Electro-optical system with heating element

Abstract

To improve detection in varying environmental conditions (e.g., atmospheric temperature, rain, etc.).SOLUTION: A microelectromechanical system (MEMS) mirror assembly 700A may comprise a frame 711 and a MEMS mirror 701 coupled to the frame. The MEMS mirror assembly may also include at least one piezoelectric actuator including a body and a piezoelectric element. When subjected to an electrical field, the piezoelectric element may be configured to bend the body, thereby moving the MEMS mirror with respect to a plane of the frame. The MEMS mirror assembly may further include at least one heating resistor configured to heat the piezoelectric element when an electric current passes through the at least one heating resistor.SELECTED DRAWING: Figure 7A

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 741,034, filed October 4, 2018, which is incorporated herein by reference in its entirety. [Background technology]

[0002] FIELD OF THE DISCLOSURE The present disclosure relates generally to techniques for scanning a surrounding environment, for example, to systems and methods for detecting objects within a surrounding environment using LIDAR technology.

[0003] The advent of driver assistance systems and autonomous vehicles requires that automobiles 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. Many different technologies have been proposed for this purpose, including radar-, LIDAR-, and camera-based systems, operating independently or redundantly.

[0004] One consideration with driver assistance systems and autonomous vehicles is the system's ability to assess 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 perform well in a variety of conditions by measuring the distance to an object by shining light at the object and measuring the reflected pulse with a sensor. Lasers are an example of a light source that can be used in LIDAR systems. As with any sensing system, for LIDAR-based sensing systems to be fully adopted by the automotive industry, the system must provide reliable data that enables the detection of distant objects. However, the maximum illumination power of LIDAR systems is currently limited by the need to make them eye-safe (i.e., to avoid damage to the human eye, which can occur if the projected light emissions are absorbed by the cornea and lens of the eye and cause thermal damage to the retina).

[0005] The systems and methods of the present disclosure are directed to improving the performance of LIDAR systems while complying with eye safety regulations. Summary of the Invention [Problem to be solved by the invention]

[0006] Embodiments according to the present disclosure provide apparatus and methods for automatically capturing and processing images from a user's environment, as well as systems and methods for processing information associated with images captured from a user's environment. [Means for solving the problem]

[0007] In one embodiment, a microelectromechanical system (MEMS) mirror assembly is disclosed. The MEMS mirror assembly includes a frame and a MEMS mirror coupled to the frame. The MEMS mirror assembly may also include at least one piezoelectric actuator including a body and a piezoelectric element. When exposed to an electric field, the piezoelectric element may be configured to bend the body, thereby moving the MEMS mirror relative to the plane of the frame. The MEMS mirror assembly may further include at least one heating resistor configured to heat the piezoelectric element when a current flows through the at least one heating resistor.

[0008] In one embodiment, a method for manipulating a microelectromechanical systems (MEMS) mirror assembly is disclosed. The method includes applying an electric field to a piezoelectric element of a piezoelectric actuator of the MEMS mirror assembly to bend a body of the piezoelectric actuator. The method may also include passing an electric current through at least one heating resistor of the MEMS mirror assembly to heat the piezoelectric element.

[0009] In one embodiment, a solid-state photodetector is disclosed. The solid-state photodetector may include an integrated circuit including at least one photosensitive photodiode configured to generate an output signal indicative of light impinging on the photosensitive photodiode. The solid-state photodetector may also include at least one heating resistor configured to heat the solid-state photodetector when a current flows through the at least one heating resistor. The electro-optical system may further include circuitry for delivering current from a current source to the at least one heating resistor.

[0010] In one embodiment, a method for operating an electro-optical system is disclosed. The method may include passing a current through at least one heating resistor of the electro-optical system to heat a photosensitive photodiode. The at least one heating resistor may be mounted on a chip on which the photosensitive photodiode is mounted. The method may also include detecting light from a field of view (FOV) of the electro-optical system by the photosensitive photodiode of the electro-optical system.

[0011] According to other disclosed embodiments, a non-transitory computer-readable storage medium can store program instructions that, when executed by at least one processor, perform any of the methods described herein.

[0012] The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the scope of the claims.

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

[0014] [Figure 1A] FIG. 1 illustrates an exemplary LIDAR system in accordance with disclosed embodiments. [Figure 1B] 1 is an image illustrating an exemplary output of a single scan cycle of a LIDAR system mounted on a vehicle, according to disclosed embodiments. [Figure 1C] 10 is another image showing a representation of a point cloud model determined from the output of a LIDAR system in accordance with disclosed embodiments. [Figure 2A] FIG. 1 illustrates a configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2B] FIG. 1 illustrates a configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2C] FIG. 1 illustrates a configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2D] FIG. 1 illustrates a configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2E] FIG. 1 illustrates a configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2F] FIG. 1 illustrates a configuration of a projection unit according to an embodiment of the present disclosure. [Figure 2G] FIG. 1 illustrates a configuration of a projection unit according to an embodiment of the present disclosure. [Figure 3A] FIG. 2 illustrates a configuration of a scan unit according to an embodiment of the present disclosure. [Figure 3B] FIG. 2 illustrates a configuration of a scan unit according to an embodiment of the present disclosure. [Figure 3C] FIG. 2 illustrates a configuration of a scan unit according to an embodiment of the present disclosure. [Figure 3D] FIG. 2 illustrates a configuration of a scan unit according to an embodiment of the present disclosure. [Figure 4A] FIG. 2 illustrates a configuration of a detection unit according to an embodiment of the present disclosure. [Figure 4B] FIG. 2 illustrates a configuration of a detection unit according to an embodiment of the present disclosure. [Figure 4C] FIG. 2 illustrates a configuration of a detection unit according to an embodiment of the present disclosure. [Figure 4D] FIG. 2 illustrates a configuration of a detection unit according to an embodiment of the present disclosure. [Figure 4E] FIG. 2 illustrates a configuration of a detection unit according to an embodiment of the present disclosure. [Figure 5A] It includes four exemplary figures showing the emission pattern for a single portion of the field of view at a single frame time. [Figure 5B] Three exemplary diagrams are included showing emission schemes at a single frame time for the entire field of view. [Figure 5C] FIG. 10 shows the actual light emission projected and the received reflection during a single frame time for the entire field of view. [Figure 6A] FIG. 1 illustrates a first exemplary implementation according to an embodiment of the present disclosure. [Figure 6B] FIG. 1 illustrates a first exemplary implementation according to an embodiment of the present disclosure. [Figure 6C] FIG. 1 illustrates a first exemplary implementation according to an embodiment of the present disclosure. [Figure 6D] FIG. 10 illustrates a second exemplary implementation according to an embodiment of the present disclosure. [Figure 7A] 1A and 1B illustrate an exemplary MEMS mirror assembly according to some embodiments of the present disclosure. [Figure 7B]1A and 1B illustrate an exemplary MEMS mirror assembly according to some embodiments of the present disclosure. [Figure 8] 1A and 1B illustrate an exemplary MEMS mirror assembly according to some embodiments of the present disclosure. [Figure 9] 1 is a flowchart of an exemplary process for operating a MEMS mirror assembly according to some embodiments of the present disclosure. [Figure 10A] FIG. 1 illustrates an exemplary electro-optical system according to some embodiments of the present disclosure. [Figure 10B] FIG. 1 illustrates an exemplary electro-optical system according to some embodiments of the present disclosure. [Figure 10C] FIG. 1 illustrates an exemplary electro-optical system according to some embodiments of the present disclosure. [Figure 11A] FIG. 1 illustrates an exemplary electro-optical system according to some embodiments of the present disclosure. [Figure 11B] FIG. 1 illustrates an exemplary electro-optical system according to some embodiments of the present disclosure. [Figure 12] 1 is a flowchart of an exemplary process for operating an exemplary electro-optical system according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers 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, substitutions, additions, or changes may be made to the components shown in the drawings, and the exemplary methods described herein may be modified by substituting, rearranging, removing, or adding steps to the disclosed methods. Therefore, the following detailed description is not limited to the disclosed embodiments and examples. The proper scope is defined by the appended claims.

[0016] Definition of Terms The disclosed embodiments may include an optical system. As used herein, the term "optical system" broadly includes any system used to generate, detect, and / or manipulate light. By way of example only, 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, polarization optics, optical modulators, optical switches, optical amplifiers, optical detectors, optical sensors, optical fibers, and semiconductor optical components may each, but are not necessarily, part of an optical system. In addition to one or more optical components, an optical system may also include other non-optical components, such as electrical components, mechanical components, chemical reaction components, and semiconductor components. The non-optical components may cooperate with the optical components of the optical system. For example, an optical system may include at least one processor for analyzing the detected light.

[0017] In accordance with the present 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 indicative of the distance between a pair of tangible objects based on reflected light. In one embodiment, the LIDAR system may determine the distance between a pair of tangible objects based on the reflection of light emitted by the LIDAR system. As used herein, the term "determining the distance" broadly includes generating an output indicative of the distance between the pair of tangible objects. The determined distance may represent a physical dimension between the pair of tangible objects. By way of example only, the determined distance may include a line of flight between the LIDAR system and another tangible object within the field of view of the LIDAR system. In another embodiment, the LIDAR system may determine the relative velocity between the 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 length units between the tangible objects (e.g., meters, inches, kilometers, millimeters), the number of arbitrary length units (e.g., the number of LIDAR system lengths), the ratio of the distance to another length (e.g., relative to the length of an object detected in the LIDAR system's field of view), an amount of time (e.g., given in standard units, arbitrary units or ratios, e.g., the time it takes light to travel between the tangible objects), one or more locations (e.g., defined using recognized coordinates, defined relative to a known location), and others.

[0018] A LIDAR system can determine the distance between a pair of material objects based on reflected light. In one embodiment, a LIDAR system can process sensor detection results to generate time information indicative of the 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, the rise time and / or fall time of which can be detected upon reception. Processing information about the time of flight of the optical signal using known information about the speed of light in the relevant medium (usually air) can provide the distance traveled by the optical signal between emission and detection. In another embodiment, a LIDAR system can determine distance based on a frequency phase shift (or multi-frequency phase shift). Specifically, a LIDAR system can process information indicative of one or more modulation phase shifts of the optical signal (e.g., by solving several simultaneous equations to provide a final measure). For example, the emitted optical signal can be modulated by one or more constant frequencies. At least one phase shift in the modulation between the emitted signal and the detected reflection can indicate the distance traveled by the light between emission and detection. The modulation may be applied to a continuous wave optical signal, a quasi-continuous wave optical signal, or another type of emitted optical signal. It should be noted that additional information may be used by the LIDAR system to determine distance, such as location information (e.g., relative position) between the signal's projection location and detection location (especially if they are far from each other), and others.

[0019] In some embodiments, a LIDAR system can be used to detect multiple objects within the environment of the LIDAR system. The term "detecting objects within the environment of the LIDAR system" broadly includes generating information indicative of objects that reflect light toward a detector associated with the LIDAR system. When two or more objects are detected by the LIDAR system, the information generated about different objects, such as a car driving down a road, a bird sitting in a tree, a person touching a bicycle, and a van moving toward a building, can be interconnected. The dimensions of the environment in which the LIDAR system detects objects can vary depending on the implementation. For example, a LIDAR system can be used to detect multiple objects within the environment of a vehicle in which the LIDAR system is installed, up to a horizontal distance of 100 m (or 200 m, 300 m, etc.) and a vertical distance of 10 m (or 25 m, 50 m, etc.). In another example, the LIDAR system can be used to detect multiple objects within a vehicle's environment or within a predetermined horizontal range (e.g., 25°, 50°, 100°, 180°, etc.) and up to a predetermined vertical height (e.g., ±10°, ±20°, +40° to 20°, ±90°, or 0° to 90°).

