LIDAR system with variable resolution multibeam scanning

Abstract

The LIDAR system may include a laser emitting unit configured to generate multiple laser beams. The LIDAR system may also include an optical system configured to transmit the multiple laser beams from the laser emitting unit to a common scanning unit. The common scanning unit may be configured to project the multiple laser beams toward a field of view of the LIDAR system to simultaneously scan the field of view along multiple scan lines across the field of view.

Description

[Technical Field]

[0001] Cross-reference of related applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 077,933 filed on 14 September 2020, U.S. Provisional Patent Application No. 63 / 081,024 filed on 21 September 2020, U.S. Provisional Patent Application No. 63 / 081,646 filed on 22 September 2020, and U.S. Provisional Patent Application No. 63 / 173,426 filed on 11 April 2021, all of which are incorporated herein by reference as a whole. Furthermore, this application claims priority to International Application No. PCT / US2021 / 047289 filed on 24 August 2021, which is incorporated herein by reference as a whole. International application PCT / US2021 / 047289 claims priority to U.S. Provisional Patent Application No. 63 / 069,403, filed on 24 August 2020, and U.S. Provisional Patent Application No. 63 / 077,933, filed on 14 September 2020, which are incorporated herein by reference as a whole. [Background technology]

[0002] background I.Technical field

[0002] This disclosure generally relates to technologies for scanning the surrounding environment, and for example, to systems and methods for detecting objects in the surrounding environment using LIDAR technology.

[0003] II. Background Information

[0003] With the advent of driver assistance systems and autonomous vehicles, automobiles need to be equipped with systems that can reliably detect and interpret their surroundings, including identifying obstacles, hazards, objects, and other physical parameters that may affect the vehicle's navigation. For this purpose, many different technologies have been proposed, including radar, LIDAR, and camera-based systems that operate independently or redundantly.

[0004]

[0004] One consideration for driver assistance systems and autonomous vehicles is the system's ability to judge its surroundings in a variety of conditions, including rain, fog, darkness, bright light, and snow. Light detection and ranging (LIDAR: also known as LADAR) is an example of a technology that can function well in a variety of conditions by measuring the distance to an object by shining light onto the object and measuring the reflected pulses with a sensor. Lasers are an example of a light source that can be used in a LIDAR system. Electro-optic systems such as LIDAR systems may include an optical deflector for projecting light emitted by a light source into the environment of the electro-optic system. The optical deflector may be controlled to pivot around at least one axis to project light to a desired position within the field of view of the electro-optic system. To control and / or monitor the movement of the optical deflector with high precision, it may be desirable to design improved systems and methods for determining the position and / or orientation of the optical deflector. [Overview of the Initiative] [Means for solving the problem]

[0005]

[0005] The systems and methods of the present disclosure relate to improvements in the ability to monitor the position and / or orientation of optical deflectors used in electro-optical systems.

[0006] overview

[0006] In one embodiment, a LIDAR system is disclosed. The LIDAR system may include a laser emission unit configured to generate a plurality of laser beams and an optical system configured to transmit the plurality of laser beams from the laser emission unit to a common scanning unit. The common scanning unit may be configured to project the plurality of laser beams toward the field of view of the LIDAR system and to simultaneously scan the field of view along a plurality of scan lines that cross the field of view.

[0007]

[0007] In another embodiment, a LIDAR system is disclosed. The LIDAR system may include a laser emission unit configured to generate a plurality of laser beams and a scan unit configured to receive the plurality of laser beams. A common scan unit may be configured to project the plurality of laser beams toward the field of view of the LIDAR system. The LIDAR system may also include at least one processor. At least one processor may be programmed to cause the scan unit to scan the field of view of the LIDAR system by guiding the plurality of beams along a first plurality of scan lines crossing the FOV, and displacing the plurality of laser beams from a first set of positions associated with the first plurality of scan lines to a second set of positions associated with a second plurality of scan lines, thereby guiding the plurality of laser beams along the second plurality of scan lines.

[0008]

[0008] In yet another embodiment, a LIDAR system is disclosed. The LIDAR system may include a monolithic laser array comprising a plurality of laser emitters configured to generate a plurality of laser beams, and a biaxial scanning mirror configured to receive the plurality of laser beams. The biaxial scanning mirror is configured to project the plurality of laser beams toward the field of view of the LIDAR system. The LIDAR system may include at least one processor. At least one processor may be programmed to activate a first laser emitter subset of multiple laser emitters, scan the laser beam generated by the first laser emitter subset across a first set of scan lines crossing the field of view of the LiDAR system, deactivate the first laser emitter subset, activate a second laser emitter subset of multiple laser emitters, scan the laser beam generated by the second laser emitter subset across a second set of scan lines crossing the field of view of the LiDAR system, deactivate the second laser emitter subset, tilt the two-axis scan mirror by a rotation angle greater than or equal to the angular length of the monolithic laser array, activate the first laser emitter subset, and scan the laser beam generated by the first laser emitter subset across a third set of scan lines crossing the field of view of the LiDAR system.

[0009]

[0009] The above general description and the following detailed description are for illustrative purposes only and do not limit the scope of the claims.

[0010] Brief explanation of the drawing

[0010] The accompanying drawings, which are incorporated into and form part of this disclosure, illustrate various embodiments of the disclosure. [Brief explanation of the drawing]

[0011] [Figure 1A]

[0011] This figure shows an exemplary LIDAR system according to the disclosed embodiment. [Figure 1B]

[0012] An image showing an exemplary output of a single scan cycle of a LIDAR system mounted on a vehicle according to the disclosed embodiments. [Figure 1C]

[0013] Another image showing the representation of a point cloud model determined from the output of a LIDAR system according to the disclosed embodiments. [Figure 2A]

[0014] A diagram showing the configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2B]

[0014] A diagram showing the configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2C]

[0014] A diagram showing the configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2D]

[0014] A diagram showing the configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2E]

[0014] A diagram showing the configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2F]

[0014] A diagram showing the configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2G]

[0014] A diagram showing the configuration of a projection unit according to an embodiment of the present disclosure. [Figure 3A]

[0015] A diagram showing the configuration of a scan unit according to an embodiment of the present disclosure. [Figure 3B]

[0015] A diagram showing the configuration of a scan unit according to an embodiment of the present disclosure. [Figure 3C]

[0015] A diagram showing the configuration of a scan unit according to an embodiment of the present disclosure. [Figure 3D]

[0015] A diagram showing the configuration of a scan unit according to an embodiment of the present disclosure. [Figure 4A]

[0016] A diagram showing the configuration of a detection unit according to an embodiment of the present disclosure. [Figure 4B]

[0016] A diagram showing the configuration of a detection unit according to an embodiment of the present disclosure. [Figure 4C]

[0016] This figure shows the configuration of a detection unit according to an embodiment of the present disclosure. [Figure 4D]

[0016] This figure shows the configuration of a detection unit according to an embodiment of the present disclosure. [Figure 4E]

[0016] This figure shows the configuration of a detection unit according to an embodiment of the present disclosure. [Figure 5A]

[0017] Includes four illustrative diagrams showing emission patterns in a single frame time for a single portion of the field of view. [Figure 5B]

[0018] Includes three illustrative diagrams showing the emission scheme in a single frame time across the entire field of view. [Figure 5C]

[0019] This figure shows the actual light emission and received reflection projected over a single frame of time across the entire field of view. [Figure 6A]

[0020] This figure shows a first exemplary embodiment according to an embodiment of the present disclosure. [Figure 6B]

[0020] This figure shows a first exemplary embodiment according to an embodiment of the present disclosure. [Figure 6C]

[0020] This figure shows a first exemplary embodiment according to an embodiment of the present disclosure. [Figure 6D]

[0021] This figure shows a second exemplary embodiment according to the embodiments of the present disclosure. [Figure 7A]

[0022] This figure shows a schematic configuration of an exemplary disclosed LIDAR system according to some embodiments of the present disclosure. [Figure 7B]

[0023] This figure shows a vertical scan of the field of view according to some embodiments of the present disclosure. [Figure 7C]

[0024] This figure shows an example of a detector having an active area separated by an inactive area, according to some embodiments of the present disclosure. [Figure 8]

[0025] This is a high-level block diagram of an exemplary architecture of an exemplary LIDAR system according to some embodiments of the present disclosure. [Figure 9A]

[0026] This figure shows an example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 9B]

[0027] This figure shows another example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 10A]

[0028] This figure shows an example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 10B]

[0028] This figure shows an example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 10C]

[0028] This figure shows an example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 10D]

[0028] This figure shows an example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 10E]

[0028] This figure shows an example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 10F]

[0028] This figure shows an example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 10G]

[0028] This figure shows an example of a monolithic laser array according to some embodiments of the present disclosure. [Figure 10H]

[0029] This figure shows an exemplary magnified image of a spot generated by a laser beam, according to some embodiments of the present disclosure. [Figure 11A]

[0030] This figure shows an exemplary LIDAR system including a beam splitter, according to some embodiments of the present disclosure. [Figure 11B]

[0030] This figure shows an exemplary LIDAR system including a beam splitter according to some embodiments of the present disclosure. [Figure 12A]

[0031] This figure shows an exemplary scan pattern obtained using a 2D scan mirror according to some embodiments of the present disclosure. [Figure 12B]

[0032] This figure shows a scan pattern obtained using multiple laser beams according to some embodiments of the present disclosure. [Figure 13A]

[0033] This figure shows an example of a monolithic detector having an active area separated by an inactive area, according to some embodiments of the present disclosure. [Figure 13B]

[0033] This figure shows an example of a monolithic detector having an active area separated by an inactive area, according to some embodiments of the present disclosure. [Figure 13C]

[0033] This figure shows an example of a monolithic detector having an active area separated by an inactive area, according to some embodiments of the present disclosure. [Figure 14A]

[0034] This figure shows an exemplary beam splitter according to some embodiments of the present disclosure. [Figure 14B]

[0034] This figure shows an exemplary beam splitter according to some embodiments of the present disclosure. [Figure 14C]

[0035] This figure shows the ports of an exemplary beam splitter used to monitor the output of a laser beam, according to some embodiments of the present disclosure. [Figure 15]

[0036] This is a schematic diagram illustrating an exemplary LIDAR system according to some embodiments of the present disclosure. [Figure 16]

[0037] This figure shows exemplary scan patterns acquired using an exemplary LIDAR system according to some embodiments of the present disclosure. [Figure 17A]

[0038] This figure shows an example of an overlap scan using multiple beam configurations according to some embodiments of the present disclosure. [Figure 17B]

[0038] This figure shows an example of an overlap scan using multiple beam configurations according to some embodiments of the present disclosure. [Figure 17C]

[0038] This figure shows an example of an overlap scan using multiple beam configurations according to some embodiments of the present disclosure. [Figure 17D]

[0039] This figure shows an enlarged view of a portion of Figure 17A according to some embodiments of the present disclosure. [Figure 18A]

[0040] This figure shows an example of a multi-step scan focused on a subregion of a LiDAR field of view, according to some embodiments of the present disclosure. [Figure 18B]

[0040] This figure shows an example of a multi-step scan focused on a subregion of the LIDAR field of view, according to some embodiments of the present disclosure. [Figure 19]

[0041] This figure shows another example of a multi-step scan focused on a subregion of a LiDAR field of view, according to some embodiments of the present disclosure. [Figure 20]

[0042] This figure shows exemplary scan patterns acquired using an exemplary LIDAR system according to some embodiments of the present disclosure. [Figure 21]

[0043] This figure shows the movement of the laser beams emitted by the laser array during four sequential scans of the LIDAR field of view. [Modes for carrying out the invention]

[0012] Detailed explanation

[0044] 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 refer to the same or similar parts. While several exemplary 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 exemplary methods described herein may be modified by replacing, rearranging, removing, or adding steps to the disclosed methods. Therefore, the following detailed description is not limited to the disclosed embodiments and examples. The appropriate scope is defined by the appended claims.

[0013] Definition of Terms

[0045] The disclosed embodiments may include optical systems. As used herein, the term “optical system” broadly includes any system used for generating, detecting, and / or manipulating light. As merely one example, an optical system may include one or more optical components for generating, detecting, and / or manipulating light. For example, light sources, lenses, mirrors, prisms, beam splitters, collimators, polarizing optics, optical modulators, optical switches, optical amplifiers, optical detectors, optical sensors, optical fibers, and semiconductor optical components may each be part of an optical system, although these are not necessarily required. In addition to one or more optical components, an optical system may also include other non-optical components, such as electrical components, mechanical components, chemical reaction components, and semiconductor components. Non-optical components can work in conjunction with the optical components of the optical system. For example, an optical system may include at least one processor for analyzing detected light.

[0014]

[0046] In accordance 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 the value of a parameter indicating the distance between a pair of tangible objects based on reflected light. In one embodiment, a LiDAR system can 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 a pair of tangible objects. The determined distance may represent the physical dimensions between a pair of tangible objects. As merely one example, the determined distance may include a line of flight distance between the LiDAR system and another tangible object within the LiDAR system’s field of view. In another embodiment, a LiDAR system can 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 arbitrary units of length (e.g., the length of the LiDAR system), the ratio of distance to another length (e.g., the ratio to the length of the object detected within the LiDAR system's field of view), a time quantity (e.g., given in standard units, arbitrary units, or ratios, e.g., as the time required for light to travel between the tangible objects), one or more locations (e.g., defined using approved coordinates, defined for known locations), and others.

[0015]

[0047] A LiDAR system can determine the distance between a pair of tangible objects based on reflected light. In one embodiment, a LiDAR system can process the detection results of a sensor to generate time information indicating a time period between the emission of an optical signal and its detection by the sensor. This time period is sometimes referred to as the "time of flight" of the optical signal. In one example, the optical signal is a short pulse, and its rise time and / or fall time can be detected upon reception. By processing information regarding the time of flight of the optical signal using known information about the speed of light in the relevant medium (usually air), the distance the optical signal travels between emission and detection can be provided. In another embodiment, a LiDAR system can determine the distance based on frequency phase shifts (or multi-frequency phase shifts). Specifically, a LiDAR system can process information indicating one or more modulation phase shifts of the optical signal (e.g., by solving a system of equations to give a final measure). For example, an emitted optical signal can be modulated by one or more constant frequencies. At least one modulation phase shift between the emitted signal and the detected reflection can indicate the distance the light has traveled between emission and detection. Modulation can be applied to continuous-wave optical signals, quasi-continuous-wave optical signals, or other types of emitted optical signals. It should be noted that additional information can be used by the LIDAR system to determine distance. This additional information may include, for example, location information between the signal projection location and the detection location (e.g., relative position) (especially if they are far apart), and other information.

[0016]

[0048] In some embodiments, a LiDAR system can be used to detect multiple objects within the LiDAR system's environment. The term "detecting objects within the LiDAR system's environment" broadly includes generating information indicating an object that reflects light towards a detector associated with the LiDAR system. If two or more objects are detected by the LiDAR system, the information generated about different objects, such as a car driving on a road, a bird perched on a tree, a person touching a bicycle, or a van moving towards a building, can communicate with each other. The dimensions of the environment in which the LiDAR system detects objects may vary depending on the implementation. For example, a LiDAR system can be used to detect multiple objects within the environment of a vehicle on which the LiDAR system is mounted, at horizontal distances up to 100m (or 200m, 300m, etc.) and vertical distances up to 10m (or 25m, 50m, etc.). In another example, a LiDAR system can be used to detect multiple objects within the vehicle environment, or within a predetermined horizontal range (e.g., 25°, 50°, 100°, 180°, etc.) and a predetermined vertical height (e.g., ±10°, ±20°, +40° to 20°, ±90°, or 0° to 90°).

[0017]

[0049] As used herein, the term “detect an object” can broadly mean determining the presence of an object (for example, an object may be located in a particular direction relative to a LIDAR system and / or another reference location, or an object may be located within a particular spatial volume). In addition to or instead of this, the term “detect an object” may mean determining the distance between an object and another location (for example, the location of a LIDAR system, a location on Earth, or the location of another object). In addition to or instead of this, the term “detecting an object” may refer to identifying an object (e.g., classifying the type of object such as a car, tree, or road; recognizing a specific object (e.g., the Washington Monument); determining a vehicle registration number; revealing the composition of an object (e.g., solid, liquid, transparent, or translucent); or determining the motion parameters of an object (e.g., whether it is moving, its speed, direction of movement, or expansion). In addition to or instead of this, the term “detecting an object” may refer to generating a point cloud map. Each of one or more points in the point cloud map corresponds to a location within an object or a location on the object's surface. In one embodiment, the data resolution for the point cloud map representation of a field of view may be associated with a 0.1° × 0.1° or 0.3° × 0.3° field of view.

[0018]

[0050] In accordance with this disclosure, the term “object” broadly includes any finite composition from which light can be reflected, at least in part. For example, an object may be at least partially solid (e.g., a car, a tree), at least partially liquid (e.g., a puddle on the road, rain), at least partially gaseous (e.g., smoke, a cloud), or composed of a large number of distinct particles (e.g., a sandstorm, fog, a spray), and may be one or more in size, such as ~1 millimeter (mm), ~5 mm, ~10 mm, ~50 mm, ~100 mm, ~500 mm, ~1 meter (m), ~5 m, ~10 m, ~50 m, ~100 m. Smaller or larger objects, and any size between these 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 is reflected from only a few sides of an object (e.g., only the side facing the LIDAR system is detected). In other cases, light is projected onto only a portion of an object (e.g., a laser beam is projected onto a road or a building). In other cases, an object may be partially obscured by another object between the LIDAR system and the detected object. In other cases, the LIDAR sensor may only detect light reflected from a portion of the object. This is because, for example, ambient light or other interference may interfere with the detection of some parts of the object.

[0019]

[0051] In accordance 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 an optical deflector to deflect light in various directions toward different parts of the field of view. In another example, scanning the environment of the LiDAR system can be achieved by changing the positioning (i.e., location 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., location 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 positions of at least one light source and at least one sensor so that they move rigidly relative to the field of view (i.e., the relative distance and orientation of at least one sensor and at least one light source are maintained).

[0020]

[0052] As used herein, the term “field of view of a LiDAR system” can broadly encompass the range of the observable environment of a LiDAR system in which objects can be detected. It should be noted that the field of view (FOV) of a LiDAR system can be affected by a variety of conditions. These conditions include, but are not limited to, the orientation of the LiDAR system (e.g., the direction of the optical axis of the LiDAR system), the position of the LiDAR system relative to the environment (e.g., distance from the ground, adjacent terrain, and obstacles), and the operating parameters of the LiDAR system (e.g., emission power, calculation settings, specified operating angle). The field of view of a LiDAR system can be defined, for example, using solid angles (e.g., defined using angles φ and θ, where φ and θ are defined, for example, in a plane perpendicular to the axis of symmetry of the LiDAR system and / or its FOV). In one example, the field of view can be defined within a specific range (e.g., up to 200 m).

[0021]

[0053] Similarly, the term “instantaneous field of view” can broadly encompass the range of the observable environment in which an object can be detected by a LIDAR system at any given moment. For example, in a scanning LIDAR system, the instantaneous field of view is narrower than the entire FOV of the LIDAR system and can be moved within the FOV of the LIDAR system to allow detection in other parts of the FOV of the LIDAR system. Moving the instantaneous field of view within the FOV of the LIDAR system can be achieved by moving the optical deflector of the LIDAR system (or an external one) to deflect the light beam into and / or from the LIDAR system in different directions. In one embodiment, a LIDAR system can be configured to scan a scene in the environment in which the LIDAR system is operating. As used herein, the term “scene” can broadly encompass some or all of the objects in the field of view of the LIDAR system in their relative positions and current state during the operating period of the LIDAR system. For example, a scene may include ground elements (e.g., soil, roads, grass, sidewalks, road signs), the sky, man-made objects (e.g., vehicles, buildings, signs), plants, people, animals, light projection elements (e.g., flashlights, the sun, other LIDAR systems), etc.

[0022]

[0054] The disclosed embodiments may include obtaining information used to generate a reconstructed 3D model. Examples of usable types of reconstructed 3D models 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 particular coordinate system (i.e., having identifiable locations within the space described by each coordinate system). The term “point cloud point” refers to a space (dimensionless or, for example, 1 cm). 3A point refers to a point within a small cell space (which may be a microscopic cell space), and its location can be described by a point cloud model using a coordinate set (e.g., (X, Y, Z), (r, φ, θ)). Just as an example, a point cloud model can store additional information for some or all of its points (e.g., color information for points generated from a camera image). Similarly, any other type of reconstructed 3D model can store additional information for some or all of its objects. Likewise, the terms “polygon mesh” and “triangular mesh” are well known in the art and should be interpreted, among other things, to include a set of vertices, edges, and faces that define the shape of one or more 3D objects (such as polyhedra). Faces may include one or more triangles (triangular meshes), quadrilaterals, or other simple convex polygons for the reason that rendering can be simplified. Faces may also include more general concave polygons, or polygons with holes. Polygon meshes can be represented using various techniques such as vertex-vertex meshes, face-vertex meshes, winged-edge meshes, and render dynamic meshes. Various parts of a polygon mesh (e.g., vertices, faces, edges) are spatially located, directly and / or relatively, within a specific coordinate system (i.e., each has an identifiable location within the space described by that coordinate system). The generation of reconstructed 3D models can be carried out using any standard, specialized, and / or novel photogrammetry techniques, many of which are known in the art. It should be noted that other types of environmental models can also be generated by LIDAR systems.

[0023]

[0055] According to the disclosed embodiments, a LIDAR system may include at least one projection unit using 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 an alternative light source such as a light-emitting diode (LED) based light source. Furthermore, the light source 112 shown throughout the drawings may emit light in different formats, such as pulsed light, 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 of approximately 800 nm to 1000 nm, approximately 850 nm to 950 nm, or approximately 1300 nm to 1600 nm. Unless otherwise indicated, the term "approximately" in relation to numerical values ​​is defined as a maximum 5% variance from the stated value. Further details of the projection unit and at least one light source are described below with reference to Figures 2A to 2C.

[0024]

[0056] According to the disclosed embodiments, a LIDAR system may include at least one scanning unit using at least one optical deflector configured to deflect light from a light source to scan a field of view. The term “optical deflector” broadly includes any mechanism or module configured to deviate light from its initial path, such as mirrors, prisms, controllable lenses, mechanical mirrors, mechanical scanning polygons, active diffraction (e.g., controllable LCDs), Risley prisms, non-mechanical electro-optical beam steering (e.g., those manufactured by Vscent), polarizing gratings (e.g., those provided by Boulder Non-Linear Systems), optical phased arrays (OPAs), and others. In one embodiment, the optical deflector may include multiple optical components, such as at least one reflective element (e.g., a mirror) and at least one refractive element (e.g., a prism, lens). In one example, the optical deflector may be movable to deviate light to a number of angles (e.g., separate angles or a continuous range of angles). Optical deflectors can be optionally controlled in various ways (e.g., deflecting by α degrees, changing the deflection angle by Δα, moving a component of the optical deflector by M millimeters, changing the rate at which the deflection angle changes). Furthermore, optical deflectors can optionally operate to change the deflection angle within a single plane (e.g., θ coordinate). Optical deflectors can optionally operate to change the deflection angle within two non-parallel planes (e.g., θ and φ coordinates). Alternatively or in addition to this, optical deflectors can optionally operate to change the deflection angle between predetermined settings (e.g., along a predetermined scan route) or otherwise. With regard to the use of optical deflectors in LIDAR systems, it should be noted that optical deflectors can be used in the outbound direction (transmission direction, also referred to as TX) to deflect light from a light source to at least a portion of the field of view. However, it is also possible to use an optical deflector in the inbound direction (receiving direction, also known as RX) to deflect light from at least a portion of the field of view to one or more optical sensors.Further details regarding the scan unit and at least one optical deflector are described below with reference to Figures 3A to 3C.

[0025]

[0057] Embodiments disclosed may include pivoting an optical deflector to scan a field of view. As used herein, the term “pivot” broadly includes rotating an object (particularly a solid object) about one or more axes of rotation while keeping the center of rotation substantially fixed. In one embodiment, pivoting an optical deflector may, but is not necessarily, involve rotating the optical deflector about a fixed axis (e.g., a shaft). For example, in some MEMS mirror implementations, the MEMS mirror can move by the action of a number of bends (benders) attached to the mirror, and the mirror may produce some degree of spatial translation in addition to rotation. Nevertheless, such a mirror can be designed to rotate about a substantially fixed axis and is therefore considered pivoting in accordance with this disclosure. In other embodiments, certain types of optical deflectors (e.g., non-mechanical electro-optical beam steering, OPA) do not require any moving components or internal movement to change the deflection angle of the deflected light. It should be noted that studies on the movement or pivoting of optical deflectors can also be applied to controlling optical deflectors to change their deflection behavior by making necessary modifications. For example, by controlling the optical deflector, it is possible to change the deflection angle of light beams arriving from at least one direction.

[0026]

[0058] The disclosed embodiments may include 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 a given instantaneous point in time or over a short period of time. In one embodiment, the instantaneous position of the optical deflector can be measured with respect to a frame of reference. The frame of reference may relate to at least one fixed point in the LiDAR system. Or, for example, the frame of reference may relate to at least one fixed point in the scene. In some embodiments, the instantaneous position of the optical deflector may involve some movement of one or more components of the optical deflector (e.g., mirrors, prisms), but this movement is typically limited to the maximum degree of change during a scan of the field of view. For example, scanning the entire field of view of a LiDAR system may involve changing the deflection of light over a range of 30°. Furthermore, the instantaneous position of at least one optical deflector may include an angular shift of within 0.05° of the optical deflector. In other embodiments, the term “instantaneous position of optical deflector” may refer to the position of the optical deflector during the acquisition of light being processed to give 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 coincide with a fixed position or orientation to which the deflector briefly stops during illumination of a particular sub-region of the LIDAR field of view. In other cases, the instantaneous position of the optical deflector may coincide with a particular position / orientation along the scanning range of the optical deflector's position / orientation to which the optical deflector passes as part of a continuous or semi-continuous scan of the LIDAR field of view. In some embodiments, the optical deflector can be moved so that it is positioned at multiple different instantaneous positions during a scan cycle of the LIDAR FOV. In other words, during the time period in which a scan cycle occurs, the deflector can be moved to a series of different instantaneous positions / orientations, and the deflector can reach different instantaneous positions / orientations at different points in time during the scan cycle.

