectional deflector 220 deflects most (e.g., approximately 50%) of this light towards the corresponding sensor 116. In lidar systems, the number of photons reaching the lidar from a long distance is very limited, and therefore, improvements in photon capture efficiency are crucial.

[0076] According to some embodiments, a device for beam splitting and steering is described. A polarized beam can be emitted from a light source having a first polarization. The emitted beam can be guided through a polarizing beam splitter component. The polarizing beam splitter component includes a one-way slit on a first side and a reflector on the opposite side. The one-way slit allows the polarized emitted beam to travel toward a quarter-wave plate / wave delayer, which converts the emitted signal from a polarized signal to a linear signal (or vice versa) so that the subsequently reflected beam cannot travel through the one-way slit.

[0077] Figure 2EAn example of a separate transmit / receive configuration of a lidar system 100 without scanning unit 104 is illustrated. To illuminate the entire field of view (or substantially the entire field of view) without deflector 114, projection unit 102 may optionally include an array of light sources (e.g., 112A-112F). In one embodiment, the array of light sources may include a linear array of light sources controlled by processor 118. For example, processor 118 may cause the linear array of light sources to sequentially project collimated laser beams into a first optional optical window 124A. The first optional optical window 124A may include a diffuser lens for diffusing the projected light and sequentially forming wide horizontal and narrow vertical beams. Optionally, some or all of at least one of the light sources 112 of system 100 may project light simultaneously. For example, processor 118 may cause the array of light sources to simultaneously project beams from multiple non-adjacent light sources 112. In the described example, light sources 112A, 112D, and 112F simultaneously project laser beams into the first optional optical window 124A, thereby illuminating the field of view with three narrow vertical beams. The light beam from the fourth light source 112D can reach the object in the field of view. The light reflected from the object can be captured by the second optical window 124B and redirected to the sensor 116. Figure 2E The depicted configuration is considered to be a separate transmit and receive configuration because the optical paths of the projected light and the reflected light are fundamentally different. It should be noted that the projection unit 102 may also include multiple light sources 112 arranged in a non-linear configuration, such as a two-dimensional array, hexagonal tiling, or any other manner.

[0078] Figure 2F The illustration shows an example of a transceiver combined configuration of a lidar system 100 without scanning unit 104. Similar to... Figure 2E In the example embodiment shown, to illuminate the entire field of view without deflector 114, projection unit 102 may include a light source array (e.g., 112A-112F). However, compared with... Figure 2E Conversely, this configuration of the lidar system 100 may include a single optical window 124 for both projected and reflected light. Using an asymmetric deflector 216, the reflected light can be redirected to the sensor 116. Figure 2E The described configuration is considered a combined transmit and receive configuration because the optical paths of the projected and reflected light are substantially similar to each other. In the context of the optical paths of the projected and reflected light, the term "substantially similar" means that the overlap between the two optical paths can be greater than 80%, greater than 85%, greater than 90%, or greater than 95%.

[0079] Figure 2G The diagram illustrates an example of a separate transmit / receive configuration for a lidar system 100. The lidar system 100 configuration in this diagram is similar to... Figure 2AThe configuration shown. For example, both configurations include a scanning unit 104 for guiding the projected light into the field of view in the outward direction. However, compared with... Figure 2A In contrast to the previous embodiment, in this configuration, the scanning unit 104 does not redirect the reflected light in the incoming direction. Instead, the reflected light passes through the second optical window 124B and enters the sensor 116. Figure 2G The described configuration is considered a separate transmit and receive configuration because the optical paths of the projected and reflected light are substantially different from each other. In the context of the optical paths of the projected and reflected light, the term "substantially different" means that the overlap between the two optical paths can be less than 10%, less than 5%, less than 1%, or less than 0.25%.

[0080] Scanning unit

[0081] Figures 3A to 3D Various configurations of the scanning unit 104 and its role in the lidar system 100 are described. Specifically, Figure 3A This is a diagram illustrating a scanning unit 104 having a MEMS mirror (e.g., square in shape). Figure 3B This is a diagram illustrating another scanning unit 104 having a MEMS mirror (e.g., circular in shape). Figure 3C This is a diagram illustrating a scanning unit 104 having a reflector array for a combined transceiver scanning lidar system, and Figure 3D This is a diagram illustrating an example lidar system 100 mechanically scanning the environment surrounding the lidar system 100. Those skilled in the art will recognize that the configuration of the depicted scanning unit 104 is merely exemplary and many variations and modifications are possible within the scope of this disclosure.

[0082] Figure 3AAn example scanning unit 104 with a uniaxial square MEMS mirror 300 is illustrated. In this example, the MEMS mirror 300 serves as at least one deflector 114. As shown, the scanning unit 104 may include one or more actuators 302 (specifically, 302A and 302B). In one embodiment, the actuator 302 may be made of semiconductor (e.g., silicon) and includes a piezoelectric layer (e.g., PZT, lead zirconate titanate, aluminum nitride), a semiconductor layer, and a base layer that change their dimensions in response to an electrical signal applied by an actuator controller. In one embodiment, the physical properties of the actuator 302 can determine the mechanical stress experienced by the actuator 302 when current passes through it. When the piezoelectric material is activated, it applies a force to the actuator 302 and causes it to bend. In one embodiment, when the mirror 300 is deflected at an angular position, the resistivity (Ractive) of one or more actuators 302 can be measured in the activated state and compared with the resistivity (Rrest) in the dormant state. Feedback from Ractive can provide information to determine the actual mirror deflection angle compared to the expected angle, and the mirror deflection can be corrected by 300° if necessary. The difference between Rrest and Ractive can be correlated to the angular deflection value via mirror actuation, which can be used to close the loop. This embodiment can be used to dynamically track the actual mirror position and can optimize the response, amplitude, deflection efficiency, and frequency of linear and resonant mode MEMS mirror schemes. This embodiment is described in more detail below with reference to Figures 32 through 34.

[0083] During scanning, current (represented by dashed lines in the figure) can flow from contact 304A to contact 304B (through actuator 302A, spring 306A, mirror 300, spring 306B, and actuator 302B). Isolation gaps (such as isolation gap 310) in the semiconductor frame 308 allow actuators 302A and 302B to become two separate islands electrically connected by spring 306 and frame 308. Current flow or any associated electrical parameters (voltage, current frequency, capacitance, relative permittivity, etc.) can be monitored via relevant position feedback. In the event of a mechanical failure (where one component is damaged), the current flowing through the structure will change and alter its functional calibration value. In extreme cases (e.g., when a spring breaks), the current will stop completely by means of the faulty component due to a break in the electrical chain.

[0084] Figure 3BAnother example scanning unit 104 with a biaxial circular MEMS mirror 300 is illustrated. In this example, the MEMS mirror 300 serves as at least one deflector 114. In one embodiment, the MEMS mirror 300 may have a diameter between approximately 1 mm and approximately 5 mm. As shown, the scanning unit 104 may include four actuators 302 (302A, 302B, 302C, and 302D), each actuator may be at a different length. In the example shown, current (shown as dashed lines in the figure) flows from contact 304A to contact 304D, but in other cases, current may flow from contact 304A to contact 304B, from contact 304A to contact 304C, from contact 304B to contact 304C, from contact 304B to contact 304D, or from contact 304C to contact 304D. Consistent with some embodiments, a biaxial MEMS mirror can be configured to deflect light in both the horizontal and vertical directions. For example, the deflection angle of the biaxial MEMS mirror can be between approximately 0° and 30° in the vertical direction and between approximately 0° and 50° in the horizontal direction. Those skilled in the art will recognize that the configuration of the depicted mirror 300 can have many variations and modifications. In one example, at least the deflector 114 can have a biaxial square mirror or a single-axis circular mirror. The examples of circular and square mirrors are provided by way of example only. Figure 3A and Figure 3B As shown in the figure. Depending on system specifications, it can take any shape. In one embodiment, actuator 302 can be incorporated as part of at least deflector 114, such that the power to move MEMS mirror 300 is applied directly toward it. Furthermore, MEMS mirror 300 can be connected to frame 308 via one or more rigid support elements. In another embodiment, at least deflector 114 can comprise an electrostatic or electromagnetic MEMS mirror.

[0085] As described above, the transceiver combined scanning lidar system utilizes at least a portion of the same optical path for emitting projected light 204 and receiving reflected light 206. The beam in the outward propagation path can be collimated and focused into a narrow beam, while the reflection in the return path diffuses into a larger spot due to dispersion. In one embodiment, the scanning unit 104 may have a large reflective area in the return path and an asymmetric deflector 216 that redirects the reflection (i.e., reflected light 206) to the sensor 116. In one embodiment, the scanning unit 104 may include a MEMS mirror with a large reflective area and a negligible impact on field of view and frame rate performance. Reference is made below. Figure 2D Additional details are provided regarding the asymmetric deflector 216.

[0086] In some embodiments (e.g., such as) Figure 3CAs illustrated in the illustration, scanning unit 104 may include an array of deflectors (e.g., a reflector array) with small optical deflectors (e.g., mirrors). In one embodiment, implementing optical deflector 114 as a group of smaller individual optical deflectors operating synchronously can allow optical deflector 114 to perform at a high scan rate with a large deflection angle. The deflector array can essentially act as a large optical deflector (e.g., a large mirror) in terms of the effective area. This deflector array can be operated using a shared steering component configuration, which allows sensor 116 to collect reflected photons from substantially the same portion of the field of view 120 concurrently illuminated by light source 112. The term "concurrent" means that two selected functions occur during overlapping or concurrent time periods, whether one begins and ends within the duration of the other, or the latter begins before the other completes.

[0087] Figure 3C An example of a scanning unit 104 is illustrated, in which a reflector array 312 has small mirrors. In this embodiment, the reflector array 312 serves as at least one deflector 114. The reflector array 312 may include a plurality of reflector units 314 configured to pivot (individually or together) and guide light pulses toward a field of view 120. For example, the reflector array 312 may be part of the outward propagation path of light projected from a light source 112. Specifically, the reflector array 312 may guide projected light 204 toward a portion of the field of view 120. The reflector array 312 may also be part of the return path of light reflected from the surface of an object located within the illuminated portion of the field of view 120. Specifically, the reflector array 312 may guide reflected light 206 toward a sensor 116 or toward an asymmetric deflector 216. In one example, the area of ​​the reflector array 312 may be from approximately 75 to approximately 150 mm². 2 Between, each reflector unit 314 may have a width of approximately 10 μm and the support structure may be less than 100 μm.

[0088] According to some embodiments, the reflector array 312 may include one or more subgroups of steerable deflectors. Each subgroup of electrically steerable deflectors may include one or more deflector units (such as reflector unit 314). For example, each steerable deflector unit 314 may include at least one of a MEMS mirror, a reflective surface component, and an electromechanical actuator. In one embodiment, each reflector unit 314 may be individually controlled by an individual processor (not shown) such that it can tilt at a specific angle along each of one or two separate axes. Alternatively, the reflector array 312 may be associated with a common controller (e.g., processor 118) configured to synchronously manage the movement of the reflector units 314 such that at least a portion of them will pivot concurrently and point in substantially the same direction.