[0020] As used herein, the term "detecting an object" can broadly refer to determining the presence of an object (e.g., the object may be in a particular orientation relative to the LIDAR system and / or another reference location, or the object may be within a particular volume of space). Additionally or alternatively, the term "detecting an object" can refer to determining the distance between the object and another location (e.g., the location of the LIDAR system, a location on Earth, or the location of another object). Additionally or alternatively, 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 particular object (e.g., the Washington Monument); determining a vehicle registration number; revealing the composition of an object (e.g., solid, liquid, transparent, translucent); or determining the motion parameters of an object (e.g., whether it is moving, its speed, direction of movement, expansion of the object). Additionally or alternatively, the term "detecting an object" may refer to generating a point cloud map, where each of the one or more points in the point cloud map corresponds to a location within the object or a location on the object surface. In one embodiment, the data resolution for the point cloud map representation of the field of view may be associated with 0.1° x 0.1° or 0.3° x 0.3° of the field of view.

[0021] In accordance with the present disclosure, the term "object" broadly includes any finite composition capable of reflecting light from at least a portion thereof. 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 a road, rain), at least partially gaseous (e.g., smoke, a cloud), or composed of many discrete particles (e.g., sandstorm, fog, spray), or of one or more dimensions, such as ∼1 millimeter (mm), ∼5 mm, ∼10 mm, ∼50 mm, ∼100 mm, ∼500 mm, ∼1 meter (m), ∼5 m, ∼10 m, ∼50 m, or ∼100 m. Smaller or larger objects, and any size in between, may 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 some 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 the object (e.g., a laser beam projected onto a road or building). In other cases, the object may be partially obstructed by another object between the LIDAR system and the detected object, and in other cases, the LIDAR sensor may only detect light reflected from part of the object, for example, because ambient light or other interference prevents detection of some parts of the object.

[0022] In accordance with the present 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 different directions toward different portions of the field of view. In another example, scanning the environment of the LIDAR system can be achieved by changing the positioning (i.e., location and / or orientation) of a sensor relative to 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 light source relative to the field of view. In yet another example, scanning the environment of the LIDAR system can be achieved by changing the position of at least one light source and at least one sensor so that they move rigidly relative to the field of view (i.e., the relative distance and orientation of the at least one sensor and at least one light source are maintained).

[0023] As used herein, the term "field of view of a LIDAR system" may broadly include the range of the observable environment of the LIDAR system within which an object can be detected. It should be noted that the field of view (FOV) of a LIDAR system may be affected by various conditions, including, but 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., the distance from the ground, adjacent terrain, and obstacles), and the operating parameters of the LIDAR system (e.g., the emission power, calculation settings, and specified operating angle). The field of view of a LIDAR system may be defined, for example, using solid angles (e.g., φ and θ angles, 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 may be defined within a specific range (e.g., up to 200 m).

[0024] Similarly, the term "instantaneous field of view" may broadly include the range of the observable environment in which objects can be detected by the 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 may be moved within the FOV of the LIDAR system to enable detection in other portions of the LIDAR system's FOV. Moving the instantaneous field of view within the FOV of the LIDAR system may be accomplished by moving an optical deflector in the LIDAR system (or external to the LIDAR system) to deflect the light beam to and / or from the LIDAR system in different directions. In one embodiment, the LIDAR system may be configured to scan a scene within the environment in which the LIDAR system is operating. As used herein, the term "scene" may broadly include some or all of the objects within the field of view of the LIDAR system, in their relative positions and current state during operation of the LIDAR system. For example, a scene may include ground elements (e.g., dirt, roads, grass, sidewalks, road markings), sky, man-made objects (e.g., vehicles, buildings, signs), plants, people, animals, light-projecting elements (e.g., flashlights, the sun, other LIDAR systems), etc.

[0025] The disclosed embodiments may include obtaining information used to generate a reconstructed three-dimensional model. Examples of types of reconstructed three-dimensional models that can be used include a point cloud model and a polygon mesh (e.g., a triangle mesh). The terms "point cloud" and "point cloud model" are well known in the art and should be interpreted to include a set of data points that are spatially positioned in a particular coordinate system (i.e., have identifiable locations within the space described by each coordinate system). The term "point cloud point" refers to a set of data points that are spatially (either dimensionless or dimensionally separated, e.g., 1 cm 3A 3D object refers to a point within a 3D object (which may be a small cell space such as a rectangle), whose location can be described by a point cloud model using a set of coordinates (e.g., (X, Y, Z), (r, φ, θ)). By way of example only, a point cloud model may store additional information for some or all of its points (e.g., color information for points generated from camera images). Similarly, any other type of reconstructed 3D model may store additional information for some or all of its objects. Similarly, the terms "polygon mesh" and "triangle mesh" are well known in the art and should be interpreted to include, among other things, a set of vertices, edges, and faces that define the shape of one or more 3D objects (such as polyhedra). The faces may include one or more triangles (triangle mesh), quadrilaterals, or other simple convex polygons, which can simplify rendering. The 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 the polygon mesh (e.g., vertices, faces, edges) are spatially positioned (i.e., have identifiable locations in the space described by each coordinate system) directly and / or relatively to a particular coordinate system. The generation of the reconstructed 3D model can be performed using any standard, proprietary, and / or novel photogrammetry technique, 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.

[0026] In accordance with disclosed embodiments, a LIDAR system may include at least one projection unit that uses 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, or a high-power laser, or an alternative light source, such as a light-emitting diode (LED)-based light source. Additionally, the light source 112 shown throughout the figures may emit light in different formats, such as pulsed light, continuous wave (CW), or quasi-CW. For example, one type of light source that may be used is a vertical-cavity surface-emitting laser (VCSEL). Another type of light source that may be used is an external cavity diode laser (ECDL). In some examples, the light source may include a laser diode configured to emit light at a wavelength between approximately 650 nm and 1150 nm. Alternatively, the light source may include a laser diode configured to emit light at a wavelength of about 800 nm to about 1000 nm, about 850 nm to about 950 nm, or about 1300 nm to about 1600 nm. Unless otherwise indicated, the term "about" in reference to a numerical value is defined as up to a 5% variance relative to the stated value. Further details regarding the projection unit and the at least one light source are described below with reference to Figures 2A to 2C.

[0027] According to disclosed embodiments, a LIDAR system may include at least one scanning unit that uses 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 original path, such as a mirror, a prism, a controllable lens, a mechanical mirror, a mechanical scanning polygon, active diffraction (e.g., a controllable LCD), a Risley prism, non-mechanical electro-optical beam steering (such as those produced by Vscent), polarization gratings (such as those offered by Boulder Non-Linear Systems), an optical phased array (OPA), 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, a lens). In one example, the optical deflector may be movable to deviate light at various angles (e.g., at discrete angles or over a continuous range of angles). The optical deflector may optionally be controllable in various ways (e.g., deflect by α degrees, change the deflection angle by Δα, move a component of the optical deflector by M millimeters, change the rate at which the deflection angle is changed). Furthermore, the optical deflector may optionally be operable to change the angle of deflection in a single plane (e.g., the θ coordinate). The optical deflector may optionally be operable to change the angle of deflection in two non-parallel planes (e.g., the θ and φ coordinates). Alternatively or additionally, the optical deflector may optionally be operable to change the angle of deflection 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 the optical deflector may be used in the outbound direction (also referred to as the transmit direction, or 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 a light deflector in the inbound direction (also referred to as the receive direction or RX) to deflect light from at least a portion of the field of view onto one or more light sensors.Further details about the scanning unit and the at least one optical deflector are described below with reference to Figures 3A to 3C.

[0028] Disclosed embodiments may include pivoting an optical deflector to scan a field of view. As used herein, the term "pivot" broadly includes rotating an object (especially a solid object) about one or more axes of rotation while maintaining a center of rotation substantially fixed. In one embodiment, pivoting an optical deflector may, but does not necessarily, include rotating the optical deflector about a fixed axis (e.g., a shaft). For example, in some MEMS mirror implementations, the MEMS mirror can move through the actuation of multiple benders connected to the mirror, allowing the mirror to undergo some spatial translation in addition to rotation. Nevertheless, such mirrors can be designed to rotate about a substantially fixed axis and are therefore considered to pivot in accordance with the present disclosure. In other embodiments, certain types of optical deflectors (e.g., non-mechanical electro-optical beam steering, OPA) do not require moving components or internal movement to change the deflection angle of the deflected light. It should be noted that the discussion regarding the movement or pivoting of an optical deflector also applies mutatis mutandis to controlling an optical deflector to change its deflection behavior, for example controlling an optical deflector to change the deflection angle of a light beam arriving from at least one direction.

[0029] 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 a location or position in space where at least one controlled component of the optical deflector is located at a moment in time or over a short period of time. In one embodiment, the instantaneous position of the optical deflector can be measured relative to a frame of reference. The frame of reference may be relative to at least one fixed point in the LIDAR system. Or, for example, the frame of reference may be relative 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 relative to the maximum degree of change during scanning of the field of view. For example, scanning the entire field of view of a LIDAR system may involve varying the deflection of the light over a 30° range. Additionally, the instantaneous position of at least one optical deflector may include an angular shift of the optical deflector within 0.05°. In other embodiments, the term "instantaneous position of the optical deflector" may refer to the position of the optical deflector during acquisition of light that is processed to provide data for a single point of a point cloud (or another type of 3D model) generated by the LIDAR system. In some embodiments, the instantaneous position of the optical deflector may correspond to a fixed position or orientation where the deflector briefly stops during illumination of a specific sub-region of the LIDAR field of view. In other cases, the instantaneous position of the optical deflector may correspond to a specific position / orientation along a scanning range of the optical deflector's position / orientation that the optical deflector passes through as part of a continuous or semi-continuous scan of the LIDAR field of view. In some embodiments, the optical deflector may be moved such that the optical deflector 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, each of which can be reached at a different time during the scan cycle.

[0030] In accordance with disclosed embodiments, a LIDAR system may include at least one sensing unit employing at least one sensor configured to detect reflections from objects within 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 related to the measured characteristics. In some embodiments, at least one sensor may include multiple detectors constructed from multiple detection elements. At least one sensor may include one or more types of optical sensors. It should be noted that at least one sensor may include multiple sensors of the same type that differ in other characteristics (e.g., sensitivity, size). Other types of sensors may also be used. It is also possible to combine several types of sensors for various reasons, such as improved detection at certain distance ranges (e.g., close ranges), improved sensor dynamic range, improved sensor temporal response, and improved detection in various environmental conditions (e.g., air temperature, rain, etc.).

[0031] In one embodiment, at least one sensor includes a silicon photomultiplier (SiPM), a solid-state single-photon sensing device constructed from avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs) that function as the detection elements on a common silicon substrate. In one example, a typical distance between SPADs is between about 10 μm and about 50 μm, and each SPAD can have a recovery time between about 20 ns and about 100 ns. Similar photomultipliers made of other non-silicon materials can also be used. Although the SiPM device operates in a 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., SPADs, APDs, SiPMs, PIN diodes, photodetectors) can be combined into a single output that can be processed by the processor of the LIDAR system. Further details regarding the sensing unit and the at least one sensor are described below with reference to Figures 4A to 4C.

[0032] According to disclosed embodiments, the LIDAR system may include or communicate with at least one processor configured to perform various functions. The at least one processor may constitute any physical device having electrical circuitry that performs logical operations on one or more inputs. For example, the at least one processor may include one or more integrated circuits (ICs), including all or part of an application-specific integrated circuit (ASIC), a microchip, a microcontroller, a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), or other circuitry suitable for executing instructions or performing logical operations. The instructions executed by the at least one processor may be preloaded, for example, into memory integrated into or embedded in the controller, or stored in a separate memory. The memory may include random access memory (RAM), read-only memory (ROM), a hard disk, an optical disk, a magnetic medium, flash memory, other permanent, fixed, or volatile memory, or any other mechanism capable of storing instructions. In some embodiments, the memory is configured to store information representing data about objects in the environment of the LIDAR system. In some embodiments, the at least one processor may include two or more processors. Each processor may have a similar configuration, or the processors may be of different configurations that are electrically connected or disconnected from one another. For example, the processors may be separate circuits or integrated into a single circuit. When two or more processors are used, the processors may be configured to operate independently or cooperatively. The processors may be coupled electrically, magnetically, optically, acoustically, mechanically, or by other means that allow them to interact. Further details regarding the processing unit and the at least one processor are described below with reference to Figures 5A-5C.