[0027]

[0059] According to the disclosed embodiments, a LIDAR system may include at least one sensing unit using at least one sensor configured to detect reflections from objects in a field of view. The term “sensor” broadly includes any device, element, or system capable of measuring electromagnetic wave characteristics (e.g., power, frequency, phase, pulse timing, pulse duration) and generating an output relating to the measured characteristics. In some embodiments, at least one sensor may include multiple detectors constructed from multiple sensing 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 with different other characteristics (e.g., sensitivity, magnitude). Other types of sensors may also be used. For example, several types of sensors may be used in combination for various reasons such as improved detection in a certain distance range (especially near distance), improved dynamic range of the sensor, improved temporal response of the sensor, and improved detection under various environmental conditions (e.g., ambient temperature, rain, etc.). In one embodiment, the sensor includes a silicon photomultiplier (SiPM), which is a solid-state single-photon sensing device constructed from avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs), functioning as sensing elements on a common silicon substrate. In one example, the typical distance between SPADs is between approximately 10 μm and 50 μm, and each SPAD may have a recovery time between approximately 20 ns and 100 ns. Similar photomultipliers made of other non-silicon materials can also be used. Although the SiPM device operates in digital / switching mode, it is an analog device because all the microcells are read out in parallel, allowing signals to be generated within a dynamic range from a single photon to hundreds and thousands of photons detected by different SPADs.It should be noted that outputs from different types of sensors (e.g., SPAD, APD, SiPM, PIN diode, photodetector) are combined into a single output that can be processed by the LIDAR system's processor. Further details about the detection unit and at least one sensor are described below with reference to Figures 4A to 4C.

[0028]

[0060] In accordance with the disclosed embodiments, a LiDAR system includes or can communicate with at least one processor configured to perform a variety of functions. The at least one processor may constitute any physical device having electrical circuits that perform logical operations for one or more inputs. For example, the at least one processor may include one or more integrated circuits (ICs) that include an application-specific integrated circuit (ASIC), a microchip, a microcontroller, a microprocessor, 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 circuits suitable for executing instructions or logical operations. Instructions executed by the at least one processor may be preloaded into memory integrated with or embedded in the controller, for example, or stored in separate memory. Memory may include random access memory (RAM), read-only memory (ROM), a hard disk, an optical disk, a magnetic medium, flash memory, other permanent memory, fixed memory, or volatile memory, or any other mechanism capable of storing instructions. In some embodiments, memory is configured to store information representing data about objects in the environment of the LiDAR system. In some embodiments, at least one processor may comprise two or more processors. Each processor may have a similar configuration, or they may have different configurations, being electrically connected or disconnected from one another. For example, processors may be separate circuits or integrated into a single circuit. When two or more processors are used, these processors may be configured to operate independently or in cooperation. These processors may be coupled electrically, magnetically, optically, acoustically, mechanically, or by other means that enable their interaction. Further details of the processing unit and at least one processor are described below with reference to Figures 5A to 5C.

[0029] System Overview

[0061] Figure 1A shows a LiDAR system 100 including a projection unit 102, a scanning unit 104, a detection unit 106, and a processing unit 108. The LiDAR system 100 can be mounted on a vehicle 110. According to embodiments of the present disclosure, the projection unit 102 may include at least one light source 112, the scanning unit 104 may include at least one optical deflector 114, the detection unit 106 may include at least one sensor 116, and the processing unit 108 may include at least one processor 118. In one embodiment, 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 optical deflector 114 to scan a field of view 120. During 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. 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 within the field of view 120. The optional optical window 124 can be used for different purposes, such as collimation of projected light and focusing of reflected light. In one embodiment, the optional optical window 124 may be an aperture, a flat window, a lens, or any other type of optical window.

[0030]

[0062] In accordance with this disclosure, the LIDAR system 100 can be used in autonomous or semi-autonomous road vehicles (e.g., automobiles, buses, vans, trucks, and any other ground vehicles). An autonomous road vehicle equipped with the LIDAR system 100 can scan the environment and drive to a destination vehicle without human input. Similarly, the LIDAR system 100 can also be used in autonomous / semi-autonomous aircraft (e.g., UAVs, drones, quadcopters, and any other aircraft or flying devices), or autonomous or semi-autonomous surface vessels (e.g., boats, ships, submarines, and any other vessels). Autonomous aircraft and surface vessels equipped with the LIDAR system 100 can scan the environment and navigate to a destination autonomously or with the help of a remote human operator. In one embodiment, a vehicle 110 (road vehicle, aircraft, or surface vessel) can use the LIDAR system 100 to help detect and scan the environment in which the vehicle 110 is operating.

[0031]

[0063] It should be noted that the LIDAR system 100 or any of its components may be used in conjunction with any of the embodiments and methods disclosed herein. Furthermore, while some embodiments of the LIDAR system 100 are described in relation to an exemplary vehicle-based LIDAR platform, the LIDAR system 100, any of its components, or any of the processes described herein may be applicable to other platform-type LIDAR systems.

[0032]

[0064] In some embodiments, the LIDAR system 100 may include one or more scanning units 104 for scanning the environment around the vehicle 110. The LIDAR system 100 can be mounted or installed on any part of the vehicle 110. A sensing unit 106 can receive reflections from the surroundings of the vehicle 110 and transmit reflection signals indicating light reflected from objects within the field of view 120 to a processing unit 108. In accordance with this disclosure, the scanning units 104 can be mounted or incorporated on the bumper, fender, side panel, spoiler, roof, headlight assembly, taillight assembly, rearview mirror assembly, hood, trunk, or any other suitable part of the vehicle 110 that can accommodate at least a portion of the LIDAR system. In some cases, the LIDAR system 100 captures a complete surrounding view of the environment around the vehicle 110. For this purpose, the LIDAR system 100 may have a 360° horizontal field of view. In one example, as shown in Figure 1A, 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 scan units (e.g., 2, 3, 4, or more scan units 104), each having a field of view, and these fields of view, when combined, can cover a horizontal field of view by scanning 360 degrees around the vehicle 110. It will be acknowledged to those skilled in the art that the LIDAR system 100 may include any number of scan units 104 arranged in any way, and each unit may have a field of view of 80° to 120° or less, depending on the number of units used. Furthermore, it is also possible to obtain a 360° horizontal field of view by mounting multiple LIDAR systems 100 on the vehicle 110, each having a single scan unit 104. Nevertheless, it should be noted that one or more LIDAR systems 100 do not need to provide a complete 360° field of view, and that in some situations a narrower field of view may be useful.For example, vehicle 110 may require a first LIDAR system 100 having a 75° field of view in front of the vehicle, and possibly a second LIDAR system 100 having a similar field of view (optionally having a smaller detection range) behind the vehicle. It should also be noted that various vertical field of view angles can be implemented.

[0033]

[0065] Figure 1B is an image showing exemplary output from a single scan cycle of a LIDAR system 100 mounted on a vehicle 110 according to a disclosed embodiment. In this example, the scan unit 104 is incorporated into the right headlight assembly of the vehicle 110. All gray dots in the image correspond to locations in the environment around the vehicle 110, determined from reflections detected by the sensing unit 106. In addition to location, each gray dot can also be associated with various types of information, such as intensity (e.g., how much light returns from that location), reflectivity, proximity to other dots, and others. In one embodiment, the LIDAR system 100 can generate multiple point cloud data entries from reflections detected in multiple scan cycles of the field of view, enabling, for example, the determination of a point cloud model of the environment around the vehicle 110.

[0034]

[0066] Figure 1C is an image showing a representation of a point cloud model determined from the output of the LIDAR system 100. According to the disclosed embodiments, a surrounding view image can be generated from the point cloud model by processing the generated point cloud data entries of the environment around 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 a plurality of features. Each feature may contain data about various aspects of objects (e.g., cars, trees, people, and roads) in the point cloud and / or environment around the vehicle 110. Features may have point cloud models of the same resolution (i.e., the same number of data points arranged in 2D arrays of arbitrarily similar size) or have different resolutions. Features can be stored in any type of data structure (e.g., raster, vector, 2D array, 1D array). Furthermore, virtual features such as representations of the vehicle 110, boundaries, or bounding boxes separating areas or objects in the image (as shown in Figure 1B, for example), and icons representing one or more identified objects can be overlaid on the representation of the point cloud model to form the final surrounding view image. For example, the symbol for vehicle 110 can be superimposed on the center of the surrounding view image.

[0035] Projection unit

[0067] Figures 2A to 2G illustrate various configurations and roles of the projection unit 102 in the LIDAR system 100. Specifically, Figure 2A shows a projection unit 102 with a single light source, Figure 2B shows multiple projection units 102 with multiple light sources aimed at a common optical deflector 114, Figure 2C shows a projection unit 102 with primary and secondary light sources 112, Figure 2D shows an asymmetric deflector used in some configurations of the projection unit 102, Figure 2E shows a first configuration of a non-scanning LIDAR system, Figure 2F shows a second configuration of a non-scanning LIDAR system, and Figure 2G shows a LIDAR system that scans in the outbound direction but not in the inbound direction. Those skilled in the art will recognize that the illustrated configurations of the projection unit 102 can have many variations and modifications.

[0036]

[0068] Figure 2A shows an example of a bistatic configuration of a LiDAR system 100 in which the projection unit 102 includes a single light source 112. The term “bistatic configuration” broadly refers to a LiDAR system configuration in which the projected light emitted from the LiDAR system and the reflected light incident on the LiDAR system follow substantially different optical paths. In some embodiments, the bistatic configuration of the LiDAR system 100 may include optical path separation by using completely different optical components, by using parallel but not completely separated optical components, or by using identical optical components for only a portion of the optical path (optical components may include, for example, windows, lenses, mirrors, beam splitters, etc.). In the example shown in Figure 2A, the bistatic configuration includes a configuration in which the outbound and inbound light pass through a single optical window 124, but the scan unit 104 includes two optical deflectors. The first optical deflector 114A is for outbound light, and the second optical deflector 114B is for inbound light (the inbound light of a LIDAR system includes emitted light reflected from objects in the scene, and may also include ambient light arriving from other sources). In the examples shown in Figures 2E and 2G, the bistatic configuration includes a configuration in which outbound light passes through the first optical window 124A and inbound light passes through the second optical window 124B. In all the configuration examples described above, the inbound and outbound optical paths are different from each other.

[0037]

[0069] In this embodiment, all components of the LIDAR system 100 can be housed in a single housing 200 or divided among multiple housings. As shown in the figure, the projection unit 102 is associated with a single light source 112 which includes a laser diode 202A (or one or more laser diodes coupled together) configured to emit light (projected light 204). In one non-limiting example, the light projected by the light source 112 may have a wavelength between about 800 nm and about 950 nm, an average power between about 50 mW and about 500 mW, a peak power between about 50 W and about 200 W, and a pulse width between about 2 ns and about 100 ns. Furthermore, the light source 112 can optionally be associated with an optical assembly 202B used for manipulating the light emitted by the laser diode 202A (e.g., for collimation or focusing). It should be noted that other types of light sources 112 are also available, and this disclosure is not limited to laser diodes. Furthermore, the light source 112 can emit light in various formats, such as light pulses, modulation frequency, continuous wave (CW), quasi-CW, or any other form corresponding to the specific light source used. The projection format and other parameters may be changed by the light source from time to time based on different factors, such as instructions from the processing unit 108. The projected light is projected towards an outbound deflector 114A, which acts as a steering element to guide the projected light into the field of view 120. In this example, the scan unit 104 also includes a pivotable feedback deflector 114B that guides photons reflected back from object 208 in the field of view 120 (reflected light 206) towards 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 118.

[0038]

[0070] In this figure, the LIDAR system 100 is connected to a host 210. According to this disclosure, the term “host” refers to any computing environment interfaced with the LIDAR system 100, which may be a vehicle system (e.g., part of vehicle 110), a test system, a security system, a survey system, a traffic control system, an urban modeling system, or any system that monitors its surroundings. Such a computing environment may include at least one processor and / or be connected to the LIDAR system 100 via the cloud. In some embodiments, the host 210 may also include interfaces to external devices such as cameras and sensors configured to measure various characteristics of the host 210 (e.g., acceleration, steering deflection, vehicle reversing, etc.). According to this disclosure, the LIDAR system 100 can be attached 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 portable computer, a movie camera). In accordance with this disclosure, by connecting the LIDAR system 100 to a host 210, the output of the LIDAR system 100 (e.g., 3D models, reflectivity images) can be provided to the host 210. Specifically, the host 210 can use the LIDAR system 100 to help detect and scan the host 210's environment or any other environment. Furthermore, the host 210 can integrate, synchronize, or otherwise use together the output of the LIDAR system 100 with the output of other detection systems (e.g., cameras, microphones, radar systems). In one example, the LIDAR system 100 may be used by a security system. An example of such an embodiment is described below with reference to Figure 6D.

[0039]

[0071] Furthermore, the LIDAR system 100 may also include a bus 212 (or other communication mechanism) for interconnecting subsystems and components to transfer information within the LIDAR system 100. Optionally, the bus 212 (or other communication mechanism) can be used to interconnect the LIDAR system 100 with a host 210. In the example in Figure 2A, the processing unit 108 includes two processors 118 for coordinating and regulating the operation of the projection unit 102, the scanning unit 104, and the detection unit 106 based at least partially on information received from internal feedback of the LIDAR system 100. In other words, the processing unit 108 can be configured to dynamically operate the LIDAR system 100 in a closed loop. A closed-loop system is characterized by having feedback from at least one of its elements and updating one or more parameters based on the received feedback. Furthermore, a closed-loop system can receive feedback and update its own operation at least partially based on that feedback. A dynamic system or element is one that can be updated during operation.

[0040]

[0072] According to some embodiments, scanning the environment around the 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 angular 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, and others. Scanning the environment around the LIDAR system 100 may also include detecting and characterizing various aspects of reflected light. Characteristics of reflected light may include, for example, time of flight (i.e., time from emission to detection), instantaneous power (e.g., power signature), average power over the entire feedback pulse, and photon distribution / signal during the feedback pulse period. By comparing the characteristics of the light pulses with the corresponding reflection characteristics, distances can be estimated, and possibly physical properties such as the reflectance of object 212 can also be estimated. By repeating this process on multiple adjacent portions 122 in a predetermined pattern (e.g., raster, Lissajous, or other pattern), a complete scan of the field of view 120 can be achieved. As will be discussed in more detail below, in some situations the LiDAR system 100 can direct light to only a portion of the portions 122 of the field of view 120 in each scan cycle. These portions may or may not be adjacent to each other.

[0041]

[0073] 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 represented by a dashed arrow. 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 LAN card that provides data communication connectivity to a compatible local area network (LAN). In another embodiment, the network interface 214 may include an Ethernet port connected to a radio frequency 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 one or more communication networks on which the LIDAR system 100 and the host 210 are intended to operate. For example, the network interface 214 can be used to provide outputs of the LIDAR system 100, such as 3D models or operating parameters of the LIDAR system 100, to an external system. In other embodiments, a communication unit can be used to receive commands from, for example, an external system, information about the inspected environment, and information from another sensor.

[0042]

[0074] Figure 2B shows an example of a monostatic configuration of a LiDAR system 100 including multiple projection units 102. The term “monostatic configuration” broadly refers to a LiDAR system configuration in which the projected light emitted from the LiDAR system and the reflected light incident on the LiDAR system follow substantially the same optical path. In one example, the outbound and inbound light beams may share at least one optical assembly through which both the outbound and inbound light beams pass. In another example, the outbound light may pass through an optical window (not shown), and the inbound light emission may pass through the same optical window (not shown). A monostatic configuration may include a scan unit 104 that includes a single optical deflector 114 which directs the projected light toward the field of view 120 and the reflected light toward the sensor 116. As shown, both the projected light 204 and the reflected light 206 are incident on an asymmetric deflector 216. The term “asymmetric deflector” refers to any optical device having two sides that can deflect a light beam incident from one side in a different direction than that which deflects a light beam incident from the second side. In one example, the asymmetric deflector does not deflect the projected light 204, but deflects the reflected light 206 toward the sensor 116. An example of an asymmetric deflector may include a polarizing beam splitter. In another example, the asymmetric 216 may include an optical isolator that allows light to pass through in only one direction. A schematic diagram of the asymmetric deflector 216 is shown in Figure 2D. In accordance with this disclosure, the monostatic configuration of the LIDAR system 100 may include an asymmetric deflector that increases detection sensitivity by preventing reflected light from entering the light source 112 and guiding all reflected light toward the sensor 116.

[0043]

[0075] In the embodiment shown in Figure 2B, the LIDAR system 100 includes three projection units 102, each having a single light source 112 aimed at a common light deflector 114. In one embodiment, multiple light sources 112 (including two or more light sources) can project light at substantially the same wavelength, and each light source 112 is generally associated with a different area of ​​the field of view (shown in the figure as 120A, 120B, and 120C). This allows for scanning of a wider field of view than could be achieved with a single light source 112. In another embodiment, multiple light sources 102 can project light at different wavelengths, and all light sources 112 can be directed to the same portion (or overlapping portion) of the field of view 120.

[0044]

[0076] Figure 2C shows an example of a LiDAR system 100 in which the projection unit 102 includes a primary light source 112A and a secondary light source 112B. The primary light source 112A can project light with wavelengths longer than those perceptible to the human eye in order to optimize the SNR and detection range. For example, the primary light source 112A can project light with wavelengths between approximately 750 nm and 1100 nm. In contrast, the secondary light source 112B can project light with wavelengths visible to the human eye. For example, the secondary light source 112B can project light with wavelengths between approximately 400 nm and 100 nm. In one embodiment, the secondary light source 112B can project light along substantially the same optical path as the light projected by the primary light source 112A. Both light sources can be time-synchronized and project light emission in simultaneous or alternating patterns. The alternating pattern means that the light sources are not active at the same time, which can reduce mutual interference. It will be recognized by those skilled in the art that other combinations of wavelength ranges and activation schedules can also be implemented.

[0045]

[0077] In some embodiments, if the secondary light source 112B is too close to the LIDAR optical output port, a person may blink. This can ensure an eye-safe mechanism that cannot be achieved with typical laser sources utilizing the near-infrared spectrum. In another embodiment, the secondary light source 112B can be used for calibration and reliability at a point of service (POS). This is done in a manner somewhat similar to the calibration of headlights on a vehicle 110 using a special reflector / pattern at a specific height from the ground. The POS operator can check the calibration of the LIDAR by simply visually inspecting the scan pattern on a characteristic target, such as a test pattern board, located at a specified distance from the LIDAR system 100. Furthermore, the secondary light source 112B can provide a means for operational reliability that the LIDAR is working for the end user. For example, the system may be configured so that a person can place their hand in front of the optical deflector 114 to test its operation.

[0046]

[0078] Furthermore, the secondary light source 112B may also have an invisible element that allows it to double as a backup system in the event of a failure of the primary light source 112A. This feature can be useful for fail-safe devices with a high functional safety rank. Given that the secondary light source 112B is visible, and also for cost and complexity reasons, the secondary light source 112B may have less power than the primary light source 112A. Therefore, if the primary light source 112A fails, the functionality of the system will be reduced to the functionality and capability set of the secondary light source 112B. Although the capability of the secondary light source 112B may be inferior to that of the primary light source 112A, the LIDAR system 100 can be designed to ensure that the vehicle 110 arrives safely at its destination.

[0047]

[0079] Figure 2D shows an asymmetric deflector 216 that may be part of the LIDAR system 100. In the illustrated example, the asymmetric deflector 216 includes a reflective surface 218 (such as a mirror) and a unidirectional deflector 220. Although not always the case, the asymmetric deflector 216 can optionally be a static deflector. The asymmetric deflector 216 can be used in a monostatic configuration of the LIDAR system 100 to enable a common optical path for transmitting and receiving light through at least one deflector 114, as shown, for example, in Figures 2B and 2C. However, typical asymmetric deflectors, such as beam splitters, are characterized by energy loss, particularly in the receiving path, which may be more sensitive to power loss than in the transmitting path.

[0048]

[0080] As shown in Figure 2D, the LIDAR system 100 may include an asymmetric deflector 216 positioned in the transmission path. The asymmetric deflector 216 includes a unidirectional deflector 220 for separating the transmitted optical signal from 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. The scanning unit 104 deflects the transmitted light toward the optical outlet. The received light travels through the optical inlet to at least one deflection element 114, which deflects the reflected signal toward another path away from the light source toward the detection unit 106. Optionally, the asymmetric deflector 216 may be combined with a polarizing light source 112 that is linearly polarized on the same polarization axis as the unidirectional deflector 220. In particular, the cross-section of the outbound light beam is significantly 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 the emitted polarized beam to the dimensions of the asymmetric deflector 216 or otherwise manipulating it. In one embodiment, the unidirectional deflector 220 may be a polarized beam splitter that is virtually transparent to the polarized beam.

[0049]

[0081] According to some embodiments, the LIDAR system 100 may further include an optical system 222 (e.g., a quarter-wavelength phase difference plate) for changing the polarization of the emitted light. For example, the optical system 222 can change the linear polarization of the emitted light beam to circular polarization. The light reflected from the field of view and returning to the system 100 passes through the deflector 114 and reaches the optical system 222, where it is circularly polarized in the opposite direction to the transmitted light. The optical system 222 then converts the received counter-polarized light into linearly polarized light that is not coaxial with the polarizing beam splitter 216. As described above, due to the optical dispersion of the beam that propagates the distance to the target, the received portion of the light is larger than the transmitted portion.

[0050]

[0082] A portion of the received light enters the unidirectional deflector 220, which reflects the light towards the sensor 106 with some power loss. However, another portion of the received light enters a reflective surface 218 surrounding the unidirectional deflector 220 (e.g., a slit in a polarizing beam splitter). The reflective surface 218 reflects the light towards the detection unit 106 with virtually no power loss. The unidirectional deflector 220 reflects light composed of various polarization axes and directions, which eventually reach the detector. Optionally, the detection unit 106 may include a sensor 116 that is independent of laser polarization and is primarily sensitive to the amount of incident photons in a specific wavelength range.

[0051]

[0083] It should be noted that the proposed asymmetric deflector 216 offers far superior performance compared to a simple mirror with a through-hole. In a mirror with a hole, all reflected light that reaches the hole is lost from the detector. However, in the deflector 216, a unidirectional deflector 220 deflects a significant portion of the light (e.g., about 50%) toward each sensor 116. In a LiDAR system, the number of photons that reach the LiDAR from a long distance is extremely limited, so improving the photon capture rate is important.

[0052]

[0084] Devices for beam splitting and steering are described according to several embodiments. A polarized beam can be emitted from a light source having a first polarization. The emitted beam can be guided to pass through a polarized beam splitter assembly. The polarized beam splitter assembly includes a unidirectional slit on the first side and a mirror on the opposite side. The unidirectional slit allows the emitted polarized beam to be directed toward a quarter-wavelength phase plate. The quarter-wavelength phase plate changes the emitted signal from a polarized signal to a linear signal (or vice versa), thereby preventing the reflected beam from passing through the unidirectional slit later.

[0053]

[0085] Figure 2E shows an example of a bistatic configuration of the LIDAR system 100 without the scan unit 104. To illuminate the entire field of view (or substantially the entire field of view) without the deflector 114, the 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 a processor 118. For example, the processor 118 may cause the linear array of light sources to continuously project parallel laser beams toward a first optional optical window 124A. The first optional optical window 124A may include a diffuser lens to diffuse the projected light to continuously form a beam that is wide horizontally and narrow vertically. Optionally, some or all of at least one light source 112 of the system 100 may project light simultaneously. For example, the processor 118 may cause the array of light sources to simultaneously project light beams from multiple non-adjacent light sources 112. In the illustrated example, light sources 112A, 112D, and 112F simultaneously project laser beams toward a first optional optical window 124A, thereby illuminating the field of view with three narrow vertical beams. A light beam from a fourth light source 112D may reach an object in the field of view. Light reflected from the object may be captured by a second optical window 124B and redirected to a sensor 116. Since the optical paths of the projected and reflected light are substantially different, the configuration shown in Figure 2E is considered a bistatic configuration. Note that the projection unit 102 may also include multiple light sources 112 arranged in a nonlinear configuration such as a two-dimensional array, in a hexagonal tile, or in any other manner.

[0054]

[0086] Figure 2F shows an example of a monostatic configuration of the LIDAR system 100 without the scan unit 104. Similar to the embodiment shown in Figure 2E, the projection unit 102 may include an array of light sources (e.g., 112A-112F) to illuminate the entire field of view without the deflector 114. However, in contrast to Figure 2E, 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 towards the sensor 116. The configuration shown in Figure 2E is considered a monostatic configuration because the optical paths of the projected and reflected light are substantially similar to each other. The term “substantially similar” in the context of the optical paths of the projected and reflected light means that the overlap between the two optical paths can be 80%, 85%, 90%, or 95% or more.

[0055]

[0087] Figure 2G shows an example of a bistatic configuration of the LIDAR system 100. The configuration of the LIDAR system 100 in this figure is similar to the configuration shown in Figure 2A. For example, both configurations include a scan unit 104 for guiding the projected light in the outbound direction towards the field of view. However, in contrast to the embodiment in Figure 2A, in this configuration, the scan unit 104 does not redirect the reflected light in the inbound direction. Instead, the reflected light passes through a second optical window 124B into the sensor 116. The configuration shown in Figure 2G is considered a bistatic configuration because the optical paths of the projected and reflected light are substantially different from each other. The term "substantially different" in the context of the optical paths of the projected and reflected light 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%.

[0056] Scan unit

[0088] Figures 3A to 3D illustrate various configurations and roles of the scan unit 104 in the LIDAR system 100. Specifically, Figure 3A shows the scan unit 104 with a MEMS mirror (e.g., rectangular), Figure 3B shows the scan unit 104 with a MEMS mirror (e.g., circular), Figure 3C shows the scan unit 104 with an array of reflectors used in a monostatic scan LIDAR system, and Figure 3D shows an exemplary LIDAR system 100 that mechanically scans the environment around the LIDAR system 100. The illustrated configurations of the scan unit 104 are merely illustrative and it will be acknowledged to those skilled in the art that there may be many variations and modifications within the scope of this disclosure.