[0089] Furthermore, at least one processor 118 can select at least one reflector unit 314 (hereinafter referred to as "TX reflector") for the outward transmission path and a set of reflector units 314 (hereinafter referred to as "RX reflector") for the return path. Consistent with this disclosure, increasing the number of TX reflectors can increase the spread of the reflected photon beam. Furthermore, reducing the number of RX reflectors can narrow the receiving field and compensate for ambient light conditions (such as clouds, rain, fog, extreme heat, and other environmental conditions) and improve the signal-to-noise ratio. Moreover, as mentioned above, the emitted beam is typically narrower than the reflected light patch and can therefore be completely deflected by a small portion of the deflection array. Furthermore, it is possible to block light reflected from the transmitting portion of the deflection array (e.g., the TX reflector) from reaching the sensor 116, thereby reducing the impact of internal reflections of the lidar system 100 on system operation. Additionally, at least one processor 118 can pivot one or more reflector units 314 to overcome mechanical damage and drift caused by, for example, thermal and gain effects. In the example, one or more reflector units 314 may move differently than expected (frequency, rate, speed, etc.), and their movement can be compensated by appropriately electrically controlled deflectors.

[0090] Figure 3D An exemplary lidar system 100 is illustrated, showing the environment of a mechanically scanning lidar system 100. In this example, the lidar system 100 may include a motor or other mechanism for rotating a housing 200 about an axis of the lidar system 100. Alternatively, a motor (or other mechanism) may mechanically rotate a rigid structure of the lidar system 100 on which one or more light sources 112 and one or more sensors 116 are mounted, thereby scanning the environment. As described above, the projection unit 102 may include at least one light source 112 configured to project light emission. The projected light emission may travel along an outward path toward a field of view 120. Specifically, as the projected light 204 travels toward an optional optical window 124, the projected light emission may be reflected by a deflector 114A through an exit aperture 314. The reflected light emission may travel along a return path from an object 208 toward a sensing unit 106. For example, as the reflected light 206 travels toward the sensing unit 106, the reflected light 206 may be reflected by a deflector 114B. Those skilled in the art will recognize that a lidar system having a rotation mechanism for synchronously rotating one or more light sources or one or more sensors can use such synchronous rotation instead of turning the internal optical deflector (or as a supplement).

[0091] In embodiments where scanning of the field of view 120 is mechanical, the projected light emission can be directed to an exit aperture 314, which is part of a wall 316 separating the projection unit 102 from the rest of the lidar system 100. In some examples, the wall 316 can be formed of a transparent material (e.g., glass) coated with a reflective material to form a deflector 114B. In this example, the exit aperture 314 can correspond to an uncoated portion of the wall 316. Additionally or alternatively, the exit aperture 314 can include a hole or cutout in the wall 316. Reflected light 206 can be reflected by the deflector 114B and directed toward an entrance aperture 318 of the sensing unit 106. In some examples, the entrance aperture 318 can include a filter window configured to allow wavelengths within a certain wavelength range to enter the sensing unit 106 and attenuate other wavelengths. Reflections from an object 208 in the field of view 120 can be reflected by the deflector 114B and strike the sensor 116. By comparing several characteristics of the reflected light 206 with those of the projected light 204, at least one aspect of the object 208 can be determined. For example, by comparing the time it takes for the projected light 204 to be emitted by the light source 112 with the time it takes for the sensor 116 to receive the reflected light 206, the distance between the object 208 and the lidar system 100 can be determined. In some examples, other aspects of the object 208 (such as shape, color, material, etc.) can also be determined.

[0092] In some examples, the lidar system 100 (or a portion thereof, including at least one light source 112 and at least one sensor 116) can rotate about at least one axis to determine a three-dimensional map of the environment surrounding the lidar system 100. For example, the lidar system 100 can rotate about a substantially vertical axis (as illustrated by arrow 320) to scan the field of view 120. Although Figure 3D The illustration shows the lidar system 100 rotating clockwise about an axis (as illustrated by arrow 320), but additionally or alternatively, the lidar system 100 may rotate counterclockwise. In some examples, the lidar system 100 may rotate 360 ​​degrees about a vertical axis. In other examples, the lidar system 100 may rotate back and forth along a sector smaller than 360 degrees. For example, the lidar system 100 may be mounted on a platform that oscillates back and forth about an axis without performing a full rotation.

[0093] Sensing unit

[0094] Figures 4A to 4E Various configurations of the sensing unit 106 and its role in the lidar system 100 are described. Specifically, Figure 4A This is a diagram illustrating an example sensing unit 106 with a detector array. Figure 4BThis is a diagram illustrating a combined transceiver scanning method using a two-dimensional sensor. Figure 4C This is a diagram illustrating an example of a two-dimensional sensor 116. Figure 4D This is a diagram illustrating the lens array associated with sensor 116, and Figure 4E Three figures are included illustrating the lens structure. Those skilled in the art will recognize that the configuration of the depicted sensing unit 106 is merely exemplary and can have many alternative variations and modifications consistent with the principles of this disclosure.

[0095] Figure 4A An example of a sensing unit 106 with a detector array 400 is illustrated. In this example, at least one sensor 116 includes the detector array 400. The lidar system 100 is configured to detect objects (e.g., bicycle 208A and cloud 208) located at different distances (which may be several meters or more) from the lidar system 100 within a field of view 120. Objects 208 can be solid objects (e.g., roads, trees, cars, people), liquid objects (e.g., fog, water, atmospheric particles), or other types of objects (e.g., dust or powdery illuminated objects). When photons emitted from the light source 112 strike objects 208, they are either reflected, refracted, or absorbed. Typically, as shown, only a portion of the photons reflected from object 208 enters the optional optical window 124. Since each distance variation of approximately 15 cm results in a 1 ns time-of-flight difference (because photons travel at the speed of light towards and from object 208), the time difference between the travel times of different photons striking different objects can be detectable by using a time-of-flight sensor with a sufficiently fast response.

[0096] Sensor 116 includes multiple detection elements 402 for detecting photons from photon pulses reflected from field of view 120. All detection elements may be included in detector array 400, which may have a rectangular arrangement (e.g., as shown) or any other arrangement. Detection elements 402 may operate concurrently or partially concurrently with each other. Specifically, each detection element 402 may emit detection information for each sampling duration (e.g., every 1 nanosecond). In one example, detector array 400 may be a SiPM (silicon photomultiplier), a solid-state single-photon sensitive device constructed from an array of single-photon avalanche diodes (SPADs, used as detection elements 402) on a common silicon substrate. Similar photomultipliers from other non-silicon materials may also be used. Although SiPM devices operate in a digital / switching mode, SiPMs are analog devices because all microcells are read out in parallel, making it possible to generate signals ranging from single photons to tens of thousands of photons detected by different SPADs. As mentioned above, more than one type of sensor (e.g., SiPM and APD) can be implemented. It is possible that the sensing unit 106 may include at least one APD integrated into the SiPM array and / or at least one APD detector located next to the SiPM on a discrete or common silicon substrate.

[0097] In one embodiment, the detection element 402 may be grouped into multiple regions 404. These regions are geometric locations or environments within the sensor 116 (e.g., within the detector array 400) and may be shaped into different forms (e.g., rectangles, squares, rings, etc., as shown, or any other shape). While not all individual detectors included within the geometry of a region 404 necessarily belong to that region, in most cases they will not belong to other regions 404 covering other areas of the sensor 310, unless some overlap is expected at the seams between regions. Figure 4A As shown, the regions can be non-overlapping regions 404, but alternatively, they can overlap. Each region can be associated with a region output circuit 406 associated with that region. The region output circuit 406 can provide region output signals for the corresponding group of detection elements 402. For example, the region output circuit 406 can be a summing circuit, but it can also take other forms that combine the outputs of individual detectors into a unit output (whether scalar, vector, or any other format). Optionally, each region 404 is a single SiPM, but not necessarily, and the region can be a sub-section of a single SiPM, a group of several SiPMs, or even a combination of different types of detectors.

[0098] In the illustrated example, the processing unit 108 is located in a separate housing 200B of the host 210 (internal or external) within (e.g., within vehicle 110), and the sensing unit 106 may include a dedicated processor 408 for analyzing reflected light. Alternatively, the processing unit 108 may be used to analyze reflected light 206. It should be noted that the lidar system 100 may be implemented with multiple housings in ways other than those illustrated. For example, the light deflector 114 may be located in a different housing than the projection unit 102 and / or the sensing module 106. In one embodiment, the lidar system 100 may include multiple housings connected to each other in different ways, such as: wired connections, wireless connections (e.g., RF connections), fiber optic cables, and any combination thereof.

[0099] In one embodiment, analyzing the reflected light 206 may include determining the time of flight of the reflected light 206 based on the output of individual detectors in different regions. Optionally, the processor 408 may be configured to determine the time of flight of the reflected light 206 based on multiple regions of the output signal. In addition to the time of flight, the processing unit 108 may also analyze the reflected light 206 to determine the average power over the entire return pulse and may determine the photon distribution / signal (“pulse shape”) during the return pulse period. In the illustrated example, the output of any detection element 402 may not be sent directly to the processor 408, but may be combined (e.g., summed) with the signals from other detectors in region 404 before being passed to the processor 408. However, this is merely an example and the circuitry of sensor 116 may send information from detection element 402 to processor 408 via other routes (not via region output circuitry 406).

[0100] Figure 4B This diagram illustrates a lidar system 100 configured to scan its environment using a two-dimensional sensor 116. Figure 4B In the example, sensor 116 is a matrix of 4x6 detectors 410 (also referred to as “pixels”). In one embodiment, the pixel size can be approximately 1×1 mm. Sensor 116 is two-dimensional in that it has more than one set (e.g., rows, columns) of detectors 410 along two non-parallel axes (e.g., orthogonal axes, as illustrated in the example). The number of detectors 410 in sensor 116 can vary between different implementations, for example, depending on the desired resolution, signal-to-noise ratio (SNR), desired detection distance, etc. For example, sensor 116 can have any value between 5 and 5000 pixels. In another example (not shown in the figure), sensor 116 can also be a one-dimensional matrix (e.g., 1x8 pixels).

[0101] It should be noted that each detector 410 may include multiple detection elements 402 (such as avalanche photodiodes (APDs), single-photon avalanche diodes (SPADs), combinations of avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs)) or include detection elements that measure both the time of flight from a laser pulse transmission event to a reception event and the intensity of the received photons. For example, each detector 410 may include any value between 20 and 5000 SPADs. The outputs of the detection elements 402 in each detector 410 may be summed, averaged, or otherwise combined to provide uniform pixel output.

[0102] In the illustrated example, sensing unit 106 may include two-dimensional sensors 116 (or multiple two-dimensional sensors 116) with a field of view smaller than the field of view 120 of lidar system 100. In this discussion, field of view 120 (which may be the entire field of view scanned by lidar system 100 without any movement, rotation, or rolling in any direction) is referred to as “first FOV 412,” while the smaller FOV of sensor 116 is referred to as “second FOV 412” (interchangeably referred to as “instantaneous field of view”). Depending on the specific application of lidar system 100, the coverage of second FOV 414 relative to first FOV 412 may vary and may, for example, be between 0.5% and 50%. In one example, second FOV 412 may extend between approximately 0.05° and 1° in the vertical dimension. Even if the lidar system 100 includes more than one two-dimensional sensor 116, the combined field of view of the sensor array can still be smaller than the first FOV 412, for example, at least 5 times, at least 10 times, at least 20 times, or at least 50 times smaller.