[0033] System Overview 1A illustrates 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 an embodiment of the present disclosure, the projection unit 102 can include at least one light source 112, the scanning unit 104 can include at least one optical deflector 114, the detection unit 106 can include at least one sensor 116, and the processing unit 108 can include at least one processor 118. In one embodiment, the at least one processor 118 can be configured to coordinate the operation of the at least one light source 112 with the movement of the at least one optical deflector 114 to scan a field of view 120. During a scanning cycle, each instantaneous position of the at least one optical deflector 114 can be associated with a particular portion 122 of the field of view 120. Additionally, LIDAR system 100 may include at least one optional optical window 124 for directing projected light toward field of view 120 and / or receiving light reflected from objects within field of view 120. Optional optical window 124 may serve different purposes, such as collimating projected light and focusing reflected light. In one embodiment, optional optical window 124 may be an aperture, a flat window, a lens, or any other type of optical window.

[0034] In accordance with the present disclosure, LIDAR system 100 can be used in autonomous or semi-autonomous road vehicles (e.g., cars, buses, vans, trucks, and any other ground vehicles). Autonomous road vehicles equipped with LIDAR system 100 can scan the environment and navigate to a destination vehicle without human input. Similarly, LIDAR system 100 can also be used in autonomous / semi-autonomous aerial vehicles (e.g., UAVs, drones, quadcopters, and any other aerial or flying device) or autonomous or semi-autonomous surface vessels (e.g., boats, ships, submarines, and any other watercraft). Autonomous aerial vehicles and surface vessels equipped with LIDAR system 100 can scan the environment and navigate to a destination autonomously or with the aid of a remote human operator. According to one embodiment, vehicle 110 (road vehicle, aircraft, or surface vessel) can use LIDAR system 100 to help detect and scan the environment in which vehicle 110 is operating.

[0035] It should be noted that LIDAR system 100 or any of its components may be used with any of the example embodiments and methods disclosed herein. Additionally, although some aspects of LIDAR system 100 are described with reference to an exemplary vehicle-based LIDAR platform, LIDAR system 100, any of its components, or any of the processes described herein may be applicable to LIDAR systems of other platform types.

[0036] 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 may be attached to or mounted on any portion of the vehicle 110. The sensing unit 106 may receive reflections from the vehicle's 110 surroundings and forward reflection signals indicative of light reflected from objects within the field of view 120 to the processing unit 108. In accordance with the present disclosure, the scanning unit 104 may be mounted to or incorporated into the vehicle's 110 bumper, fender, side panel, spoiler, roof, headlight assembly, taillight assembly, rearview mirror assembly, hood, trunk, or any other suitable portion capable of housing at least a portion of a LIDAR system. In some cases, the LIDAR system 100 captures a complete surrounding view of the vehicle's 110 environment. As such, the LIDAR system 100 may have a 360° horizontal field of view. In one example, as shown in FIG. 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 scanning units (e.g., two, three, four, or more scanning units 104), each with a field of view that, when combined, covers a horizontal field of view by scanning 360 degrees around the vehicle 110. Those skilled in the art will recognize that the LIDAR system 100 may include any number of scanning units 104 arranged in any manner, with each unit having a field of view of 80 degrees to 120 degrees or less, depending on the number of units used. Furthermore, a 360 degree horizontal field of view may be achieved by mounting multiple LIDAR systems 100 on the vehicle 110, each with a single scanning unit 104. Nevertheless, it should be noted that one or more LIDAR systems 100 need not provide a full 360 degree field of view, and that a narrower field of view may be useful in some situations.For example, a vehicle 110 may require a first LIDAR system 100 with a 75° field of view in front of the vehicle, and possibly a second LIDAR system 100 with a similar FOV (optionally with a smaller detection range) in the rear. It should also be noted that various vertical field of view angles may be implemented.

[0037] 1B is an image showing an example output from a single scan cycle of LIDAR system 100 mounted on vehicle 110, according to disclosed embodiments. In this example, scan unit 104 is integrated into the right headlight assembly of vehicle 110. Every gray dot in the image corresponds to a location in the environment around vehicle 110 determined from reflections detected by sensing unit 106. In addition to location, each gray dot may 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 so on. In one embodiment, LIDAR system 100 may generate multiple point cloud data entries from reflections detected over multiple scan cycles of the field of view, enabling, for example, the determination of a point cloud model of the environment around vehicle 110.

[0038] FIG. 1C is an image showing a representation of a point cloud model determined from the output of the LIDAR system 100. According to disclosed embodiments, a surround 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, which processes the point cloud information to identify multiple features. Each feature can include data regarding various aspects of objects (e.g., cars, trees, people, and roads) in the point cloud and / or the environment around the vehicle 110. The features can have the same resolution of the point cloud model (i.e., have the same number of data points arranged, optionally in a similarly sized 2D array) or different resolutions. The features can be stored in any type of data structure (e.g., raster, vector, 2D array, 1D array). Additionally, virtual features, such as a representation of the vehicle 110, a boundary line, or a bounding box separating regions or objects in the image (e.g., as shown in FIG. 1B), and icons representing one or more identified objects, can be overlaid on the representation of the point cloud model to form the final surround view image. For example, a symbol of a vehicle 110 may be superimposed in the center of the surround view image.

[0039] Projection Unit 2A-2G illustrate various configurations of the projection unit 102 and its role in the LIDAR system 100. Specifically, FIG. 2A illustrates a projection unit 102 with a single light source, FIG. 2B illustrates multiple projection units 102 with multiple light sources aligned to a common optical deflector 114, FIG. 2C illustrates a projection unit 102 with primary and secondary light sources 112, FIG. 2D illustrates an asymmetric deflector used in some configurations of the projection unit 102, FIG. 2E illustrates a first configuration of a non-scanning LIDAR system, FIG. 2F illustrates a second configuration of a non-scanning LIDAR system, and FIG. 2G illustrates a LIDAR system that scans in the outbound direction and does not scan in the inbound direction. Those skilled in the art will recognize that the illustrated configurations of the projection unit 102 may have many variations and modifications.

[0040] 2A illustrates an example of a bistatic configuration for 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 exiting the LIDAR system and the reflected light entering the LIDAR system follow substantially different optical paths. In some embodiments, the bistatic configuration for the LIDAR system 100 may include separation of the optical paths through the use of completely different optical components, through the use of parallel but not completely separated optical components, or through the use of 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 illustrated in FIG. 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 (inbound light in 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, a bistatic configuration involves outbound light passing through the first optical window 124A and inbound light passing through the second optical window 124B. In all of the above configuration examples, the inbound and outbound optical paths are different from each other.

[0041] In this embodiment, all components of the LIDAR system 100 can be housed within a single housing 200 or split among multiple housings. As shown, the projection unit 102 is associated with a single light source 112 including a laser diode 202A (or one or more laser diodes coupled together) configured to emit light (projection 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. Additionally, the light source 112 can optionally be associated with an optical assembly 202B used to manipulate (e.g., for collimation, focusing, etc.) the light emitted by the laser diode 202A. It should be noted that other types of light sources 112 can also be used, and the present disclosure is not limited to laser diodes. Furthermore, the light source 112 can emit light in various formats, such as optical pulses, modulated frequencies, continuous wave (CW), quasi-CW, or any other form corresponding to the particular 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 projection light is projected toward an outbound deflector 114A, which functions as a steering element to direct the projection light toward the field of view 120. In this example, the scanning unit 104 also includes a pivotable return deflector 114B, which directs photons reflected back from an object 208 within the field of view 120 (reflected light 206) toward the sensor 116. The reflected light is detected by the sensor 116, and information about the object (e.g., the distance to the object 212) is determined by the processing unit 118.

[0042] In this figure, LIDAR system 100 is connected to host 210. In accordance with the present disclosure, the term "host" refers to any computing environment that interfaces with LIDAR system 100 and may be a vehicle system (e.g., part of vehicle 110), a testing 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 LIDAR system 100 via the cloud. In some embodiments, host 210 may also include an interface to external devices such as cameras and sensors configured to measure various characteristics of host 210 (e.g., acceleration, steering wheel deflection, vehicle backing, etc.). In accordance with the present disclosure, LIDAR system 100 may be fixed to a stationary object associated with host 210 (e.g., a building, a tripod) or to a portable system associated with host 210 (e.g., a portable computer, a movie camera). In accordance with the present disclosure, LIDAR system 100 can be connected to a host 210 to provide output (e.g., 3D models, reflectance images) of LIDAR system 100 to host 210. Specifically, host 210 can use LIDAR system 100 to help detect and scan its environment or any other environment. Additionally, host 210 can integrate, synchronize, or otherwise use output of LIDAR system 100 with outputs of other sensing systems (e.g., cameras, microphones, radar systems). In one example, LIDAR system 100 can be used by a security system.

[0043] The LIDAR system 100 may also include a bus 212 (or other communication mechanism) that interconnects subsystems and components for transferring information within the LIDAR system 100. Optionally, the bus 212 (or another communication mechanism) can be used to interconnect the LIDAR system 100 with a host 210. In the example of FIG. 2A , the processing unit 108 includes two processors 118 for coordinated regulation of the operation of the projection unit 102, the scanning unit 104, and the sensing unit 106 based, at least in part, 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 the 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 based, at least in part, on the feedback. A dynamic system or element is one that can be updated during operation.

[0044] 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 the reflected light. The characteristics of the reflected light may include, for example, time of flight (i.e., time from emission to detection), instantaneous power (e.g., power signature), average power throughout the return pulse, and photon distribution / signal during the return pulse. By comparing the characteristics of the light pulses with the characteristics of the corresponding reflections, distance and, in some cases, physical properties such as the reflection intensity of the object 212 can be estimated. By repeating this process for multiple adjacent portions 122 in a predetermined pattern (e.g., a raster, Lissajous, or other pattern), a complete scan of the field of view 120 can be achieved. As discussed in more detail below, in some situations, the LIDAR system 100 may direct light to only some of the portions 122 of the field of view 120 in each scan cycle. These portions may be adjacent to one another, but this is not necessarily the case.

[0045] 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 dashed arrows. In one embodiment, the network interface 214 may include an integrated services digital network (ISDN) card, a cable modem, a satellite modem, or a modem that provides a data communication connection to a corresponding type of telephone line. As another example, the network interface 214 may include a LAN card that provides a data communication connection 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 the communication network or networks over which the LIDAR system 100 and the host 210 are intended to operate. For example, the network interface 214 may be used to provide output from the LIDAR system 100, such as a 3D model or operational parameters of the LIDAR system 100, to an external system. In other embodiments, the communication unit may be used to receive commands from an external system, to receive information about the inspected environment, and to receive information from other sensors, for example.

[0046] FIG. 2B illustrates an example of a monostatic configuration of the LIDAR system 100 including multiple projection units 102. The term "monostatic configuration" broadly refers to a LIDAR system configuration in which projected light exiting the LIDAR system and reflected light entering the LIDAR system travel substantially the same optical path. In one example, the outbound and inbound optical beams may share at least one optical assembly through which both the outbound and inbound optical beams pass. In another example, the outbound light may pass through an optical window (not shown), and the inbound optical radiation may pass through the same optical window (not shown). A monostatic configuration may include a configuration in which the scanning unit 104 includes a single optical deflector 114 that 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 it 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 deflector 216 may include an optical isolator that allows light to pass only in one direction. A schematic diagram of the asymmetric deflector 216 is shown in FIG. 2D. In accordance with the present disclosure, a monostatic configuration of the LIDAR system 100 may include an asymmetric deflector that prevents reflected light from entering the light source 112 and directs all reflected light toward the sensor 116, thereby increasing detection sensitivity.