[0057]

[0089] Figure 3A shows an exemplary scan unit 104 equipped with a single-axis rectangular MEMS mirror 300. In this example, the MEMS mirror 300 functions as at least one deflector 114. As shown, the scan unit 104 may include one or more actuators 302 (specifically 302A and 302B). In one embodiment, the actuator 302 may be fabricated from a semiconductor (e.g., silicon) and includes a piezoelectric layer (e.g., PZT, lead zirconate titanate, aluminum nitride) that changes size in response to an electrical signal applied by an actuation controller, a semiconductor layer, and a base layer. In one embodiment, the physical properties of the actuator 302 may determine the mechanical stress applied to the actuator 302 when current flows through it. When the piezoelectric material is activated, it applies force to the actuator 302, causing it to bend. In one embodiment, the resistivity (Ractive) of one or more actuators 302 in an active state when the mirror 300 is deflected to a specific angular position can be measured and compared to the resistivity (Rrest) in a resting state. The feedback, including Ractive, provides information for determining the actual mirror deflection angle compared to the predicted angle, and allows for correction of the deflection of mirror 300 as needed. The difference between Rrest and Ractive can be correlated to the mirror drive to an angular deflection value that can function to close the loop. This embodiment is used for dynamic tracking of the actual mirror position and can optimize the response, amplitude, deflection efficiency, and frequency in both linear and resonant mode MEMS mirror schemes. This embodiment is described in more detail below with reference to Figures 32 to 34.

[0058]

[0090] During scanning, current can flow from contact 304A to contact 304B (through actuator 302A, spring 306A, mirror 300, spring 306B, and actuator 302B) (represented by dashed lines in the diagram). Due to the insulating gap of the semiconductor frame 308, such as insulating gap 310, actuators 302A and 302B can become two separate islands electrically connected via spring 306 and frame 308. The current, or any associated electrical parameters (voltage, current frequency, capacitance, relative permittivity, etc.), can be monitored by associated position feedback. In the event of a mechanical failure in which one of the components is damaged, the current flowing through the structure changes and deviates from the functional calibration value. In extreme circumstances (e.g., if a spring breaks), the current is completely interrupted due to the circuit break of the electrical chain by the failed element.

[0059]

[0091] Figure 3B shows another exemplary scan unit 104 equipped with a biaxial circular MEMS mirror 300. In this example, the MEMS mirror 300 functions 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 scan unit 104 may include four actuators 302 (302A, 302B, 302C, and 302D), each of which may be of different lengths. In the illustrated example, current (represented by 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. According to some embodiments, the biaxial MEMS mirror can be configured to deflect light in the horizontal and vertical directions. For example, the deflection angle of a biaxial MEMS mirror can be between approximately 0° and 30° vertically and between approximately 0° and 50° horizontally. Those skilled in the art will recognize that the illustrated configuration of the mirror 300 can have many variations and modifications. In one example, at least the deflector 114 may have a biaxial square mirror or a single-axis circular mirror. Examples of circular and square mirrors are shown in Figures 3A and 3B merely as examples. Any shape can be adopted depending on the system specifications. In one embodiment, the actuator 302 is incorporated as at least an integral part of the deflector 114 to directly provide power for moving the MEMS mirror 300. Furthermore, the MEMS mirror 300 may be connected to the frame 308 by one or more rigid support elements. In another embodiment, at least the deflector 114 may include an electrostatic or electromagnetic MEMS mirror.

[0060]

[0092] As described above, a monostatic scan LiDAR system utilizes at least a portion of the same optical path for the emission of projected light 204 and the reception of reflected light 206. The light beam in the outbound path can be collimated and focused into a narrow beam, while the reflection in the return path spreads out to a larger optical area due to dispersion. In one embodiment, the scan unit 104 may have a large reflection area in the return path and an asymmetric deflector 216 that redirects the reflection (i.e., reflected light 206) towards the sensor 116. In one embodiment, the scan unit 104 may include a MEMS mirror with a large reflection area, with negligible impact on field of view and frame rate performance. Further details of the asymmetric deflector 216 are given below with reference to Figure 2D.

[0061]

[0093] In some embodiments (as illustrated, for example, in Figure 3C), the scan unit 104 may include a deflector array (e.g., a reflector array) with small optical deflectors (e.g., mirrors). In one embodiment, by implementing the optical deflector 114 as a group of individual small optical deflectors operating synchronously, the optical deflector 114 can perform at a larger deflection angle and a higher scan rate. The deflector array can effectively function as a large optical deflector (e.g., a large mirror) with respect to the effective area. The deflector array can be operated using a shared steering assembly configuration. This configuration allows the sensor 116 to collect reflected photons from substantially the same portion of the field of view 120 that is simultaneously illuminated by the light source 112. The term “simultaneously” means that the two selected functions occur during coincident or overlapping time periods. In this case, one may start and end during the duration of the other, or the latter may start before the completion of the other.

[0062]

[0094] Figure 3C shows an example of a scan unit 104 equipped with a reflector array 312 having small mirrors. In this embodiment, the reflector array 312 functions as at least one deflector 114. The reflector array 312 may include a plurality of reflector units 314 that pivot (individually or together) and are configured to direct light pulses toward the field of view 120. For example, the reflector array 312 may be part of the outbound path of light projected from the light source 112. Specifically, the reflector array 312 can direct projected light 204 toward a portion of the field of view 120. Alternatively, the reflector array 312 may 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 can direct reflected light 206 toward the sensor 116 or toward the asymmetric deflector 216. In one example, the area of ​​the reflector array 312 is approximately 75 to approximately 150 mm². 2 It can be between these two values. Here, each reflector unit 314 has a width of approximately 10 μm, and the support structure can be less than 100 μm.

[0063]

[0095] 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 units 314. For example, each steerable deflector unit 314 may include at least one of a MEMS mirror, a reflective surface assembly, and an electromechanical actuator. In one embodiment, each reflector unit 314 may be individually controlled by an individual processor (not shown) to tilt to a specific angle along each of one or more distinct 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 so that at least some of the reflector units 314 pivot simultaneously and point in substantially the same direction.

[0064]

[0096] Furthermore, at least one processor 118 can select at least one reflector unit 314 for the outbound path (hereinafter referred to as the "transmitting mirror") and a group of reflector units 314 for the return path (hereinafter referred to as the "receiving mirror"). Increasing the number of transmitting mirrors according to this disclosure may increase the spread of the reflected photon beam. Furthermore, decreasing the number of receiving mirrors may narrow the receiving field, compensate for ambient light conditions (clouds, rain, fog, extreme heat, and other environmental conditions), and improve the signal-to-noise ratio. Also, as described above, the emitted light beam is typically narrower than the reflected light portion and can be sufficiently detected by a small portion of the deflection array. Furthermore, light reflected from the portion of the deflection array used for transmission (e.g., the transmitting mirror) can be prevented from reaching the sensor 116, thereby reducing the effect of internal reflections on the system operation of the LIDAR system 100. Furthermore, at least one processor 118 can pivot one or more reflector units 314 to overcome mechanical problems and drift, such as thermal and gain effects. In one example, one or more reflector units 314 may move in a manner different from the intended one (frequency, rate, speed, etc.), but their movement can be compensated for by appropriately electrically controlling the deflectors.

[0065]

[0097] Figure 3D shows an exemplary LiDAR system 100 that mechanically scans the environment. In this example, the LiDAR system 100 may include a motor or other mechanism for rotating the housing 200 about the axis of the LiDAR system 100. Alternatively, the motor (or other mechanism) can mechanically rotate the rigid structure of the LiDAR system 100, on which one or more light sources 112 and one or more sensors 116 are mounted, thereby enabling scanning of 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 can travel along an outbound path toward the field of view 120. Specifically, if the projected light 204 travels toward an optional optical window 124, the projected light emission can be reflected by the deflector 114A and pass through the exit aperture 314. The reflected light emission can travel from object 208 toward the detection unit 106 along a return path. For example, if the reflected light 206 travels toward the detection unit 106, the reflected light 206 is reflected by the deflector 114B. It will be recognized by those skilled in the art that a LIDAR system equipped with a rotation mechanism for synchronously rotating one or more light sources or one or more sensors may use this synchronous rotation instead of (or in addition to) manipulating an internal light deflector.

[0066]

[0098] In embodiments where the 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 that separates the projection unit 102 from the rest of the LIDAR system 100. In some examples, the wall 316 can be made of a transparent material (e.g., glass) covered with a reflective material to form a deflector 114B. In this example, the exit aperture 314 may correspond to a portion of the wall 316 that is not covered with the reflective material. In addition to or instead of this, the exit aperture 314 may include a hole or cut in the wall 316. The reflected light 206 can be reflected by the deflector 114B and directed towards the incident aperture 318 of the sensing unit 106. In some examples, the incident aperture 318 may include a filter window configured to allow wavelengths within a specific wavelength range to enter the sensing unit 106 while attenuating other wavelengths. The reflection of object 208 from the field of view 120 can be reflected by the deflector 114B and incident on the sensor 116. By comparing some characteristics of the reflected light 206 with the projected light 204, at least one aspect of object 208 can be determined. For example, by comparing the time when the projected light 204 was emitted by the light source 112 with the time when the sensor 116 received the reflected light 206, the distance between object 208 and the LIDAR system 100 can be determined. In some examples, other aspects of object 208, such as shape, color, and material, can also be determined.

[0067]

[0099] In some examples, the LiDAR system 100 (or a part thereof including at least one light source 112 and at least one sensor 116) can be rotated about at least one axis to determine a three-dimensional map of the LiDAR system 100. For example, to scan a field of view 120, the LiDAR system 100 can be rotated about a substantial vertical axis, as indicated by arrow 320. Figure 3D shows the LiDAR system 100 being rotated clockwise about the axis, as indicated by arrow 320, but in addition to or instead of this, the LiDAR system 100 may be rotated counterclockwise. In some examples, the LiDAR system 100 can be rotated 360 degrees about the vertical axis. In other examples, the LiDAR system 100 can be rotated back and forth along a sector smaller than 360 degrees of the LiDAR system 100. For example, the LiDAR system 100 can be mounted on a platform that oscillates back and forth about an axis without performing a full rotation.

[0068] Detection unit

[0100] Figures 4A to 4E illustrate various configurations and roles of the detection unit 106 in the LIDAR system 100. Specifically, Figure 4A is a diagram showing an exemplary detection unit 106 with a detector array, Figure 4B is a diagram showing a monostatic scan using a two-dimensional sensor, Figure 4C is a diagram showing an example of a two-dimensional sensor 116, Figure 4D is a diagram showing a lens array associated with the sensor 116, and Figure 4E includes three diagrams showing the lens structure. Those skilled in the art will recognize that the illustrated configurations of the detection unit 106 are merely illustrative and may have many alternative variations and modifications consistent with the principles of this disclosure.

[0069]

[0101] Figure 4A shows an example of a detection unit 106 equipped with a detector array 400. In this example, at least one sensor 116 includes the detector array 400. The LIDAR system 100 is configured to detect objects (e.g., a bicycle 208A and clouds 208B) within a field of view 120 located at different distances from the LIDAR system 100 (which may be several meters or more). The object 208 may be a solid object (e.g., a road, a tree, a car, a person), a fluid object (e.g., fog, water, particles in the air), or another type of object (e.g., dust or irradiated powdery material). When photons emitted from the light source 112 strike the object 208, the photons are reflected, refracted, or absorbed. Typically, as shown in the figure, only a portion of the photons reflected from object 208A enters the optional optical window 124. Since a change in distance of up to 15 cm results in a 1 ns difference in travel time (because photons travel at the speed of light between the object 208 and the object), the time difference in travel time of different photons that strike different objects can be detected by an optical time sensor with a sufficiently rapid response.

[0070]

[0102] Sensor 116 includes multiple detection elements 402 for detecting photons in a photon pulse reflected back from the field of view 120. All detection elements may be contained in a detector array 400, which may have a rectangular arrangement (e.g., as shown) or any other arbitrary arrangement. The detection elements 402 may operate simultaneously or partially simultaneously. Specifically, each detection element 402 may provide detection information for each sampling period (e.g., every nanosecond). In one example, the detector array 400 may be a silicon photomultiplier tube (SiPM), which is a solid-state single-photon sensing device constructed from an array of single-photon avalanche diodes (SPADs, which function as detection elements 402) on a common silicon substrate. Similar photomultiplier tubes made of other non-silicon materials may also be used. Although the SiPM device operates in digital / switching mode, the SiPM is an analog device because all the microcells are read out in parallel, allowing signals to be generated within a dynamic range from a single photon to hundreds and thousands of photons detected by different SPADs. As described above, two or more types of sensors may be implemented (e.g., SiPM and APD). In some cases, the detection unit 106 includes at least one APD integrated with the SiPM array and / or at least one APD detector positioned adjacent to the SiPM, on a separate or common silicon substrate.

[0071]

[0103] In one embodiment, the detection elements 402 can 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 can be formed into various shapes (e.g., rectangles, squares, rings, etc., as shown in the figure, or any other arbitrary shape). Not all individual detectors contained within the geometric area of ​​a region 404 belong to that region, but in most cases, unless some overlap at the boundaries between regions is desirable, those detectors do not belong to other regions 404 covering other areas of the sensor 310. As shown in Figure 4A, these regions may be non-overlapping regions 404, but they may also overlap. A region output circuit 406 associated with that region can be associated with all regions. The region output circuit 406 can provide a region output signal for the corresponding group of detection elements 402. For example, the region of the output circuit 406 may be an adder circuit, but a combination of the outputs of other forms of each detector into a single output can also be employed (whether scalar, vector, or any other arbitrary format). Selectively, each region 404 is a single SiPM, but this is not necessarily the case; a region may be a small part of a single SiPM, a group of several SiPMs, or a combination of different types of detectors.

[0072]

[0104] In the illustrated example, the processing unit 108 is located in a separate housing 200B (either inside or outside) the host 210 (e.g., in a vehicle 110), and the detection 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 can be implemented in multiple housings in ways different from the illustrated example. For example, the optical deflector 114 may be located in a housing different from the projection unit 102 and / or the detection module 106. In one embodiment, the LIDAR system 100 may include multiple housings interconnected in different ways, such as by electrical wire connections, wireless connections (e.g., RF connections), fiber optic cables, and any combination of the above.

[0073]

[0105] In one embodiment, the analysis of the reflected light 206 may include determining the time of flight of the reflected light 206 based on the outputs 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 the output signals of multiple regions. In addition to the time of flight, the processing unit 108 can analyze the reflected light 206 to determine the average power of the entire feedback pulse and to determine the photon distribution / signal ("pulse shape") during the feedback pulse period. In the illustrated example, the output of any detection element 402 is not sent directly to the processor 408 but can be combined (e.g., added) with signals from other detectors in region 404 before being passed to the processor 408. However, this is merely illustrative, and the sensor 116 circuitry may also transmit information from the detection element 402 to the processor 408 via other routes (without going through the region output circuitry 406).

[0074]

[0106] Figure 4B shows a LiDAR system 100 configured to scan the environment using a two-dimensional sensor 116. In the example in Figure 4B, the sensor 116 is a matrix of 4 × 6 detectors 410 (also referred to as "pixels"). In one embodiment, the pixel size can be approximately 1 × 1 mm. The sensor 116 is two-dimensional in the sense that it has two or more sets (e.g., rows, columns) of detectors 410 on two non-parallel axes (e.g., orthogonal axes as shown in the illustrated example). The number of detectors 410 in the sensor 116 can vary in various implementations depending on, for example, the desired resolution, signal-to-noise ratio (SNR), desired detection distance, etc. For example, the sensor 116 may have any number of pixels from 5 to 5,000. In another example (not shown in the figure), the sensor 116 may be a one-dimensional matrix (e.g., 1 × 8 pixels).

[0075]

[0107] Each detector 410 may include multiple detection elements 402. The detection elements 402 are, for example, avalanche photodiodes (APDs), single-photon avalanche diodes (SPADs), a combination of avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs), or 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 photon. For example, each detector 410 may include any number of SPADs from 20 to 5,000. The outputs of the detection elements 402 within each detector 410 can be added, averaged, or otherwise combined to provide a unified pixel output.

[0076]

[0108] In the illustrated example, the detection unit 106 may include a two-dimensional sensor 116 (or multiple two-dimensional sensors 116) having a field of view smaller than the field of view 120 of the LIDAR system 100. In this consideration, the field of view 120 (the entire field of view that can be scanned by the LIDAR system 100 without moving, rotating, or swaying in any direction) is referred to as the "first FOV 412," and the field of view of the smaller sensor 116 is referred to as the "second FOV 412" (which can be rephrased as the "instantaneous FOV"). The target range of the second FOV 414 relative to the first FOV 412 varies depending on the specific application of the LIDAR system 100, and can be, for example, between 0.5% and 50%. In one example, the second FOV 412 may be elongated vertically between 0.05° and 1°. Even if the LIDAR system 100 includes two or more two-dimensional sensors 116, the combined field of view of those sensor arrays is still smaller than the first FOV 412, and can be, for example, at least one-fifth, at least one-tenth, at least one-twentieth, or at least one-fiftieth.

[0077]

[0109] To cover the first FOV 412, the scan unit 106 can guide photons arriving from different parts of the environment at different time points to the sensor 116. In the illustrated monostatic configuration, the scan unit 106 can guide reflected light 206 to the sensor 116, provided that the projected light 204 is guided toward the field of view 120 and at least one deflector 114 is positioned at the instantaneous location. Typically, at each time point during scanning of the first FOV 412, the light beam emitted by the LIDAR system 100 covers a portion of the environment larger than the second FOV 414 (at the angular aperture) and includes the portion of the environment focused by the scan unit 104 and the sensor 116.

[0078]

[0110] Figure 4C shows an example of a two-dimensional sensor 116. In this embodiment, the sensor 116 is an 8×5 matrix of detectors 410, each detector 410 containing a plurality of detection elements 402. In one example, detector 410A is located in the second row (labeled "R2") and third column (labeled "C3") of the sensor 116 and contains a matrix of 4×3 detection elements 402. In another example, detector 410B is located in the fourth row (labeled "R4") and sixth column (labeled "C6") of the sensor 116 and contains a matrix of 3×3 detection elements 402. Thus, the number of detection elements 402 in each detector 410 may be constant or different, and different detectors 410 in a common array may have different numbers of detection elements 402. The outputs of all detection elements 402 in each detector 410 can be added, averaged, or otherwise combined to provide a single pixel output value. In the example shown in Figure 4C, the detectors 410 are arranged in a rectangular matrix (rows and columns of straight lines), but other arrangements such as a circular arrangement or a honeycomb arrangement may also be used.

[0079]

[0111] According to some embodiments, measurements from each detector 410 make it possible to determine 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 arbitrarily selected optical window 124. The time of flight value can be determined by photon detection and counting methods such as time-correlated single photon counter (TCSPC), analog photon detection methods such as signal integration and qualification (by analog-to-digital conversion or a simple comparator), or by other means.

[0080]

[0112] In some embodiments, and also referring to Figure 4B, during 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 design of the sensor 116 allows for the association of reflected light from a single portion of the field of view 120 with multiple detectors 410. Thus, the scan resolution of the LIDAR system can be expressed by multiplying the number of instantaneous positions (per scan cycle) by the number of detectors 410 in the sensor 116. The information from each detector 410 (i.e., each pixel) represents the basic data elements from which the captured field of view is constructed in three-dimensional space. This includes, for example, the basic elements of a point cloud representation, having a spatial position and an associated reflectance value. In one embodiment, reflections from a single portion of the field of view 120 detected by multiple detectors 410 could have come back from various objects located within that single portion of the field of view 120. For example, a single portion of the field of view 120 may be larger than 50 × 50 cm in the far field of view and could easily contain two, three, or more objects partially overlapping each other.

[0081]

[0113] Figure 4D is a cross-sectional view of a portion of sensor 116 according to an example of the subject disclosed herein. The illustrated portion of sensor 116 includes a portion of a detector array 400 containing four detection elements 402 (e.g., four SPADs, four APDs). The detector array 400 may be a photodetector sensor implemented with complementary metal-oxide-semiconductor (CMOS). Each of the detection elements 402 has a detection area positioned within the periphery of the substrate. Sensor 116 can be used in monostatic LiDAR systems with a narrow field of view (e.g., since the scan unit 104 scans different fields of view at different times). A narrow field of view for the incident light beam, if implemented, eliminates the problem of out-of-focus imaging. As illustrated in Figure 4D, sensor 116 may include multiple lenses 422 (e.g., microlenses), each lens 422 which can direct incident light toward a different detection element 402 (e.g., toward the active area of ​​the detection element 402), which may be usable when out-of-focus imaging is not a problem. Since most of the light reaching the sensor 116 can be deflected towards the active area of ​​the detection element 402, the optical fill factor and sensitivity of the detector array 400 can be increased using the lens 422.

[0082]

[0114] A detector array 400, as illustrated in Figure 4D, can include several layers embedded in a silicon substrate by various methods (e.g., implants), resulting in a detection area, contact elements for the metal layer, and insulating elements (e.g., shallow trench implants (STIs), guard rings, optical trenches, etc.). The detection area is the volumetric element in a CMOS detector, enabling the optical conversion of incident photons into current when the device is subjected to an appropriate voltage bias. In the case of APD / SPAD, the detection area, through a combination of electric fields, pulls electrons generated by photon absorption towards the multiplication area, where photon-induced electrons are amplified, causing avalanche breakdown of the multiplied electrons.

[0083]

[0115] The front-lit detector (as shown in Figure 4D, for example) has its input optical port on the same side as the metal layer on top of the semiconductor (silicon). The metal layer is necessary to provide electrical connections between the individual photodetector elements (e.g., anode and cathode) and various other elements such as the bias voltage, quenching / ballast elements, and other photodetectors in the common array. The optical port through which photons pass when incident on the detector's sensing area consists of a passage through the metal layer. It should be noted that the passage of light from several directions through this passage can be blocked by one or more metal layers (e.g., metal layer ML6 illustrated on the leftmost detector element 402 in Figure 4D). Such blocking reduces the overall light absorption efficiency of the detector.

[0084]

[0116] Figure 4E shows three detection elements 402, each associated with a lens 422, according to an example of the subject matter disclosed herein. Each of the three detection elements in Figure 4E, denoted 402(1), 402(2), and 402(3), represents a lens configuration that can be implemented in association with one or more detection elements 402 of the sensor 116. It should be noted that combinations of these lens configurations are also possible.

[0085]

[0117] In the lens configuration illustrated with respect to the detection element 402(1), the focal point of the associated lens 422 can be located above the semiconductor surface. Optionally, the apertures of different metal layers of the detection element can have varying sizes that match the cone shape of the focused light produced 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. Larger metal layers may be important for power transmission and ground shielding. This technique may be useful, for example, in monostatic LiDAR designs with a narrow field of view when the incident light beam consists of parallel rays and the imaging focal point has no effect on the detection signal.

[0086]

[0118] In the lens configuration illustrated with respect to the detection element 402(2), the efficiency of photon detection by the detection element 402 can be improved by identifying the sweet spot. Specifically, a photodetector implemented in CMOS may have a sweet spot within the detection volume area where the probability of a photon undergoing the avalanche effect is highest. Therefore, as illustrated in the detection element 402(2), the focal point of the lens 422 can be positioned at the sweet spot location within the detection volume area. The lens shape and distance from the focal point can take into account the refractive index of all elements through which the laser beam passes along the path from the lens to the detection sweet spot location embedded in the semiconductor material.

[0087]

[0119] In the lens configuration illustrated with respect to the detection element on the right side of Figure 4E, diffusers and reflectors can be used to improve the efficiency of photon absorption in semiconductor materials. Specifically, near-IR wavelengths require a significantly long path in the silicon material to achieve a high probability of absorption of photons traveling along this path. In a typical lens configuration, photons may traverse the detection area and be absorbed, not becoming detectable electrons. A long absorption path that improves the probability of photons producing electrons results in a detection area size that is impractical (e.g., tens of micrometers) for CMOS devices manufactured using typical manufacturing processes. The rightmost detector element in Figure 4E illustrates a technique for handling incident photons. The associated lens 422 focuses the incident light onto the diffuser element 424. In one embodiment, the photosensor 116 may further include a diffuser located in a gap away from at least some of the outer surfaces of the detector. For example, the diffuser 424 can direct the light beam laterally (e.g., as vertically as possible) towards the detection area and the reflective optical trench 426. The diffuser is located at the focal point, above the focal point, or below the focal point. In this embodiment, incident light can be focused onto a specific location where the diffuser element is positioned. Optionally, the detector element 422 is designed to optically avoid inactive areas where photon-induced electrons may be lost, reducing effective detection efficiency. A reflective optical trench 426 (or other form of optically reflective structure) causes photons to travel back and forth within the detection area, thereby increasing the likelihood of detection. Ideally, the photons are trapped in the cavity consisting of the detection area and the reflective trench indefinitely until they are absorbed and generate an electron / hole pair.

[0088]

[0120] In accordance with this disclosure, a long path is generated to absorb incident photons and contribute to a high detection probability. Optical trenches can also be implemented in the detection element 422 to reduce the crosstalk effect of parasitic photons in the avalanche that may leak to other detectors and cause false detection events. According to some embodiments, the photodetector array can be optimized to utilize a higher yield of received signals, that is, to receive as many received signals as possible and to minimize signal loss due to internal degradation. The photodetector array can be improved by (a) selectively designing a metal layer on the substrate to shift the focus to a location above the semiconductor surface, (b) directing the focus to the most responsive / sensitive area (i.e., the "sweet spot") of the substrate, (c) adding diffusers above the substrate to direct the signal towards the "sweet spot", and / or adding reflective material to trenches to reflect the deflected signal back to the "sweet spot".

[0089]

[0121] It should be noted that in some lens configurations, lens 422 may be positioned so that its focal point is above the center of the corresponding detection element 402, but this is not always the case. In other lens configurations, the focal position of lens 422 relative to the center of the corresponding detection element 402 is shifted based on the distance of each detection element 402 from the center of the detection array 400. This may be useful in relatively large detection arrays 400 where detector elements further from the center receive light at angles significantly off-axis. Shifting the focal location (for example, towards the center of the detection array 400) allows for correction of the incident angle. Specifically, shifting the focal location (for example, towards the center of the detection array 400) allows for correction of the incident angle while using substantially the same lens 422 for all detection elements positioned at the same angle to the detector surface.