[0103] To cover the first FOV 412, the scanning unit 106 can guide photons arriving from different parts of the environment to the sensor 116 at different times. In the illustrated transceiver configuration, the scanning unit 106 can also guide reflected light 206 to the sensor 116 along with guiding the projected light 204 toward the field of view 120 and when at least one light deflector 114 is in a momentary position. Typically, at each moment during the scanning of the first FOV 412, the beam emitted by the lidar system 100 covers a portion of the environment larger than the second FOV 414 (in the corner opening) and includes the portion of the environment from which light is collected by the scanning unit 104 and the sensor 116.

[0104] Figure 4CThis is a diagram illustrating an example of a two-dimensional sensor 116. In this embodiment, sensor 116 is a matrix of 8x5 detectors 410, and each detector 410 includes multiple detection elements 402. In one example, detector 410A is located in the second row (denoted as "R2") and third column (denoted as "C3") of sensor 116, and it includes a matrix of 4x3 detection elements 402. In another example, detector 410B, located in the fourth row (denoted as "R4") and sixth column (denoted as "C6") of sensor 116, includes a matrix of 3x3 detection elements 402. Thus, the number of detection elements 402 in each detector 410 can be constant or can be varied, and different detectors 410 in a common array can have different numbers of detection elements 402. The outputs of all detection elements 402 in each detector 410 can be summed, averaged, or otherwise combined to provide a single pixel output value. It should be noted that, although Figure 4C The detector 410 in the example is a rectangular matrix (rows and columns), but other arrangements, such as circular or cellular arrangements, can also be used.

[0105] According to some embodiments, measurements from each detector 410 can enable the determination of the time of flight from the light pulse emission event to the reception event and the intensity of the received photon. The reception event may be the result of the light pulse being reflected from object 208. The time of flight may be a timestamp value representing the distance from the reflecting object to an optional optical window 124. The time of flight value can be implemented using photon detection and counting methods (such as a time-correlated single-photon counter (TCSPC)), analog methods for photon detection (such as signal integration and identification (via an analog-to-digital converter or a plain comparator)), or other methods.

[0106] In some embodiments and referenced Figure 4BDuring a scan cycle, each instantaneous position of at least one optical deflector 114 can be associated with a specific portion 122 of the field of view 120. The sensor 116 is designed to allow correlation between reflected light from a single portion of the field of view 120 and multiple detectors 410. Therefore, the scan resolution of the lidar system can be represented by multiplying the number of instantaneous positions (per scan cycle) by the number of detectors 410 in the sensor 116. Information from each detector 410 (i.e., each pixel) represents the basic data elements from which the captured field of view in three-dimensional space is constructed. This can include, for example, basic elements of a point cloud representation with spatial location and associated reflection intensity values. In one embodiment, reflections from a single portion of the field of view 120 detected by multiple detectors 410 can be returned from different objects located within that single portion of the field of view 120. For example, a single portion of the field of view 120 can be larger than 50x50 cm in the far field, which can easily include two, three, or more objects that partially overlap each other.

[0107] Figure 4D This is a cross-sectional view of a portion of a sensor 116 according to an example of the currently disclosed subject matter. The shown portion of sensor 116 includes a portion of a detector array 400 comprising four detection elements 402 (e.g., four SPADs, four APDs). Detector array 400 may be a photodetector sensor implemented in complementary metal-oxide-semiconductor (CMOS). Each detection element 402 has a sensitive region located within the substrate environment. While not necessarily required, sensor 116 can be used in transceiver combined lidar systems with a narrow field of view (e.g., because scanning unit 104 scans different portions of the field of view at different times). A narrow field of view for the incident beam (if implemented) eliminates the problem of defocus imaging. Figure 4D As illustrated, sensor 116 may include multiple lenses 422 (e.g., microlenses), each lens 422 directing incident light toward a different detection element 402 (e.g., toward the active region of detection element 402), which is useful when defocusing is not an issue. Lenses 422 can be used to increase the optical fill factor and sensitivity of detector array 400 because most of the light reaching sensor 116 can be deflected toward the active region of detection element 402.

[0108] like Figure 4DAs illustrated, the detector array 400 may include several layers embedded in a silicon substrate by various methods (e.g., implantation) to create sensitive regions, contact elements with metal layers, and isolation elements (e.g., shallow trench implantation (STI), guard rings, optical trenches, etc.). The sensitive regions may be volumetric elements in a CMOS detector that enable the optical conversion of incident photons into current when a sufficient voltage bias is applied to the device. In the case of an APD / SPAD, the sensitive regions will be a combination of electric fields that pull electrons generated by photon absorption towards a multiplication region where photon-induced electrons are amplified, resulting in a breakdown avalanche of multiplied electrons.

[0109] The detector is illuminated on the front side (e.g., as shown in the image). Figure 4D The image shown has an input optical port on the same side as the metal layer residing on top of the semiconductor (silicon). The metal layer is needed to enable electrical connections between each individual photodetector element (e.g., anode and cathode) and various other elements (such as bias voltages, quench / ballast elements, and other photodetectors in the common array). The optical port through which photons illuminate the sensitive area of ​​the detector is formed by channels through the metal layer. It should be noted that light passing through this channel from some directions can be transmitted through one or more metal layers (e.g., metal layer ML6, as shown). Figure 4D The leftmost detector element 402 (shown in the image) is blocked. This blockage reduces the overall optical light absorption efficiency of the detector.

[0110] Figure 4E The illustration shows three detection elements 402 according to an example of the currently disclosed subject matter, each detection element having an associated lens 422. Figure 4E The diagram illustrates a lens configuration that can be implemented in association with one or more of the detection elements 402 of sensor 116, represented as 402(1), 402(2), and 402(3). It should be noted that combinations of these lens configurations can also be implemented.

[0111] In the lens configuration shown with respect to detection element 402(1), the focal point of the associated lens 422 can be located above the semiconductor surface. Alternatively, the openings in different metal layers of the detection element can have different sizes aligned with the focusing cone generated by the associated lens 422. Such a structure can improve the signal-to-noise ratio and resolution of the array 400 as a whole device. Large metal layers can be important for power delivery and grounding shielding. This approach can be useful, for example, for transceiver lidar designs with narrow field of view, where the incident beam consists of parallel rays and the imaging focus has no effect on the detected signal.

[0112] In the lens configuration shown with respect to detection element 402(2), the photon detection efficiency of detection element 402 can be improved by identifying the sweet spot. Specifically, the photodetector implemented in CMOS can have the sweet spot in the sensitive volume region where the probability of photons generating an avalanche effect is highest. Therefore, the focal point of lens 422 can be located at the sweet spot location within the sensitive volume region, as demonstrated by detection element 402(2). The lens shape and distance from the focal point can take into account the refractive index of all elements along the path of the laser beam from the lens to the sweet spot location embedded in the semiconductor material.

[0113] In relation to Figure 4E The lens configuration shown for the detection element on the right can utilize diffusers and reflective elements to improve photon absorption efficiency in the semiconductor material. Specifically, near-IR wavelengths require significantly longer silicon material paths to achieve a high probability of absorption of photons that have traveled through them. In a typical lens configuration, photons can pass through the sensitive region and may not be absorbed into detectable electrons. For CMOS devices fabricated using typical casting processes, the long absorption path, which increases the probability of photons generating electrons, causes the size of the sensitive region to vary towards impractical dimensions (e.g., tens of μm). Figure 4E The rightmost detector element demonstrates a technique for processing incident photons. An associated lens 422 focuses the incident light onto a diffuser element 424. In one embodiment, the light sensor 116 may also include a diffuser located in a gap away from the outer surface of at least some of the detectors. For example, the diffuser 424 may steer the beam laterally (e.g., as vertically as possible) toward the sensitive region and the reflective optical groove 426. The diffuser is located at, above, or below the focal point. In this embodiment, the incident light may be focused at the specific location of the diffuser element. Optionally, the detector element 422 is designed to optically avoid inactive regions where photon-induced electrons might be lost and reduce effective detection efficiency. The reflective optical groove 426 (or other form of optical reflection structure) causes photons to bounce back and forth on the sensitive region, thereby increasing the likelihood of detection. Ideally, photons will be trapped indefinitely in the cavity formed by the sensitive region and the reflective groove until the photons are absorbed and generate electron / hole pairs.

[0114] Consistent with this disclosure, a long path is created to allow the irradiated photons to be absorbed and contribute to a higher detection probability. Optical trenches can also be implemented in detection element 422 to reduce crosstalk effects from parasitic photons generated during avalanche events, which could leak to other detectors and cause false detection events. According to some embodiments, the photodetector array can be optimized to utilize a higher received signal yield, meaning that the same amount of received signal is received and less signal is lost due to internal degradation. The photodetector array can be improved by: (a) moving the focus to a location above the semiconductor surface, optionally by appropriately designing a metal layer above the substrate; (b) directing the focus to the most responsive / sensitive region (or “optimal point”) of the substrate; and (c) adding a diffuser above the substrate to redirect the signal toward the “optimal point”, and / or adding a reflective material to the trench so that the deflected signal is reflected back to the “optimal point”.

[0115] While in some lens configurations, lens 422 may be positioned such that its focal point is above the center of the corresponding detection element 402, it should be noted that this is not always the case. In other lens configurations, the focal point of lens 422 is shifted relative to the center of the corresponding detection element 402 based on the distance of the corresponding detection element 402 from the center of the detection array 400. This can be useful in relatively large detection arrays 400, where detector elements further away from the center receive light at increasingly off-axis angles. Shifting the position of the focal point (e.g., toward the center of the detection array 400) allows for correction of the angle of incidence. Specifically, shifting the position of the focal point (e.g., toward the center of the detection array 400) allows for correction of the angle of incidence while using substantially the same lens 422 for all detection elements, which are positioned at the same angle relative to the surface of the detector.

[0116] When using a relatively small sensor 116 that covers only a small portion of the field of view, adding an array of lenses 422 to the array of detection elements 402 is useful because, in this case, reflected signals from the scene arrive at the detector array 400 from substantially the same angle, thus making it easy to focus all the light onto individual detectors. It should also be noted that, in one embodiment, lenses 422 can be used in a lidar system 100 to facilitate an increase in the overall detection probability of the entire array 400 (preventing photons from being “wasted” in dead zones between detectors / sub-detectors), at the expense of spatial uniqueness. This embodiment contrasts with prior art embodiments such as CMOS RGB cameras, which prioritize spatial uniqueness (i.e., light propagating in the direction of detection element A is not allowed to be directed by a lens toward detection element B, i.e., “escaping” to another detection element in the array). Optionally, sensor 116 includes an array of lenses 422, each lens associated with a corresponding detection element 402, and at least one of the lenses 422 deflects light propagating to the first detection element 402 toward the second detection element 402 (thereby increasing the overall detection probability of the entire array).

[0117] Specifically, consistent with some embodiments of this disclosure, the light sensor 116 may include an array of photodetectors (e.g., detector array 400), each photodetector (e.g., detector 410) configured to allow current to flow when light passes through the outer surface of the respective detector. Furthermore, the light sensor 116 may include at least one microlens configured to direct light toward the photodetector array, the at least one microlens having a focal point. The light sensor 116 may also include at least one layer of conductive material inserted between the at least one microlens and the photodetector array and having a gap therein to allow light to pass from the at least one microlens to the array, the dimensions of this at least one layer being designed to maintain space between the at least one microlens and the array such that the focal point (e.g., the focal point may be planar) is located in the gap at a position spaced apart from the detection surface of the photodetector array.