[0047] 2B , the LIDAR system 100 includes three projection units 102, each including a single light source 112 aimed at a common optical deflector 114. In one embodiment, the multiple light sources 112 (including two or more light sources) can project light at substantially the same wavelength, with each light source 112 generally associated with a different area of ​​the field of view (illustrated as 120A, 120B, 120C). This allows for scanning of a wider field of view than could be achieved with a single light source 112. In another embodiment, the multiple light sources 102 can project light at different wavelengths, with all light sources 112 directed at the same (or overlapping) portion of the field of view 120.

[0048] FIG. 2C illustrates 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 at wavelengths longer than those perceptible to the human eye to optimize SNR and detection range. For example, the primary light source 112A can project light at wavelengths between approximately 750 nm and 1100 nm. In contrast, the secondary light source 112B can project light at wavelengths visible to the human eye. For example, the secondary light source 112B can project light at wavelengths between approximately 400 nm and 700 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 can project light emissions simultaneously or in an alternating pattern. An alternating pattern means that the light sources are not active at the same time, reducing mutual interference. Those skilled in the art will recognize that other combinations of wavelength ranges and activation schedules can also be implemented.

[0049] According to some embodiments, if the secondary light source 112B is too close to the LIDAR optical output port, it may cause a person to blink. This may ensure an eye-safety feature not possible with typical laser sources that utilize the near-infrared spectrum. In another embodiment, the secondary light source 112B may be used for calibration and reliability at the point of service (POS). This is done somewhat similarly to headlight calibration, which is done on a vehicle 110 using a special reflector / pattern at a specific height above the ground. The POS operator can check the LIDAR calibration by simply visually inspecting the scan pattern on a distinctive target, such as a test pattern board, at a specified distance from the LIDAR system 100. Furthermore, the secondary light source 112B may provide a means for operational reliability that the LIDAR is working for the end user. For example, the system may be configured to allow a person to place their hand in front of the optical deflector 114 to test its operation.

[0050] The secondary light source 112B may also have an invisible element that doubles as a backup system in the event that the primary light source 112A fails. This feature may be useful for fail-safe devices with a high functional safety rating. 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. Thus, if the primary light source 112A fails, the system functionality will degrade to the function and capability set of the secondary light source 112B. Although the capabilities of the secondary light source 112B may be less than those of the primary light source 112A, the LIDAR system 100 may be designed to allow the vehicle 110 to safely arrive at its destination.

[0051] 2D illustrates 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 necessarily the case, the asymmetric deflector 216 may optionally be an electrostatic deflector. The asymmetric deflector 216 may be used in a monostatic configuration of the LIDAR system 100, for example, as shown in FIGS. 2B and 2C, to allow for a common optical path for transmitting and receiving light via at least one deflector 114. However, typical asymmetric deflectors, such as beam splitters, are characterized by energy losses, especially in the receive path, which may be more sensitive to power losses than the transmit path.

[0052] As shown in FIG. 2D , the LIDAR system 100 may include an asymmetric deflector 216 positioned in the transmit 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 may be generated by the projection unit 102 and travel through the unidirectional deflector 220 to the scanning unit 104. The scanning unit 104 deflects the transmitted light toward an optical outlet. The received light travels through an optical inlet to at least one deflecting element 114, which deflects the reflected signal onto a different path away from the light source toward the detection unit 106. Optionally, the asymmetric deflector 216 may be combined with a polarized light source 112 that is linearly polarized with the same polarization axis as the unidirectional deflector 220. Notably, the cross-section of the outbound light beam is significantly smaller than that of the reflected signal. Accordingly, LIDAR system 100 may include one or more optical components (e.g., lenses, collimators) to focus or otherwise manipulate the emitted polarized beam to the dimensions of asymmetric deflector 216. In one embodiment, unidirectional deflector 220 may be a polarizing beam splitter that is substantially transparent to the polarized beam.

[0053] According to some embodiments, the LIDAR system 100 may further include an optical system 222 (e.g., a quarter-wave retarder) 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. Light reflected from the field of view back to the system 100 passes through the polarizer 114 to the optical system 222 and is circularly polarized opposite to the transmitted light. The optical system 222 then converts the received opposite-circularly polarized light to linearly polarized light that is not aligned with the polarizing beam splitter 216. As noted above, the received light portion is larger than the transmitted light portion due to optical dispersion of the beam as it travels the distance to the target.

[0054] A portion of the received light is incident on the unidirectional deflector 220, which reflects the light with some power loss towards the sensor 106. However, another portion of the received light is incident on a reflective surface 218 (e.g., a slit in a polarizing beam splitter) surrounding the unidirectional deflector 220. The reflective surface 218 reflects the light with substantially no power loss towards the detection unit 106. The unidirectional deflector 220 reflects light composed of various polarization axes and directions, which ultimately reaches 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.

[0055] It should be noted that the proposed asymmetric deflector 216 offers much better performance than a simple mirror with a through-hole. In a mirror with a hole, all reflected light that reaches the hole is lost to the detector. However, in the deflector 216, the unidirectional deflector 220 deflects a significant portion of that light (e.g., about 50%) toward each sensor 116. In a LIDAR system, the number of photons that reach the LIDAR from a remote distance is very limited, so improving the photon capture rate is important.

[0056] According to some embodiments, a device for beam splitting and steering is described. A polarized beam can be emitted from a light source having a first polarization. The emitted beam can be directed to pass through a polarizing beam splitter assembly. The polarizing beam splitter assembly includes a one-way slit on a first side and a mirror on the opposite side. The one-way slit can transmit the emitted polarized beam toward a quarter-wave retarder. The quarter-wave retarder changes the emitted signal from a polarized signal to a linear signal (or vice versa), thereby preventing the reflected beam from subsequently passing through the one-way slit.

[0057] 2E shows an example of a bistatic configuration of the LIDAR system 100 without the scanning 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 the processor 118. For example, the processor 118 may cause the linear array of light sources to sequentially project collimated laser beams toward the first optional optical window 124A. The first optional optical window 124A may include a diffuser lens to diffuse the projected light to form a series of horizontally wide and vertically narrow beams. Optionally, some or all of the 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 source 112A, light source 112D, and light source 112F simultaneously project laser beams toward first optional optical window 124A, thereby illuminating the field of view with three narrow, perpendicular beams. A light beam from fourth light source 112D can reach an object within the field of view. Light reflected from the object can be captured by second optical window 124B and redirected to sensor 116. Because the optical paths of the projected and reflected light are substantially different, the configuration shown in FIG. 2E is considered a bistatic configuration. Note that projection unit 102 can also include multiple light sources 112 arranged in a nonlinear configuration, such as a two-dimensional array, in hexagonal tiles, or in any other manner.

[0058] FIG. 2F illustrates an example of a monostatic configuration of the LIDAR system 100 without the scanning unit 104. Similar to the example embodiment shown in FIG. 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 FIG. 2E, this configuration of the LIDAR system 100 may include a single optical window 124 for both the projected and reflected light. Using an asymmetric deflector 216, the reflected light may be redirected to the sensor 116. Because the optical paths of the projected and reflected light are substantially similar to one another, the configuration shown in FIG. 2E is considered a monostatic configuration. 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 may be 80% or more, 85% or more, 90% or more, or 95% or more.

[0059] FIG. 2G shows an example of a bistatic configuration of LIDAR system 100. The configuration of LIDAR system 100 in this figure is similar to the configuration shown in FIG. 2A. For example, both configurations include a scanning unit 104 for directing projected light in the outbound direction toward the field of view. However, in contrast to the embodiment of FIG. 2A, in this configuration, the scanning unit 104 does not redirect reflected light in the inbound direction. Instead, the reflected light passes through second optical window 124B to enter sensor 116. Because the optical paths of the projected light and reflected light are substantially different from one another, the configuration shown in FIG. 2G is considered a bistatic configuration. The term “substantially different” in the context of the optical paths of the projected light and reflected light means that the overlap between the two optical paths may be less than 10%, less than 5%, less than 1%, or less than 0.25%.

[0060] Scan Unit 3A-3D illustrate various configurations of the scan unit 104 and its role in the LIDAR system 100. Specifically, FIG. 3A illustrates a scan unit 104 with a MEMS mirror (e.g., square), FIG. 3B illustrates a scan unit 104 with a MEMS mirror (e.g., circular), FIG. 3C illustrates a scan unit 104 with an array of reflectors used in a monostatic scanning LIDAR system, and FIG. 3D illustrates an example LIDAR system 100 that mechanically scans the environment around the LIDAR system 100. Those skilled in the art will recognize that the illustrated configurations of the scan unit 104 are merely exemplary and that many variations and modifications are possible within the scope of the present disclosure.

[0061] FIG. 3A illustrates an exemplary scan unit 104 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 can include one or more actuators 302 (specifically, actuators 302A and 302B). In one embodiment, the actuators 302 can be fabricated from a semiconductor (e.g., silicon) and include a piezoelectric layer (e.g., PZT, lead zirconate titanate, aluminum nitride), a semiconductor layer, and a base layer that change dimensions in response to an electrical signal applied by an actuation controller. In one embodiment, the physical properties of the actuators 302 can determine the mechanical stress applied to the actuator 302 when a current is passed through them. When the piezoelectric material is activated, it exerts a force on the actuator 302, causing it to bend. In one embodiment, the resistivity of one or more actuators 302 in an active state (Ractive) when the mirror 300 is deflected to a particular angular position can be measured and compared to the resistivity in a resting state (Rrest). Feedback including Ractive provides information to determine the actual mirror deflection angle compared to the expected angle, allowing for correction of the mirror 300 deflection as needed. The difference between Rrest and Ractive can be correlated to the mirror drive to an angular deflection value, which can serve to close the loop. This embodiment can be used for dynamic tracking of the actual mirror position to optimize 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 32-34.

[0062] 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 the dashed line in the figure). Due to insulating gaps in the semiconductor frame 308, such as insulating gap 310, actuators 302A and 302B can become two separate islands electrically connected through spring 306 and frame 308. The current, or any associated electrical parameters (voltage, current frequency, capacitance, dielectric constant, etc.), can be monitored with associated position feedback. In the event of a mechanical failure that damages one of the components, the current flowing through the structure will change and deviate from its functional calibration value. In extreme situations (e.g., if the spring breaks), the current flow will be completely interrupted due to the electrical chain being interrupted by the failed element.

[0063] FIG. 3B illustrates another exemplary scan unit 104 including a two-axis 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 a dashed line in the figure) flows from contact 304A to contact 304D; however, 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 two-axis MEMS mirror can be configured to deflect light in both horizontal and vertical directions. For example, the deflection angle of the dual-axis MEMS mirror may 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 mirror 300 may have many variations and modifications. In one example, at least deflector 114 may comprise a dual-axis square mirror or a single-axis circular mirror. Examples of circular and square mirrors are shown in FIGS. 3A and 3B by way of example only. Any shape may be employed depending on the system specifications. In one embodiment, actuator 302 is incorporated as an integral part of at least deflector 114 to directly provide power to move MEMS mirror 300. Furthermore, MEMS mirror 300 may be connected to frame 308 by one or more rigid support elements. In another embodiment, at least deflector 114 may include an electrostatic or electromagnetic MEMS mirror.

[0064] As described above, a monostatic scanning LIDAR system utilizes at least a portion of the same optical path for emitting projected light 204 and receiving reflected light 206. The light beam on the outbound path may be collimated and focused into a narrow beam, while the reflection on the return path spreads out into a larger light portion due to dispersion. In one embodiment, the scan unit 104 may have a large reflective area in the return path and may include an asymmetric deflector 216 that redirects the reflection (i.e., reflected light 206) toward the sensor 116. In one embodiment, the scan unit 104 may include a MEMS mirror with a large reflective area, with negligible impact on field of view and frame rate performance. Further details regarding the asymmetric deflector 216 are provided below with reference to FIG. 2D .