[0090]

[0122] Adding an array of lenses 422 to the array of detection elements 402 may be useful when using a relatively small sensor 116 that covers only a small portion of the field of view. In such cases, the reflected signals from the scene reach the detector array 400 from substantially the same angle, so all the light can be easily focused onto the individual detectors. In one embodiment, the lenses 422 can also be used in the LIDAR system 100 to increase the detection probability of the entire array 400 (preventing photons from being "wasted" in dead areas between detectors / sub-detectors) at the expense of spatial distinctness. This embodiment is in contrast to conventional implementations such as CMOS RGB cameras that prioritize spatial distinctness (i.e., light propagating in the direction of detection element A cannot be guided by the lens towards detection element B, i.e., it cannot be "bleeded" to another detection element in the array). Optionally, the sensor 116 includes an array of lenses 422, each correlated to a corresponding detection element 402, wherein at least one of the lenses 422 deflects the light propagating to the first detection element 402 toward the second detection element 402 (thereby increasing the detection probability of the entire array).

[0091]

[0123] Specifically, according to some embodiments of the present disclosure, the photosensor 116 may include an array of photodetectors (e.g., a detector array 400), each photodetector (e.g., a detector 410) configured to conduct an electric current when light passes over the outer surface of each detector. Furthermore, the photosensor 116 may include at least one microlens configured to guide light toward the array of photodetectors, the at least one microlens having a focal point. The photosensor 116 may further include at least one layer of conductive material interposed between the at least one microlens and the array of photodetectors, having a gap that allows light to pass from the at least one microlens to the array, the at least one layer being sized to maintain space between the at least one microlens and the array, and positioning a focal point (e.g., the focal point may be planar) at a location spaced apart from the detection surface of the array of photodetectors within the gap.

[0092]

[0124] In related embodiments, each detector may include a plurality of single-photon avalanche diodes (SPADs) or a plurality of avalanche photodiodes (APDs). The conductive material may be a multilayer metal constriction, and at least one layer of the conductive material may be electrically connected to the detectors in the array. In one example, the at least one layer of the conductive material may include a plurality of layers. Furthermore, the gap may be shaped to converge from at least one microlens toward the focal point and diverge from the focal region toward the array. In other embodiments, the light sensor 116 may further include at least one reflector adjacent to each photodetector. In one embodiment, a plurality of microlenses may be arranged in a lens array, and a plurality of detectors may be arranged in a detector array. In another embodiment, the plurality of microlenses may include a single lens configured to project light to a plurality of detectors in the array.

[0093]

[0125] Referring to Figures 2E, 2F, and 2G as non-limiting examples, it can be seen that one or more sensors 116 of system 100 may receive light from the scan deflector 114 or directly from the FOV without scanning. Even if light from the entire FOV arrives at at least one sensor 116 simultaneously, in some embodiments, one or more sensors 116 may sample only a portion of the FOV for a detection output at any given time. For example, if the projection unit 102 illuminates different parts of the FOV at different times (by using the deflector 114 and / or activating different light sources 112 at different times), light may arrive at all pixels or sensors 116 of the detection unit 106, and only the pixels / sensors expected to detect the LIDAR illumination may actively collect data for a detection output. In this way, the rest of the pixels / sensors do not unnecessarily collect ambient noise. Referring to scanning—in the outbound or inbound direction—it can be seen that scans of substantially different scales can be implemented. For example, in some embodiments, the scanned area may cover 1% or 0.1% of the FOV, while in other embodiments, the scanned area may cover 10% or 25% of the FOV. Needless to say, all other relative parts of the FOV value can also be implemented.

[0094] Processing unit

[0126] Figures 5A to 5C illustrate various functions of the processing unit 108 according to some embodiments of the present disclosure. Specifically, Figure 5A is a diagram showing the emission pattern of a single portion of the field of view within a single frame time, Figure 5B is a diagram showing the emission scheme of the entire field of view within a single frame time, and Figure 5C is a diagram showing the actual light emission projected toward the field of view during a single scan cycle.

[0095]

[0127] Figure 5A shows four examples of emission patterns within a single frame time of a single portion 122 of the field of view 120 associated with the instantaneous position of at least one optical deflector 114. According to embodiments of this disclosure, the processing unit 108 can control (or coordinate the operation of at least one light source 112 and at least one optical deflector 114) at least one light source 112 and the optical deflector 114 so that the light beam can be varied during scanning of the field of view 120. According to other embodiments, the processing unit 108 can control only at least one light source 112, and the optical deflector 114 can be moved or pivoted in a fixed, predetermined pattern.

[0096]

[0128] Figures A through D in Figure 5A show 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 so that the initial light emission is projected toward portion 122 of the field of view 120 during scanning of the field of view 120. If 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 can receive pilot information from the sensor 116 about the reflection 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., different time points and / or different parts of segments).

[0097]

[0129] Based on information about the reflection associated with the initial light emission, the processing unit 108 can be configured to determine the type of light emission that will subsequently be projected toward portion 122 of the field of view 120. The subsequent light emission determined for a particular portion of the field of view 120 may occur during the same scan cycle (i.e., within the same frame) or in a subsequent scan cycle (i.e., within a subsequent frame).

[0098]

[0130] In Figure B, the processor 118 can control the operation of the light source 112 so that light pulses of different intensities are projected toward a single portion 122 of the field of view 120 during scanning of the field of view 120. In one embodiment, the LIDAR system 100 may be operable to generate one or more different types of depth maps. The types of depth maps may be, for example, one or more of the following: a point cloud model, a polygon mesh, a depth image (holding depth information for each pixel or 2D array of the image), or any other type of 3D model of the scene. A sequence of depth maps may be a time series in which different depth maps are generated at different points in time. Each depth map in a sequence associated with a scan cycle (which can be rephrased as a "frame") may be generated within a period of the corresponding subsequent frame time. In one example, a typical frame time may last less than one second. In some embodiments, the LIDAR system 100 may have a fixed frame rate (e.g., 10 frames per second, 25 frames per second, 50 frames per second) or the frame rate may be dynamic. In other embodiments, the frame times of different frames in a sequence may not be identical. For example, the LIDAR system 100 can implement a rate of 10 frames per second and generate the first depth map in (average) 100 milliseconds, the second frame in 92 milliseconds, the third frame in 142 milliseconds, and so on.

[0099]

[0131] In Figure C, the processor 118 can control the operation of the light source 112 so that light pulses associated with different durations are projected toward a single portion 122 of the field of view 120 during scanning of the field of view 120. In one embodiment, the LIDAR system 100 may be able to operate to generate a different number of pulses in each frame. The number of pulses may vary between 0 and 32 pulses (e.g., 1, 5, 12, 28, or more pulses) and can be obtained based on information obtained from previous emissions. The time between light pulses depends on the desired detection range and can be between 500 ns and 5000 ns. In one example, the processing unit 108 can receive information from the sensor 116 about the reflection associated with each light pulse. Based on this information (or lack thereof), the processing unit 108 can determine whether additional light pulses are needed. It should be noted that the processing time and emission time periods in Figures A to D are not to scale. Specifically, the processing time may be significantly longer than the emission time. In Figure D, the processing unit 102 may include a continuous wave light source. In one embodiment, the initial light emission includes a period of time during which light is emitted, and subsequent emissions may be continuous with or discontinuous to the initial light emission. In one embodiment, the intensity of continuous emissions may change over time.

[0100]

[0132] In some embodiments of this disclosure, the emission pattern can be determined for each portion of the field of view 120. In other words, the processor 118 can control the light emission to enable differentiation of illumination of different portions of the field of view 120. In one example, the processor 118 can determine the emission pattern for a single portion 122 of the field of view 120 based on the detection of reflected light from the same scan cycle (e.g., initial emission). This makes the LIDAR system 100 highly dynamic. In another example, the processor 118 can determine the emission pattern for a single portion 122 of the field of view 120 based on the detection of reflected light from a previous scan cycle. For subsequent emission, differences in the pattern of subsequent emission may occur by determining different values ​​of light source parameters, such as one of the following: a. The overall energy of subsequent emissions b. Energy profile of subsequent emissions c. Number of light pulse repetitions per frame d. Optical modulation characteristics such as duration, rate, peak, average power, and pulse shape. e. Wave properties of subsequent emissions, such as polarization and wavelength.

[0101]

[0133] In accordance with this disclosure, the differentiation of subsequent emissions can be used for different applications. For example, the emission power level can be limited in portions of the field of view 120 where safety is a concern, while a higher power level can be emitted in 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, optical system safety, detection material safety, and others. In another example, based on detection results from the same or previous frames, more energy can be directed to more beneficial portions of the field of view 120 (e.g., regions of interest, distant targets, low-reflectivity targets, etc.), while limiting the irradiation 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 several times within a single scan frame time. For example, subsequent emissions can be determined after each pulse emission, or after a certain number of pulses.

[0102]

[0134] Figure 5B shows three examples of emission schemes in a single frame time of the field of view 120. According to embodiments of this disclosure, at least the processing unit 108 can use acquired information to dynamically adjust the operating mode of the LIDAR system 100 and / or determine parameter values ​​of specific components of the LIDAR system 100. Acquired information can be determined from processing data captured in the field of view 120 or received (directly or indirectly) from the host 210. The processing unit 108 can use acquired information to determine a scan scheme for scanning different parts of the field of view 120. Acquired information may include current light conditions, current climatic conditions, the current driving environment of the host vehicle, the current location of the host vehicle, the current trajectory of the host vehicle, the current topography of the road around the host vehicle, or any other conditions or objects that can be detected by light reflection. In some embodiments, the determined scan scheme may include at least one of the following: (a) designation of the portion within the field of view 120 that is actively scanned as part of a scan cycle; (b) projection plan of projection unit 102 that defines the light emission profile in different portions of the field of view 120; (c) deflection plan of scan unit 104 that defines, for example, the deflection direction and frequency and specifies idle elements in the reflector array; and (d) detection plan of detection unit 106 that defines the sensitivity or response pattern of the detector.

[0103]

[0135] Furthermore, the processing unit 108 can determine the scan scheme by at least partially obtaining the identification 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 can determine the scan scheme by at least partially obtaining the identification of at least one high region of interest and at least one low region of interest within the field of view 120. The identification of at least one region of interest within the field of view 120 may be determined, for example, from processing data captured within the field of view 120, based on data from another sensor (e.g., camera, GPS), received (directly or indirectly) from the host 210, or by any combination of the above. In some embodiments, the identification of at least one region of interest may include the identification of a portion, area, section, pixel, or object within the field of view 120 that is important to monitor. Examples of areas that may be identified as a region of interest may include crosswalks, moving objects, people, nearby vehicles, or any other environmental conditions or objects that may be useful for vehicle navigation. Examples of areas that may be identified as regions of no interest (or low interest) include static (non-moving) distant buildings, skylines, areas above the horizon, and objects within the field of view. Once at least one region of interest within the field of view 120 has been identified, the processing unit 108 can determine or modify an existing scan scheme. In addition to determining or modifying 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 may activate detectors 410 that are expected to correspond to regions of interest and deactivate detectors 410 that are expected to correspond to regions of no interest. In another example, the processing unit 108 may modify the detector sensitivity, for example, to increase the sensor sensitivity for long-range detection with low reflectance power.

[0104]

[0136] Figures A through C in Figure 5B show examples of different scan schemes for scanning the field of view 120. Each square within the field of view 120 represents a different portion 122 associated with the instantaneous position of at least one deflector 114. The luminous flux levels represented by the square filling pattern are described in explanatory text 500. Figure A shows a first scan scheme in which all portions have the same importance / priority and are assigned a default luminous flux. The first scan scheme can be used in the initial stage or periodically alternated with another scan scheme to monitor the entire field of view for unexpected / new objects. In one example, the light source parameters of the first scan scheme can be configured to generate light pulses with a constant amplitude. Figure B shows a second scan scheme in which high luminous flux is assigned to a portion of the field of view 120, and default and low luminous fluxes are assigned to the rest of the field of view 120. Low luminous flux can be assigned to the portion of the field of view 120 of least interest. Figure C shows a third scan scheme in which small vehicles and buses (see silhouette) are identified within the field of view 120. This scanning scheme allows for tracking the contours of vehicles and buses with high power, while allocating (or not allocating) low levels of light beam to the central portion of the vehicle or bus. This light beam allocation concentrates a large portion of the optical budget on the contours of identified objects, while less is allocated to the less important central portion.

[0105]

[0137] Figure 5C shows the emission of light toward the field of view 120 during a single scan cycle. In the illustrated 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 contains one or more white dots representing the number of light pulses projected toward that portion, and some portions contain black dots representing the reflected light from that portion detected by the sensor 116. As illustrated, the field of view 120 is divided into three portions: sector I on the right side of the field of view 120, sector II in the center of the field of view 120, and sector III on the left side of the field of view 120. In this exemplary scan cycle, sector I is initially assigned a single light pulse per portion, sector II, previously identified as a region of interest, is initially assigned three light pulses per portion, and sector III is initially assigned two light pulses per portion. As shown, the scan of the field of view 120 reveals four objects 208. Specifically, these are two free-form objects in the near field of view (e.g., between 5 and 50 meters), a rounded rectangular object in the medium field of view (e.g., between 50 and 150 meters), and a triangular object in the far field of view (e.g., between 150 and 500 meters). While the study in Figure 5C uses pulse count as an example of beam allocation, it should be noted that beam allocation to different parts of the field of view can be performed in other ways. For example, pulse duration, pulse angular 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, and others can be used. The description of light emission, such as a single scan cycle in Figure 5C, illustrates the various functions of the LIDAR system 100. In the first embodiment, the processor 118 is configured to detect a first object (e.g., a rectangular object with rounded corners) at a first distance using two light pulses, and to detect a second object (e.g., a triangular object) at a second distance greater than the first distance using three light pulses.In a second embodiment, the processor 118 is configured to allocate more light to the portion of the field of view where a region of interest is identified. Specifically, in this example, sector II is identified as a region of interest and is therefore allocated three light pulses, while the rest 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 so that only a single light pulse is projected onto portions B1, B2, and C1 of Figure 5C, which are part of sector III to which two light pulses were initially allocated per portion. This is because the processing unit 108 has detected a near-field object based on the first light pulse. Also, as a result of other considerations, it is possible to allocate fewer pulses than the maximum. For example, if an object at a first distance (e.g., a near-field object) is detected in at least some areas, the overall amount of light emitted to this portion of the field of view 120 can be reduced.

[0106]

[0138] Further details and examples of the various components of the LIDAR system 100 and their associated functions are included in the applicant's 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. These are included in their entirety by reference.

[0107] Exemplary implementation: Vehicle

[0139] Figures 6A to 6C illustrate an implementation of the LIDAR system 100 in a vehicle (e.g., vehicle 110). Any embodiment of the LIDAR system 100 described above or below can be incorporated into vehicle 110 to provide a distance-sensing vehicle. Specifically, in this example, the LIDAR system 100 integrates a plurality of scanning units 104 and optionally a plurality of projection units 102 within a single vehicle. In one embodiment, the vehicle can utilize such a LIDAR system to improve power, range, and accuracy within and beyond overlapping zones, and to improve redundancy in the more sensitive parts of the FOV (e.g., in the direction of forward movement of the vehicle). As shown in Figure 6A, vehicle 110 may include a first processor 118A for controlling scanning of field 120A, a second processor 118B for controlling scanning of field 120B, and a third processor 118C for controlling the synchronization of scanning of these two fields. In one example, processor 118C may be a vehicle controller and may have a shared interface between a first processor 118A and a second processor 118B. The shared interface forms an overlap in temporal and / or spatial space, enabling data exchange at the intermediate processing level and synchronization of combined field-of-view scanning. In one embodiment, the data exchanged using the shared interface may be (a) the time of flight of the received signal associated with the overlapping field of view and / or nearby pixels, (b) the laser steering position status, and (c) the detection status of an object in the field of view.

[0108]

[0140] Figure 6B shows an overlapping region 600 between field of view 120A and field of view 120B. In the illustrated example, the overlapping region relates to 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 to processors 118A and 118B, each processor can be designed to limit the amount of light emitted into the overlapping region 600 to comply with eye safety limits for light from multiple light sources, or for other reasons such as maintaining an optical budget. Furthermore, processors 118A and 118B can avoid interference between the light emitted from the two light sources by loose synchronization between scan unit 104A and scan unit 104B, and / or by controlling the laser transmission timing, and / or by timing the activation of the detection circuit.

[0109]

[0141] Figure 6C illustrates how the overlapping region 600 between fields 120A and 120B can be used to increase the detection distance of the vehicle 110. According to this disclosure, the effective detection range can be increased by utilizing two or more light sources 112 that project nominal light emissions within the overlapping zone. The term “detection range” may include the approximate distance from the 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, with a detection range of 200 meters, the LIDAR system 100 can detect objects located 200 meters (or less) from the vehicle 110 with more than 95%, more than 99%, and more than 99.5% of the time, even when 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 may have a false alarm rate of less than 1%. In one embodiment, projected light from two light sources positioned in a temporal and spatial space can be used to improve the signal-to-noise ratio (SNR) and thus enhance the range and / or quality of service of objects located in overlapping areas. Processor 118C can extract high-level information from reflected light in fields 120A and 120B. The term "extract information" may include any process of identifying information related to objects, individuals, locations, events, etc., within the captured image data by any means known to those skilled in the art. Furthermore, by sharing high-level information such as objects (road demarcations, backgrounds, pedestrians, vehicles, etc.) and motion vectors, processors 118A and 118B enable each processor to direct attention to surrounding areas that are likely to soon become areas of interest. For example, it can be determined that a moving object in field 120A will soon enter field 120B.

[0110] Example implementation: Survey system

[0142] Figure 6D shows an implementation of the LIDAR system 100 in a survey system. As described 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 survey system may include multiple LIDAR units. In the example shown in Figure 6D, the survey system can use a single rotatable LIDAR system 100 to acquire 3D data representing the field of view 120 and process this 3D data to detect people 652, vehicles 654, environmental changes, or any other data important for security.

[0111]

[0143] In accordance with several embodiments of this disclosure, 3D data can be analyzed to monitor retail processes. In one embodiment, 3D data can be used in retail processes requiring physical security (e.g., detection of intrusion into retail facilities, vandalism inside or around retail facilities, unauthorized access to protected areas, and suspicious activity around vehicles in parking lots). In another embodiment, 3D data can be used for public safety (e.g., detection of people slipping and falling on store premises, spilling hazardous liquids on store floors or resulting obstruction of passage, attacks or kidnappings in store parking lots, obstruction of fire emergency exits, and congestion inside or outside store areas). In yet another embodiment, 3D data can be used for collecting business confidential data (e.g., tracking people passing through store areas to reveal how many people pass through, where they stop, how long they stop, and how their shopping habits compare to purchasing habits).

[0112]

[0144] In accordance with other embodiments of this disclosure, 3D data can be analyzed and used for traffic violation enforcement. Specifically, 3D data can be used to identify vehicles traveling at speeds exceeding the legal limit or any other road traffic law requirement. In one example, the LIDAR system 100 can be used to detect vehicles that have crossed a stop line or designated stopping point when the traffic light is red. In another example, the LIDAR system 100 can be used to identify vehicles traveling in lanes reserved for public transport. In yet another example, the LIDAR system 100 can be used to identify vehicles making a U-turn at an intersection where certain U-turns are prohibited on a red light.

[0113]

[0145] Examples of various disclosed embodiments are described above and below with respect to the control unit that controls the scanning of the deflector, but it should be noted that various features of the disclosed embodiments are not limited to such systems. Rather, techniques for allocating light to different parts of the LIDAR FOV may be applicable to types of light-based sensing systems (LIDAR or others) where it may be desirable or required to direct different amounts of light to different parts of the field of view. In some cases, as described herein, such light allocation techniques may have a positive effect on detection capability, but other advantages may also arise.

[0114]

[0146] It should also be noted that in various sections of this disclosure and the claims, terms such as “first,” “second,” and “third” may be used to refer to various components or parts of components (e.g., light sources, sensors, sensor pixels, field of view portions, field of view pixels, etc.). These terms are used solely to facilitate the description of the various embodiments disclosed and are not intended to be limiting or to indicate any required correlation with similarly named elements or components in other embodiments. For example, a feature described as relating to “first sensor” in one embodiment described in one section of this disclosure may or may not relate to “first sensor” in a different embodiment described in a different section of this disclosure.

[0115]

[0147] It should be noted that the LIDAR system 100 or any of its components may be used in conjunction with any of the specific embodiments and methods disclosed below. Nevertheless, the specific embodiments and methods disclosed below are not necessarily limited to the LIDAR system 100 and may, in some cases, be implemented in or by other systems (but not limited to, other LIDAR systems, other electro-optical systems, other optical systems, etc., where applicable). Furthermore, although system 100 is described in relation to an exemplary vehicle-based LIDAR platform, system 100, any of its components, and any of the processes described herein may be applicable to LIDAR systems deployed on other platform types. Similarly, the embodiments and processes disclosed below may be implemented in or by LIDAR systems (or other systems such as other electro-optical systems) installed on non-vehicle platforms or in systems deployed regardless of any particular platform.

[0116] Exemplary implementation: LIDAR system with variable resolution multibeam scanning

[0148] LiDAR systems and other optical systems employing one or more laser light sources and scanning mirrors can be highly complex. Furthermore, meeting eye safety requirements may involve the use of a wide field of view. Therefore, LiDAR systems may include numerous components to acquire and collect data over a wide FOV while providing high system reliability. Existing systems typically include a laser emitter, scanning mirror, and detector (referred to as a laser rangefinder [LRF]) for each beam emitted from the laser. However, existing systems can be highly complex, have numerous components (e.g., requiring multiple LRFs), and be expensive. Therefore, there is a need to provide LiDAR and other optical systems that can provide the desired level of detection range and sensitivity while reducing system complexity, the number of parts, and cost. The embodiments disclosed herein aim to address this need.

[0117]

[0149] Figure 7A shows a schematic configuration of an exemplary disclosed LIDAR system 100 configured to generate multiple beams of emitted light, which are steered by a scanning mirror, detected by a single detector, and enable scanning of a field of view (FOV) of ±50 degrees (horizontal), all on the same optical path including a single set of optical components. As shown in Figure 7, a laser beam 714 may be emitted from a quad laser array 712. The laser beam 714 may be generated by multiple laser emitters, laser bars / arrays, or a single laser beam split into multiple beams. The laser beam 714 may be guided to a scanning mirror 720 (e.g., a MEM scanner) by a system of lenses 716 and folding mirrors 718 (e.g., optical system 710). The laser beam 714 may be steered by the scanning mirror 720. The reflected light 716 may enter the LIDAR system 100, be guided to a dichroic mirror (polarizing splitter) 740, and then focused to a single detector 750 having a lens 760. As shown in Figure 7A, each of the beams 742 is guided through shared optical components (e.g., 716, 718, 720, 740, etc.), which can reduce the number of components and therefore the cost of the LIDAR system 100.

[0118]

[0150] Figure 7B shows a vertically scannable FOV (100° × 15°) 770. A scan mirror 720 can guide the laser beam 714 along a scan line 772. The reflected laser beam 714 from a position along the scan line 772 can be guided to a detector 750. Figure 7C shows an example of a detector 750 having an active area 752 separated by an inactive area 754. As shown in Figure 7C, the detector 750 can detect spots (e.g., A, B, C, D) of the reflected laser beam 716. Similarly, as shown in Figure 7C, each active area 752 may have multiple pixels or channels (e.g., six channels as shown in Figure 6). Although a vertical scan line is shown in Figure 7B, it is intended that the LIDAR system may be configured to scan the FOV 770 along a horizontal scan line as an addition or alternative. Furthermore, the number of spots and / or pixels described above is exemplary and non-limiting, each active area 752 may have any number of channels, and the detector 750 may be configured to detect any number of spots of the reflected laser beam 716. As shown in Figures 7A-7C, the disclosed monostatic configuration can transmit and receive multiple beams on the same optical path and save many optical components and multiple MEM modules with a 100 × 15 degree FOV.

[0119]

[0151] A LiDAR system including some of the above features is disclosed. For example, Figures 1A, 2A-2G, 3C, 3D, 4A, 4B, and 7A show an exemplary LiDAR system 100 in accordance with this disclosure. In some embodiments, the LiDAR system may include a laser emission unit configured to generate multiple laser beams. In some embodiments, the LiDAR system may include an optical system configured to transmit multiple laser beams from the laser emission unit to a common scanning unit. As described above, the LiDAR system 100 may include a laser emission unit 102 (e.g., a projection unit). In some embodiments, the laser emission unit may include one or more light sources that may be laser light sources. Similarly, as described above, one or more laser light sources may include one or more laser diodes 202A that can be configured to emit one or more laser light beams 204. The disclosed LiDAR system 100 is intended to include a laser emission unit 102 configured to emit two or more laser light beams (see, for example, Figures 2B, 2C, 2E, 2F, etc.). In some embodiments, the LIDAR system 100 may include a laser source in the form of a laser array, and the laser array is intended to include two or more laser emitters. Various laser sources can be employed. For example, the laser sources associated with the laser array may include pulsed lasers having wavelengths of 860 nm to 950 nm. Multiple laser sources may be included in the laser array, and the array may be arranged in a 1D pattern or a 2D pattern. Laser sources arranged in a 1D configuration may include a laser bar array containing multiple (e.g., two or more) laser sources.

[0120]

[0152] Figure 8 shows a high-level block diagram of an exemplary architecture for the LiDAR system 100. As shown in Figure 8, the LiDAR system 100 may include a power supply 810, a controller 820, an optical module 830, a laser array 840, a sensor array 850, and a scanner 860. Similarly, as shown in Figure 8, a light beam 842 from the laser array 840 may be incident on a 2D scanner 860 that can guide the light into the FOV 870. A reflected light beam 844 returning from the FOV 870 may be received by the 2D scanner 860, which may guide the reflected light beam 844 to a sensor array 850 that can be configured to detect the reflected light beam 844. The controller 820 may perform time-of-flight calculations to determine the distances to various objects within the FOV 870, and a point cloud of distance values ​​may be generated for each scan of the FOV 870. In some embodiments, a common optical component 880 may be used both to transmit laser light 842 emitted from the laser array 840 to the 2D scanner 860 and FOV 870, and to guide the reflected light 842 received by the 2D scanner 860 from the FOV 870 to the sensor array 850. Such a configuration can offer significant advantages in terms of reduced complexity, cost, reliability, and performance. This configuration can further reduce blooming artifacts compared to continuous detector array and laser array schemes because the laser beams are optically separated and the active area at the detector is isolated.