[0118] In related embodiments, each detector may include multiple single-photon avalanche diodes (SPADs) or multiple avalanche photodiodes (APDs). The conductive material may be a multilayered metal constriction, and at least one conductive material layer may be electrically connected to the detectors in the array. In one example, at least one conductive material layer comprises multiple layers. Furthermore, the gaps may be shaped to converge from at least one microlens toward a focal point and diverge from the region of the focal point toward the array. In other embodiments, the light sensor 116 may also include at least one reflector adjacent to each photodetector. In one embodiment, multiple microlenses may be arranged in a lens array, and multiple detectors may be arranged in a detector array. In another embodiment, the multiple microlenses may include a single lens configured to project light onto the multiple detectors in the array.

[0119] References through non-restrictive examples Figure 2E , Figure 2F and Figure 2G It is important to note that one or more sensors 116 of system 100 can receive light from the scanning deflector 114, or light directly from the FOV in the absence of scanning. Even if light from the entire FOV arrives at at least one sensor 116 simultaneously, in some implementations, one or more sensors 116 can sample only a portion of the FOV at any given time for output detection. For example, if the illumination of projection unit 102 illuminates different portions of the FOV at different times (whether using deflector 114 and / or by activating different light sources 112 at different times), light can reach all pixels or sensors 116 of sensing unit 106, and only the pixel / sensor intended to detect LiDAR illumination can actively collect data for output detection. In this way, the remaining pixels / sensors do not unnecessarily collect ambient noise. Regarding scanning—in the outward or inward direction—note that substantially different scanning scales can be implemented. For example, in some implementations, the scan area can cover 1‰ or 0.1‰ of the FOV, while in other implementations, the scan area can cover 10% or 25% of the FOV. Of course, all other relative portions of the FOV value can also be implemented.

[0120] Processing unit

[0121] Figures 5A to 5C Different functions of the processing unit 108 according to some embodiments of this disclosure are described. Specifically, Figure 5A This is a diagram illustrating the emission patterns within a single frame time for a single portion of the field of view. Figure 5B This is a diagram illustrating the emission patterns over a single frame time span across the entire field of view. Figure 5C This is a diagram illustrating the actual light emission projected into the field of view during a single scan cycle.

[0122] Figure 5A Four examples of emission modes for a single portion 122 of a field of view 120 associated with the instantaneous position of at least one optical deflector 114 within a single frame time are illustrated. Consistent with embodiments of this disclosure, processing unit 108 can control at least one light source 112 and optical deflector 114 (or coordinate the operation of at least one light source 112 and at least one optical deflector 114) in a manner that allows the luminous flux to vary as the field of view 120 is scanned. Consistent with other embodiments, processing unit 108 can control only at least one light source 112, and optical deflector 114 can move or pivot in a fixed, predefined pattern.

[0123] Figure 5A Figure A and D depict the power of light emitted toward a single portion 122 of the field of view 120 over time. In Figure A, the processor 118 can control the operation of the light source 112 in such a way that the initial light emission during scanning of the field of view 120 is projected toward portion 122 of the field of view 120. When the projection unit 102 includes a pulsed light source, the initial light emission may include one or more initial pulses (also referred to as “pilot pulses”). The processing unit 108 may receive pilot information from the sensor 116 regarding reflections associated with the initial light emission. In one embodiment, the pilot information may be represented as a single signal based on the output of one or more detectors (e.g., one or more SPADs, one or more APDs, one or more SiPMs, etc.), or as multiple signals based on the output of multiple detectors. In one example, the pilot information may include analog and / or digital information. In another example, the pilot information may include a single value and / or multiple values ​​(e.g., for different times and / or portions of a segment).

[0124] Based on information about the reflections associated with the initial light emission, the processing unit 108 can be configured to determine the type of subsequent light emission to be projected toward a portion 122 of the field of view 120. The subsequent light emission determined for a specific portion of the field of view 120 can be performed during the same scan cycle (i.e., in the same frame) or in a subsequent scan cycle (i.e., in a subsequent frame).

[0125] In Figure B, processor 118 can control the operation of light source 112 in such a way that light pulses of varying intensities are projected toward a single portion 122 of field of view 120 during scanning of field of view 120. In one embodiment, lidar system 100 can be operable to generate one or more different types of depth maps, such as any one or more of the following types: point cloud models, polygonal meshes, depth images (preserving depth information for each pixel of an image or 2D array), or any other type of 3D model of a scene. The sequence of depth maps can be a time series, in which different depth maps are generated at different times. Each depth map in the sequence associated with a scan cycle (interchangeably referred to as a "frame") can be generated over the duration of a corresponding subsequent frame time. In one example, a typical frame time can last less than one second. In some embodiments, lidar system 100 can have a fixed frame rate (e.g., 10 frames per second, 25 frames per second, 50 frames per second), or the frame rate can be dynamic. In other embodiments, the frame times of different frames can be different across the sequence. For example, the lidar system 100 can achieve a rate of 10 frames per second, which includes generating a first depth map in 100 milliseconds (average), generating a second frame in 92 milliseconds, and generating a third frame in 142 milliseconds, and so on.

[0126] In Figure C, processor 118 can control the operation of light source 112 in such a way that light pulses associated with different durations are projected toward a single portion 122 of field of view 120 during scanning of field of view 120. In one embodiment, lidar system 100 can be operable to generate a different number of pulses in each frame. The number of pulses can vary between 0 and 32 pulses (e.g., 1, 5, 12, 28 or more pulses) and can be based on information derived from previous emissions. The time between light pulses can depend on the desired detection range and can be between 500 ns and 5000 ns. In one example, processing unit 108 can receive information from sensor 116 about the reflections associated with each light pulse. Based on this information (or the absence of this information), processing unit 108 can determine whether additional light pulses are needed. Note that the processing time and emission time in Figures AD are not proportional to the duration. Specifically, the processing time can be substantially longer than the emission time. In Figure D, projection unit 102 can include a continuous wave light source. In one embodiment, the initial light emission may include a time period of emitted light, and subsequent emission may be a continuation of the initial emission, or there may be discontinuities. In one embodiment, the intensity of continuous emission may change over time.

[0127] Consistent with some embodiments of this disclosure, the emission mode can be determined for each portion of the field of view 120. In other words, the processor 118 can control the emission of light to allow for differentiation of illumination for different portions of the field of view 120. In one example, the processor 118 can determine the emission mode of a single portion 122 of the field of view 120 based on the detection of reflected light from the same scan cycle (e.g., the initial emission), making the lidar system 100 highly dynamic. In another example, the processor 118 can determine the emission mode of a single portion 122 of the field of view 120 based on the detection of reflected light from a previous scan cycle. Differences in the modes of subsequent emissions can arise due to determining different values ​​for the light source parameters used for subsequent emissions, such as any of the following:

[0128] a. Total energy of subsequent launches.

[0129] b. Energy profile of subsequent launches.

[0130] c. The number of light pulse repetitions per frame.

[0131] d. Optical modulation characteristics, such as duration, rate, peak value, average power, and pulse shape.

[0132] e. The wave characteristics of subsequent emissions, such as polarization, wavelength, etc.

[0133] Consistent with this disclosure, the distinction between subsequent transmissions can be used for different purposes. In one example, the transmission power level can be limited in a portion of the field of view 120 where safety is a consideration, while a higher power level can be transmitted for other portions of the field of view 120 (thus improving the signal-to-noise ratio and detection range). This relates to eye safety, but may also relate to skin safety, the safety of the optical system, the safety of sensitive materials, and so on. In another example, based on detection results from the same frame or the previous frame, more energy can be directed toward portions of the field of view 120 where the energy will be more useful (e.g., regions of interest, targets at greater distances, low-reflectivity targets, etc.), while limiting illumination energy to other portions of the field of view 120. It should be noted that the processing unit 108 can process detection signals from a single instantaneous field of view multiple times within a single scan frame; for example, subsequent transmissions can be determined after each pulse transmission or after multiple pulse transmissions.

[0134] Figure 5BThree examples of emission schemes for a single frame time of field of view 120 are illustrated. Consistent with embodiments of this disclosure, the acquired information can be used, at least on processing unit 108, to dynamically adjust the operating mode of lidar system 100 and / or determine parameter values ​​for specific components of lidar system 100. The acquired information can be determined by processing data captured in field of view 120 or received from host 210 (directly or indirectly). Processing unit 108 can use the acquired information to determine a scanning scheme for scanning different portions of field of view 120. The acquired information may include current light conditions, current weather conditions, the current driving environment of the host vehicle, the current position of the host vehicle, the current trajectory of the host vehicle, the current terrain of the road surrounding the host vehicle, or any other conditions or objects detectable by light reflection. In some embodiments, the determined scanning scheme may include at least one of the following: (a) designating a portion of the field of view 120 as to be actively scanned as part of a scanning cycle; (b) a projection plan of projection unit 102 that defines the light emission profile at different portions of the field of view 120; (c) a deflection plan of scanning unit 104 that defines, for example, deflection direction, frequency, and designation of idle elements within the reflector array; and (d) a detection plan of sensing unit 106 that defines a detector sensitivity or responsivity mode.

[0135] Furthermore, the processing unit 108 may determine a scanning scheme at least in part by obtaining the identifiers of at least one region of interest and at least one region of non-interest within the field of view 120. In some embodiments, the processing unit 108 may determine a scanning scheme at least in part by obtaining the identifiers of at least one region of high interest and at least one region of low interest within the field of view 120. For example, the identifier of at least one region of interest within the field of view 120 may be determined as follows: for example, by processing data captured in the field of view 120, based on data from another sensor (e.g., camera, GPS), received (directly or indirectly) from the host 210, or any combination thereof. In some embodiments, the identifier of at least one region of interest may include: an identifier of a portion, area, sector, pixel, or object within the field of view that is important for monitoring. Examples of areas that can be identified as regions of interest may include pedestrian crossings, moving objects, people, nearby vehicles, or any other environmental conditions or objects that may aid in vehicle navigation. Examples of areas that can be identified as regions of non-interest (or low interest) may be static (non-moving) distant buildings, skylines, horizons, and areas above objects in the field of view. Once the identification of at least one region of interest within the field of view 120 is obtained, the processing unit 108 can determine a scanning scheme or modify an existing scanning scheme. To further determine or modify the light source parameters (as described above), the processing unit 108 can allocate detector resources based on the identification of at least one region of interest. In one example, to reduce noise, the processing unit 108 can activate detector 410 located in areas expected to be regions of interest and disable detector 410 located in areas expected to be uninterested. In another example, the processing unit 108 can change the detector sensitivity, for example, increasing the sensor sensitivity for long-range detection with low reflective power.

[0136] Figure 5BFigures A and C depict examples of different scanning schemes for scanning the field of view 120. Each square in the field of view 120 represents a different portion 122 associated with the instantaneous position of at least one light deflector 114. Figure 500 details the levels of luminous flux represented by the filling pattern of the squares. Figure A depicts a first scanning scheme in which all portions have the same importance / priority and are assigned a default luminous flux. The first scanning scheme can be used during the startup phase or periodically interleaved with another scanning scheme to monitor for unexpected / new objects throughout the field of view. In one example, the light source parameters in the first scanning scheme can be configured to generate light pulses with a constant amplitude. Figure B depicts a second scanning scheme in which a portion of the field of view 120 is assigned a high luminous flux, while the remainder of the field of view 120 is assigned a default luminous flux and a low luminous flux. The least interesting portion of the field of view 120 can be assigned a low luminous flux. Figure C depicts a third scanning scheme in which compact vehicles and buses (see outline view) are identified in the field of view 120. In this scanning scheme, the edges of vehicles and buses can be tracked at high power, while the center mass of the vehicles and buses can be allocated less optical flux (or no optical flux). This optical flux allocation allows for a greater concentration of the optical budget on the edges of the identified objects and a smaller concentration on their less important centers.