[0065] In some embodiments (e.g., as illustrated in FIG. 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, the optical deflector 114 is implemented as a group of small individual optical deflectors operating synchronously, allowing the optical deflector 114 to perform at larger deflection angles and higher scan rates. The deflector array can effectively function as a large optical deflector (e.g., a large mirror) in terms of active 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 two selected functions occur during coincident or overlapping time periods, where one begins and ends during the duration of the other, or where one begins before the other is completed.

[0066] 3C illustrates an example of a scanning unit 104 that includes a reflector array 312 with small mirrors. In this embodiment, the reflector array 312 functions as at least one deflector 114. The reflector array 312 may include multiple reflector units 314 configured to pivot (individually or together) and 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 may direct the projected light 204 toward a portion of the field of view 120. The reflector array 312 may also be part of the return path of light reflected from the surface of an object located within the illuminated portion of the field of view 120. Specifically, the reflector array 312 may direct the reflected light 206 toward the sensor 116 or toward the asymmetric deflector 216. In one example, the reflector array 312 has an area of ​​about 75 to about 150 mm 2 Here, each reflector unit 314 has a width of about 10 μm, and the support structure can be lower than 100 μm.

[0067] 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 the 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 a respective processor (not shown) to tilt at a specific angle along each of one or more separate axes. Alternatively, the reflector array 312 may be associated with a common controller (e.g., the processor 118) configured to synchronize and manage the movement of the reflector units 314 such that at least some of the reflector units 314 pivot simultaneously to point in approximately the same direction.

[0068] Additionally, the at least one processor 118 may select at least one reflector unit 314 for the outbound path (hereinafter referred to as a "transmit mirror") and a group of reflector units 314 for the return path (hereinafter referred to as a "receive mirror"). In accordance with the present disclosure, increasing the number of transmit mirrors may increase the spread of the reflected photon beam. Furthermore, reducing the number of receive mirrors may narrow the receive field, compensate for ambient light conditions (e.g., clouds, rain, fog, extreme heat, and other environmental conditions), and improve the signal-to-noise ratio. Also, as noted above, the emitted light beam is typically thinner than the reflected light portion and therefore can be adequately detected by a smaller portion of the deflector array. Furthermore, light reflected from the portion of the deflector array used for transmission (e.g., a transmit mirror) may be blocked from reaching the sensor 116, thereby reducing the effect of internal reflections in the LIDAR system 100 on system operation. The at least one processor 118 can also pivot one or more reflector units 314 to overcome mechanical disturbances and drift due to, for example, thermal and gain effects. In one example, one or more reflector units 314 may move differently than intended (frequency, rate, speed, etc.), but these movements can be compensated for by appropriately electronically controlling the deflectors.

[0069] 3D illustrates an exemplary LIDAR system 100 that mechanically scans its environment. In this example, the LIDAR system 100 may include a motor or other mechanism for rotating the housing 200 about an axis of the LIDAR system 100. Alternatively, the motor (or other mechanism) may mechanically rotate a rigid structure of the LIDAR system 100, on which the one or more light sources 112 and one or more sensors 116 are mounted, thereby scanning the environment. As described above, the projection unit 102 may include at least one light source 112 configured to project optical emissions. The projected optical emissions may travel along an outbound path toward the field of view 120. Specifically, when the projection light 204 travels toward the optional optical window 124, the projected optical emissions may be reflected by the deflector 114A and pass through the exit aperture 314. The reflected optical emissions may travel from the object 208 along a return path toward the detection unit 106. For example, if the reflected light 206 travels towards the sensing unit 106, the reflected light 206 is reflected by the deflector 114B. It will be appreciated by those skilled in the art that a LIDAR system that includes 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) steering an internal optical deflector.

[0070] In embodiments in which the scanning of the field of view 120 is mechanical, the projected optical emissions can be directed to an exit aperture 314 that is part of a wall 316 that separates the projection unit 102 from other portions of the LIDAR system 100. In some examples, the wall 316 can be formed of a transparent material (e.g., glass) covered with a reflective material to form the deflector 114B. In this example, the exit aperture 314 can correspond to the portion of the wall 316 that is not covered with the reflective material. Additionally or alternatively, the exit aperture 314 can include a hole or cut in the wall 316. The reflected light 206 can be reflected by the deflector 114B and directed toward an entrance aperture 318 of the detection unit 106. In some examples, the entrance aperture 318 can include a filter window configured to allow wavelengths within a certain wavelength range to enter the detection unit 106 while attenuating other wavelengths. The reflection of the object 208 from the field of view 120 may be reflected by the deflector 114B and incident on the sensor 116. By comparing some properties of the reflected light 206 with the projected light 204, at least one aspect of the object 208 may be determined. For example, by comparing the time when the projected light 204 was emitted by the light source 112 and the time when the sensor 116 received the reflected light 206, the distance between the object 208 and the LIDAR system 100 may be determined. In some examples, other aspects of the object 208, such as the shape, color, or material, may also be determined.

[0071] In some examples, the LIDAR system 100 (or a portion thereof including at least one light source 112 and at least one sensor 116) can be rotated about at least one axis to determine a three-dimensional map of the surroundings of the LIDAR system 100. For example, to scan the field of view 120, the LIDAR system 100 can be rotated about a substantially vertical axis, as indicated by arrow 320. While FIG. 3D illustrates rotating the LIDAR system 100 clockwise about the axis, as indicated by arrow 320, the LIDAR system 100 can additionally or alternatively 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 that is less than 360 degrees of the LIDAR system 100. For example, the LIDAR system 100 can be mounted on a platform that rocks back and forth about an axis without performing a complete rotation.

[0072] Detection Unit 4A-4E illustrate various configurations of the sensing unit 106 and their roles in the LIDAR system 100. Specifically, FIG. 4A illustrates an exemplary sensing unit 106 with a detector array, FIG. 4B illustrates monostatic scanning using a two-dimensional sensor, FIG. 4C illustrates an example two-dimensional sensor 116, FIG. 4D illustrates a lens array associated with the sensor 116, and FIG. 4E includes three diagrams illustrating lens configurations. Those skilled in the art will recognize that the sensing unit 106 configurations shown are merely exemplary and may have many alternative variations and modifications consistent with the principles of the present disclosure.

[0073] 4A shows an example of a sensing unit 106 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 a cloud 208) within the 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 atmosphere), or another type of object (e.g., dust or irradiated powder-like object). When photons emitted from the light source 112 strike the object 208, the photons are reflected, refracted, or absorbed. Typically, as shown, only a portion of the photons reflected from the object 208A enter the optional optical window 124. Since a change in distance of up to 15 cm results in a travel time difference of 1 ns (as photons travel at the speed of light to and from object 208), the time difference in the travel times of different photons hitting different objects may be detectable by an optical timing sensor with a sufficiently fast response.

[0074] The sensor 116 includes multiple detector elements 402 for detecting photons of the photon pulses reflected back from the field of view 120. All of the detector elements may be included in a detector array 400, which may have a rectangular arrangement (e.g., as shown) or any other arrangement. The detector elements 402 may operate simultaneously or partially simultaneously. Specifically, each detector element 402 may provide detection information every sampling period (e.g., every 1 nanosecond). In one example, the detector array 400 may be a silicon photomultiplier (SiPM), a solid-state single-photon sensing device constructed from an array of single-photon avalanche diodes (SPADs, which function as detector elements 402) on a common silicon substrate. Similar photomultipliers made of other non-silicon materials may also be used. Although the SiPM device operates in a digital / switching mode, it is an analog device because all 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 mentioned above, more than one type of sensor may be implemented (e.g., SiPM and APD). In some cases, the sensing unit 106 includes at least one APD integrated into the SiPM array and / or at least one APD detector positioned adjacent to the SiPMs, on a separate or common silicon substrate.

[0075] In one embodiment, the detector 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 in a variety of shapes (e.g., rectangular, square, annular, etc., as shown, or any other shape). Not all of the individual detectors contained within the geometric area of ​​a region 404 belong to that region, but in most cases, they do not belong to other regions 404 that cover other areas of the sensor 310, unless some overlap at the boundaries between regions is desired. As shown in FIG. 4A, these regions can be non-overlapping regions 404, but they can also overlap. Every region can have an associated region output circuit 406. The region output circuit 406 can provide a region output signal for the corresponding group of detector elements 402. For example, the region output circuit 406 can be a summing circuit, although other forms of combining the outputs of each detector into a single output (whether scalar, vector, or any other format) can also be employed. Optionally, each region 404 is a single SiPM, but this is not necessarily the case; a region may be a small portion of a single SiPM, a group of several SiPMs, or a combination of different types of detectors.

[0076] In the illustrated example, the processing unit 108 is located in a separate housing 200B (inside or outside of) the host 210 (e.g., in the vehicle 110), and the sensing unit 106 may include a dedicated processor 408 for analyzing the reflected light. Alternatively, the processing unit 108 may be used to analyze the 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 different housing from the projection unit 102 and / or the sensing module 106. In one embodiment, the LIDAR system 100 can include multiple housings connected to each other in different ways, such as by electrical wire connections, wireless connections (e.g., RF connections), fiber optic cables, and any combination of the above.

[0077] In one embodiment, analyzing 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 may analyze the reflected light 206 to determine the average power over the entire return pulse and the photon distribution / signal ("pulse shape") during the return pulse. In the illustrated example, the output of any detection element 402 is not sent directly to the processor 408, but may be combined (e.g., summed) with signals from other detectors in the region 404 before being passed to the processor 408. However, this is merely an example, and the circuitry of the sensor 116 may also send information from the detection elements 402 to the processor 408 via other routes (e.g., without passing through the region output circuitry 406).

[0078] FIG. 4B illustrates a LIDAR system 100 configured to scan its environment using a two-dimensional sensor 116. In the example of FIG. 4B, the sensor 116 is a 4×6 matrix of detectors 410 (also referred to as “pixels”). In one embodiment, the pixel size may 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 in two non-parallel axes (e.g., orthogonal axes as shown in the illustrated example). The number of detectors 410 in the sensor 116 may vary in various implementations depending, for example, on the desired resolution, signal-to-noise ratio (SNR), desired detection distance, etc. For example, the sensor 116 may have anywhere from 5 to 5,000 pixels. In another example (not shown), the sensor 116 may be a one-dimensional matrix (e.g., 1×8 pixels).

[0079] Each detector 410 may include multiple detector elements 402, such as avalanche photodiodes (APDs), single-photon avalanche diodes (SPADs), a combination of avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs), or detector elements that measure both the time of flight from a laser pulse transmit event to a receive event and the intensity of the received photon. For example, each detector 410 may include anywhere from 20 to 5,000 SPADs. The outputs of the detector elements 402 in each detector 410 may be summed, averaged, or otherwise combined to provide an integral pixel output.

[0080] In the illustrated example, the sensing 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. For purposes of this discussion, the field of view 120 (the entire field of view that can be scanned by the LIDAR system 100 without moving, rotating, or rolling in any direction) will be referred to as the "first FOV 412," and the smaller field of view of the sensor 116 will be referred to as the "second FOV 412" (which can alternatively be referred to as the "instantaneous FOV"). The coverage of the second FOV 414 relative to the first FOV 412 will vary depending on the specific application of the LIDAR system 100 and may be, for example, between 0.5% and 50%. In one example, the second FOV 412 may be vertically elongated 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 may still be smaller than the first FOV 412, for example, at least 5 times, at least 10 times, at least 20 times, or at least 50 times smaller.

[0081] To cover the first FOV 412, the scanning unit 106 can direct photons arriving from different parts of the environment at different times to the sensor 116. In the illustrated monostatic configuration, while directing the projected light 204 towards the field of view 120, the scanning unit 106 can direct the reflected light 206 to the sensor 116 when the at least one deflector 114 is positioned at an instantaneous position. Typically, at each time during the scanning of the first FOV 412, the light beam emitted by the LIDAR system 100 covers a portion of the environment that is larger (in terms of angular aperture) than the second FOV 414 and includes the portions of the environment that are collected by the scanning unit 104 and the sensor 116.