[0121]

[0153] In some embodiments, a laser emission unit may include multiple laser emitters. For example, as shown in Figures 2B, 2C, and 2E, the laser emission unit 102 may include multiple laser emitters 112A to 112F that can be configured to project two or more beams of laser light. In some embodiments, a laser emission unit may include a single monolithic laser array containing multiple laser emitters. For example, the laser emission unit 102 may include multiple laser emitters (e.g., 112A to 112F) manufactured on a single silicon wafer. Thus, the laser emission unit can take the form of a monolithic laser array. The term monolithic laser array refers to an array of laser light sources manufactured on a single (e.g., monolithic) silicon wafer. Since the laser light sources are manufactured on a single silicon wafer, the laser light sources on a monolithic laser array can be well aligned with each other. Figure 9A shows an example of a monolithic laser array 900 containing multiple laser emitters (e.g., 912, 914, 916, etc.). In some embodiments, a monolithic laser array comprises a one-dimensional laser array. For example, as shown in Figure 9A, the laser array 900 may be a one-dimensional laser array including active regions 912, 914, 916, etc. (e.g., laser emitters) arranged in a single column. However, in some embodiments, the laser array 900 is intended to be a two-dimensional laser array including active regions separated from each other and arranged in a two-dimensional matrix. In some embodiments, the multiple laser emitters may be edge emitters. For example, one or more of the laser emitters 912, 914, 916, etc. in the laser array 900 may include edge emitter lasers. However, one or more of the laser emitters 912, 914, 916, etc. may include other types of laser emitters (e.g., vertical cavity surface-emitting lasers (VCSELs)). In some embodiments, each of the multiple laser beams may be a pulsed laser beam having a wavelength between 860 nm and 950 nm.For example, as described above, one or more laser emitters 912, 914, 916, etc., may be pulsed laser emitters configured to emit pulsed lasers having wavelengths between 860 nm and 950 nm. In some embodiments, one or more laser emitters 912, 914, 916, etc., may also be configured to emit laser light having wavelengths between 1300 nm and 1600 nm.

[0122]

[0154] In some embodiments, a monolithic laser array may include multiple active regions corresponding to multiple laser emitters and multiple inactive regions, where the multiple laser emitters are separated from each other by one or more of the multiple inactive regions. A monolithic laser array may include multiple active regions (e.g., laser light emitting regions or laser emitters) separated from each other by inactive regions (e.g., non-laser-emitting inactive regions). For example, as shown in Figure 9A, the laser array 900 may include multiple (e.g., eight) laser light emitting regions or laser emitters 912, 914, 916, 918, 920, 922, 924, and 926. The laser array 900 may also include multiple inactive regions (e.g., non-laser-emitting regions) 901-909. Adjacent active regions are intended to be separated by one or more inactive regions. For example, as shown in Figure 9A, active regions 914 and 916 may be separated by an inactive region 902. Similarly, active regions 920 and 922 may be separated by an inactive region 905. It is intended that multiple inactive regions may be arranged between active regions. For example, as shown in Figure 9A, active regions 922 and 924 may be separated by inactive regions 906 and 907. Each active region may correspond to a channel. Thus, for example, Figure 9A shows a laser array 900 having eight channels. It is intended that the laser array 900 may have any number of channels.

[0123]

[0155] In some embodiments, a monolithic laser array may include four active laser channels. In some embodiments, a monolithic laser array may include eight active laser channels. In some embodiments, a monolithic laser array may include sixteen active laser channels. In some embodiments, a monolithic laser array may include thirty-two active laser channels. For example, a laser array may include sixteen laser sources arranged in a 1D array, each having a wavelength of approximately 905 nm. Light emitted from the laser sources can travel through various optical components related to the optical path, including, for example, lenses and collimators. Figure 9B shows an exemplary monolithic laser array 950 which may include sixteen or thirty-two active regions 956. For example, as shown in Figure 9B, the monolithic laser array 950 includes active laser emission regions 956 (e.g., n1~n 32 ) may include adjacent pairs of active laser emission regions 956, and one or more non-laser emission inactive regions 958 (e.g., m1~m 31 They are separated by ). An example in Figure 9B includes 16 laser channels (or 16 laser sources in an array). Other numbers of laser sources may also be used. For example, some embodiments may include 4, 8, 32, 64 laser sources, or any other desired number of laser sources.

[0124]

[0156] In some embodiments, multiple laser emitters may include multiple monolithic laser arrays. For example, instead of manufacturing a single laser array with 32 active regions, it may be possible to manufacture two monolithic laser arrays, each having 16 active regions. For example, as shown in Figure 9B, laser array 950 may include monolithic laser arrays 960 and 962. Laser array 960 has inactive regions 958 (e.g., m1~m 15 ) Active regions (e.g., laser emitters) 956 (e.g., n1~n 16 ) may include. Similarly, the laser array 962 may include an inactive region 958 (e.g., m16 ~m 31 ) separated active regions (such as laser emitters) 956 (such as n 17 ~n 32 ) may be included. Also, as shown in FIG. 9B, both monolithic laser arrays 960 and 962 can be fabricated on the same wafer. Alternatively, monolithic laser arrays 960 and 962 can be fabricated on different wafers or on different portions of the same wafer. The laser arrays 960 and 962 can be diced from the wafer and then assembled adjacent to each other to form a single 1D laser array 950. The laser arrays 960 and 962 can be assembled by an appropriate manufacturing or assembly process (such as bonding) to accurately align the laser arrays 960 and 962.

[0125]

[0157] Laser sources may be arranged in various configurations within a 1D array. In some embodiments, the ratio of active to inactive regions in a monolithic laser array may be 1:1. For example, in some embodiments, a 1D laser array may be configured to operate with a 1:1 ratio of active laser channels to inactive intervening spaces between laser channels. This can be achieved in several ways. For example, 16 laser channels may be arranged in a 1D array 1000 such that each pair of adjacent laser sources can be separated by an inactive intervening space equal in size to each laser source. As a result, as shown in Figure 10A, the 1D array may include an alternating repeating sequence of one laser source 1010 adjacent to one inactive intervening space 1020 in the array. As shown in Figure 10A, the laser source 1010 and the inactive intervening region 1012 may be of similar size (e.g., about 0.01 mm × 0.1 mm or 0.001 mm × 0.1 mm). After the laser beams are emitted, each beam can be collimated by one or more collimators 1112. Once the beams are collimated, their spot size in the far field can be expressed as an angular size. Thus, for example, as shown in Figure 10A, the beams emitted from the laser array 1000 in Figure 10A may have an angular width of 0.1° after collimation, and the spacing between adjacent collimated beams may be 0.2°. Non-limiting examples of angular beam spot sizes are, for example, 0.07° × 0.11°, 0.1 × 0.05°, or 0.1 × 0.1°, or 0.1 × 0.2°, or 0.1 × 0.4°. The laser array 1000 contains 16 such units, but array configurations of other 1:1 ratios may also be used. For example, as shown in Figure 10B, eight active laser channels 1020 may be interleaved by eight inactive spaces 1022 of the same or different sizes. As shown in Figure 10B, the laser source 1020 and the inactive intervening region 1022 may be of similar size (e.g., 0.01 mm × 0.2 mm). As another example, as shown in Figure 10C, four active laser channels 1030 may be interleaved by four inactive spaces 1032 of the same or different sizes.As shown in Figure 10C, the laser source 1030 and the inactive intervening region 1032 may be of similar size (e.g., 0.01 mm × 0.4 mm). In each case, the output of the laser sources may be selected to provide the desired total output. For example, a 16-channel array may contain 16 30W laser sources, an 8-channel array may contain 8 60W laser sources, and a 4-laser source array may contain 4 120W laser sources, all producing a total maximum output of 480W. The emitters may have any suitable power level (e.g., between 20W and 200W).

[0126]

[0158] In some embodiments, the ratio of active region width to inactive region width in a monolithic laser array may be 1:2. In addition to 1:1 arrays, arrays with a 1:2 ratio may also be used, as shown in Figures 10A-10C. For example, as shown in Figures 10D-10F, each of the exemplary arrays described above may include an inactive intervening space twice the width of each laser source. Thus, in each of the 16-channel, 8-channel, and 4-channel array examples, each pair of laser sources may be separated by an inactive space having twice the width of one laser source. Thus, for example, as shown in Figure 10D, each laser source 1040 may have a width of 0.05 mm, and each inactive space 1042 may have a width of about 0.1 mm (e.g., 110 microns). In another example, as shown in Figure 10E, each laser source 1050 may have a width of 0.1 mm, and each inactive space 1052 may have a width of about 0.2 mm. Similarly, as shown in Figure 10F, each laser source 1060 may have a width of 0.2 mm, and each inactive space 1062 may have a width of about 0.4 mm. Other ratios of laser sources to inactive spaces are also considered. In some embodiments, the ratio of active to inactive regions in a monolithic laser array may be 1:3. In some embodiments, the ratio of active to inactive regions in a monolithic laser array may be 1:5. In some embodiments, the ratio of active to inactive regions in a monolithic laser array may be in the range of 1:1 to 1:10. Figure 10G shows an example where the active to inactive region ratio is 1:5. In this example, each active laser source is separated by an inactive space having a width equal to five times the width of one laser source. For example, as shown in Figure 10G, each laser source 1070 may have a width of about 0.1 mm, and each inactive space 1072 may have a width of about 0.5 mm.

[0127]

[0159] In some embodiments, two or more inactive regions within a monolithic laser array may have different dimensions relative to each other. While it has been stated above that both the inactive and active regions of a laser array are of equal size, it is intended that different active regions within a laser array may be of different sizes. Therefore, for example, as shown in Figure 9B, an inactive region m1 of laser array 950 may have a width w1 that is different from the width w2 of the inactive region m2 of laser array 950. As another example, as shown in Figure 9B, the active region n of laser array 950 may have different dimensions relative to each other. 16 The active area n of the laser array 950 31 It may have a width w3 that is different from the width w4.

[0128]

[0160] In some embodiments, the total length (L1) of the monolithic laser array may be between 0.5 mm and 20 mm. In another exemplary embodiment, the total length of the monolithic laser array 900 may be in the range of 1 mm to 6 mm, although other lengths are also intended.

[0129]

[0161] For example, as shown in Figure 9A, the total length of the monolithic laser array 900 may be L1. The total length of the monolithic laser array may be determined based on other size considerations, such as the size of the silicon wafer, the number of desired laser beams from the monolithic laser array, and / or the size of the laser projection system. The total length L1 of the monolithic laser array is intended to be in the range of tens of millimeters to hundreds of millimeters. In one exemplary embodiment, the total length of the monolithic laser array 900 may be in the range of 0.5 mm to 20 mm.

[0130]

[0162] The ratio of active laser sources to inactive intervening space in a laser array can be achieved in any suitable form. In some cases, each laser source may be separated by an inactive material (e.g., any non-laser-emitting material). However, in other examples, the ratio may be achieved by using a closely spaced array of laser sources that is electronically controlled to provide a desired spacing ratio (e.g., to meet the requirements of a particular application, a specific detection situation, eye safety requirements, etc.). In some embodiments, the laser emitters may be configured to be activated by a common trigger signal supplied to each of the multiple laser emitters. For example, as shown in Figure 8, each active region of the laser array 900 may be configured to emit laser light when a trigger signal is received. A single trigger signal may be supplied to each active region (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.) with the intention of causing each active region to emit laser light simultaneously. For example, a single voltage pulse may be supplied to multiple active regions of the laser array 900 or 1000. After receiving a voltage pulse, each active region that received the voltage pulse (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.) may simultaneously emit pulses of laser light. In some embodiments, the laser emission unit may include a plurality of laser emitters, each of which may be activated individually. As described above, the laser emission unit 102 may include one or more laser emitters 112A-112F. Alternatively, the laser emission unit 102 may include one or more laser arrays 900 and / or 1000, each of which may include a plurality of active regions or laser emitters (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.). Similarly, as described above, each active region may be configured to emit laser light upon receiving a trigger signal, such as a voltage pulse.Therefore, each of the laser emission active regions (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.) can be individually and / or individually activated by supplying voltage pulses to each of the active regions (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.) individually or separately.

[0131]

[0163] In some embodiments, the laser emission unit may include multiple laser emitters, where one or more subgroups of laser emitters may be activated, and the remaining laser emitters may not be activated. For example, a laser array may include 32 active laser channels that can operate in modes of various ratios. Thus, a 32-channel laser array may operate in a 1:1 active-to-inactive spatial arrangement by activating every other channel (16 channels) together and leaving 16 interleaving laser sources inactive. In one operating mode, voltage pulses may be supplied to only one set of the 16 channels, while the remaining 16 channels are not. In this case, the first set of 16 laser sources receiving the voltage pulses may emit laser light, while the second set of 16 laser sources not receiving the voltage pulses may remain inactive.

[0132]

[0164] In some embodiments, multiple laser emitters may be activated according to a random emission timing protocol. As described above, one or more laser emitters (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.) may be configured to emit laser light pulses after receiving a trigger signal such as a voltage pulse. It may also be possible to control the time at which laser pulses are emitted from one or more laser emitters (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.) by controlling the time at which a voltage pulse is delivered to one or more of those laser emitters (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.). Thus, for example, in another mode, two groups of 16 interleaving channels in a 32-channel laser array may be activated alternately in a 1:1 ratio configuration. For example, a first set of 16 channels may be activated at time t1. After a certain period, a second set of the 16 channels may be activated at time t2. Alternation may occur at the pulse frequency of the laser source, or at any multiple of the pulse frequency (or according to any other timing pattern).

[0133]

[0165] In some embodiments, multiple laser emitters may be selectively activated depending on the position of the array relative to the field of view. For example, if, in a particular orientation of the scanner, a first subset of multiple laser emitters is guided outside the FOV and a second subset of multiple laser emitters is inside the FOV, the first subset may be controlled to stop emitting while the second subset remains activated.

[0134]

[0166] In some embodiments, multiple laser emitters may be activated such that two or more of the multiple laser emitters have different pulse rates from one another. As described above, it may also be possible to control the timing at which laser pulses are emitted from one or more laser emitters (e.g., 912-926) by controlling the timing at which voltage pulses are delivered to one or more of the laser emitters (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.). Therefore, the rate at which laser light is emitted from selected emitters may also differ, for example, by delivering voltage pulses at different pulse rates to selected laser emitters (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.).

[0135]

[0167] In some embodiments, multiple laser emitters can be activated such that two or more of the multiple laser emitters have different intensity levels from each other. The intensity of the laser light emitted by each of the laser emitters (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.) may depend on the voltage level of the trigger signal or voltage pulse delivered to each of the laser emitters (e.g., 912-926, 956, 1020, 1030, 1040, 1050, etc.). Therefore, by providing different laser emitters (e.g., 912-926) with trigger signals or voltage pulses having different voltage levels, different laser emitters can be activated to emit laser light pulses of different intensities.

[0136]

[0168] Similar operations can be employed to achieve active-to-inactive ratios other than 1:1. For example, to provide a 1:2 ratio, each of eight sets of active laser sources may be spaced apart by two inactive laser sources. In one operating mode, the inactive laser sources may remain inactive while laser pulses are emitted from the eight active sources. In other cases, eight (or any other number) sets of active lasers out of a total set of 24 laser sources may be varied in any desired timing pattern (e.g., alternating pulses, pulse multiples, etc.). Similar operating schemes can be employed in arrays operating at a 1:5 ratio, or at any other desired ratio.

[0137]

[0169] It should also be noted that a particular laser array may operate at different active-to-inactive ratios at different points in time. For example, during a single scan of the FOV or a subregion of the FOV, the array may operate at a 1:1 ratio. During a different scan of the FOV or a different subregion of the FOV, a different ratio (e.g., 1:2, 1:4, 1:5, etc.) may be used. Furthermore, the laser sources selected to be active during a particular clock cycle may be predetermined or randomized, maintaining a desired active-to-inactive interval ratio.

[0138]

[0170] Various conditions can be used to determine the active-to-inactive ratio to be used. In some cases, the ratio may remain fixed. However, in other cases, the selected ratio may be triggered based on detected events. For example, pedestrian detection may ensure the selection of a higher ratio of inactive space to active space, for instance, to increase visual safety margin. Various other event triggers can also be used to select a desired interval ratio.

[0139]

[0171] As described above, many different laser array configurations can be used according to the requirements of a particular application. Referring again to Figures 10D-10F, a particular laser source array may include 16, 8, or 4 channels, among many other possible channel counts. These channels may be configured as part of a fixed laser array, and each laser source (e.g., 1040, 1050, 1060) may be positioned at a desired distance from its adjacent laser sources to produce beams spaced apart by a certain angular distance. For example, in an eye-safe configuration, this angular distance may be at least about 5.2 mrad. In some embodiments, the inactive space between the laser sources (e.g., 1042, 1052, 1062, respectively) may contain any non-photo-emitting material. However, in other cases, the laser array 1000 may consist of closely spaced laser sources with little or no non-photo-emitting material between each laser source in the laser array. Such embodiments can offer a considerable degree of flexibility, as the laser sources of the laser array can be selectively operated according to the requirements of a particular application.

[0140]

[0172] In some embodiments, for example in Figures 10D–10F, a particular laser array may include 48 closely spaced laser sources (or any number of laser sources). In the particular example illustrated, each laser source may produce a beam with an angular dimension of 0.1 degrees × 0.05 degrees after collimation. In some cases, all laser sources may be activated simultaneously. In other cases, any other laser source may be activated during an irradiation event (e.g., a single clock-timed pulse from a laser source selected from the array). The operation of any other laser sources in a closely spaced laser array provides a 1:1 ratio of active to inactive space. Similarly, every other laser source may be activated during an irradiation event to provide a 1:3 ratio of active to inactive space (as shown in the leftmost example below). In this particular example, where each closely spaced laser source may produce a beam spot with an angular dimension of 0.1 degrees × 0.05 degrees, activating every other laser source may result in a spacing of approximately 0.15 degrees (or approximately 2.6 mrad) between active laser sources.

[0141]

[0173] In another example, as shown in Figure 10E, the laser array 1000 may include the same laser source array as described above (i.e., an array of 48 closely spaced lasers, each having an angular dimension of 0.1 degrees × 0.05 degrees). In this example, the 1:2 ratio of active space to inactive space can be achieved by irradiating the first two lasers in each of the six groups together (e.g., lasers 1, 2, 7, 8, 13, 14, etc.) and leaving the remaining lasers inactive. In this case, each group of two irradiated lasers may have a total angular dimension of 0.1 degrees × 0.1 degrees, and the spacing between active laser groups may be 0.3 degrees or about 5.23 mrad (which may reduce the emission level or meet certain criteria for eye safety).

[0142]

[0174] In Figure 10F, a 1:2 ratio of active to inactive space can be achieved by irradiating the first four lasers in each of the 12 groups (e.g., lasers 1, 2, 3, 4, 13, 14, 15, 16, etc.) together, while leaving the remaining lasers inactive. In this case, each group of four irradiated lasers may have a total angular dimension of 0.1 degrees × 0.2 degrees, and the spacing between active laser groups may be 0.4 degrees or about 7 mrad (which may meet certain standards regarding eye safety).

[0143]

[0175] In some embodiments, each of multiple laser beams generates an elongated spot having an angular width of 0.002 to 0.2 degrees and an angular length of 0.02 to 0.2 degrees. For example, when a laser beam emitted from a laser array is incident on an object in the field of view, the beam can generate a spot of laser light on the object. The shape of the emitted beam (spot) may be symmetrical or uniaxially elongated. An elongated shape may improve eye safety in some cases. Figure 10H shows an exemplary magnified image of a spot generated by a laser beam emitted from, for example, a laser array 900. As shown in Figure 10H, the spot may have an angular width between 0.04 to 0.08 degrees and an angular length between 0.09 to 0.15 degrees. To further enhance eye safety, the ratio of active to inactive spacing in the laser array (e.g., 950, 1000) may be selected to preserve the minimum angular spacing between active laser beams. The minimum spacing may be determined, for example, by a government or safety standards agency. In some cases, the minimum angular spacing between beams can be 5 mrad or approximately 0.29 degrees.

[0144]

[0176] In some embodiments, the laser emission unit may include a laser emitter configured to generate a primary laser beam and a beam splitter configured to split the primary laser beam into a plurality of sub-beams that provide a plurality of laser beams. In some embodiments, the optical system may include a beam splitter. While laser arrays capable of generating a plurality of laser beams have been described above, in some embodiments, the laser emission unit 102 of the LIDAR system 100 may also include a laser emitter 112 configured to generate a primary laser beam and a beam splitter configured to split the primary laser beam into two or more sub-beams that can provide a desired plurality of laser beams. The beam splitter may include one or more prisms, partially silver-plated mirrors, deflectors with dichroic optical coatings, and the like.

[0145]

[0177] Figure 14A shows an exemplary beam splitter 1440 which may include multiple stacked and coated glass plates positioned at a 45-degree angle to the initial laser beam. Rather than the typical manufacturing technique of cutting, coating, and then bonding, the beam splitter 1440 in Figure 14A may be manufactured by coating individual glass plates 1410 to provide the desired reflectivity. The coated plates 1420 may be stacked and bonded to form a stack 1430 of bonded plates. The stack 1430 may then be cut into individual beam splitters 1440. Steps for producing an N-splitter may include: 1) Starting with N-1 flat glass plates 1410. 2) Coating one side of each plate for the desired reflectivity to prepare the coated plates 1420. 3) Coating the back side of the last plate with a reflective coating of approximately 100%. 4) Stacking all the plates together to form a stack 1430, and then bonding them with a non-refracting adhesive. (5) The plate is cut in three dimensions (as shown by the dashed lines in Figure 14A) to provide individual beam splitters 1440.

[0146]

[0178] Another type of beam splitter that may be used with the embodiments disclosed herein includes a molded barrel having dielectric-coated partial-reflection inclined mirrors, as shown in Figure 14B. In this embodiment, the laser beam may be split when it passes through the partial-reflection mirrors, and when such mirrors are arranged in series, the incident laser beam may be split multiple times. The power ratio may be determined by the partial reflectance of each mirror and may be controlled using a fitted AR coating. Such a configuration may include a half-open molded barrel having sockets for the inclined mirrors. Each mirror may be window-shaped and may be cut from a larger coated glass plate. Manufacturing steps for producing such a beam splitter may include: 1) Starting with N thin glass plates 1440; 2) Coating one side of each plate with a dielectric coating for the desired reflectance and the opposite side with an AR approximately 0.5% reflective coating; 3) Cutting the mirrors from each plate as small window-shaped pieces 1450; 4) Molding the barrel 1460; 5) Combining the mirrors 1450 into the molded barrel 1460.

[0147]

[0179] In some embodiments, an output meter may be integrated with the multi-beam splitter described above. For example, one port of the splitter may be used to monitor the laser output. In a multi-port splitter configured to split an incident laser beam into N sub-beams, the splitter may include N+1 ports, one of which may be used to monitor the laser output or to detect any irregularities. As shown in Figure 14C, the detector 1470 (PD) for monitoring the output may be positioned uniaxially with the laser emitter (to detect transmitted light) or, alternatively, oriented at a different angle to detect reflected light from the beam splitter.

[0148]

[0180] In one embodiment, the incident laser beam may be split into four equal sub-beams, and a fifth port may be used for monitoring the laser output, for example. However, the beam required for output monitoring does not need to have the same intensity as the split sub-beams. For example, in one embodiment, the residual beam after splitting may represent about 2% of the incident laser beam output / intensity, and the residual beam may be used for laser monitoring. This example may be provided using a coating having reflectivity and transmittance at the four interfaces, as shown in Table 1 below.

[0149] [Table 1]

[0150]

[0181] In some embodiments, the beam splitter may be configured to transmit each of a plurality of laser beams and re-direct a plurality of reflected beams received from the field of view of the LIDAR system. Figure 11A shows an exemplary LIDAR system 100 including a beam splitter 1110. As shown in Figure 11A, the LIDAR system 100 may include a monolithic laser array 950 configured to emit one or more laser light beams (e.g., 1102, 1104, 1106, 1108). One or more laser light beams may be collimated by one or more collimators 1112 before beams 1102, 1104, 1106, and / or 1108 are incident on the beam splitter 1110. The beam splitter 1110 may pass the laser beams 1102, 1104, 1106, and / or 1108 through the deflectors 1121 and 1123, which may be configured to guide the laser beams 1102, 1104, 1106, and / or 1108 toward the FOV 1170. Although only two deflectors 1121 and 1123 are shown in Figure 11A, the LIDAR system 100 is intended to include three or more deflectors 1121 and 1123 configured to guide one or more of the light beams 1102, 1104, 1106, and / or 1108 toward the FOV 1170. One or more objects within the FOV 170 may reflect one or more of the light beams 1102, 1104, 1106, and / or 1108. As shown in Figure 11A, the reflected light beams may be represented as laser light beams 1152, 1154, 1156, and / or 1158. Although the reflected laser light beams 1152, 1154, 1156, and / or 1158 are shown in Figure 11A as being directly incident on the beam splitter 1110, it is intended that some or all of the light beams 1152, 1154, 1156, and / or 1158 may be directed toward the beam splitter 1110 by deflectors 1121, 1123, and / or other deflectors.When the light beams 1152, 1154, 1156, and / or 1158 reach the splitter 1110, the splitter 1110 may be configured to guide the reflected light beams 1152, 1154, 1156, and / or 1158 received from the FOV 1170 through the lens 1122 toward the detector 1130. Figure 11A shows four light beams emitted by the monolithic laser array 950, but the monolithic laser array 950 is intended to emit any number of light beams (e.g., fewer or more than four).