[0137] Figure 5C The illustration depicts light emission toward a field of view 120 during a single scan cycle. In the depicted example, the field of view 120 is represented by an 8x9 matrix, where each of the 72 cells corresponds to a separate portion 122 associated with a different instantaneous position of at least one light deflector 114. In this exemplary scan cycle, each portion includes one or more white dots representing the number of light pulses projected toward that portion, and some portions include black dots representing reflected light from that portion detected by sensor 116. As shown, the field of view 120 is divided into three regions: region I on the right side of the field of view 120, region II in the middle of the field of view 120, and region III on the left side of the field of view 120. In this exemplary scan cycle, region I is initially assigned a single light pulse for each portion; region II, previously identified as a region of interest, is initially assigned three light pulses for each portion; and region III is initially assigned two light pulses for each portion. Moreover, as shown in the figure, the scanning field of view 120 reveals four objects 208: two free-form objects in the near field (e.g., between 5 and 50 meters), a rounded square object in the mid-field (e.g., between 50 and 150 meters), and a triangular object in the far field (e.g., between 150 and 500 meters). Although Figure 5CThe discussion uses the number of pulses as an example of luminous flux allocation, but it should be noted that luminous flux allocation to different parts of the field of view can also be achieved in other ways, such as: pulse duration, pulse radii, wavelength, instantaneous power, photon density at different distances from the light source, average power, pulse power intensity, pulse width, pulse repetition rate, pulse sequence, pulse duty cycle, wavelength, phase, polarization, etc. Figure 5C The illustration of light emission as a single scan cycle demonstrates the different capabilities of the lidar system 100. In a first embodiment, the processor 118 is configured to use two light pulses to detect a first object (e.g., a rounded square object) at a first distance and three light pulses to detect a second object (e.g., a triangular object) at a second distance greater than the first distance. In a second embodiment, the processor 118 is configured to allocate more light to the portion of the field of view that identifies the region of interest. Specifically, in this example, region II is identified as the region of interest, and therefore it is allocated three light pulses, while the remainder of the field of view 120 is allocated two or fewer light pulses. In a third embodiment, the processor 118 is configured to control the light source 112 in such a way that only light is directed towards the region of interest. Figure 5C Sections B1, B2, and C1 project a single light pulse, even though they are part of region III, which was initially allocated two light pulses per section. This is because processing unit 108 detects an object in the near field based on the first light pulse. Allocations of less than the maximum pulse amount could also be the result of other considerations. For example, in at least some regions, detection of an object (e.g., a near-field object) at a first distance could result in a reduction in the total amount of light emitted into this section of the field of view 120.

[0138] Further details and examples of the different components of the lidar system 100 and their associated functions are included in U.S. Patent Application No. 15 / 391,916, filed December 28, 2016; U.S. Patent Application No. 15 / 393,749, filed December 29, 2016; U.S. Patent Application No. 15 / 393,285, filed December 29, 2016; and U.S. Patent Application No. 15 / 393,593, filed December 29, 2016, all of which are incorporated herein by reference in their entirety.

[0139] Example implementation: Vehicle

[0140] Figures 6A to 6CThe illustration shows an implementation of a lidar system 100 in a vehicle (e.g., vehicle 110). Any aspect of the lidar system 100 described above or below can be incorporated into vehicle 110 to provide range sensing of the vehicle. Specifically, in this example, the lidar system 100 integrates multiple scanning units 104 and potentially multiple projection units 102 within a single vehicle. In one embodiment, a vehicle can utilize such a lidar system to improve power, range, and accuracy in and outside the overlap area, as well as redundancy in sensitive portions of the field of view (FOV), such as the vehicle's forward direction of movement. Figure 6A As shown, vehicle 110 may include a first processor 118A for controlling the scanning of field of view 120A, a second processor 118 for controlling the scanning of field of view 120B, and a third processor 118C for controlling the synchronization of scanning the two fields of view. In one example, processor 118C may be a vehicle controller and may have a shared interface between the first processor 118A and the second processor 118. The shared interface enables the exchange of data at an intermediate processing level and enables the scanning of the combined fields of view to be synchronized to form an overlap in time and / or space. In one embodiment, the data exchanged using the shared interface may be: (a) the time of flight of received signals associated with pixels in and / or near the overlapping fields of view; (b) the laser steering position state; and (c) the detection state of objects in the fields of view.

[0141] Figure 6B The diagram illustrates an overlapping region 600 between fields of view 120A and 120B. In the depicted example, the overlapping region is associated with 24 portions 122 from field of view 120A and 24 portions 122 from field of view 120B. Assuming the overlapping region is defined and known by processors 118A and 118, each processor can be designed to limit the amount of light emitted in the overlapping region 600 to comply with eye safety limits across multiple light sources, or for other reasons (such as maintaining an optical budget). Furthermore, processors 118A and 118 can avoid interference between light emitted from the two light sources through loose synchronization between scanning units 104A and 104B and / or by controlling laser transmission timing and / or enabling timing through detection circuitry.

[0142] Figure 6CThe illustration shows how the overlapping region 600 between fields of view 120A and 120B can be used to increase the detection range of vehicle 110. Consistent with this disclosure, two or more light sources 112 that project their nominal light emission into the overlapping region can be fully utilized to increase the effective detection range. The term "detection range" can include an approximate distance from vehicle 110 at which the lidar system 100 can clearly detect an object. In one embodiment, the maximum detection range of the lidar system 100 is approximately 300 meters, approximately 400 meters, or approximately 500 meters. For example, for a detection range of 200 meters, the lidar system 100 can detect objects 200 meters (or less) from vehicle 110 more than 95%, more than 99%, or more than 99.5% of the times, even if the reflectivity of the object is less than 50% (e.g., less than 20%, less than 10%, or less than 5%). Furthermore, the lidar system 100 can have a false alarm rate of less than 1%. In one embodiment, the SNR can be improved by utilizing light projected from two light sources juxtaposed in time and space, thereby increasing the service range and / or quality of objects located in the overlapping region. Processor 118C can extract high-level information from reflected light in fields of view 120A and 120B. The term "extract information" can include any processing that identifies information associated with objects, individuals, locations, events, etc., in captured image data by any means known to those skilled in the art. Furthermore, processors 118A and 118 can share high-level information, such as objects (road dividers, background, pedestrians, vehicles, etc.) and motion vectors, enabling each processor to alert it to an upcoming region of interest. For example, it can be determined that a moving object in field of view 120A will soon enter field of view 120B.

[0143] Example Implementation: Monitoring System

[0144] Figure 6D The illustration shows an implementation of the lidar system 100 in a surveillance system. As mentioned above, the lidar system 100 can be fixed to a stationary object 650, which may include a motor or other mechanism for rotating the housing of the lidar system 100 to obtain a wider field of view. Alternatively, the surveillance system may include multiple lidar units. Figure 6D In the illustrated example, the surveillance system may use a single rotatable lidar system 100 to acquire 3D data representing a field of view 120 and process the 3D data to detect people 652, vehicles 654, changes in the environment, or any other form of security-critical data.

[0145] Consistent with some embodiments of this disclosure, 3D data can be analyzed to monitor retail business processes. In one embodiment, 3D data can be used in retail business processes involving physical security (e.g., detecting intrusions within a retail facility, deliberate vandalism within or around a retail facility, unauthorized approach to secure areas, and suspicious behavior around cars in a parking lot). In another embodiment, 3D data can be used for public safety (e.g., detecting people slipping and falling on store property, spills or blockages of hazardous liquids on store floors, attacks or kidnappings in store parking lots, obstruction of fire exits, and crowding in or outside store areas). In yet another embodiment, 3D data can be used for business intelligence data collection (e.g., tracking people passing through a store area to determine, for example, how many people pass through, where they stay, how long they stay, and how their shopping habits compare to their purchasing habits).

[0146] Consistent with other embodiments of this disclosure, 3D data can be analyzed and used for traffic enforcement. Specifically, 3D data can be used to identify vehicles exceeding legal speed limits or other road safety requirements. In one example, the lidar system 100 can be used to detect vehicles crossing the stop line or designated stopping position when a red traffic light is displayed. In another example, the lidar system 100 can be used to identify vehicles traveling in lanes reserved for public transportation. In yet another example, the lidar system 100 can be used to identify vehicles turning at intersections where turning is prohibited at red lights.

[0147] Detection based on photodiode

[0148] In some electro-optical systems (e.g., lidar systems, flash cameras, barcode scanners), light may be emitted before sensing its impact on the system's environment, and the reflected light can reach the system's sensor at a high intensity. For example, within a short period after light emission, the sensor may receive a large amount of internal reflections of light within the system (e.g., reflections from the system's optics) and / or reflections from one or more objects in the system's immediate environment. This intense reflection can saturate the sensor, potentially impairing the system's ability to accurately detect reflections until the sensor recovers from saturation. For instance, some photodiode-based sensors, such as silicon photomultiplier tubes (SiPMs), may include one or more single-photon avalanche diodes (SPADs) and may spend a non-negligible amount of time resetting to their nominal sensitivity after light detection (or following other types of triggering, e.g., due to electrical conditions applied to such photodiode sensors). By way of example only, SPAD-based sensors may have a recovery period for quenching the sensor and restoring it to its operating level before it is ready to detect additional photons. Methods and systems may need to be designed to reset the recovery period of a photodiode-based sensor at an appropriate time (and reduce its sensitivity) so that the sensor may be in or not in recovery mode when a photon strikes it.

[0149] This disclosure provides methods and systems for adjusting the sensitivity of at least one photodiode. In one embodiment, the electro-optic system may include at least one photodiode for detecting reflections of light pulses from a field of view. The electro-optic system may also include a sensitivity damper configured to temporarily reduce the sensitivity of at least one photodiode. The electro-optic system may also include a controller configured to trigger the sensitivity damper to reduce the sensitivity of at least one photodiode to below a nominal sensitivity threshold. For example, sensitivity reduction can be used to prevent blinding saturation and / or blinding of the sensor (which may be caused by internal reflections in the system, reflections from objects in the immediate environment of the system, and / or highly reflective objects in the field of view).

[0150] Figure 7 This is a diagram illustrating an exemplary lidar system 700 consistent with the disclosed embodiments. Figure 7 As shown, the lidar system 700 may include a light emitting component 702, a detection module 710, and a processing unit 714.

[0151] The light emitting component 702 can be configured to emit light into the field of view of the lidar system 700 based on instructions received from the processing unit 714. The light emitting component 702 may include a light source 704 and optics 708. The light source 704 can be configured to emit light. The processing unit 714 can be programmed to cause the light emitting component to scan the field of view multiple times during a frame, within which a point cloud can be constructed based on reflections received from the scans during that frame (via, for example, the lidar system 700). In some embodiments, the processing unit 714 can be programmed to cause the light emitting component to scan the field of view more than 2, 3, 5, 10, 20, 50, 100, 200, more than 1,000 times, or any intermediate number of times during a frame.