[0082] FIG. 4C illustrates an example of a two-dimensional sensor 116. In this embodiment, the sensor 116 is an 8×5 matrix of detectors 410, each of which includes multiple detector 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 includes a 4×3 matrix of detector 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 includes a 3×3 matrix of detector elements 402. Thus, the number of detector elements 402 in each detector 410 may be constant or may vary, and different detectors 410 in a common array may have different numbers of detector elements 402. The outputs of all of the detector elements 402 in each detector 410 may be summed, averaged, or otherwise combined to provide a single pixel output value. Although the detectors 410 in the example of FIG. 4C are arranged in a rectangular matrix (linear rows and linear columns), other arrangements may also be used, such as a circular arrangement or a honeycomb arrangement.

[0083] According to some embodiments, measurements from each detector 410 allow for the determination of the time of flight from a light pulse emission event to a receive event and the intensity of the received photon. The receive event may be the result of a light pulse being reflected from an object 208. The time of flight may be a timestamp value representing the distance from the reflecting object to the optional optical window 124. The time of flight value may be known by photon detection and counting methods such as Time Correlated Single Photon Counter (TCSPC), analog photon detection methods such as signal integration and qualification (via analog-to-digital conversion or a simple comparator), or other methods.

[0084] In some embodiments, and with reference to FIG. 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 association of reflected light from a single portion of the field of view 120 with multiple detectors 410. Thus, the scanning resolution of the LIDAR system can be expressed as the number of instantaneous positions (per scan cycle) multiplied by the number of detectors 410 in the sensor 116. The information from each detector 410 (i.e., each pixel) represents a basic data element upon which the captured field of view in three-dimensional space is constructed. This includes, for example, the basic elements of a point cloud representation, with spatial location and associated reflected intensity values. In one embodiment, reflections from a single portion of the field of view 120 detected by multiple detectors 410 may be returned 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 and may easily include two, three, or more objects partially overlapping each other.

[0085] FIG. 4D is a cross-sectional view of a portion of a sensor 116 according to an example of the presently disclosed subject matter. The depicted portion of the sensor 116 includes a portion of a detector array 400 including four detector elements 402 (e.g., four SPADs, four APDs). The detector array 400 may be a photodetector sensor implemented in complementary metal-oxide semiconductor (CMOS). Each of the detector elements 402 has a sensing area positioned within a substrate periphery. Although not necessarily required, the sensor 116 may be used in a monostatic LiDAR system with a narrow field of view (e.g., because the scanning unit 104 scans different portions of the field 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 FIG. 4D, the sensor 116 may include multiple lenses 422 (e.g., microlenses), each capable of directing incident light toward a different detector element 402 (e.g., toward the active area of ​​the detector element 402), which may be usable when out-of-focus imaging is not an issue. Lens 422 can be used to increase the optical fill factor and sensitivity of detector array 400 by deflecting most of the light reaching sensor 116 towards the active area of ​​detector elements 402 .

[0086] A detector array 400, such as that illustrated in FIG. 4D, can include several layers embedded in a silicon substrate by various methods (e.g., implants) to provide a sensing area, contact elements to metal layers, and insulating elements (e.g., shallow trench implant (STI), guard rings, optical trenches, etc.). The sensing area is the volumetric element in a CMOS detector, allowing the optical conversion of incident photons into electrical current when the proper voltage bias is applied to the device. In the case of an APD / SPAD, the sensing area, through a combination of electric fields, pulls electrons generated by photon absorption toward the multiplication area, where the photon-induced electrons are amplified, causing an avalanche breakdown of the multiplied electrons.

[0087] A front-side illuminated detector (e.g., as shown in FIG. 4D ) has an input optical port on the same side as the metal layer overlying the semiconductor (silicon). The metal layer must provide electrical connections between the individual photodetector elements (e.g., anodes and cathodes) and various elements such as bias voltages, quenching / ballast elements, and other photodetectors in a common array. The optical port through which photons enter the detector's sensing area consists of a passage through the metal layer. It should be noted that the passage of light from some directions through this passage may be blocked by one or more metal layers (e.g., metal layer ML6 shown on the left-most detector element 402 in FIG. 4D ). Such blocking reduces the detector's overall light absorption efficiency.

[0088] 4E illustrates three detector elements 402, each with an associated lens 422, in accordance with an example of the presently disclosed subject matter. Each of the three detector elements in FIG. 4E, labeled 402(1), 402(2), and 402(3), illustrates a lens configuration that may be implemented in association with one or more of the detector elements 402 of sensor 116. It should be noted that combinations of these lens configurations may also be implemented.

[0089] In the lens configuration illustrated for detector element 402(1), the focal point of the associated lens 422 can be located above the semiconductor surface. Optionally, the apertures in different metal layers of the detector element can have different sizes that match the cone of 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. Large metal layers can be important for power transmission and ground shielding. This approach can be useful, for example, in monostatic LiDAR designs with narrow fields of view, where the incident light beam consists of parallel rays and the imaging focal point has no effect on the detection signal.

[0090] The lens configuration illustrated for detection element 402(2) can improve the efficiency of photon detection by detection element 402 by identifying a sweet spot. Specifically, a photodetector implemented in CMOS can have a sweet spot within the detection volume where photons have the highest probability of avalanching. Thus, as exemplified for detection element 402(2), the focal point of lens 422 can be positioned at a sweet spot location within the detection volume. The lens shape and distance from the focal point can take into account the refractive index of all elements traversed by the laser beam along a path from the lens to the detection sweet spot location embedded within the semiconductor material.

[0091] The lens configuration shown for the detector element on the right in FIG. 4E can use a diffuser and a reflective element to improve the efficiency of photon absorption in semiconductor materials. Specifically, near-IR wavelengths require a significantly longer path through silicon material to achieve a high absorption probability for photons traveling this path. In a typical lens configuration, photons may traverse the detection area and potentially be absorbed without generating detectable electrons. The long absorption path, which improves the probability that a photon will generate an electron, results in detection area sizes (e.g., tens of microns) that are impractical for CMOS devices fabricated using typical manufacturing processes. The rightmost detector element in FIG. 4E illustrates a technique for processing incident photons. An associated lens 422 focuses incident light onto a diffuser element 424. In one embodiment, the light sensor 116 can 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., possibly vertically) toward the detection area and the reflective optical trench 426. The diffuser may be located at the focal point, above the focal point, or below the focal point. In this embodiment, incident light may be focused onto the specific location where the diffuser element is located. Optionally, the detector element 422 is designed to optically avoid inactive areas where photon-induced electrons may be lost, reducing effective detection efficiency. The reflective optical trench 426 (or other form of optically reflective structure) steers photons back and forth within the sensing area, thereby increasing the likelihood of detection. Ideally, photons are trapped within the cavity consisting of the sensing area and the reflective trench indefinitely until they are absorbed and generate electron-hole pairs.

[0092] In accordance with the present disclosure, a long path is created to absorb incoming photons, contributing to a high probability of detection. Optical trenches can also be implemented in the detection elements 422 to reduce the crosstalk effect of parasitic photons in the avalanche that can leak to other detectors and generate false detection events. According to some embodiments, photodetector arrays can be optimized to take advantage of a higher yield of received signals, i.e., to receive as much received signal as possible and lose as little signal due to internal signal degradation. Photodetector arrays can be improved by (a) moving the focal point to a location above the semiconductor surface, optionally by appropriately designing a metal layer above the substrate; (b) steering the focal point to the most responsive / sensitive area of ​​the substrate (i.e., the "sweet spot"); (c) adding a diffuser above the substrate to direct the signal toward the "sweet spot"; and / or adding reflective material to the trench to reflect deflected signals back to the "sweet spot."

[0093] It should be noted that in some lens configurations, the lens 422 may be positioned so that its focal point is above the center of the corresponding detector element 402, but this is not necessarily the case. In other lens configurations, the location of the focal point of the lens 422 relative to the center of the corresponding detector element 402 is shifted based on the distance of each detector element 402 from the center of the detector array 400. This can be useful in relatively large detector arrays 400 where detector elements further from the center receive light at angles that are more off-axis. Shifting the location of the focal point (e.g., toward the center of the detector array 400) allows for correction of the angle of incidence. Specifically, shifting the location of the focal point (e.g., toward the center of the detector array 400) allows for correction of the angle of incidence while using substantially the same lens 422 for all detector elements positioned at the same angle relative to the detector surface.

[0094] Adding an array of lenses 422 to an array of detector elements 402 can be useful when using a relatively small sensor 116 that covers only a small portion of the field of view. In such cases, reflected signals from the scene arrive at the detector array 400 from substantially the same angle, making it easy to focus all of the light onto individual detectors. Also, in one embodiment, lenses 422 can be used in the LIDAR system 100 to promote increased detection probability across the array 400 (preventing photons from being "wasted" in dead areas between detectors / sub-detectors) at the expense of spatial distinctiveness. This embodiment contrasts with conventional implementations such as CMOS RGB cameras, which prioritize spatial distinctiveness (i.e., light propagating in the direction of detector element A cannot be directed by a lens toward detector element B, i.e., it cannot "bleed" to another detector element in the array). Optionally, the sensor 116 includes an array of lenses 422, each correlated to a corresponding detection element 402, with at least one of the lenses 422 deflecting light propagating to a first detection element 402 toward a second detection element 402 (which can increase the detection probability across the array).

[0095] Specifically, according to some embodiments of the present disclosure, the optical sensor 116 can include an array of photodetectors (e.g., detector array 400), with each photodetector (e.g., detector 410) configured to generate a current when light passes through an outer surface of the detector. Additionally, the optical sensor 116 can include at least one microlens configured to direct light toward the array of photodetectors, with the at least one microlens having a focal point. The optical sensor 116 can further include at least one layer of conductive material interposed between the at least one microlens and the array of photodetectors and having a gap for passing light from the at least one microlens to the array, with the at least one layer sized to maintain a space between the at least one microlens and the array and positioning the focal point (e.g., the focal point can be a plane) within the gap at a location spaced apart from the detection surface of the array of photodetectors.

[0096] In a related embodiment, each detector may include multiple single-photon avalanche diodes (SPADs) or multiple avalanche photodiodes (APDs). The conductive material may be a multi-layer metal constriction, and at least one layer of conductive material may be electrically connected to the detectors in the array. In one example, the at least one layer of conductive material includes multiple layers. Furthermore, the gap may be shaped to converge from the at least one microlens toward a focal point and diverge from the focal area toward the array. In another embodiment, the photosensor 116 may further include at least one reflector adjacent to each photodetector. In one embodiment, multiple microlenses may be arranged in a lens array, and multiple detectors may be arranged in a detector array. In another embodiment, the multiple microlenses may include a single lens configured to project light onto multiple detectors in the array.

[0097] 2E, 2F, and 2G, as non-limiting examples, it can be seen that one or more sensors 116 of system 100 can receive light from the scanning 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 can sample only a portion of the FOV for detection output at any given time. For example, if the illumination of the projection unit 102 illuminates different portions of the FOV at different times (by using or not using the deflector 114 and / or by activating different light sources 112 at different times), light can arrive at all pixels or sensors 116 of the detection unit 106, and only pixels / sensors expected to detect LIDAR illumination can actively collect data for detection output. In this way, the rest of the pixels / sensors do not unnecessarily collect ambient noise. When referring to scanning—in the outbound or inbound direction—it can be seen that scanning 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. Any other relative fraction of the FOV value may, of course, be implemented.

[0098] Processing Unit 5A-5C illustrate various functions of processing unit 108 according to some embodiments of the present disclosure. Specifically, FIG. 5A illustrates the emission pattern of a single portion of the field of view within a single frame time, FIG. 5B illustrates the emission scheme of the entire field of view within a single frame time, and FIG. 5C illustrates the actual light emission projected towards the field of view during a single scan cycle.