[0151]

[0182] In some embodiments, a beam splitter may be configured to redirect each of a plurality of laser beams and transmit a plurality of reflected beams received from the field of view of the LIDAR system. As an example, Figure 11B shows an exemplary LIDAR system 100 which may include a monolithic laser array 950, a collimator 1112, a beam splitter 1110, deflectors 1121, 1123, a lens and / or optical filter 1122, and a detector 1130. As shown in Figure 11B, the monolithic laser array 950 may emit one or more laser light beams 1102, 1104, 1106, and / or 1108 that can be collimated by one or more collimators 1112 before being incident on the beam splitter 1110. The beam splitter 1110 may be configured to direct one or more of the laser beams 1102, 1104, 1106, and / or 1108 toward the deflectors 1121, 1123, and the deflectors 1121, 1123 may be configured to direct one or more of the laser beams 1102, 1104, 1106, and / or 1108 toward the FOV 1170. As described above, one or more objects within the FOV 1170 may reflect one or more of the laser beams 1102, 1104, 1106, and / or 1108. The reflected laser beams 1152, 1154, 1156, and / or 1158 may be directed by the deflectors 1121, 1123 to enter the beam splitter 1110. It is also intended that some or all of the reflected laser beams 1152, 1154, 1156, and / or 1158 may reach the beam splitter 1110 without being directed toward the beam splitter 1110 by the deflectors 1121, 1123. As shown in Figure 11B, the beam splitter 1110 may be configured to allow the reflected laser beams 1152, 1154, 1156, and / or 1158 to pass through the beam splitter 1110 toward the detector 1130. One or more lenses and / or optical filters 1122 may receive the reflected laser beams 1152, 1154, 1156, and / or 1158 and direct these beams toward the detector 1130.Figure 11B shows four light beams introduced by the monolithic laser array 950, but the monolithic laser array 950 is intended to emit any number of light beams (e.g., fewer or more than four).

[0152]

[0183] In some embodiments, the optical system may include at least one folding mirror into which multiple laser beams are incident. For example, as shown in Figure 7A, the LIDAR system 100 may include an optical system 701 which may include a folding mirror 718. The folding mirror 718 may be configured to receive one or more laser beams 714 from a quad laser array 712. In some embodiments, the optical system may include at least one collimation lens configured to collimate multiple laser beams. For example, as shown in Figure 7A, the optical system 701 may include a collimator 716 configured to guide the laser beams 714 toward the folding mirror 718. In another example, as shown in Figures 11A and 11B, the LIDAR system 100 may include a collimator 1112 configured to receive one or more laser beams (e.g., 1102, 1104, 1106, 1108) from a laser array 950 and guide the received laser beams toward a beam splitter 1110. In some embodiments, the optical system may include a receiving lens system configured to receive multiple laser beams. For example, one or more collimators 716 or 1112 may each include a receiving lens system configured to receive one or more laser beams emitted by the laser array 712 or 950.

[0153]

[0184] In some embodiments, a common scanning unit may be configured to project multiple laser beams toward the field of view of the LiDAR system, simultaneously scanning the field of view along multiple scan lines that cross the field of view. In some embodiments, the LiDAR system may include a scanning unit configured to receive multiple laser beams, and the common scanning unit is configured to project multiple laser beams toward the field of view of the LiDAR system. As described above with reference to Figures 7A and 8, the LiDAR system 100 may include scanning units (e.g., 720, 860). In some embodiments, the common scanning unit may include a light-transmitting scan rhythm. In some embodiments, the common scanning unit may include a diffraction-based scanner. In some embodiments, the common scanning unit may include a liquid crystal on silicon scanner. In some embodiments, the common scanning unit may include a single biaxial scanning mirror onto which multiple laser beams are incident. In some embodiments, the common scanning unit includes a pair of monoaxial scanning mirrors. Scanning units 720, 860 may include various optical components configured to guide the laser light toward the field of view. For example, the scan units 720 and 860 may include one or more light-transmitting scamp rhythms, diffracting elements, liquid crystal deflectors, MEM mirrors, etc. Similarly, as described above, two or more beams originating from a beam splitter (e.g., 220 or 1110) or laser array (e.g., 900, 950) may be incident on a scan mirror device (e.g., 720 or 860). The scan mirror device may include a single mechanically operated biaxial scan mirror. Alternatively, the scan mirror device may include two or more mirrors or transmission scanners. This configuration may offer two important advantages over conventional LIDAR systems: 1) Each beam may be spaced apart and have an intensity below the eye safety threshold so that the LIDAR system 100 is safe for the eye within any range.2) By supplying the beam to a single scan mirror (e.g., 720, 860) and arranging the beam projected from the scan mirror onto the FOV perpendicular or horizontal to each other, an extended vertical FOV can be provided compared to a single beam or multiple beams per mirror system incident on a scan mirror that does not have a vertical spot orientation within the FOV.

[0154]

[0185] In some embodiments, a two-axis scan mirror is rotatable around two axes, including a tilt axis and a scan axis. For example, the scan units 720, 860 may include any type of scan mirror arrangement, including any of the scanners described in the above section. In some embodiments, the scan units 720, 860 may include a MEM mirror or an array of MEM mirrors. A MEMS mirror may be rotatable around two axes that may be orthogonal. For example, the scan units 720, 860 may include a MEMS mirror similar to the MEM mirror in Figure 3B, having two generally orthogonal axes of rotation. One of the two axes may allow the scan units 720, 860 to tilt (e.g., to guide the laser beam vertically in the FOV), and the other axis may allow the scan units 720, 860 to scan (e.g., to guide the laser beam horizontally in the FOV). The mirrors for a two-axis 2D scan may be actuated using a mechanical configuration (e.g., motor-driven, magnetic, etc.).

[0155]

[0186] In some embodiments, rotation of a biaxial scan mirror around a scanning axis causes the movement of multiple laser beams along multiple scan lines that cross the field of view of the LIDAR system. For example, in some LIDAR systems 100, as described above, a single laser source can be scanned across the LIDAR FOV using a scanner such as a 2D scanner (e.g., scan units 720, 860). Figure 12A shows an exemplary scan pattern 1200 obtained using a 2D scan mirror (e.g., the MEM mirror in Figure 3B, or a biaxial mechanically rotating mirror) capable of guiding a laser beam from a single laser source across the illustrated scan pattern. For clarity, it should be noted that the on-axis values ​​are normalized to the maximum amplitude of the scan so that the maximum amplitude is 1. For example, by sequentially rotating scan units 720, 860 around a scanning axis, the laser beam can be guided horizontally along multiple points, as represented by scan line 1201. Furthermore, by sequentially rotating scan units 720, 860 around a scanning axis, the laser beam can be guided vertically along multiple points. The combined 2D motion of scan units 720 and 860 can generate the scan pattern shown in Figure 12A, which includes scan lines 1201, 1203, 1205, and so on.

[0156]

[0187] As shown in Figure 12A, the horizontal scan lines 1201, 1203, and 1205 do not need to be equally spaced. For example, to scan a specific area of ​​the LIDAR FOV, such as areas above and below the horizon, a vertical tilt increment greater than the minimum available tilt increment may be selected with respect to the 2D scan mirror. In the illustrated example, areas above and below the scan center may be scanned with a different vertical tilt increment than the vertical tilt increment of the scan center. The scan center may be oriented, for example, towards the horizon. For example, areas above and below the scan center may be scanned using a vertical tilt increment of 0.6°, which may correspond to the entire laser array angular size, thus producing a coarse sampling resolution equal to the laser pitch in the array. The laser pitch refers to the distance between the centers of the active laser light emission regions of the laser array. However, in the area containing the scan center, the minimum vertical tilt angle may be used to provide closer-spaced scan lines within that area, and even to provide a higher sampling / point cloud resolution within that area. Assuming a laser active area to inactive area ratio of 1:N-1, the line spacing can be reduced by a factor of N. In this example, the vertical resolution of the point cloud may depend on the line spacing, and the horizontal resolution may depend on the frequency at which a single laser source is pulsed as the 2D scan mirror scans along each horizontal scan line. The higher the pulse frequency, the higher the possible horizontal resolution of the point cloud generated from the LIDAR system.

[0157]

[0188] In some embodiments, rotation of a biaxial scan mirror around a tilt axis may result in the displacement of multiple laser beams from a first set of positions associated with a first set of scan lines to a second set of positions associated with a second set of scan lines. In some embodiments of the LIDAR system 100, it is intended that multiple laser sources may be used rather than relying on a single laser source. It is also intended that light beams from one or more laser sources may be split to provide multiple laser beams available for scanning. Similarly, as described above, a laser array (e.g., a 1D laser array as described in the examples in the above section) may be used to provide multiple laser beams for scanning the LIDAR FOV. When multiple laser light beams from either a laser array (e.g., 950) or a beam splitter (e.g., 220, 1110) are directed to a scan unit (e.g., 720, 860), rotation of the scan units 720, 860 around a scanning axis may generate multiple horizontal scan lines traversing the first set of positions. Furthermore, the rotation of the scan units 720, 860 around the tilt axis can vertically shift multiple horizontal scan lines, thereby generating a second set of scan lines that crosses a second set of positions vertically spaced apart from a first set of positions. In some embodiments, the rotational speed around the scan axis may be faster than the rotational speed around the tilt axis. Figure 12B shows a scan pattern 1220 obtained using multiple laser beams. As shown in Figure 12B, multiple laser beams can enable the generation of horizontal scan lines 1221, 1223, 1225, etc. When the scan units 720, 860 rotate around the tilt axis, the horizontal scan lines (e.g., 1221, 1223, 1224, 1225, etc.) may be vertically displaced by a distance DH corresponding to the rotation of the scan units (e.g., 720, 860) around the tilt axis.

[0158]

[0189] In some embodiments, a common scanning unit may include a first single-axis scanning mirror and a second single-axis scanning mirror, where multiple laser beams are incident on the first single-axis scanning mirror and then proceed to the second single-axis scanning mirror. While the scanning units 720, 860 that can rotate around two axes of rotation have been described above, in some embodiments, the scanning units 720, 860 may include mirrors or deflectors that can rotate around only one axis of rotation. For example, the scanning units 720, 860 may include mirrors or deflectors similar to the mirror in Figure 3A. In these embodiments, the first single-axis scanning mirror may receive a laser beam from the laser emission unit 102 and guide the laser beam to the second single-axis scanning mirror, which may then guide the laser beam toward the field of view.

[0159]

[0190] In some embodiments, the first monoaxial scan mirror may be configured to rotate around the scanning axis to cause movement of multiple laser beams along multiple scan lines traversing the field of view of the LIDAR system. In some embodiments, the first monoaxial scan mirror may be configured to rotate around the tilt axis to cause displacement of multiple laser beams from a first set of positions associated with the first multiple scan lines to a second set of positions associated with the second multiple scan lines. For example, by using a combination of two or more 1D scanners, and by rotating the first and second monoaxial scan mirrors around two different axes of rotation, a 2D scan similar to scan pattern 1200 or 1220 can be generated. As an example, Figures 11A and 11B show a pair of deflectors 1121, 1123, one of which may be rotatable around the scanning axis and the other rotatable around the tilt axis. For example, as shown in Figure 11B, the first single-axis scan mirror 1121 may be rotatable left-right around a first axis (e.g., a vertical axis or a scanning axis), allowing laser beams 1102, 1104, 1106, 1108, etc., to generate horizontal scan lines similar to lines 1201, 1203, 1205, etc., shown in Figure 12B. Furthermore, by rotating the second single-axis scan mirror 1123 around a second axis (e.g., an axis perpendicular to the first axis or a tilt axis), the scan lines 1201, 1203, 1205, etc., can be shifted by a distance DH, as shown in Figure 12B.

[0160]

[0191] In some embodiments, the field of view of a LiDAR system may have a vertical angular dimension between 6 and 90 degrees, and the field of view of a LiDAR system may have a horizontal angular dimension between 20 and 140 degrees. As described above, the scan units 720, 860 can rotate around the scan axis and / or tilt axis to project laser light over a desired field of view. Reflected laser beams from the field of view may be detected to detect the presence of one or more objects within the field of view. The range of the field of view may depend on many factors, including the maximum rotation span of the scan units 720, 860 around their respective scan and tilt axes, the divergence angle of the laser beam, and the angles between multiple laser beams projected from the scan units 720, 860. In some exemplary embodiments, the field of view is intended to extend over scan angles in the range of 20 to 140 degrees and tilt angles in the range of 6 to 90 degrees. It should be understood that the range of the FOV is described with respect to world coordinates. For example, the scan units 720 and 860 may include a 20 x 20 mm twin-axis rotating mirror that can provide a 140 x 44 degree FOV.

[0161]

[0192] In some embodiments, the field of view scanning of the LIDAR system may be performed at a frame rate between 5 Hz and 40 Hz. Therefore, the field of view scan may be repeated many times per second or per minute, for example, to continuously detect any changes in the position of one or more objects within the field of view. In one embodiment, the scan units 720, 860 may scan the field of view at a frame scan rate of 20 Hz (e.g., 20 times per second). It should be understood that the scan units 720, 860 may be configured to support a specific scan rate or a scan rate range of 5 to 50 Hz, depending on the requirements of a particular application. In one exemplary embodiment, 16 emitted pulsed light beams may be projected from the scan units 720, 860 toward the FOV. The spots formed by the reflected laser light beams may have a size of 0.07 degrees × 0.10 or 0.11 degrees. The vertical arrangement of the spots may depend on the configuration of the laser sources on the laser source array. For example, the amount of space between each laser source may result in corresponding space between the returned spots.

[0162]

[0193] In one exemplary embodiment, the laser beam spots may have a vertical angular dimension of 0.1 degrees and may be spaced about 0.2 degrees apart (or a ratio of about 2:1 between open space and laser emitter). For 16 channels, the overall vertical pattern (or "comb") of the light beams projected toward the FOV may occupy an angular height of about 4.6 degrees. This comb may be steered horizontally across the width of the FOV by a 2D scanner (e.g., scan units 720, 860), and the horizontal resolution may be determined by the scan speed and the pulse rate of the laser source. When the 2D scanner reaches its horizontal limit, the 2D scanner may be incremented vertically (e.g., rotated around a tilt axis) to continue horizontal scanning of the FOV with a new set of horizontal scan lines. Of course, in other examples, other pulse rates, scan rates, laser sizes, laser spacing, etc., may also be used. Furthermore, although the disclosed examples describe a vertical comb pattern scanned horizontally across the FOV, some embodiments may employ a horizontally oriented light source array, where a horizontally oriented 1D array of transmitted laser light spots is scanned vertically across the FOV. Additionally, a 2D array of laser sources may also be employed. The lasers may be arranged in a square or rectangular pattern, or any other type of pattern (e.g., a hexagonal array). It should be understood that the disclosed figures are illustrative and non-limiting.

[0163]

[0194] In some embodiments, multiple laser beams are incident on a common position on a single biaxial scanning mirror. For example, as shown in Figure 7A, multiple laser beams 714 may be guided to a common position 722 on the MEMS mirror 720. However, in other embodiments, multiple laser beams 714 may be guided to different parts of the MEMS mirror 720. The rotation of the MEMS mirror 720 may be adjusted to guide the laser beams 714 toward the field of view. Multiple laser beams guided toward the field of view by the MEMS mirror 720 may be separated from each other by equal or unequal angles. In some embodiments, multiple laser beams may be projected from a single biaxial scanning mirror, and the angular spacing between adjacent beams is intended to be at least 2.5 mrad. In some embodiments, the angular spacing may be in the range of 2.5 mrad to 15 mrad.

[0164]

[0195] In some embodiments, the LIDAR system may include at least one processor configured to control the orientation of one or more components of a common scanning unit to cause scanning of the LIDAR system's field of view with multiple laser beams along a series of scan lines. For example, as described elsewhere in this disclosure, the scanning units 720, 860 may be individually controlled by a processor (e.g., 118) so that the scanning units 720, 860 may rotate toward a particular angle along each of one or two separate axes. By controlling the scanning units 720, 860, the processor 118 may be able to direct one or more laser beams toward different parts of the field of view, thereby enabling the LIDAR system 100 to scan the field of view using one or more laser beams as described above.

[0165]

[0196] In some embodiments, a LIDAR system may include detectors configured to emit electrical signals in response to reflected beams received from the field of view of the LIDAR system. For example, as described above, the LIDAR system 100 may include one or more detectors (e.g., a detection unit 116) configured to detect one or more objects in the field of view. Detector 116 may include a plurality of detection elements 402 for detecting laser light reflected back from the field of view 120. The detectors may be configured similarly to any of the detectors discussed in the above section. For example, in some embodiments, the detectors may include an array of sensors (e.g., a multi-channel SiPM sensor array or a SPAD array or an APD array). The detectors may include arrays of detector channels, SPADs, SiPMs, APDs, etc.

[0166]

[0197] In some cases, the detector may be arranged in a 1D configuration. In some embodiments, the detector may include a single monolithic array of photosensitive active regions. For example, detector 116 may be a monolithic detector that can be manufactured on a single silicon wafer. Figures 11A and 11B show an exemplary monolithic detector 1130. In some embodiments, the photosensitive active regions may be separated from each other by one or more inactive regions. For example, as shown in Figures 11A and 11B, the monolithic detector 1130 may include multiple photosensitive active regions 1132 separated by inactive regions 1134. The sizes of the active regions 1132 and 1134 may be equal or unequal.

[0167]

[0198] In some embodiments, the ratio of photosensitive active regions to inactive regions within the detector is 1:1. For example, in some embodiments, the 1D detector 1130 may be configured to operate with a 1:1 ratio of active regions to inactive regions. This can be achieved in several ways. For example, as shown in Figure 13A, the detector 1130 has n active regions (n1~n N ) and N-1 inactive regions (m1~m N-1) may include, and each pair of active regions may be separated by an inactive region. As shown in Figure 13A, the 1D detector may include an alternating repeating sequence of active regions 1310 adjacent to one inactive region 1312 in an array of equal size. Thus, the ratio of active to inactive regions may be 1:1.

[0168]

[0199] In some embodiments, the ratio of photosensitive active regions to inactive regions within the detector is 1:2. In addition to 1:1 arrays, arrays with a 1:2 ratio may also be used, as shown in Figure 13A above. For example, as shown in Figure 13B, the detector 1130 may instead include an alternating repeating sequence of active regions 1310 adjacent to inactive regions 1322, where the inactive regions 1322 may have a width twice that of each active region 1310. Other ratios of laser source to inactive space are also considered. In some embodiments, the ratio of photosensitive active regions to inactive regions within the detector is 1:3. In some embodiments, the ratio of photosensitive active regions to inactive regions within the detector is 1:5. In some embodiments, the ratio of photosensitive active regions to inactive regions within the detector is between 1:1 and 1:10. Figure 13C shows an example where the active to inactive region ratio is 1:5. In this example, each active region 1310 is separated by an inactive region 1324 having a width equal to five times the width of the active region 1310.

[0169]

[0200] The monolithic detector 1130 may have any number of active and inactive regions. For example, N for the detector array 1310 in Figures 13A-13C may range from 1 to any desired number. Therefore, for example, N may be 4, 8, 16, 32, 64, etc. In some embodiments, the detector may include 4 photosensitive active regions (e.g., N=4). In some embodiments, the detector may include 8 photosensitive active regions (e.g., N=8). In some embodiments, the detector may include 16 photosensitive active regions (e.g., N=16). In some embodiments, the detector may include 32 photosensitive active regions (e.g., N=32).

[0170]

[0201] In some embodiments, two or more of the multiple laser beams may have different divergences. Each of the laser beams (e.g., 714, 1102, 1104, 1106, 1108, etc.) is shown as a single line in Figures 7A, 11A, 11B, etc., but each laser beam is expected to diverge after leaving the laser irradiation system 102. Thus, each of the laser beams 714, 1102, 1104, 1106, 1108 may be represented by multiple rays that diverge from each other as the distance toward the field of view increases. It is also intended that the divergence amounts or divergence angles of the different laser beams (e.g., 714, 1102, 1104, 1106, 1108, etc.) may or may not be equal. In some embodiments, each of the reflected beams may generate a beam spot that is incident on two or more photosensitive active regions. The multiple rays representing each laser beam may be reflected from the field of view. Multiple reflected rays can form spots on a detector (e.g., 1130). In some embodiments, it is intended that the spots of the reflected laser beam rays may be incident on, for example, only one active region 1310 of the detector 1130, or on two or more active regions of the detector 1130. Figure 13A shows an exemplary spot 1350 that may be incident on two or more active regions 1310 (e.g., n2, n3) of the detector 1130. By ensuring that the spot 1350 is incident on multiple active regions 1310, it may be possible to ensure that the multiple active regions generate signals corresponding to the detected objects that reflected the laser beam. The separate signals corresponding to regions on the detected object allow for increased resolution with respect to those regions, i.e., each active region is an individual pixel of a subregion within the region of the detected object.

[0171]

[0202] In some embodiments, the ratio of the distance between active regions to the distance between beam spots incident on the detector is a predetermined value. For example, the distance between beam spots generated by laser beams emitted from a laser array may be a predetermined multiple of the distance between active regions (e.g., 1132) of the detector 1130. Therefore, for example, the spacing between beam spots may be 0.5, 1.0, or 1.5 times the spacing between active regions 1132 of the detector 1130. Also, the size of each beam spot may be a multiple of the size of the active region 1132. For example, each beam spot may be 0.5, 1.0, or 1.5 times the size of the active region 1132. It should be understood that the scaling factors 0.5, 1.0, 1.5, etc. are illustrative and non-limiting, and other scaling factors are also intended.

[0172]

[0203] In some embodiments, the LIDAR system may include an array of microlenses and / or a diffuser configured to guide the reflected beam into each photosensitive active region of the detector. When multiple beams are used, the detector 1130 may be configured so that each beam enters one or more active regions of the detector 1130. In these cases, the pitch of the detector 1130 (e.g., the distance between the centers of the active regions) may need to correspond to the pitch between the active laser emission regions, such as laser arrays 900, 950. The space between the active regions of the detector 1130 may be "dead" space on the silicon, and it is advantageous to minimize this dead space. Whenever the emitter configuration changes (e.g., pitch, space between emitters, etc.), the detector configuration may need to be changed accordingly.

[0173]

[0204] To address this problem, a “adapter” for the beam may be provided to extend or project the beam onto a specific region on the detection element. This allows the reflected laser beam to produce an image on the adapter plane rather than the plane of the detector 1130. The adapter may include a mask and an element for extending or diffusing (diverging) the beam to the correct detection element. This element may be a diffuser or may include one or more microlenses. For example, an array of microlenses may be used to guide the light received by the adapter to the appropriate active region of the detector 1130. Using such an adapter may allow the detector 1130 to be expanded to a larger size (with less dead space) where the reflected laser beam can be diffused. An additional advantage of this adapter may be that it can decouple the detector from its dependence on the emitter configuration. For example, if the pitch between the laser emission active regions in the laser array 900 or 950 is changed, a suitable adapter element may be used to guide the reflected laser beam to the active region of the detector 1130 without requiring a completely new silicon-fabricated detector.

[0174] Exemplary implementation: A LiDAR system with variable resolution multibeam scanning achieved by changing the tilt increment of the deflector.

[0205] A LIDAR system may use an emission system that emits two or more beams. In some embodiments, a LIDAR system may use a beam splitter to split a laser beam originating from a single light source into two or more beams. Alternatively, the emission system may include a laser array, which may include two or more laser emitters capable of producing two or more beams of laser light. The two or more beams (originating from the beam splitter or laser array) may be incident on a scanning device (e.g., a scanning mirror, prism, or other type of scanning device). In some cases, the scanning device may include a single biaxial scanning mirror. Alternatively, the scanning device may include two or more mirrors or a transmission scanner. This configuration may offer certain advantages over conventional LIDAR systems, such as: 1) Each beam may be spaced apart so as to improve the eye safety of the LIDAR system to any extent; and 2) A multi-beam system including multiple aligned beams that can be produced together may provide the ability to selectively control the scan resolution for a field of view or for a portion of a field of view.

[0175]

[0206] For example, the system may optionally operate or configure to provide variable resolution in the vertical or horizontal direction, depending on whether the system employs horizontal or vertical scan lines to scan the field of view. In one embodiment, the spots resulting from the split laser beam may be equidistant from each other, and the scan mirror may relate to a minimum vertical tilt increment (e.g., 0.2 degrees, which relates to the maximum resolution). In some cases, the scan mirror may operate using a tilt increment greater than the minimum vertical tilt increment to generate scan lines with variable vertical spacing over a selected area of ​​the FOV. In other cases, the beam may be split such that the resulting spots are not equidistant, but can be closer together and further apart along the vertical in areas overlapping the horizon. In yet another embodiment, the combination of the mirror tilt angle and the spot spacing may allow for overlapping or interleaving of scan lines from two or more different spots, which may enable a higher scan resolution than the maximum resolution provided by the minimum vertical tilt increment of the mirror.

[0176]

[0207] Such variable resolution can offer an opportunity to reduce the processing overhead associated with each scan of the FOV. For example, an intermediate region of the FOV (e.g., region or area of ​​interest) that may relate to an area near the horizon and typically contains more distant objects or objects of interest at a higher density can be scanned at a relatively high resolution (e.g., using scans related to more closely spaced vertical laser spots and / or more closely spaced laser scan lines). In contrast, a region of the FOV further from the horizon that may contain objects located closer to the LIDAR can be scanned at a lower resolution (e.g., using more widely spaced spots and / or scan lines). Furthermore, the LIDAR system may include one or more light sources, where the beam from each light source is split into two or more split beams.

[0177]

[0208] In some embodiments, the disclosed LiDAR system may include a laser emission unit configured to generate multiple laser beams, a scanning unit configured to receive multiple laser beams, wherein a common scanning unit is configured to project the multiple laser beams toward the field of view of the LiDAR system, and at least one processor. The disclosed LiDAR system may include features similar to those described above with respect to other disclosed LiDAR systems, such as the systems shown in Figures 7A, 8, 11A, 11B. The 2D scanner (e.g., 720, 860) may include any type of scanning device configuration, including any of the configurations described above. In some cases, the 2D scanner may include a MEM mirror or an array of MEM mirrors. In other cases, a single relatively large mirror (e.g., about 20 mm × 20 mm, or 30 mm × 18 mm) may be used. In some cases, the mirrors of a two-axis 2D scanner may be actuated using a mechanical arrangement (motor-driven, magnetic, etc.). In some cases, a combination of two or more 1D scanners and / or rotating polygons may be used to generate a 2D scan.