[0152] In some embodiments, light source 704 may include one or more light sources of one or more types described elsewhere in this disclosure (e.g., lasers, LEDs, vertical-cavity surface-emitting lasers (VCSELs), pixel arrays, etc.). In some embodiments, light source 704 may include two or more light sources configured to emit light. For example, light source 704 may include a first light source and a second light source. The first light source may be configured to emit a first light emission, and the second light source may be configured to emit a second light emission. The first light emission may differ from the second light emission. For example, the first light emission may have a wavelength, intensity, power level, etc., or combinations thereof, different from the second light emission.

[0153] In some embodiments, the lidar system 700 (or light emitting assembly 702) may include a light deflector (not shown) configured to deflect light from at least one light source into the field of view. The light deflector may include a microelectromechanical system (MEMS) mirror, a rotating prism, an optical phased array controller, a vertical-cavity surface-emitting laser (VCSEL) array controller, a scanning mirror, or a combination thereof.

[0154] In some embodiments, the light emitting component 702 may include a spatial light modulator (not shown) configured to modulate the luminous flux to vary across a scan of the field of view. For example, the spatial light modulator may be configured to block (and / or suppress) light emission from one or more light sources. The spatial light modulator may include one or more spatial filters that selectively filter (and / or block) light emission (or a portion thereof) emitted from light source 704. Optics 708 may be configured to direct light emission from the spatial light modulator into the field of view. For example, the spatial light modulator may allow light emission from light source 704 to be delivered into the field of view of the lidar system 700. In some embodiments, the spatial light modulator may modulate light emission from light source 704 in a non-binary manner. For example, the spatial light modulator may suppress a portion of the light emission (e.g., the intensity of the light emission is reduced by the spatial light modulator), and the suppressed light emission may be emitted into the corresponding portion of the field of view.

[0155] Processing unit 714 can be programmed to control one or more components of lidar system 700. For example, processing unit 714 can be configured to control light emitting assembly 702 to emit light into the field of view (or one or more segments thereof) of lidar system 700. In some embodiments, processing unit 714 may include processor 716 configured to perform the functions of processing unit 714 described herein. Processor 716 may be similar to processor 118 described elsewhere in this disclosure. For example, processor 716 can be programmed to control at least one light source to emit one or more light pulses into the field of view. As another example, processor 716 may be operable to determine whether an object is located in the field of view of lidar system based on reflected signals of light received from the environment of lidar system by at least one sensor.

[0156] In some embodiments, the lidar system 700 may include a fast-scanning mirror (e.g., a 1D scanning mirror or a 2D scanning mirror). The processing unit 714 controls the scanning mirror such that it can scan the entire field of view (FOV) served by the mirror multiple times per frame (e.g., more than 5 times, more than 10 times, more than 20 times, more than 50 times, more than 200 times, more than 1,000 times, or any intermediate number, etc.). Optionally, the processing unit 714 may control the synchronization between the fast-scanning mirror and at least one light source, such that in each scan of the FOV by the mirror, only a small portion of the FOV being served can be illuminated and scanned in each scan cycle within that frame.

[0157] The detection module 710 may include at least one sensor (not shown), which may include one or more photodiodes configured to detect reflections from the field of view of the lidar system 700. The sensor may include any device, element, or system capable of measuring characteristics of electromagnetic waves (e.g., power, frequency, phase, pulse timing, pulse duration) and generating an output related to the measured characteristics. In some embodiments, the sensor may include multiple detectors consisting of multiple detection elements. The sensor may include one or more types of optical sensors. For example, at least one sensor may include multiple sensors of the same type, which may differ in other characteristics (e.g., sensitivity, size, etc.). Other types of sensors may also be used. Combinations of several types of sensors may be used for various reasons, such as to improve detection over a range span (especially in the near range); to improve the dynamic range of the sensor; to improve the time response of the sensor; and to improve detection under changing environmental conditions (e.g., atmospheric temperature, rain, etc.). In one embodiment, at least one sensor may include a SiPM (Silicon Photomultiplier), a solid-state single-photon sensitive device constructed from an array of avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs), used as a detection element on a common silicon substrate. In one example, the typical distance between SPADs can be between approximately 7 μm and approximately 50 μm, and each SPAD can have a recovery time between approximately 5 ns and approximately 100 ns. Similar photomultipliers from other non-silicon materials can also be used. Although SiPM devices can operate in a digital / switching mode, SiPMs are analog devices because the microcells can be read in parallel, enabling them to generate signals ranging from single photons to tens of thousands of photons detected by different SPADs within a dynamic range. Outputs from different types of sensors (e.g., SPADs, APDs, SiPMs, PIN diodes, photodetectors) can be combined to form a single output that can be processed by a processor in a lidar system. Reference Figures 4A to 4C Additional details regarding the sensor are described. Optionally, the lidar system 700 may include scanning units for directing flash illumination to different portions of the field of view at different times. In this case, spatial light modulation determination may be performed for each portion of the field of view (e.g., if eye safety is a concern), but not necessarily (e.g., if sensor pixel failure is a concern). In some embodiments, the sensor may include a detector array, which may include a focal plane detector array. In some embodiments, the detection module 710 may be a silicon photomultiplier tube (SiPM).

[0158] In some embodiments, the detection module 710 may further include a sensitivity damper (not shown) configured to temporarily reduce the sensitivity of at least one photodiode. For example, the sensitivity damper may include circuitry configured to reduce the voltage applied to at least one photodiode, which may reduce the sensitivity of at least one photodiode.

[0159] In some embodiments, the detection module 710 may further include a controller (not shown) configured to trigger a sensitivity damper to reduce the sensitivity of at least one photodiode. For example, the controller may be programmed to trigger the sensitivity damper to reduce the voltage applied to at least one photodiode to a predetermined voltage value at which the at least one photodiode may not operate properly or optimally, potentially reducing the sensitivity of at least one photodiode to a sensitivity level below a nominal sensitivity threshold. The controller may also be programmed to trigger the sensitivity damper to restore the voltage applied to at least one photodiode back to an operating voltage value at which the at least one photodiode can operate properly or optimally, potentially restoring the sensitivity of at least one photodiode to a sensitivity level equal to or greater than the nominal sensitivity threshold.

[0160] In some embodiments, the controller may be configured to receive timing information representing the duration of a light pulse being emitted into the field of view, and to trigger a sensitivity damper based on the received timing information to reduce the sensitivity of the photodiode. The timing information may be explicit (e.g., a specific time for emitting the light pulse), relative (e.g., pulse emission timing in nanoseconds), a clock signal, etc., or a combination thereof.

[0161] Figure 8A , Figure 8B and Figure 8C These are diagrams illustrating various exemplary detection modules consistent with the disclosed embodiments. (The diagrams are located in...) Figure 8A , Figure 8B and Figure 8C The detection modules 810, 820, and 830 shown in the figure can be used in a lidar system or any other type of electro-optical system described in this disclosure. For example, detection modules 810, 820, and / or 830 can be integrated as sensors 116 and / or sensing units 106 of lidar system 100.

[0162] like Figure 8AAs shown, the detection module 810 may include at least one photodiode 811, a controller 812, and a sensitivity damper 813. The photodiode 811 may be configured to detect the reflection of one or more light pulses from the field of view of the electro-optic system and transmit the reflected signal to the processor of the electro-optic system (e.g., processor 716). The controller 812 may be configured to control the photodiode 811 and / or the sensitivity damper 813. For example, the controller 812 may be configured to trigger the sensitivity damper 813 to adjust the sensitivity of the photodiode 811. The sensitivity damper 813 may be configured to temporarily adjust the sensitivity of the photodiode 811. For example, the controller 812 may be configured to trigger the sensitivity damper 813, which may be configured to temporarily reduce the sensitivity of the photodiode 811 by, for example, reducing the voltage applied to the photodiode 811.

[0163] In some embodiments, photodiode 811 may have a recovery duration between a light detection event (detection of one or more photons by the photodiode) and the recovery of operating sensitivity. For example, photodiode 811 may include at least one silicon photomultiplier tube (SiPM), which may include one or more single-photon avalanche diodes (SPADs). By way of example only, photodiode 811 may include a SPAD that may have a recovery time between 5 nanoseconds and 100 nanoseconds. In some embodiments, the recovery time of photodiode 811 may be shortened by components of detection module 810 (e.g., controller 812, sensitivity damper 813, etc.) by, for example, overcharging photodiode 811.

[0164] In some embodiments, photodiode 811 may include two or more photodiodes, which may be of the same type or different types. Alternatively or additionally, the recovery times of the photodiodes may be the same or different.

[0165] In some embodiments, controller 812 may be configured to trigger sensitivity damper 813 before the light pulse is emitted into the field of view to reduce the sensitivity of photodiode 811, such that the sensitivity of photodiode 811 at the pulse emission timing may be lower than the nominal sensitivity threshold of photodiode 811 (at which photodiode 811 operates appropriately or optimally to maximize SNR (the tradeoff between noise and sensitivity)). For example, the reduced sensitivity of photodiode 811 at the pulse emission timing may be equal to or lower than 20%, 10%, 5%, 2%, 1%, 0.5%, or 0.1% of the nominal sensitivity threshold of photodiode 811. As another example, the reduced sensitivity may be one order of magnitude (or two or three orders of magnitude) lower than the nominal sensitivity threshold. Alternatively, controller 812 may be configured to trigger sensitivity damper 813 to reduce the sensitivity of photodiode 811 after the light pulse is emitted into the field of view, such that the sensitivity of photodiode 811 may be significantly lower than the nominal sensitivity threshold of photodiode 811 during the time period after the pulse emission timing.

[0166] In some embodiments, the sensitivity damper 813 can be implemented as a software module, which can be executed by the controller 812 (or the system's processor, such as processor 716). For example, the controller 812 can execute the software module to control the circuitry connected to the photodiode 811 to temporarily adjust (decrease or increase) the voltage applied to the photodiode 811. Alternatively or additionally, the controller 812 can execute the software module to control a light source (e.g., light source 704 or a different light source) to direct light onto the photodiode 811 before (or after) a light pulse is emitted into the field of view, such that an avalanche of the photodiode 811 can be triggered before (or after) the pulse emission timing.

[0167] In some embodiments, the sensitivity damper 813 may include circuitry configured to temporarily adjust the voltage applied to the photodiode 811. Figure 8B An exemplary detection module 820 including such circuitry is illustrated. Detection module 820 may include a photodiode 821, which may be similar to photodiode 811. Detection module 820 may also include a controller 822, which may be similar to controller 812. Detection module 820 may also include circuitry 823, which may be part of a sensitivity damper (not shown).

[0168] Circuit 823 can be triggered by controller 822 to temporarily reduce the voltage applied to photodiode 821 or the voltage level of photodiode 821, which may reduce the sensitivity of photodiode 821. Alternatively, circuit 823 can be configured to turn off photodiode 821 or the voltage applied to photodiode 821. After turning off and / or reducing the voltage, the voltage applied to at least one photodiode can be restored to above a nominal voltage threshold, thereby restoring the sensitivity of photodiode 821. For example, circuit 823 can be configured to reduce the bias voltage of photodiode 821 (e.g., a voltage Va applied to a p-n junction, which is reverse biased at voltage Va). In some embodiments, circuit 823 can be configured to reduce the voltage to a value equal to or lower than the breakdown voltage of photodiode 821. Alternatively, circuit 823 can be configured to reduce the voltage by at least half of the difference between the operating voltage and the breakdown voltage of photodiode 821. Alternatively, circuit 823 can be configured to reduce the voltage of photodiode 821 to a value equal to or below a threshold voltage (or avalanche threshold voltage), such that the sensitivity of photodiode 821 is below the nominal sensitivity threshold. By way of example only, circuit 823 can be configured to reduce the voltage of photodiode 821 to 20V or lower. Alternatively, circuit 823 can be configured to short-circuit photodiode 821 to ground.