[0099] 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 the at least one optical deflector 114. According to an embodiment of the present disclosure, the processing unit 108 may control the at least one light source 112 and the optical deflector 114 (or coordinate the operation of the at least one light source 112 and the at least one optical deflector 114) to vary the light flux in scanning the field of view 120. According to other embodiments, the processing unit 108 may control only the at least one light source 112, and the optical deflector 114 may move or pivot in a fixed, predetermined pattern.

[0100] Diagrams A to D of FIG. 5A show the power of light emitted toward a single portion 122 of the field of view 120 over time. In diagram A, the processor 118 can control the operation of the light source 112 so that an initial light emission is projected toward the 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 about reflections associated with the initial light emission from the sensor 116. 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., at different times and / or different portions of the segment).

[0101] Based on information about the reflection associated with the initial light emission, processing unit 108 can be configured to determine a type of light emission to subsequently project toward portion 122 of field of view 120. The subsequent light emission determined for a particular portion of field of view 120 can be performed during the same scan cycle (i.e., in the same frame) or in a subsequent scan cycle (i.e., in a subsequent frame).

[0102] In FIG. 1B, 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 a scan of the field of view 120. In one embodiment, the LIDAR system 100 can be operable to generate one or more different types of depth maps, such as a point cloud model, a polygon mesh, a depth image (which retains depth information for each pixel or 2D array of an image), or any other type of 3D model of a scene. The sequence of depth maps can be a time series in which different depth maps are generated at different times. Each depth map in the sequence associated with a scan cycle (which can also be referred to as a "frame") can be generated within a corresponding subsequent frame time period. In one example, a typical frame time can last less than one second. In some embodiments, the LIDAR system 100 has a fixed frame rate (e.g., 10 frames per second, 25 frames per second, 50 frames per second), or the frame rate can be dynamic. In other embodiments, the frame times of different frames in the sequence may not be identical. For example, the LIDAR system 100 may implement a rate of 10 frames per second, producing a first depth map in (on average) 100 milliseconds, a second frame in 92 milliseconds, a third frame in 142 milliseconds, etc.

[0103] 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 can be operable to generate a different number of pulses in each frame. The number of pulses can vary between 0 and 32 pulses (e.g., 1, 5, 12, 28, or more pulses) and can be based on information 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 of information), the processing unit 108 can determine whether additional light pulses are needed. It should be noted that the durations of the processing and emission times in Figures A through D are not to scale. Specifically, the processing time can be significantly longer than the emission time. In Figure D, the processing unit 102 can include a continuous wave light source. In one embodiment, the initial light emission comprises a period of time during which light is emitted, and the subsequent emissions may be continuous or discontinuous to the initial light emission, hi one embodiment, the intensity of the subsequent emissions may vary over time.

[0104] According to some embodiments of the present disclosure, an 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 allow for differentiated 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 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 detection of reflected light from a previous scan cycle. Differences in the pattern of subsequent emissions can be created by determining different values ​​for light source parameters, such as any one of the following, for subsequent emissions: a. The total energy of the subsequent emissions b. Energy profile of subsequent emissions c. Optical pulse repetition rate per frame d. Optical modulation characteristics such as duration, rate, peak and average power, and pulse shape e. Wave properties of subsequent emissions, such as polarization and wavelength

[0105] In accordance with the present disclosure, differentiation of subsequent emissions can be used for different purposes. In one example, emission power levels can be limited in portions of the field of view 120 where safety is a consideration, while higher power levels can be emitted in other portions of the field of view 120 (thereby improving the signal-to-noise ratio and detection range). This relates to eye safety, but may also relate to skin safety, optical system safety, sensing material safety, and more. In another example, based on detection results from the same or previous frames, more energy can be directed toward more informative portions of the field of view 120 (e.g., regions of interest, distant targets, low-reflectivity targets, etc.), while limiting the illumination energy in 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 emission.

[0106] 5B shows three example emission schemes for a single frame time of the field of view 120. According to embodiments of the present disclosure, at least the processing unit 108 can use the acquired information to dynamically adjust the operating mode of the LIDAR system 100 and / or determine parameter values ​​for certain components of the LIDAR system 100. The acquired information can be determined from processed data captured in the field of view 120 or received (directly or indirectly) from the host 210. The processing unit 108 can use the acquired information to determine a scan scheme for scanning different portions of the field of view 120. The acquired information can include current light conditions, current weather 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 can include at least one of the following: (a) a designation of the portion within the field of view 120 that is actively scanned as part of a scan cycle; (b) a projection plan of the projection unit 102 that defines the light emission profile in different portions of the field of view 120; (c) a deflection plan of the scan unit 104 that defines, for example, the deflection direction, frequency, and designates idle elements within the reflector array; and (d) a detection plan of the detection unit 106 that defines the sensitivity or response pattern of the detector.

[0107] Further, processing unit 108 can determine a scanning scheme, at least in part, by obtaining an identification of at least one region of interest within field of view 120 and at least one region of non-interest within field of view 120. In some embodiments, processing unit 108 can determine a scanning scheme, at least in part, by obtaining an identification of at least one region of high interest within field of view 120 and at least one region of low interest within field of view 120. The identification of the at least one region of interest within field of view 120 can be determined, for example, from processed data captured within field of view 120, based on data from another sensor (e.g., camera, GPS), received (directly or indirectly) from host 210, or by any combination of the above. In some embodiments, the identification of the at least one region of interest can include an identification of a portion, area, section, pixel, or object within field of view 120 that is important to monitor. Examples of areas that may be identified as regions of interest can include a crosswalk, a moving object, a person, a nearby vehicle, or any other environmental condition or object that can aid in vehicle navigation. Examples of areas that may be identified as regions of no interest (or regions of low interest) may be static (non-moving) distant buildings, skylines, areas above the horizon, and objects within the field of view. Upon obtaining identification of at least one region of interest within the field of view 120, processing unit 108 may determine a scanning scheme or modify an existing scanning scheme. In addition to determining or modifying light source parameters (as described above), processing unit 108 may allocate detector resources based on the identification of the at least one region of interest. In one example, to reduce noise, processing unit 108 may activate detectors 410 expected to correspond to regions of interest and disable detectors 410 expected to correspond to regions of no interest. In another example, processing unit 108 may modify detector sensitivity to increase sensor sensitivity for long-range detection, for example, where reflected power is low.

[0108] Diagrams A through C in FIG. 5B show examples of different scanning schemes for scanning the field of view 120. Each square in the field of view 120 represents a different portion 122 associated with the instantaneous position of at least one deflector 114. Legend 500 describes the light flux levels represented by the fill pattern of the squares. Diagram A shows a first scanning scheme in which all portions have the same importance / priority and are assigned a default light flux. This first scanning scheme can be utilized during startup or can be periodically alternated with another scanning scheme to monitor the entire field of view for unexpected / new objects. In one example, the light source parameters for the first scanning scheme can be configured to generate light pulses with a constant amplitude. Diagram B shows a second scanning scheme in which a high light flux is assigned to a portion of the field of view 120 and default and low light fluxes are assigned to the remaining portion of the field of view 120. Low light fluxes can be assigned to portions of the field of view 120 that are of least interest. Diagram C shows a third scanning scheme in which small vehicles and buses (see silhouettes) are identified within the field of view 120. This scanning scheme allows the contours of vehicles and buses to be tracked with high power and a lower level of flux (or no flux) allocated to the center of the vehicles and buses, allowing more of the optical budget to be concentrated on the contours of identified objects and less on the less important center portions.

[0109] FIG. 5C illustrates 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 8×9 matrix, with each of the 72 cells corresponding to a distinct portion 122 associated with a different instantaneous position of at least one optical deflector 114. In this exemplary scan cycle, each portion includes one or more white dots representing the number of light pulses projected toward that portion, and some portions include black dots representing reflected light from that portion detected by 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 illustrated, scanning the field of view 120 reveals four objects 208. Two free-form objects are shown in the near field (e.g., between 5 and 50 meters), a rectangular object with rounded corners in the mid-field (e.g., between 50 and 150 meters), and a triangular object in the far field (e.g., between 150 and 500 meters). While the discussion of FIG. 5C uses pulse number as an example of flux allocation, it should be noted that flux allocation to different portions of the field of view can be implemented 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 illustration of light emission as a single scan cycle in FIG. 5C illustrates various functions of the LIDAR system 100. In a first embodiment, the processor 118 is configured to use two light pulses to detect a first object (e.g., a rectangular object with rounded corners) at a first distance, and three light pulses to detect a second object (e.g., a triangular object) at a second distance greater than the first distance.In a second embodiment, the processor 118 is configured to allocate more light to portions of the field of view where a region of interest has been identified. Specifically, in this example, sector II was identified as a region of interest and therefore allocated three light pulses, while the remainder of the field of view 120 was allocated two or fewer light pulses. In a third embodiment, the processor 118 is configured to control the light source 112 to project only a single light pulse onto portions B1, B2, and C1 of FIG. 5C , which are portions of sector III that were initially allocated two light pulses per portion. This is done because the processing unit 108 detected a near-field object based on the first light pulse. Also, allocation of a less-than-maximum pulse amount can be performed as a result of other considerations. For example, if an object at a first distance (e.g., a near-field object) is detected in at least some regions, the overall amount of light emitted into this portion of the field of view 120 can be reduced.

[0110] Further details and examples of the various components of LIDAR system 100 and their associated functions are contained in commonly owned U.S. patent application Ser. No. 15 / 391,916, filed Dec. 28, 2016, commonly owned U.S. patent application Ser. No. 15 / 393,749, filed Dec. 29, 2016, commonly owned U.S. patent application Ser. No. 15 / 393,285, filed Dec. 29, 2016, commonly owned U.S. patent application Ser. No. 15 / 393,593, filed Dec. 29, 2016, all of which are incorporated herein by reference in their entireties.

[0111] Exemplary Implementation: Vehicle 6A-6C illustrate an implementation of LIDAR system 100 in a vehicle (e.g., vehicle 110). Any of the aspects of LIDAR system 100 described above or below can be incorporated into vehicle 110 to provide a distance-sensing vehicle. Specifically, in this example, LIDAR system 100 integrates multiple scanning units 104 and possibly multiple projection units 102 within a single vehicle. In one embodiment, the vehicle utilizes such a LIDAR system to provide improved power, range, and accuracy within and beyond the overlap zone, as well as improved redundancy in sensitive portions of the FOV (e.g., in the direction of forward vehicle movement). As shown in FIG. 6A, vehicle 110 may include a first processor 118A for controlling the scanning of field of view 120A, a second processor 118B for controlling the scanning of field of view 120B, and a third processor 118C for controlling synchronization of the scanning of the two fields of view. In one example, processor 118C can be a vehicle controller and can have a shared interface between first processor 118A and second processor 118. The shared interface allows for data exchange at an intermediate processing level and synchronization of the scanning of the combined field of view to create overlap in temporal and / or spatial space. In one embodiment, the data exchanged using the shared interface can be (a) time-of-flight of received signals associated with the overlapped field of view and / or neighboring pixels, (b) laser steering position status, and (c) detection status of objects within the field of view.

[0112] 6B shows an overlap region 600 between field of view 120A and field of view 120B. In the illustrated example, the overlap region relates to 24 portions 122 from field of view 120A and 24 portions 122 from field of view 120B. Assuming the overlap region is defined and known to processors 118A and 118, each processor can be designed to limit the amount of light emitted in overlap 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 118 can avoid interference of light emitted by the two light sources through loose synchronization between scan unit 104A and scan unit 104B, and / or by controlling the timing of laser transmissions and / or the timing of enabling detection circuitry.