[0178]

[0209] In some embodiments, the LIDAR system may include a biaxial scan mirror configured to receive multiple laser beams, and the biaxial scan mirror is configured to project the multiple laser beams toward the field of view of the LIDAR system. In some embodiments, a common scan unit may include a single biaxial scan mirror onto which multiple laser beams are incident. In some embodiments, the biaxial scan mirror is rotatable on two axes, including a tilt axis and a scan axis. As described above, the scan units 720, 860 may include any type of scan mirror configuration, including any of the configurations described in the above section. In some embodiments, the scan units 720, 860 may include a MEM mirror or an array of MEM mirrors. A MEMS mirror may be rotatable around two axes that can be orthogonal. For example, the scan units 720, 860 may include a MEM mirror having two generally orthogonal axes of rotation, similar to the MEMS mirror in Figure 3B. One of the two axes may allow the scan units 720 and 860 to tilt (for example, to guide the laser beam vertically across the FOV), and the other axis may allow the scan units 720 and 860 to scan (to guide the laser beam horizontally across the FOV). Furthermore, in some embodiments, the rotational speed around the scanning axis may be faster than the rotational speed around the tilt axis. Thus, the scanning axis may be called the fast axis and the tilt axis may be called the slow axis. It should be noted that all of the laser emission units and scan arrangements described above may be implemented in these disclosed embodiments of the LIDAR system 100.

[0179]

[0210] In some embodiments, a common scanning unit may include a first single-axis scanning mirror and a second single-axis scanning mirror, and multiple laser beams are incident on the first single-axis scanning mirror and then on the second single-axis scanning mirror. As described above, in some embodiments, the scanning units 720, 860 may include mirrors or deflectors that can rotate around only one axis of rotation. For example, the scanning units 720, 860 may include mirrors or deflectors similar to the mirror in Figure 3A. In these embodiments, the first single-axis scanning mirror may receive a laser beam from the laser emission unit 102 and guide the laser beam to the second single-axis scanning mirror, which may then guide the laser beam toward the field of view.

[0180]

[0211] In some embodiments, multiple laser beams may be projected from a common scanning unit such that the multiple laser beams can be angularly equidistant from each other. In some embodiments, the multiple laser beams are projected from a common scanning unit with an angular spacing of at least 2.5 mrad to 6 mrad between adjacent beams. As described above, for example with respect to the exemplary scanning unit 720 in Figure 7A, multiple laser beams guided toward the field of view by a scanning mirror configuration may be separated from each other by equal or unequal angles. In some embodiments, it is intended that the angular spacing may be in the range of 2.5 mrad to 6 mrad. In some embodiments, the beam spots in the field of view of the LIDAR system resulting from the multiple laser beams may be equidistant from each other. As described above, each of the multiple laser beams guided toward the FOV may generate a beam spot within the FOV. Similarly, as described above, the multiple beams may be separated from each other by equal or unequal angles. As a result, the beam spots in the FOV formed by the multiple laser beams may be equidistant when the beams are separated by equal angles.

[0181]

[0212] In some embodiments, a LiDAR system may include a laser source in the form of a laser array. Light from the laser array may be incident on a 2D scanner and projected onto the LiDAR field of view (FOV). Reflected light returning from the FOV may be received by the 2D scanner, which guides the reflected light to a sensor array, which detects the reflected light. Time-of-flight calculations may be performed to determine the distance to various objects within the FOV, and a point cloud of distance values ​​may be generated for each scan of the FOV. In some embodiments, a common optical path may be used to transmit the laser light emitted from the laser array to the 2D scanner and toward the FOV, and to guide the reflected light received by the 2D scanner from the FOV toward the sensor array. Such a configuration may offer significant advantages in terms of reduced complexity, cost, reliability, and performance.

[0182]

[0213] Various laser sources can be employed. In some cases, the laser sources associated with the laser array include pulsed lasers having wavelengths of 860 nm to 950 nm. In some cases, the laser sources may have wavelengths of approximately 905 nm. It is also intended that multiple laser sources may be included in a laser array that can be arranged in a 2D or 1D pattern. In some cases, the laser sources may be arranged in a 1D configuration to provide a laser bar array containing multiple (e.g., two or more) laser sources.

[0183]

[0214] In some embodiments, the laser emission unit may include a laser emitter configured to generate a primary laser beam and a beam splitter configured to split the primary laser beam into multiple sub-beams providing multiple laser beams. In the disclosed embodiments, various types of beam splitters may be used to generate two or more sub-beams from a single incident laser beam. In some cases, the disclosed embodiments may include a multiplier laser beam splitter (multisplitter) to create a multi-channel optical system from a single laser source. As an extension of conventional beam splitters, a multisplitter can split a laser beam into a desired number of beams at a desired power ratio. The use of a single laser source can enable significant reductions in system size, power consumption, and optical components, as well as improved channel synchronization and correlation.

[0184]

[0215] Multisplitters can be used with lasers of various wavelengths, including 905 nm and 1550 nm, which are employed by LIDAR systems. Multisplitters can be fabricated from industrial dielectric materials such as glass for VIS-NIR, GaAs for IR, silicon, and various polymers. Furthermore, depending on specific requirements such as AOI range, transmittance, temperature, polarization invariance, and cost, either dielectric coatings or thin metal deposition may be used. Multisplitters can be free-space beam splitters or waveguide (e.g., fiber) splitters, which can typically be selected for a single-mode 1550 nm laser. Light from lasers is typically polarized, and the beam splitters described may be highly sensitive to polarization.

[0185]

[0216] Figure 15 provides additional details regarding the optical configuration of the disclosed LIDAR system 100. In this example, the laser source 1502 may include 16 laser emitters arranged in a 1D array, each having a wavelength of approximately 905 nm. Light emitted from the 16 laser emitters may travel through various optical components related to the optical path, including, for example, lenses and collimators. The 2D scanner 1510 in Figure 15 may include a 20 × 20 mm mirror capable of providing a 140 × 44 degree FOV scanned at a frame scan rate of 20 Hz. The scanner may be configured to support a specific scan rate or a scan rate range of up to 5–50 Hz, depending on the requirements of the particular application. The 16 emitted pulsed laser beams may be projected from the 2D scanner 1510 toward the FOV. As described above, some or all of the beams projected toward the FOV may be reflected by one or more objects within the FOV. The reflected laser beams may form a spot of laser light on a detector (e.g., 1520) associated with the LIDAR system 100. As shown in Figure 15, each reflected laser spot returning from the FOV may have a size of approximately 0.07 degrees × 0.10 or 0.11 degrees. The reflected laser spots can be received by the detector 1520. The vertical arrangement of the reflected laser spots may also depend on the configuration of the laser sources (or emitters) on the laser source array. For example, the amount of space between adjacent pairs of laser sources may result in corresponding space between corresponding pairs of laser spots reflected from the FOV.

[0186]

[0217] In some embodiments, at least one processor may be programmed to cause a scan unit to scan the field of view of the LiDAR system by guiding multiple beams along a first set of scan lines crossing the field of view (FOV). In some embodiments, rotation of a biaxial scan mirror around a scan axis causes movement of multiple laser beams along a first set of scan lines and a second set of scan lines crossing the field of view of the LiDAR system. As described above, the scan units (e.g., 720, 860) may be configured to receive a single or multiple laser beam and guide the beams into the FOV. Similarly, as described above, the processor 118 may be configured to rotate the scan units 720, 860 around a scan axis to guide laser beams in the left-right direction across a portion of the FOV in the form of one or more scan lines (e.g., 1201, 1203, 1205, etc.). Similarly, as described above, when receiving multiple laser beams, the scan units 720, 860 may be configured to rotate around the scanning axis to guide the laser beams laterally across a portion of the FOV in the form of one or more scan lines in the shape of a comb (e.g., 1221, 1223, 1225, etc.).

[0187]

[0218] In some embodiments, at least one processor can be programmed to displace multiple laser beams from a first set of positions associated with a first set of scan lines to a second set of positions associated with a second set of scan lines, and to guide multiple laser beams along the second set of scan lines. In some embodiments, rotation of a biaxial scan mirror around a tilt axis can result in the displacement of multiple laser beams from a first set of positions associated with a first set of scan lines to a second set of positions associated with a second set of scan lines. Furthermore, as described above, the processor 118 can cause rotation of scan units 720, 860 around a tilt axis, shifting multiple horizontal scan lines (e.g., 1221, 1223, 1225, etc.) vertically, thereby generating a second set of scan lines that crosses a second set of positions vertically spaced apart from the first set of positions. Figure 12B shows a scan pattern 1220 obtained using multiple laser beams. As shown in Figure 12B, multiple laser beams can enable the generation of horizontal scan lines 1221, 1223, 1224, etc. When scan units 720 and 860 rotate around the tilt axis, the horizontal scan lines (e.g., 1221, 1223, 1224, etc.) may be displaced vertically by a distance DH corresponding to the rotation of the scan units (e.g., 720 and 860) around the tilt axis.

[0188]

[0219] In some embodiments, the first and second sets of scan lines may be oriented horizontally with respect to the field of view of the LIDAR system. As shown in Figure 15, the laser sources may have a vertical angular dimension of 0.1 degrees and may be spaced about 0.2 degrees apart (or a ratio of about 2:1 between open space and the laser emitter). For 16 channels, the overall vertical pattern (or "comb" formed by the multiple light beams) of the multiple light beams projected toward the FOV may occupy an angular height of about 4.6 degrees. This comb of laser light beams may be steered horizontally across the width of the FOV by rotating the 2D scanner 1510 around the scanning axis, and the horizontal resolution may be determined by the scan speed and the pulse rate of the laser source. In one example, when the 2D scanner 1510 reaches its horizontal limit, the 2D scanner 1510 may be incrementally rotated vertically around the tilt axis to continue horizontal scanning of the FOV with a new set of horizontal scan lines. Naturally, various pulse rates, scan rates, laser sizes, and laser intervals can also be used.

[0189]

[0220] While a 1D laser array has been described above, a 2D array of laser sources can also be employed. The lasers may be arranged in a square or rectangular pattern, or any other type of pattern (e.g., a hexagonal arrangement). It should also be understood that the scanner 1510 may be similar to one or more scanners described above (e.g., scan units 720 or 860).

[0190]

[0221] The example described above includes 16 laser channels (or 16 laser sources in the array). Other numbers of laser sources may also be used. For example, some embodiments may include 4, 8, 32, 64 laser sources, or any other desired number of laser sources. The laser sources may be arranged in various configurations within the 1D array. Figures 10A to 10G above show some exemplary configurations of laser sources arranged in a 1D array.

[0191]

[0222] The available resolution of a LiDAR system can depend on many factors. In some cases (e.g., a single-laser source system), the resolution may depend on factors including the mirror tilt increment used between scan lines and the laser pulse frequency used while scanning across the scan lines. In other cases, such as a multi-laser system, the available resolution may depend on the spacing between laser sources in the laser array (e.g., 950), in addition to the mirror tilt increment and the laser pulse frequency during scanning.

[0192]

[0223] For example, in some LIDAR systems, as described above, a single laser source can be scanned across the LIDAR FOV using a scanner such as a 2D scanner. As shown in Figure 12A, a 2D scanning mirror (e.g., a MEM mirror or a two-axis mechanical rotating mirror) may be used to scan light from a single laser source across the FOV. The horizontal scan lines 1201, 1203, 1205, etc., do not have to be equally spaced. For example, to scan a specific area of ​​the LIDAR FOV, such as areas above and below the horizon, a vertical tilt increment with respect to the 2D scanning mirror that is larger than the minimum available tilt increment may be selected. In the example shown in Figure 12A, the areas above and below the horizon may be scanned using a vertical tilt increment of 0.6°, which may correspond to the laser pitch in the array, for example, producing a coarse sampling resolution equal to the laser pitch in the array. However, in the area including the horizon, the smallest vertical tilt angle may be used to provide closer-spaced scan lines within that area, and even to provide higher point cloud resolution within that area.

[0193]

[0224] In the example shown in Figure 12A, the vertical resolution of the point cloud may depend on the line spacing, and the horizontal resolution may depend on the frequency at which a single laser source is pulsed as the 2D scan mirror scans along each horizontal scan line. The higher the pulse frequency, the higher the possible horizontal resolution of the point cloud generated from the LIDAR system.

[0194]

[0225] In some LIDAR systems, multiple laser sources may be used rather than relying on a single laser source. In some cases, light beams from one or more laser sources may be split to provide multiple laser beams available for scanning. In some embodiments, a laser array (e.g., the 1D laser array described in the example in the section above) may be used to provide multiple laser beams for scanning the LIDAR FOV.

[0195]

[0226] In multi-beam systems including 2D scanning mirrors, the resulting point cloud resolution may continue to depend on the inclination increment (e.g., vertical inclination increment) at which the laser is driven, and the resolution may also depend on the pulse frequency at which the laser source is driven. However, in multi-beam systems, the available point cloud resolution may also depend on the laser source or the spacing of the generated laser beams. As described below, some multi-beam systems can enable higher resolution in areas of FOV where interest may be relatively high, and lower resolution in areas of FOV where interest may be relatively low. For example, for a laser source having N1 laser spots (e.g., N1 laser beams), each divided by N2 pixels in the detector, and with a laser [active:inactive] ratio of [1:N3-1], the maximum resolution can be determined as follows: Res = line spacing / (N1 × N2 × N3).

[0196]

[0227] The described laser source arrays may be characterized by their effective angular dimensions (e.g., the portion of the solid angle from which light from the array is projected toward the FOV). In the examples shown in Figures 10D–10F, each of the illustrated laser arrays 1000 may have an angular dimension of 2.4 degrees. Therefore, when scanning the LIDAR FOV, if the scan mirror rotates by 2.4 degrees around its tilt axis between each scan pattern line, the FOV is scanned with horizontal scan lines spaced apart by the angular dimension specified by the laser source spacing within each array. For example, a 4-channel array scanned with a vertical increment of 2.4 degrees results in horizontal scan lines separated by 0.6 degrees. An 8-channel array provides horizontal scan lines separated by 0.3 degrees, and a 16-channel array provides horizontal scan lines separated by 0.15 degrees.

[0197]

[0228] It should be noted that the described laser array (e.g., a 16-laser source array) may be operated selectively with any number of active channels, and the number of active channels (e.g., active laser emitters) may be changed during a single-frame scan of the LiDAR FOV, during a scan along a single scan line of the scan pattern, or over any time interval or spatial domain with respect to the LiDAR FOV scan.

[0198]

[0229] The laser array and scanning system described above offer the possibility of achieving horizontal scanline spacings even closer than the spacing between active laser emitters (or laser emission regions) within the laser array. For example, in some embodiments, the scan mirror can be controlled to rotate around its vertical tilt axis by an angular increment smaller than the angular dimension of the laser array (e.g., less than 2.4 degrees for the laser arrays in Figures 10D-10F). In such embodiments, the controlled rotation of the mirror can provide a scan pattern with horizontal line spacings approximately equal to the spacing between laser sources within the laser array. In some cases, the spacing between scanlines may correspond to the angular dimension of a single laser source within the array (e.g., 0.05 degrees in the 16-channel example, 0.1 degrees in the 8-channel example, and 0.2 degrees in the 4-channel example).

[0199]

[0230] In some embodiments, the laser pulse rate associated with one or more of the multiple laser beams may be constant over at least a first set of scan lines. In some embodiments, the laser pulse rate associated with one or more of the multiple laser beams may vary over at least a first set of scan lines. As described above, the horizontal resolution obtained during each scan may be determined by the scan speed (e.g., the rate at which the scan mirror rotates around the scan axis) and the pulse rate of the laser source (e.g., the rate at which laser light pulses are emitted from each laser emission region of the laser array). The pulse rate associated with one or more of the multiple beams used to generate the scan pattern (e.g., a first set of scan lines) is intended to be kept constant or vary during a single scan of the FOV. For example, a higher pulse rate may be used with respect to some laser beams or over a portion of the FOV to obtain better resolution over that portion of the FOV.

[0200]

[0231] In some embodiments, at least one processor may be programmed to activate a first subset of multiple laser emitters and scan the laser beam generated by the first subset of laser emitters across a first set of scan lines traversing the field of view of the LiDAR system. As described above, in the disclosed LiDAR system, multiple laser beams can be generated by activating only a portion of the active region (or emitter) of the laser array (e.g., 950) and leaving the remaining active region (or emitter) inactive. Thus, in one embodiment, the processor 118 may be programmed to generate multiple light beams by activating only some of the active regions (e.g., 956) of the laser array 950, for example. Also, as described above, the processor 118 may be configured to rotate a scan mirror to guide the generated light beam across a first set of scan lines traversing the field of view.

[0201]

[0232] In some embodiments, at least one processor may be programmed to deactivate a first subset of laser emitters, activate a second subset of laser emitters, and scan the laser beam generated by the second subset of laser emitters across a second set of scan lines traversing the field of view of the LIDAR system. As described above, processor 118 may activate or deactivate some or all of the laser emitters in the laser array 950. After performing a first scan using the laser beam from the first subset of the laser light emission active region of the laser array (e.g., 950), processor 118 may deactivate the first subset and instead activate a second subset of the active region of the laser array. Furthermore, similar to the first scan, processor 118 may control the rotation of the scan mirror to perform a second scan along a second set of scan lines across the FOV. The processor 118 is intended to control the rotation of the scan mirror around the scan axis without rotating the mirror around the tilt axis, thereby enabling the generation of a second scan over the same portion of the FOV. However, as described below, alternatively, the processor 118 may rotate the scan mirror around the tilt axis before performing the second scan and / or any subsequent scans.

[0202]

[0233] In some embodiments, none of the second set of scan lines may be spatially positioned between the scan lines in the first set of scan lines. As shown in Figure 12B, in some embodiments, the rotation of the scan units 720, 860 around the tilt axis may displace each horizontal scan line (e.g., 1221, 1223, 1225, etc.) generated during the first scan by a distance DH corresponding to the angular dimension of the laser array (e.g., 2.4 degrees) in Figures 10D-10F. Thus, for example, scan lines 1221, 1223, 1225, etc. may correspond to the first scan pattern. After rotating the scan mirror by an angle greater than the angular dimension of the laser array (e.g., ≥2.4 degrees), horizontal scan lines 1231, 1233, 1235, etc. may be generated during the second scan. Since the scan mirror is rotated by an angle greater than or equal to the angular dimension of the laser array, each scan line, e.g., 1231, 1233, 1235, can be displaced by a distance DH from the horizontal scan lines 1221, 1223, 1225, respectively. Thus, in some embodiments, at least one processor can cause the scan unit to displace multiple laser beams from a first set of positions associated with the first set of scan lines to a second set of positions associated with the second set of scan lines by rotating the scan unit around the tilt axis by an angle of rotation greater than or equal to the angular width of the first set of scan lines. For example, as described above, if the processor 118 rotates the scan mirror by an angle greater than or equal to the angular dimension of the laser array (e.g., ≥2.4 degrees), the second scan pattern (including the second set of scan lines) is also displaced by the same angle of rotation relative to the first scan pattern (including the first set of scan lines).

[0203]

[0234] The processor 118 can repeat the processes identified above many times. Therefore, for example, in some embodiments, at least one processor may be programmed to deactivate a second laser emitter subset, tilt the biaxial scan mirror by an angle of rotation greater than or equal to the angular length of the monolithic laser array, activate a first laser emitter subset, and scan the laser beam generated by the first laser emitter subset across a third set of scan lines traversing the field of view of the LIDAR system. For example, as described above, the processor 118 can repeat the scanning process to perform a third scan across the FOV by deactivating a second subset of the active region of the laser array (e.g., 950) and reactivating a first subset of the active region of the laser array. Furthermore, before performing the third scan, the processor 118 may rotate the scan mirror around the tilt axis by an angle that may be greater than or equal to the angular length of the laser array. Doing so ensures that the third set of scan lines does not overlap with the second set of scan lines. However, the processor 118 is intended to rotate the scan mirror around the tilt axis by an angle smaller than the angular length of the laser array. In that case, at least some of the third set of scan lines may overlap with at least some of the second set of scan lines.

[0204]

[0235] In some embodiments, at least one processor may cause the scan unit to displace multiple laser beams from a first set of positions associated with the first set of scan lines to a second set of positions associated with the second set of scan lines by rotating the scan unit around a tilt axis by an angle of rotation smaller than the angular width of the first set of scan lines. For example, processor 118 may rotate the scan mirror by an angle smaller than the angular dimension of the laser array (e.g., <2.4 degrees). In this case, each scan line, e.g., 1231, 1233, 1235, may be displaced by a distance less than DH from the horizontal scan lines 1221, 1223, 1225, respectively. As a result, at least some of the scan lines 1231, 1233, and / or 1235 may be positioned between the scan lines 1231, 1233, and / or 1235. Thus, in some embodiments, at least one scan line of the second set of scan lines may be spatially positioned between two scan lines included in the first set of scan lines.

[0205]

[0236] In some embodiments, none of the second plurality of scan lines may be spatially positioned between the scan lines in the first plurality of scan lines, and at least one processor is further programmed to cause the scan unit to guide multiple beams along a third plurality of scan lines crossing the FOV, such that at least one of the third plurality of scan lines is spatially positioned between two scan lines included in the second plurality of scan lines. The above-described features of rotating the scan mirror by an angle greater than or equal to the angular dimension of the laser array (e.g., ≥2.4 degrees) or rotating the scan mirror by an angle less than the angular dimension of the laser array (e.g., <2.4 degrees) can be combined in many different ways. For example, a first scan may be performed, and then the scan mirror may be rotated by an angle greater than or equal to the angular dimension of the laser array (e.g., ≥2.4 degrees) before performing a second scan. As a result, none of the scan lines of the second scan may be positioned between the scan lines of the first scan, as described above. Next, the scan mirror may be rotated by an angle smaller than the angular dimension of the laser array (e.g., <2.4 degrees) before performing the third scan. As a result, as described above, at least some of the scan lines of the third scan may be spatially positioned between at least some of the scan lines of the second scan.

[0206]

[0237] In some embodiments, at least one processor is further programmed to cause the scan unit to guide multiple beams along a fourth set of scan lines crossing the FOV, with at least one of the fourth set of scan lines spatially positioned between two scan lines included in the second set of scan lines, and also between two scan lines included in the third set of scan lines. The above process of rotating the scan mirror by different angles can be repeated. For example, after performing a third scan, the scan mirror may be rotated by an angle smaller than the angular spacing between the active laser emission regions of the laser array (e.g., less than 0.2 degrees for the laser array in Figure 10E, or less than 0.4 degrees for the laser array in Figure 10F) before performing a fourth scan. By rotating the scan mirror by a small angle, the scan lines of the fourth scan may be displaced by a distance smaller than the distance between adjacent scan lines. As a result, the scan lines in the fourth scan may overlap with the scan lines associated with the second and third scan patterns. That is, at least some scanlines in the fourth pattern may be between scanlines in the second pattern, and at least some other scanlines in the fourth pattern may be between scanlines in the third pattern.

[0207]

[0238] In some cases, the vertical rotation of the scan mirror can be controlled to provide a variable resolution scan. For example, in the scan shown in Figure 12B, with respect to regions 1280 and 1282 near the top and bottom of the scan, respectively, the scan mirror may be rotated around its vertical tilt axis by an angular increment of at least the same magnitude as the angular dimension of the laser array. However, in region 1284 including the horizon (e.g., between ±5 degrees), the scan mirror may be rotated around its vertical tilt axis by an angular increment smaller than the angular dimension of the laser array.

[0208]

[0239] In the scanning example in Figure 12B, an array of 16 laser sources is used and can operate with an active source to inactive area ratio of 1:2, as shown in Figure 15. In the example in Figure 12B, there may be 16 laser beams, each emitted by two adjacent groups of laser sources. Each beam may have a vertical angular dimension of 0.05 degrees, and each of the 16 laser beams may be emitted from two laser beam groups with a total vertical dimension of 0.1 degrees. The active laser groups may be separated by inactive spaces with a total vertical angular dimension of 0.2 degrees. This can provide a 1:2 ratio of active to inactive spaces in the array. Thus, the horizontal spacing of the lines scanned by the 16-source laser array may be 0.3 degrees. The total vertical angular dimension of the laser array (16 laser sources with an angular dimension of 0.1 degrees, separated by 15 inactive intervening spaces, each with an angular dimension of 0.2 degrees) may be approximately 4.6 degrees.

[0209]

[0240] Figure 16 shows an exemplary scan pattern that can be obtained using the disclosed LIDAR system 100. As shown in Figure 16, the region 1610 between approximately -6 degrees and approximately +6 degrees (which may include the horizon) may correspond to a region of greater interest where higher resolution may be desired. This higher resolution can be achieved, for example, by increasing the tilt of the scan mirror around its vertical scanning axis by an amount smaller than the total angular dimension of the laser array. For example, six horizontal scans may be performed in the region between approximately -6 degrees and approximately +6 degrees. Higher vertical resolution can be provided by spacing the horizontal scans of the laser array closer together (e.g., 0.1 degrees in region 1620). Horizontal resolution can also be increased by increasing the laser pulse frequency in these regions (e.g., 0.1 degrees in region 1620).

[0210]

[0241] Resolution can be further increased. For example, by generating each of 16 laser beams from only one of two laser sources, each generated beam can be emitted from a laser source with a vertical angular dimension of 0.5 degrees. By overlapping subsequent horizontal scans and further adjusting the laser pulse frequency, a resolution of (e.g.) 0.05 degrees × 0.05 degrees can be provided. Such techniques can be used to scan a specific region of interest (ROI), such as region 1630. Such ROIs may be predetermined within the FOV or identified based on trigger events such as detection of a specific object or object type, partial object detection, detection of objects within a specific distance range, or detection of overlapping objects.

[0211]

[0242] Another example of scanning that includes an improvement in resolution in the region containing the horizon and / or the region of interest is represented by region 1610. In these regions, the distance (or vertical angular displacement) between each scan line is smaller than the total length of the multiple beam spots in the laser array. In this way, a portion of the area being scanned "overlaps" with previous scan lines, and more pixels may be sampled in the overlapping portion.

[0212]

[0243] Higher resolution can be achieved by using multi-beam scanning and controlling the vertical offset of the scan so that there is overlap between parts of the previously scanned area and subsequent scans. For example, an exploded view of region 1610 within the FOV is shown in Figure 16. It can be seen that the resolution between 5 and 15 degrees is 0.15 × 0.3, while the resolution increases to 0.05 × 0.05 at the center of the ROI region. Between these regions, a transition resolution between low and high resolution may exist.