[0169] In some embodiments, the period during which the voltage triggered by the sensitivity damper drops below the nominal voltage threshold and / or the period during which the voltage recovers to or above the nominal voltage threshold may depend on the characteristics of the photodiode (e.g., its capacitance and / or resistance) and / or other components of the electro-optic system.

[0170] In some embodiments, a sensitivity damper (e.g., sensitivity damper 813) may be configured to trigger a photodiode avalanche (before or after a light pulse is emitted into the field of view), such that the sensitivity of the photodiode may decrease during a period following the avalanche event. For example, the sensitivity damper may include a light source configured to direct light onto the photodiode (or its photosensitive portion) before the light pulse is emitted into the field of view, thereby triggering a photodiode avalanche. The triggering of the avalanche may be timed by a controller such that the photodiode will still be in recovery mode at the pulse emission timing (and therefore the photodiode's sensitivity will be temporarily reduced), and thus will not be saturated by the reflection of the light pulse (or at least not to the extent that no avalanche event would occur). Figure 8CAn exemplary detection module 830 is illustrated, including a light source (which may be part of a sensitivity damper (not shown)). Detection module 830 may be similar to detection module 810. Detection module 830 may include a photodiode 831, which may be similar to photodiode 811. Detection module 830 may also include a controller 832, which may be similar to controller 812.

[0171] The controller 832 can be configured to control the light source 833 to direct light onto the photodiode 831, which may cause the photodiode 831 to avalanche. For example, the controller 832 can be configured to control the light source to direct light onto the photodiode 831 before the light pulse is emitted into the field of view, which may cause the photodiode 831 to avalanche, so that the photodiode 831 can be in recovery time when the light pulse is emitted into the field of view.

[0172] In some embodiments, light source 833 may include a light source for emitting light pulses into the field of view. For example, the electro-optic system may include a light deflector configured to direct one or more light pulses onto a photodiode to cause the photodiode to avalanche and subsequently direct one or more light pulses into the field of view (or vice versa). Alternatively, light source 833 may include a different light source than the light source for emitting light pulses into the field of view, which may emit light detectable by the photodiode. For example, light source 833 may emit light having a wavelength range that at least partially overlaps with the wavelength range of light detectable by photodiode 831.

[0173] Light source 833 may include a light-emitting diode (LED), a laser, or a combination thereof. For example, light source 833 may include an LED that emits light having a wavelength in the range of 760 to 960 nm. In some embodiments, light source 833 may emit light onto a photodiode at the same intensity level as the light pulse emitted into the field of view of the electro-optic system. Alternatively, light source 833 may emit light onto a photodiode at an intensity level different from (lower or higher than) the intensity level of the light pulse emitted into the field of view of the electro-optic system. For example, light source 833 may emit light onto a photodiode at an intensity level that is 2, 5, 10, or 20 times lower (or higher) than the intensity level of the light pulse emitted into the field of view of the electro-optic system. In some embodiments, light source 833 may emit light having the same wavelength as the light pulse. Alternatively, light source 833 may emit light having a wavelength different from the wavelength of the light pulse.

[0174] In some embodiments, the light source 833 may illuminate the photodiode to reduce sensitivity (before or after a light pulse is emitted into the field of view) and may also have other uses (e.g., to determine that the photodiode is operational regardless of external reflections from the field of view of the electro-optical system). In some embodiments, the light source 833 may be external to the detection module and configured to be controlled by the controller 832 or other components of the electro-optical system (e.g., the processor 716).

[0175] It should be noted that other techniques for reducing the sensitivity of photodiodes can also be implemented, and are not limited to the examples disclosed herein.

[0176] In some embodiments, the sensitivity of the photodiode may decrease to the nominal sensitivity threshold before the light pulse is emitted into the field of view. Figure 9 A graph illustrating the sensitivity of an exemplary photodiode over time, consistent with the disclosed embodiments, is shown. Figure 9 As illustrated, a light pulse may be emitted into the field of view of the electro-optical system at time T2. A photodiode 811 may receive stray light, such as internal reflections of the light pulse and / or reflections from one or more objects in the immediate environment of the system. Stray light may include more photons over a short period, which may affect the sensitivity of the photodiode 811. For example, in some cases, stray light may cause (or is more likely to cause) avalanche in the photodiode 811, which may reduce its sensitivity. The light pulse may reach a target and be reflected by it. The reflection from the target may be received by the photodiode (e.g., photodiode 811) at time T3. Sensitivity reduction (linearly or exponentially) of the photodiode 811, occurring before the light pulse is emitted into the field of view (i.e., at time T2), may occur at time T1. For example, as described elsewhere in this disclosure, controller 812 can trigger sensitivity damper 813 to reduce (linearly or exponentially) the sensitivity of photodiode 811 at time T1, for example, by reducing the voltage applied to photodiode 811 or directing light to photodiode 811. The sensitivity of photodiode 811 may decrease below a nominal sensitivity threshold (not shown). After a certain period of time, sensitivity damper 813 can be configured to restore (linearly or exponentially) the sensitivity of photodiode 811. For example, sensitivity damper 813 may restore the voltage applied to photodiode 811 (linearly or exponentially) to the operating voltage, or not direct light to photodiode 811. The sensitivity of photodiode 811 may accordingly increase to or above the nominal sensitivity threshold, and the sensitivity of photodiode 811 may be maintained at an optimal level when reflected from a target (i.e., at time T3).

[0177] Alternatively or additionally, the sensitivity of the photodiode may decrease to the nominal sensitivity threshold after the light pulse is emitted into the field of view. Figure 10 A graph illustrating the sensitivity of an exemplary photodiode over time, consistent with the disclosed embodiments, is shown. Figure 10 As illustrated, a light pulse may be emitted into the field of view of the electro-optical system at time T1. A photodiode (e.g., photodiode 811) may receive stray light, such as internal reflections of the light pulse, which may affect the sensitivity of photodiode 811. The light pulse may reach a target and be reflected by the target. The reflection from the target may be received by the photodiode (e.g., photodiode 811) at time T3. After the light pulse is emitted into the field of view, a sensitivity reduction for reducing the sensitivity of photodiode 811 may occur at time T2. For example, as described elsewhere in this disclosure, controller 812 may trigger sensitivity damper 813 to reduce the sensitivity of photodiode 811 at time T2, for example, by reducing the voltage applied to photodiode 811 or directing light to photodiode 811. The sensitivity of photodiode 811 may decrease below a nominal sensitivity threshold (not shown). After a certain period of time, sensitivity damper 813 may be configured to restore the sensitivity of photodiode 811. For example, the sensitivity damper 813 can restore the voltage applied to the photodiode 811 to its operating voltage, or prevent light from being directed to the photodiode 811. However, when a reflection from a target strikes the photodiode 811 (i.e., at time T3), the sensitivity of the photodiode 811 may not yet have reached its optimal (or operating) level (e.g., the photodiode 811 is in the recovery phase). When the target is a bright or highly reflective object that may be far from the system, a reduced sensitivity may be required so that the photodiode 811 may not be saturated by the target's reflection.

[0178] Figure 11 This is a flowchart illustrating an exemplary process 1100 for detecting reflections of light pulses from the environment of a lidar system, consistent with the disclosed embodiments. Process 1100 may be performed by one or more components of a lidar system (e.g., lidar system 700). While the following description of process 1100 is provided with reference to detection module 710, those skilled in the art will understand that other components of lidar system 700 or any electro-optical system disclosed herein may be configured to perform one or more steps of process 1100.

[0179] At step 1101, the detection module 710 may be configured to reduce the sensitivity of at least one photodiode to below a nominal sensitivity threshold. The detection module 710 may be configured to reduce the sensitivity of the photodiode according to any means used to reduce the sensitivity disclosed herein. For example, the detection module 710 may be configured to reduce the sensitivity of the photodiode by reducing the voltage applied to the photodiode to below a nominal voltage threshold or by directing light onto the photodiode.

[0180] At step 1103, the detection module 710 may be configured to detect reflections of light pulses emitted into the field of view of the electro-optic system by one or more objects. In some embodiments, the processor of the electro-optic system (e.g., processor 716) may be configured to detect one or more objects based on the detected reflections.

[0181] In some embodiments, the processor of the electro-optic system (e.g., processor 716) may be configured to detect one or more objects based on detected reflections as described elsewhere in this disclosure. For example, detection module 710 may be configured to receive reflections of light from the environment of lidar system 700 and transmit the reflected signals to processing unit 714. Processing unit 714 may be programmed to detect objects within the field of view based on the received signals.

[0182] In some embodiments, the reduction in the sensitivity of the photodiode can occur before the light pulse is emitted into the field of view of the electro-optic system. Figure 12 This is a flowchart illustrating an exemplary process 1200 for detecting reflections of light pulses from the environment of a lidar system, consistent with the disclosed embodiments. While the following description of process 1200 is provided with reference to detection module 710 and light source 704, those skilled in the art will understand that other components of lidar system 700 or any electro-optical system disclosed herein may be configured to perform one or more steps of process 1200.

[0183] At step 1201, the detection module 710 may be configured to reduce the sensitivity of at least one photodiode to below a nominal sensitivity threshold. The detection module 710 may be configured to reduce the sensitivity of the photodiode according to any means used to reduce the sensitivity disclosed herein. For example, the detection module 710 may be configured to reduce the sensitivity of the photodiode by reducing the voltage applied to the photodiode to below a nominal voltage threshold or by directing light onto the photodiode.

[0184] At step 1203, the light source 704 may be configured to emit a light pulse into the field of view of the electro-optic system. In some embodiments, when the light pulse is emitted into the field of view, the sensitivity of the photodiode may be below the nominal sensitivity threshold described elsewhere in this disclosure. The sensitivity of the photodiode may gradually recover (or increase) after a predetermined period of time.

[0185] At step 1205, the detection module 710 may be configured to detect reflections of light pulses emitted by one or more objects into the field of view of the electro-optic system. In some embodiments, when the reflection of the light pulse by one or more objects strikes a photodiode, the sensitivity of the photodiode may be at or greater than a nominal sensitivity threshold as described elsewhere in this disclosure. In some embodiments, the processor of the electro-optic system (e.g., processor 716) may be configured to detect one or more objects based on the detected reflections.

[0186] In some embodiments, the processor of the electro-optic system (e.g., processor 716) may be configured to detect one or more objects based on detected reflections as described elsewhere in this disclosure. For example, detection module 710 may be configured to receive reflections of light from the environment of lidar system 700 and transmit the reflected signals to processing unit 714. Processing unit 714 may be programmed to detect objects within the field of view based on the received signals.

[0187] Alternatively or additionally, the decrease in the sensitivity of the photodiode can occur after the light pulse is emitted into the field of view of the electro-optic system.

[0188] Figure 13 This is a flowchart illustrating an exemplary process 1300 for detecting reflections of light pulses from the environment of a lidar system, consistent with the disclosed embodiments. While the following description of process 1300 is provided with reference to detection module 710 and light source 704, those skilled in the art will understand that other components of lidar system 700 or any electro-optical system disclosed herein may be configured to perform one or more steps of process 1300.

[0189] At step 1301, the light source 704 may be configured to emit light pulses into the field of view of the electro-optic system. In some embodiments, when the light pulses are emitted into the field of view, the sensitivity of the photodiode may be at or below a nominal sensitivity threshold as described elsewhere in this disclosure.

[0190] At step 1303, the detection module 710 may be configured to reduce the sensitivity of at least one photodiode to below a nominal sensitivity threshold. The detection module 710 may be configured to reduce the sensitivity of the photodiode according to any means used to reduce the sensitivity disclosed herein. For example, the detection module 710 may be configured to reduce the sensitivity of the photodiode by reducing the voltage applied to the photodiode to below a nominal voltage threshold or by directing light onto the photodiode. The sensitivity of the photodiode may gradually recover (or increase) after a predetermined period of time.

[0191] At step 1305, the detection module 710 may be configured to detect reflections of light pulses emitted by one or more objects into the field of view of the electro-optic system. In some embodiments, the sensitivity of the photodiode may be less than a nominal sensitivity threshold when reflected photons from the light pulses from one or more objects strike the photodiode. In some embodiments, the processor of the electro-optic system (e.g., processor 716) may be configured to detect one or more objects based on the detected reflections.

[0192] In some embodiments, the processor of the electro-optic system (e.g., processor 716) may be configured to detect one or more objects based on detected reflections as described elsewhere in this disclosure. For example, detection module 710 may be configured to receive reflections of light from the environment of lidar system 700 and transmit the reflected signals to processing unit 714. Processing unit 714 may be programmed to detect objects within the field of view based on the received signals.

[0193] In some embodiments, the sensitivity of the photodiode can be reduced based on a feedback mechanism (e.g., based on the reflection of a previous light pulse by one or more previously received objects). Figure 14 This is a flowchart illustrating an exemplary process 1400 for detecting reflections of light pulses from the environment of a lidar system, consistent with the disclosed embodiments. While the following description of process 1400 is provided with reference to detection module 710 and light source 704, those skilled in the art will understand that other components of lidar system 700 or any electro-optical system disclosed herein may be configured to perform one or more steps of process 1400.

[0194] At step 1401, the light source 704 may be configured to emit a first light pulse into the field of view of the electro-optic system. In some embodiments, when the light pulse is emitted into the field of view, the photodiode can operate under its optimal conditions (i.e., the sensitivity of the photodiode can be at or above a nominal sensitivity threshold). Alternatively, the sensitivity of the photodiode may decrease to less than a nominal sensitivity threshold as described elsewhere in this disclosure. The sensitivity of the photodiode may be less than the nominal sensitivity threshold when the light pulse is emitted into the field of view. The sensitivity of the photodiode may gradually recover (or increase) after a predetermined period of time.

[0195] At step 1403, the detection module 710 can be configured to detect reflections of the first light pulse by one or more objects. In some embodiments, when the reflection of the first light pulse by one or more objects strikes the photodiode, the sensitivity of the photodiode can be at or greater than a nominal sensitivity threshold. Alternatively, the sensitivity of the photodiode can be less than the nominal sensitivity threshold.

[0196] In some embodiments, the detection module 710 and / or the processor of the electro-optical system (e.g., processor 716) may be configured to determine whether to reduce the sensitivity of the photodiode associated with the next light pulse to be emitted into the field of view (or referred to herein as the second light pulse). For example, the detection module 710 may determine that reflection of the first light pulse has saturated the photodiode (e.g., reflection may be associated with a highly reflective object) and may determine that the sensitivity of the photodiode should decrease to a level below the nominal sensitivity threshold after the second light pulse is emitted into the field of view. The sensitivity of the photodiode may decrease when the reflection of the second light pulse from the same object hits the photodiode, and the reflection may not cause photodiode avalanche. As another example, the detection module 710 may determine that internal reflection of the first light pulse (which may occur immediately after the emission of the light pulse) may impair the performance of the photodiode (e.g., cause photodiode avalanche). The detection module 710 may determine that the sensitivity of the photodiode should decrease to a level below the nominal sensitivity threshold before the second light pulse is emitted into the field of view.

[0197] In some embodiments, the detection module 710 may determine the timing for reducing sensitivity and reduce sensitivity based on the determined timing. For example, if the detection module 710 determines that some received reflections of a first light pulse associated with an object cause photodiode avalanche, then the detection module 710 may estimate the timing at which the reflection of a second light pulse (which is to be emitted) from the same object reaches the photodiode. The detection module may also determine the timing for reducing photodiode sensitivity based on the estimated timing of the reflection of the second light pulse from the object reaching the photodiode, such that when the reflection of the second light pulse from the object hits the photodiode, the photodiode may still be in recovery mode (e.g., the photodiode's sensitivity is less than the nominal sensitivity threshold).

[0198] At step 1405, the detection module 710 may be configured to reduce the sensitivity of at least one photodiode to less than a nominal sensitivity threshold before or after the second light pulse is emitted into the field of view. The detection module 710 may be configured to reduce the sensitivity of the photodiode according to any means used to reduce the sensitivity disclosed herein. For example, the detection module 710 may be configured to reduce the sensitivity of the photodiode by reducing the voltage applied to the photodiode to less than a nominal voltage threshold or by directing light onto the photodiode.

[0199] At step 1407, the detection module 710 may be configured to detect reflections of a second light pulse emitted by one or more objects into the field of view of the electro-optic system. In some embodiments, if the sensitivity of the photodiode is reduced before the second light pulse is emitted into the field of view, the sensitivity of the photodiode may be at or greater than the nominal sensitivity threshold described elsewhere in this disclosure when reflections of the second light pulse by one or more objects strike the photodiode. In other embodiments, if the sensitivity of the photodiode is reduced after the second light pulse is emitted into the field of view, the sensitivity of the photodiode may be less than the nominal sensitivity threshold when reflections of the second light pulse by one or more objects strike the photodiode.

[0200] In some embodiments, the processor of the electro-optic system (e.g., processor 716) may be configured to detect one or more objects based on detected reflections as described elsewhere in this disclosure. For example, detection module 710 may be configured to receive reflections of light from the environment of lidar system 700 and transmit the reflected signals to processing unit 714. Processing unit 714 may be programmed to detect objects within the field of view based on the received signals.

[0201] The foregoing description has been given for illustrative purposes. It is not exhaustive and is not limited to the precise forms or embodiments disclosed. Modifications and adaptations will be apparent to those skilled in the art in light of the specification and practice of the disclosed embodiments. Additionally, although aspects of the disclosed embodiments are described as being stored in memory, those skilled in the art will recognize that these aspects may also be stored on other types of computer-readable media, such as auxiliary storage devices, like hard disks or CD-ROMs, or other forms of RAM or ROM, USB media, DVDs, Blu-rays, or other optical drive media.

[0202] Computer programs based on the written description and disclosed methods are within the skill level of an experienced developer. Various programs or program modules can be created using any techniques known to those skilled in the art, or can be designed in conjunction with existing software. For example, program parts or modules can be designed or designed using the .NET Framework, the .NET Compact Framework (and related languages ​​such as Visual Basic, C, etc.), Java, C++, Objective-C, HTML, HTML / AJAX combinations, XML, or HTML containing Java applets.

[0203] Furthermore, while illustrative embodiments have been described herein, the scope of any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., across aspects of various embodiments), adaptations, and / or alterations will be understood by those skilled in the art based on this disclosure. Limitations in the claims should be interpreted broadly based on the language used in the claims and are not limited to the examples described in this specification or during the examination of the application. These examples should be interpreted as non-exclusive. Moreover, the steps of the disclosed method can be modified in any way, including by reordering the steps and / or inserting or deleting steps. Therefore, it is intended that the specification and embodiments be considered illustrative only, and the true scope and spirit are indicated by the full scope of the following claims and their equivalents.

Claims

1. A system for controlling at least one photodiode, comprising: at least one light source configured to emit a light pulse; at least one photodiode for detecting a reflection of the emitted light pulse; a sensitivity damper configured to temporarily reduce a sensitivity of the at least one photodiode; and a controller configured to trigger the sensitivity damper to reduce the sensitivity of the at least one photodiode to a reduced sensitivity that is less than a nominal sensitivity threshold at a time relative to the emission of the light pulse by the at least one light source, such that the at least one photodiode is in a recovery mode between a light detection event of a reflection of an external target of the light pulse that occurs after an internal reflection of the light pulse and a restoration of an operational sensitivity, such that the reduced sensitivity causes the at least one photodiode to not be saturated by the reflection from the detected object of the external target in the recovery mode, wherein a recovery time depends on a characteristic of the photodiode.

2. The system of claim 1, wherein the at least one photodiode is configured to detect a reflection of the light pulse from a field of view of a lidar system.

3. The system of claim 1, wherein the controller is configured to trigger the sensitivity damper when the light pulse is emitted to the field of view.

4. The system of claim 1, wherein the controller is configured to trigger the sensitivity damper after the light pulse is emitted to the field of view.

5. The system of claim 1, wherein the controller is configured to trigger the sensitivity damper before the light pulse is emitted to the field of view.

6. The system of claim 1, wherein the controller is further configured to receive timing information indicative of a duration for which the light pulse is to be emitted to the field of view.

7. The system of claim 6, wherein the controller is further configured to trigger the sensitivity damper based on the received timing information.

8. The system of claim 1, wherein the at least one photodiode comprises a silicon photomultiplier (SiPM).

9. The system of claim 1, wherein the at least one photodiode comprises a single-photon avalanche diode (SPAD).

10. The system of claim 9, wherein the SPAD has a recovery time between 5 nanoseconds and 100 nanoseconds.

11. The system of claim 1, wherein the sensitivity damper comprises a circuit for reducing a voltage level of the at least one photodiode.

12. The system of claim 11, wherein reducing the voltage comprises reducing the voltage to a voltage value that is equal to or below a breakdown voltage of the at least one photodiode.

13. The system of claim 11, wherein reducing the voltage comprises reducing the voltage by at least half of a difference between an operating voltage and a breakdown voltage of the at least one photodiode.

14. The system of claim 11, wherein reducing the voltage comprises reducing the voltage to a voltage value that is equal to or below a threshold voltage.

15. The system of claim 14, wherein the threshold voltage is 20 V.

16. The system of claim 1, wherein the sensitivity dampener comprises a circuit configured to short the photodiode to ground.

17. The system of claim 1, wherein the reduced sensitivity is equal to or lower than 20% of the nominal sensitivity threshold.

18. The system of claim 1, wherein the reduced sensitivity is equal to or lower than 10% of the nominal sensitivity threshold.

19. The system of claim 1, wherein the reduced sensitivity is equal to or lower than 5% of the nominal sensitivity threshold.

20. The system of claim 1, wherein the reduced sensitivity is equal to or lower than 1% of the nominal sensitivity threshold.

21. The system of claim 1, wherein the reduced sensitivity is two orders of magnitude lower than the nominal sensitivity threshold.

22. A method for controlling at least one photodiode, comprising: triggering a sensitivity dampener to reduce a sensitivity of the at least one photodiode to a reduced sensitivity that is less than a nominal sensitivity threshold at a time defined relative to an emission of a light pulse emitted by at least one light source associated with the at least one photodiode; and detecting, by the at least one photodiode, a reflection of the light pulse; wherein the at least one photodiode is in a recovery mode between a reflection of an external target of the light pulse that occurs after detecting an internal reflection of the light pulse and a restoration of an operating sensitivity, such that the reduced sensitivity causes the at least one photodiode to not be saturated by the reflection of the external target from the detected object in the recovery mode, wherein a recovery time depends on characteristics of the photodiode.

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