[0213]

[0244] Several examples of overlapping scans using multiple beam configurations are shown in Figures 17A, 17B, and 17C (e.g., using 16, 8, or 4 beams). For example, Figure 17A shows a scan using 16 beams, where scans 1702–1708 are scans with rotations of the scan mirror around a tilt axis of approximately 1 / 3 of the angular length of the laser array, respectively. The resulting composite scan is represented by 1722. As can be seen from the composite scan 1722, the resolution gradually increases towards the center of the scan. Similarly, Figure 17B shows a scan using 8 beams, where scans 1732–1739 are scans with rotations of the scan mirror around a tilt axis of approximately 1 / 3 of the angular length of the laser array, respectively. The resulting composite scan is represented by 1740. Figure 17C similarly illustrates scans using four beams, where scans 1752–1758 each involve rotations of the scan mirrors around a tilt axis of approximately 1 / 3 the angular length of the laser array. In these examples, the distance between scan lines (i.e., corresponding to the angular displacement of the scan mirrors around the vertical scanning axis) is equal to 1 / 3 the angular length of the laser array, so the resolution can be increased to three times the resolution of the multi-beam resolution. In other words, in examples involving laser arrays with an active-to-passive spatial ratio of 1:2, subsequent horizontal scans allow scanning of areas that were only overlapped by the passive area of ​​the laser array during previous scans (e.g., 1724, 1742, 1762, etc.) by shifting the light from the laser array vertically by 1 / 3 the angular length of the array.

[0214]

[0245] In some embodiments, at least one processor may cause the scan unit to displace multiple laser beams from a first set of positions associated with the first set of scan lines to a second set of positions associated with the second set of scan lines by rotating the scan unit around a tilt axis by an angle of rotation smaller than the angular spacing between pairs of adjacent scan lines of the first set of scan lines. Figure 17D shows a magnified view of a portion of Figure 17A and further illustrates the resolution improvements achievable by overlapping scanning of multibeam sources. As shown in Figure 17D, during scan A, the horizontal line of the LIDAR FOV is scanned with a vertical resolution of 0.3 degrees (the spacing between active laser sources in the array) (only 6 channels are shown from an example of 16 channels). During the subsequent horizontal scan, i.e., scan B, the processor 118 may angularly displace the scan mirror by 1 / 3 of the vertical angular resolution of 0.3 degrees. As a result, scan B partially overlaps with scan A. As shown in Figure 17D, this overlap in the scan causes 1 / 2 of the inactive area of ​​scan A to be scanned during scan B. Similarly, in the subsequent scan C, where the mirror is tilted again by only one-third of the 0.3-degree vertical angular resolution, the remaining half of the inactive area of ​​scan A is covered by scan C. As a result, the vertical resolution achievable in this overlapping area can increase from 0.3 degrees using scan A alone to 0.1 degrees using the overlap of scans A, B, and C.

[0215]

[0246] In some embodiments, a duplicate scan may be performed in two steps. In the first step, the scan mirror may be rotated around the tilt axis by an angle corresponding to the angular width of the collimated beam emitted by the active region of the laser array, and then a subsequent scan may be performed. This process may be continued n times, where n = (angular distance between adjacent collimated beams / angle by which the scan mirror is rotated). After n scans are completed, in the second step, the scan mirror may be rotated around the tilt axis by an angle corresponding to the angular distance between adjacent collimated beams, and then an additional scan may be performed. For example, consider a situation where the ratio of active to inactive regions of the laser array is 1:2, the angular size of each collimated beam is approximately 0.1°, and the angular width between adjacent collimated beams is approximately 0.2°. In this case, three scans may be performed in the first step by rotating the scan mirror about 0.1° around the tilt axis after each scan. In the second step, a fourth scan may be performed after rotating the scan mirror by an angle approximately equal to the total angular width of the multiple laser beams emitted by the laser array (for example, for 16 beams with an active-to-inactive region ratio of 1:2, the total angular width of the multiple laser beams emitted by the laser array is approximately 4.6° to 5°). In this case, the angular displacement around the tilt axis would be 0.1°, 0.1°, 4.6°, 0.1°, 0.1°, 4.6°, etc. This multi-step scan scheme can provide a generally uniform sampling resolution across the entire FOV.

[0216]

[0247] In some embodiments, at least one processor may cause the scan unit to displace multiple laser beams from a first set of positions associated with a first set of scan lines to a second set of positions associated with a second set of scan lines by rotating the scan unit around a tilt axis by a rotation angle between 1 / 4 and 1 / 2 of the angular width of the beams generated by the monolithic laser array. While a tilt angle of 1 / 3 of a vertical angular resolution of 0.3 degrees was discussed above, it is intended that the scan mirror can be rotated by any amount. For example, in some embodiments, the processor 118 may rotate the scan mirror by 1 / 4 to 1 / 2 of the vertical angular resolution or angular width of the beams generated by the laser array.

[0217]

[0248] In some embodiments, at least one processor may cause the scan unit to displace multiple laser beams from a first set of positions associated with a first set of scan lines to a second set of positions associated with a second set of scan lines by rotating the scan unit around the tilt axis by a rotation angle between 0.05 and 5 degrees. Returning to the example in Figure 15, assuming that the width of the active area is 0.1 degrees and the spacing between the active areas is 0.2 degrees, rotating the laser array around the tilt axis by 1 / 3 of the angular width means a rotation of approximately 16 degrees × 0.1 = 1.6 degrees. On the other hand, if the number of active areas is 32, the amount of rotation becomes 3.2 degrees. Therefore, the amount of rotation corresponding to a 1 / 3 shift may depend on the size of the laser array. The amount of rotation of the scan mirror around the tilt axis may be in the range of approximately 0.05 to 5 degrees, however, the range of the tilt axis may vary. For example, in some embodiments, at least one processor may cause a scan unit to displace multiple laser beams from a first set of positions associated with a first set of scan lines to a second set of positions associated with a second set of scan lines by rotating the scan unit around a tilt axis by a rotation angle between 0.05 degrees and 0.5 degrees.

[0218]

[0249] Using the aforementioned techniques, a resolution relative to the laser pitch can be achieved. If the laser spot is divided using a receiver, a vertical resolution of approximately half the angular size of the laser spot (e.g., 0.05 degrees) can be achieved. Numerous other configurations can be achieved by adjusting the rotation around the tilt axis. For example, in some cases, one or more overlapping scans may be performed on a selected ROI to provide higher resolution in those areas. However, one or more subsequent overlapping scans do not need to include a horizontal scan of the entire LIDAR FOV. Rather, subsequent scans may focus on any one or more subregions of the LIDAR FOV that have a width less than or equal to the entire FOV.

[0219]

[0250] Further examples of multi-step scans focused on sub-regions of the LIDAR FOV are shown in Figures 18A and 18B. A multi-step scan involves continuously scanning a first region during a first period, followed by scanning a second region (e.g., a sub-region of the LIDAR FOV) during a second period. For example, as shown in Figure 18A, the first scan (represented by scan lines 1810, 1812, 1814, etc.) may be performed during the first period, and the second scan (represented by scan lines 1820, 1822, 1824, etc.) may be performed during the second period. As also shown in Figure 18B, the second scan may be performed over a second region 1840, which may be smaller than the first region 1830. In some cases, the partial region of interest may extend across the entire FOV, while in other cases, the partial region of interest may have a width smaller than the FOV.

[0220]

[0251] Figure 19 shows a multistep scan including a low-resolution scan of the entire FOV 1910 and subsequent high-resolution scans of subsections 1920 of the FOV (e.g., at slower rates and higher pulse rates). The subsections may be the entire horizontal range (this solution may be implemented for resonant horizontal scanning) or may relate to subsections of the HFOV and VFOV. A multistep scan including subsequent scans of subregions having the entire range of the FOV on at least one axis (e.g., horizontal) may be advantageously implemented with scanners that scan with resonant oscillations in the horizontal direction. A multistep scan including subsequent scans of horizontal and vertical range subsections may be achieved by quasi-static control of the scan rate in both directions or by adjusting the scanner's resonance.

[0221]

[0252] In some embodiments, at least one processor may be further programmed to cause a scan unit to scan a first region of the field of view of the LiDAR system by directing multiple beams along a first set of scan lines, and to scan a second region of the field of view by directing multiple beams along a second set of scan lines, such that none of the first set of scan lines overlap with each other, and at least some of the second set of scan lines overlap with each other. As described above, the processor 118 may be configured, for example, to rotate a scan mirror (e.g., scan units 720, 860) around a tilt axis by an angle greater than or equal to the angular width of the laser array. In this way, a first set of scan lines may be generated, none of which overlap with each other. The processor 118 may acquire the first set of scan lines while scanning a first region of the field of view. Similarly, as described above, the processor 118 may be configured to rotate the scan mirrors (e.g., scan units 720, 860) around the tilt axis by an angle smaller than the angular width of the laser array while scanning a second region of interest of the FOV. In this way, a second set of scan line sets may be generated, at least some of which may overlap with each other and some of which may overlap with some of the first set of scan line sets. For example, as shown in Figure 19, scan line set 1910 may constitute one of the sets in the first set of scan line sets, and scan line set 1920 may constitute one of the sets in the second set of scan line sets.

[0222]

[0253] In some embodiments, at least one processor may be further programmed to cause the scan unit to scan a first region of the LIDAR system's field of view by directing multiple beams along a first set of scan lines, and to scan a second region of the field of view by directing multiple beams along a second set of scan lines, such that the overlap angles in the first set of scan lines are smaller than the overlap angles in the second set of scan lines. Instead of acquiring a first set of scan lines that do not overlap, in some embodiments, the processor 118 may also be configured to acquire a first set of scan lines by rotating the scan mirror by an angle smaller than the angular width of the laser array while scanning the first region of the FOV. However, the processor 118 may rotate the scan mirror while acquiring the first set of scan lines by an angle greater than the angle by which the scan mirror is rotated while acquiring the second set of scan lines. Doing so can increase the resolution in the first region of the FOV, and can further increase the resolution in the second region of the FOV.

[0223]

[0254] In some embodiments, a second region of the field of view may be a region of interest. As described above, there may be substantial overlap between the scanline sets within the second region of the FOV. Substantial overlap may help improve the resolution in the second region of interest, which may include a particular portion of the FOV that could be the region of interest. In some embodiments, the region of interest may include the horizon. In some embodiments, the region of interest may include a detected object. For example, a particular portion of the FOV may be a region of interest because the LIDAR system may have detected the presence of an object. In some embodiments, the object may be a pedestrian. In some embodiments, the object may be a vehicle. For example, in a LIDAR system implemented in a vehicle (e.g., an autonomous vehicle), it may be desirable to determine whether a detected object, such as a pedestrian or another vehicle, is within the field of view, so that the autonomous vehicle can, in some cases, take evasive action to minimize the possibility of a collision with the detected object.

[0224]

[0255] In some embodiments, at least one processor may be programmed to identify a region of interest based on the type of object detected in a second region of the field of view. For example, processor 118 may acquire a first set of scan lines corresponding to a first region of the field of view. Based on the first set of scan lines, processor 118 may determine the presence of an object in a second region of the field of view that may be included in the scanned first region of the field of view. Processor 118 may also determine the type of detected object (e.g., pedestrian, vehicle, stationary object, moving object, etc.). Based on the determination of the type of object in the second region, processor 118 may identify the second region as a region of interest. For example, in an implementation of a vehicle-based LIDAR system, processor 118 may identify the second region as a region of interest if it determines that the object in the second region is a stationary object. In some embodiments, objects may be detected based on reflected signals received from previous full-frame scans of the field of view. In some embodiments, objects may be detected based on reflected signals received from one or more previous scan lines associated with the current frame scan of the field of view. Based on the scanline set obtained during previous scans of most of the FOV, it is intended that objects in a second region of the FOV may be detected. Alternatively, objects in the second region of the FOV may be detected based on the scanline set obtained from the current scan of the FOV.

[0225]

[0256] In some embodiments, at least one processor is further programmed to cause a scan unit to scan a portion of the field of view of the LiDAR system to provide a partial frame scan of the field of view, the scan of the portion of the field of view is performed using multiple overlapping scan line sets. As described above, the processor 118 may cause a scan mirror (e.g., scan unit 720 or 860) to scan the entire FOV or only a portion of the FOV. Thus, in some embodiments, the processor 118 may control the scan mirror to acquire a scan of a portion of the FOV (e.g., a partial frame scan). While acquiring a partial frame scan, the processor 118 may be configured to rotate the scan mirror by a certain angle (e.g., less than the angular width of the laser array) around the tilt axis so that the scan line sets acquired during the scan overlap. In some embodiments, a portion of the field of view may be a region of interest identified based on objects detected in that portion of the field of view. In some embodiments, the objects may be pedestrians or vehicles. In some embodiments, the objects may be moving objects. As described above, the processor 118 may identify a region of interest based on objects determined based on the scan line sets. The processor 118 is intended to be programmed to detect objects using a scanline set obtained over a portion of the field of view. Similarly, as described above, the processor 118 may be programmed to identify objects as pedestrians, vehicles, stationary or moving objects, etc. In some embodiments, instead of using a scanline set obtained by scanning a portion of the field of view, objects may also be detected based on reflected signals received from previous full-frame scans of the field of view. Thus, for example, the processor 118 may detect objects using a scanline set obtained by scanning the field of view over a previous period.

[0226]

[0257] In some embodiments, the laser emission unit is a monolithic laser array comprising a plurality of laser emitters. In some embodiments, the monolithic laser array is a one-dimensional array. In some embodiments, the LIDAR system may include a plurality of laser emitters configured to generate a plurality of laser beams. In some embodiments, the monolithic laser array may include a plurality of active regions corresponding to the plurality of laser emitters and a plurality of inactive regions, wherein the plurality of laser emitters are separated from each other by one or more of the plurality of inactive regions. In some embodiments, the monolithic laser array comprises 4 to 64 laser emitters. In some embodiments, the length of the monolithic laser array is between 0.5 mm and 20 mm. As discussed above, with respect to Figures 9A and 9B, the emission unit 102 of the LIDAR system 100 may include a laser array (e.g., 900, 950) which may include a plurality of active laser light emission regions separated by inactive non-laser light emission regions. Similarly, as described above, the number of active regions in the laser light arrays 900, 950 may range from 1 to any desired number. For example, the laser array 900 or 950 may include 4, 8, 32, 64, or any other desired number of active regions. Similarly, as described above, the length of the laser array 900 or 950 may range between 0.5 mm and 20 mm. It should be understood that one or more of the laser array characteristics described above apply to any of the laser arrays used in the disclosed LIDAR system.

[0227]

[0258] In some embodiments, a first plurality of scan lines and a second plurality of scan lines may be oriented perpendicular to the field of view of the LIDAR system. Although the above description discloses a vertical comb pattern scanned horizontally across the FOV, some embodiments may employ a horizontally oriented light source array, in which a horizontally oriented 1D array of transmitted laser light spots is scanned vertically across the FOV. All of the principles, configurations, and embodiments described above also apply to vertical scanning systems in which, after each vertical scan of the LIDAR FOV achieved by rotating the scan mirror around its vertical scanning axis, the scan mirror is angularly incremented around its horizontal scanning axis. Such a technique may provide a scan pattern like that shown in Figure 20, for example. Figure 20 shows an exemplary scan pattern including a plurality of scan line sets 2010 corresponding to a plurality of laser beams being scanned vertically, followed by the scanning mirror being rotated horizontally. Each scan line set may include vertical scan lines 2012, 2014, 2016, and so on. As also shown in Figure 20, region 2020 may include scan lines that are closer together, and these scan lines can be realized by rotating the scan mirror left and right by an angle smaller than the angular width of the laser array (e.g., 900, 950, etc.). In such a system, it is intended that the laser array (900, 950, etc. in Figures 9A and 9B) may be oriented horizontally along the left-right direction rather than the up-down direction.

[0228]

[0259] As described above, in some cases, a laser array may include a fixed number of laser channels spaced apart by inactive, non-photo-emitting material. In such cases, higher resolution can be achieved in a particular ROI along the vertical (or horizontal) direction using the partial overlap technique described above. In other cases, as shown in Figure 21, a laser array may include an array of closely spaced lasers that can operate according to various irradiation timing schemes. Such electronic control may allow for a variable and selectable ratio of active-to-inactive space along the laser array, and may enable high-resolution scanning by electronically controlled laser source irradiation. For example, Figure 21 represents a laser array with 16 closely spaced laser sources, each having a vertical angular dimension of 0.05 degrees. During the first scan (scan A) of a region of interest (e.g.) in the FOV, there is 0.15 degrees of inactive space between the laser sources, and every third laser source is activated such that each active source is spaced 0.2 degrees apart. During scan A, lasers 1, 5, 9, and 13 are active. In this example, the active-to-inactive space ratio is 1:3.

[0229]

[0260] During the subsequent scan B, instead of angularly displacing the scan mirror to a new vertical orientation to execute the next set of horizontal scan lines, the mirror may remain in the same vertical orientation (fixed orientation or a specific predetermined rotation path to compensate for the keystone effect) as used in scan A. Alternatively, instead of rotating the mirror perpendicular to the scan lines previously included in the inactive space associated with the array during scan A, a different set of lasers may be irradiated during horizontal scan B. In the illustrated example, lasers 2, 6, 10, and 14 are irradiated. Similarly, in scan C, the mirror may again remain in the same vertical orientation as used during scans A and B. In scan C, lasers 3, 7, 11, and 15 may be activated. Furthermore, in scan D, lasers 4, 8, 12, and 16 may be activated. In this way, four sequential horizontal scans of the FOV region can be performed without changing the vertical scan orientation / pattern. However, in this region, the effective resolution achieved is greater than the resolution available from any of scans A, B, C, or D. If scan A can provide a vertical resolution of 0.2 degrees, the achievable vertical resolution that can result from the combination of scans A, B, C, and D is 0.05 degrees.

[0230]

[0261] The foregoing description is presented for illustrative purposes only. It is not exhaustive and is not limited to the exact forms or embodiments disclosed. Modifications and adaptations will be apparent to those skilled in the art from a review of this specification and the implementation of the disclosed embodiments. Furthermore, although the embodiments of the disclosed embodiments are described as being stored in memory, those skilled in the art will recognize that these embodiments can also be stored in other forms of computer-readable media, such as hard disks or CD-ROMs, or other forms of RAM or ROM, USB media, DVDs, Blu-rays, or other optical drive media.

[0231]

[0262] Computer programs based on the described description and disclosed methods are within the skills of experienced developers. Various programs or program modules can be generated using any of the techniques known to those skilled in the art or designed in association with existing software. For example, program sections or program modules can be designed in or by means of.Net framework,.Net Compact Framework (and related languages such as Visual Basic and C), Java, C++, Objective-C, HTML, combinations of HTML / AJAX, XML, or Java applets in HTML or by these.

[0232]

[0263] Furthermore, although exemplary embodiments have been described herein, the scope of any and all embodiments having equivalent elements, changes, omissions, combinations (e.g., aspects across various embodiments), adaptations, and / or modifications will be recognized by those skilled in the art based on this disclosure. Limitations in the claims are to be construed broadly based on the language used in the claims and are not limited to the examples described herein or during the examination of this application. These examples are to be construed as non-exclusive. Further, the steps of the disclosed method can be arbitrarily changed, including changing the order of the steps and / or inserting or deleting steps. Accordingly, the present specification and examples are to be regarded as merely illustrative, and the true scope and spirit are intended to be indicated by the full scope of the following claims and their equivalents.

Claims

1. It is a LIDAR system, A laser emission unit configured to generate multiple laser beams, A scan unit configured to guide the plurality of laser beams toward the field of view of the LIDAR system, wherein the field of view extends in a first direction from a minimum angular range to a maximum angular range, and the plurality of laser beams are spaced apart from each other in a second direction intersecting the first direction. Equipped with at least one processor, The at least one processor provides the scan unit, The method involves guiding each of the plurality of laser beams along a plurality of parallel first scan lines from the minimum angular range to the maximum angular range in the first direction, wherein the plurality of parallel first scan lines are grouped into a first portion and a second portion, and each of the first portion and the second portion includes two or more of the plurality of parallel first scan lines. By displacing the plurality of laser beams from a plurality of first positions associated with the plurality of parallel first scan lines to a plurality of second positions associated with the plurality of parallel second scan lines, None of the plurality of parallel second scan lines are spatially located in the first portion of the plurality of parallel first scan lines, and At least one of the plurality of parallel second scan lines is spatially located in the second portion of the plurality of parallel first scan lines, Each of the plurality of laser beams is guided along the plurality of parallel second scan lines from the minimum angular range to the maximum angular range of the field of view in the first direction. A LIDAR system programmed to perform this action.

2. The plurality of parallel second scan lines are grouped into a third portion and a fourth portion, and each of the third portion and the fourth portion includes two or more of the plurality of parallel second scan lines. The aforementioned at least one processor, By displacing the plurality of laser beams from the plurality of second positions associated with the plurality of parallel second scan lines to the plurality of third positions associated with the plurality of parallel third scan lines, None of the plurality of parallel third scan lines are spatially located in the third portion of the plurality of parallel second scan lines, At least one of the plurality of parallel third scan lines is spatially located in a fourth portion of the plurality of parallel second scan lines, Each of the plurality of laser beams is guided along the plurality of parallel third scan lines from the minimum angular range to the maximum angular range of the field of view in the first direction. The LIDAR system according to claim 1, further programmed to perform the following:

3. The LIDAR system according to claim 2, wherein at least one of the plurality of parallel third scan lines is spatially located in the second portion of the plurality of parallel first scan lines.

4. The LIDAR system according to claim 2, wherein none of the plurality of parallel third scan lines are located in the second portion of the plurality of parallel first scan lines.

5. The LIDAR system according to claim 1, wherein the first portion includes at least half of the plurality of parallel first scan lines.

6. The LIDAR system according to claim 1, wherein the at least one processor is further programmed to displace the plurality of laser beams from the plurality of first positions to the plurality of second positions by rotating the scan unit around a tilt axis by an angle of rotation greater than or equal to the angular width of at least one scan line of the plurality of parallel first scan lines.

7. The LIDAR system according to claim 6, wherein the angular width of each scan line in the plurality of parallel first scan lines is 0.1 degrees, the angular spacing between adjacent scan lines in the plurality of parallel first scan lines is 0.2 degrees, and the rotation angle is 0.4 degrees.

8. The LIDAR system according to claim 1, wherein the laser emission unit is a monolithic laser array including a plurality of laser emitters.

9. The LIDAR system according to claim 8, wherein the monolithic laser array is a one-dimensional array.

10. The LIDAR system according to claim 8, wherein the monolithic laser array includes a plurality of active regions corresponding to the plurality of laser emitters and a plurality of inactive regions, and the plurality of laser emitters are separated from each other by one or more of the plurality of inactive regions.

11. The LIDAR system according to claim 1, wherein at least one processor is further programmed to displace the plurality of laser beams from the plurality of first positions to the plurality of second positions by rotating the scan unit around a tilt axis by a rotation angle between 0.05 and 5 degrees.

12. The LIDAR system according to claim 1, wherein the scan unit is configured to rotate on two axes, including a tilt axis and a scanning axis.

13. The LIDAR system according to claim 12, wherein the at least one processor is further programmed to rotate the scan unit around the scanning axis, thereby causing the scan unit to guide each of the plurality of laser beams from the minimum angular range to the maximum angular range in the first direction.

14. The LIDAR system according to claim 1, wherein the scanning unit includes a first single-axis scanning mirror and a second single-axis scanning mirror, and the plurality of laser beams are incident on the first single-axis scanning mirror and then incident on the second single-axis scanning mirror.

15. The LIDAR system according to claim 1, wherein the plurality of laser beams are guided from the scanning unit toward the field of view such that the plurality of laser beams are equidistant from each other at angles.

16. The LIDAR system according to claim 1, wherein the plurality of laser beams are guided from the scan unit toward the field of view at an angular interval of 2.5 mrad to 6 mrad between adjacent beams.

17. The LiDAR system according to claim 1, wherein the field of view of the LiDAR system has a vertical angle dimension between 6 degrees and 90 degrees, and the field of view of the LiDAR system has a horizontal angle dimension between 20 degrees and 140 degrees.

18. The LiDAR system according to claim 1, wherein the scanning of the field of view of the LiDAR system by the scanning unit is performed at a frame rate between 5 Hz and 40 Hz.

19. The LIDAR system according to claim 10, wherein the ratio of active regions to inactive regions in the monolithic laser array is in the range of 1:1 to 1:

10.

20. The LiDAR system according to claim 1, further comprising a detector configured to emit an electrical signal in response to a reflected beam received from the field of view of the LiDAR system, wherein the detector comprises a single monolithic array of photosensitive active regions separated from each other by one or more inactive regions.

21. The LIDAR system according to claim 20, wherein the ratio of the photosensitive active region to the inactive region in the detector is between 1:1 and 1:

10.

22. A method for operating a LIDAR system to scan a field of view extending from a minimum angular range to a maximum angular range in a first direction using a plurality of laser beams, The plurality of laser beams are spaced apart from each other in a second direction intersecting the first direction, and the method is, The laser emission unit generates the plurality of laser beams; Control the scan unit, (a) Guiding each of the plurality of laser beams along a plurality of parallel first scan lines from the minimum angular range to the maximum angular range in the first direction, wherein the plurality of parallel first scan lines are grouped into a first portion and a second portion, and each of the first portion and the second portion includes two or more of the plurality of parallel first scan lines; (b) Displacing the plurality of laser beams from a plurality of first positions associated with a plurality of parallel first scan lines to a plurality of second positions associated with a plurality of parallel second scan lines, None of the plurality of parallel second scan lines are spatially located in the first portion of the plurality of parallel first scan lines; At least one of the plurality of parallel second scan lines is spatially located in the second portion of the plurality of parallel first scan lines; and At least one of the plurality of parallel second scan lines is spatially located in the second portion situated between two of the plurality of parallel first scan lines; (c) Each of the plurality of laser beams is guided along a plurality of parallel second scan lines from the minimum angular range to the maximum angular range of the field of view in the first direction, thereby enabling high resolution for the second portion. Methods that include...

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