[0113] FIG. 6C illustrates how an overlap region 600 between fields of view 120A and 120B can be used to increase the detection range of the vehicle 110. In accordance with the present disclosure, utilizing two or more light sources 112 that project a nominal light emission within the overlap zone can increase the effective detection range. The term “detection range” may include the approximate distance from the vehicle 110 at which the LIDAR system 100 can unambiguously 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, at a detection range of 200 meters, the LIDAR system 100 may detect objects located 200 meters (or less) from the vehicle 110 more than 95%, more than 99%, or 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 spaced in time and space can be used to improve the SNR and, therefore, the coverage and / or quality of service of objects located in the overlapping area. Processor 118C can extract high-level information from the reflected light in fields of view 120A and 120B. The term "extracting 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, processors 118A and 118B share high-level information, such as objects (road divisions, background, pedestrians, vehicles, etc.) and motion vectors, allowing each processor to focus attention on surrounding areas that may soon become areas of interest. For example, it can be determined that a moving object in field of view 120A will soon enter field of view 120B.

[0114] Exemplary Implementation: Survey System Figure 6D illustrates an implementation of LIDAR system 100 in a surveillance system. As mentioned above, LIDAR system 100 can be fixed to a stationary object 650, which may include a motor or other mechanism for rotating the housing of LIDAR system 100 to obtain a wider field of view. Alternatively, the surveillance system can include multiple LIDAR units. In the example shown in Figure 6D, the surveillance 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, changes in the environment, or any other form of data important to security.

[0115] In accordance with some embodiments of the present disclosure, 3D data can be analyzed to monitor retail processes. In one embodiment, the 3D data can be used in retail processes requiring physical security (e.g., detecting break-ins within a retail facility, vandalism in or around a retail facility, unauthorized access to secured areas, and suspicious activity around automobiles in a parking lot). In another embodiment, the 3D data can be used for public safety (e.g., detecting people slipping and falling on store grounds, spilling or blocking dangerous liquids on store floors, assaults or kidnappings in store parking lots, blocked fire exits, and crowding within or outside a store area). In another embodiment, the 3D data can be used for business-sensitive data collection (e.g., tracking people passing through a store area to determine how many people pass by, where they stop, how long they stop, and how their shopping habits compare to purchasing habits).

[0116] According to other embodiments of the present disclosure, the 3D data can be analyzed and used for traffic enforcement. Specifically, the 3D data can be used to identify vehicles traveling above the legal speed limit or any other traffic law requirement. In one example, the LIDAR system 100 can be used to detect vehicles crossing a stop line or designated stopping position when the light is red. In another example, the LIDAR system 100 can be used to identify vehicles traveling in lanes reserved for public transportation. In yet another example, the LIDAR system 100 can be used to identify vehicles turning at an intersection where certain turns are prohibited when the light is red.

[0117] MEMS mirror assembly with built-in heating resistor

[0118] To enable microelectromechanical systems (MEMS) containing moving components, and particularly MEMS mirrors or other large surfaces, to operate at low temperatures, novel MEMS systems are described below that include one or more built-in heating resistors. Having one or more built-in heating elements configured to heat one or more components (e.g., actuators) of the MEMS system can help maintain an optimal environment in which the MEMS system operates.

[0119] While this disclosure provides examples of MEMS mirror assemblies for MEMS systems that may be part of a scanning LIDAR system, it should be noted that aspects of this disclosure, in their broadest sense, are not limited to MEMS assemblies for LIDAR systems. Rather, it is contemplated that the principles described above may also be applied to other types of electro-optical systems (e.g., cameras, rangefinders, electron microscopes).

[0120] 3A-3D illustrate an exemplary MEMS scanning device 104. Additionally, although this disclosure describes a MEMS system including a MEMS mirror, other types of MEMS systems including a MEMS functional surface, such as a piston or valve, are also contemplated. For example, instead of including a MEMS mirror, the MEMS system may include a piezoelectrically activated component (e.g., a piston, a valve) configured to pivot a light-guiding surface. As an example, the MEMS system may include a piezoelectrically activated pivoting surface.

[0121] In some embodiments, an exemplary MEMS system may include a MEMS assembly including a MEMS mirror configured to move about at least one axis and at least one actuator configured to cause movement of the MEMS mirror. The MEMS mirror assembly may also include at least one heating element configured to heat at least a portion of the actuator when an electrical current is passed through the heating element. In some embodiments, the MEMS mirror assembly may be fabricated from a single wafer die. In other embodiments, the MEMS mirror assembly may be fabricated from two or more wafer dies secured together (e.g., a glass wafer and a silicon wafer bonded together to form a sealed compartment).

[0122] 7A, 7B, and 8 show exemplary MEMS mirror assemblies 700A, 700B, and 800 according to some embodiments of the present disclosure. While MEMS mirror assemblies 700A, 700B, and 800 are described individually in some cases, one or more components of one MEMS mirror assembly may be used in another MEMS mirror assembly. MEMS mirror assembly 700A may include a frame 711, a MEMS mirror 701, one or more actuators (e.g., actuators 721, 722, 723, and 724), one or more interconnection elements 741, 742, 743, and 744, and one or more heating elements (e.g., heating resistors 751, 752, 753, and 754). Frame 711 may provide structural support for the MEMS mirror 701 while allowing the MEMS mirror 701 to pivot about one or more rotational axes relative to frame 711. MEMS mirror 701 may include a reflective surface. MEMS mirror 701 may be a movable MEMS mirror in that it may be translatable relative to frame 711 and / or rotatable about one or more axes relative to frame 711. Interconnection elements 741, 742, 743, and 744 may be coupled to MEMS mirror 701 and configured to facilitate rotation of MEMS mirror 701 about at least one axis of rotation. Actuators 721, 722, 723, and 724 may apply a mechanical force to one or more of interconnection elements 741, 742, 743, and 744 to cause translational or rotational movement of the MEMS mirror relative to the frame. Heating resistors 751, 752, 753, and 754 may be configured to heat one or more of actuators 721, 722, 723, and 724. Although not necessarily so, the MEMS mirror assembly 700A may implement any of the structures or functionality described with respect to the scan unit 104 and / or the optical deflector 114 (eg, with respect to Figures 3A and 3B).

[0123] In some embodiments, the MEMS mirror assembly 700A may also include a controller 761, a power source 771, and one or more sensors (not shown). The controller 761 may be configured to control the activation of one or more of the heating resistors. For example, the controller 761 may control the application of current to the heating resistor 751, thereby heating a nearby actuator (e.g., actuator 721). In some embodiments, the controller 761 may also be configured to control the activation of one or more actuators. The power source 771 may be configured to provide power for heating. In some embodiments, the power source 771 may also provide power to the controller 761. One or more sensors may be configured to monitor the conditions under which the MEMS mirror assembly 700A operates. For example, the MEMS mirror assembly 700A may include one or more temperature sensors configured to monitor the temperature of one or more components of the MEMS mirror assembly 700A. The sensors may also be configured to send signals and / or information related to the condition(s) that they monitor to the controller 761.

[0124] Frame 711 may include any support structure to which the MEMS mirror may be mounted such that the MEMS mirror may be able to rotate and / or translate relative to the frame. For example, frame 711 may include a portion of a wafer die used to fabricate the MEMS mirror that may structurally support the MEMS mirror while allowing the MEMS mirror to pivot about one or more axes of rotation relative to the frame.

[0125] In some embodiments, frame 711 can be spaced apart from the active area of ​​MEMS mirror 701 (any portion that can move out of the plane of frame 711 or otherwise relative to frame 711), except for one or more actuators (e.g., actuators 721, 722, 723, and 724) and / or interconnection elements (e.g., interconnection elements 741, 742, 743, 744). Frame 711 can include a continuous frame or a frame made of two or more separate parts. For example, the frame can be made from a wafer layer including one or more silicon layers, possibly including at least one silicon layer that is part of the MEMS mirror. Layers of materials other than silicon can also be used.

[0126] MEMS mirror 701 may be configured to allow light to deviate from its initial path. MEMS mirror 701 may be a movable MEMS mirror in that MEMS mirror 701 may be translatable relative to frame 711 and / or rotatable about one or more axes relative to frame 711. For example, MEMS mirror 701 may be translatable or rotatable about exemplary axes 781, 782, and / or 783 (into the plane of the figure) as shown in FIG. 7A . For example, MEMS mirror 701 may be rotated within the plane of frame 711.

[0127] In some embodiments, the MEMS mirror 701 may include a MEMS structure with a rotatable portion that rotates relative to the plane of the wafer (or frame 711). Alternatively or additionally, the MEMS mirror 701 may include a MEMS structure with a translatable portion that translates relative to the plane of the wafer (or frame 711). In some exemplary embodiments, the rotatable portion (and / or translatable portion) may include a reflective coating or surface to form a MEMS mirror capable of reflecting or deflecting light from a light source. Although the MEMS mirror 701 is shown in FIGS. 7A (and 7B) as having a circular shape, it is contemplated that the MEMS mirror 701 may have a square, polygonal (e.g., octagonal), elliptical, or any other geometric shape suitable for use with a MEMS assembly. While this disclosure describes examples of MEMS mirrors and frames, it should be noted that aspects of the disclosure, in its broadest sense, are not limited to the disclosed examples of MEMS mirrors and / or frames.

[0128] The MEMS mirror assembly 700A may include one or more actuators configured to cause the MEMS mirror 701 to pivot about at least one axis (e.g., axes 781, 782, and / or 783). The actuators (e.g., actuators 721, 722, 723, 724) may include one or more movable structural members of the MEMS mirror assembly that may be capable of causing translational and / or rotational movement of the MEMS mirror relative to a frame. The disclosed actuators may be an integral part of the MEMS mirror assembly or may be separate and distinct from the MEMS mirror assembly. The disclosed actuators may be attached directly or indirectly to the disclosed MEMS mirror. In some embodiments, one or more actuators of the mirror assembly 700A may be one or more of the actuators disclosed in International Application No. PCT / IB2018 / 001467, entitled "LIDAR SYSTEMS AND METHODS," filed November 28, 2018, which is incorporated herein by reference in its entirety.

[0129] In some embodiments, an actuator may include an actuator body (e.g., made of silicon) and a piezoelectric element. By way of example, actuator 721 may include a body (whose part number is not shown) and a piezoelectric element 731. Similarly, actuators 722, 723, and 724 may each include a body and a corresponding piezoelectric element 732, 733, or 734. The piezoelectric element may be configured to bend the body and move the active area when exposed to an electric field.

[0130] In some embodiments, MEMS mirror assembly 700A may include two or more types of actuators. Different types of actuators enable movement of the active area in different directions. Actuators 721 and 722 may be different types of actuators. Piezoelectric element 731 may be configured to bend the body of actuator 721 when exposed to a first electric field, causing the MEMS mirror 701 to move in a first direction, and piezoelectric element 732 may be configured to bend the body of actuator 722 when exposed to a second electric field, causing the MEMS mirror 701 to move in a second direction.

[0131] MEMS mirror assembly 700A may also include one or more interconnection elements (e.g., interconnection elements 741, 742, 743, 744) through which one or more actuators are coupled to MEMS mirror 701. For example, interconnection element 741 may provide an electrical and / or mechanical connection between one or more actuation arms of actuator 721, springs (not shown) associated with the actuation arms, and MEMS mirror 701. In some exemplary embodiments, the interconnection element may be directly attached to one or more of the actuation arms, springs, and / or MEMS mirror 701. Alternatively or additionally, the interconnection element may include two or more connector members that may be coupled to each other and attached to one or more actuation arms, springs, and / or MEMS mirror 701. In some embodiments, the interconnect element 741 may include one or more connectors disclosed in International Application No. PCT / IB2018 / 001467, filed November 28, 2018, entitled "LIDAR SYSTEMS AND METHODS," which is incorporated herein by reference in its entirety. The interconnect element may be made from silicon, metal, or any other material used in the MEMS mirror assembly 700A. The interconnect element may be made as an extension of one or more wafer layers present in the actuator, the MEMS mirror 701, or both.

[0132] MEMS mirror assembly 700A further includes one or more heating elements (e.g., heating resistors 751, 752, 753, and 754) configured to heat one or more components (or portions thereof) of the MEMS mirror assembly. For example, the heating element may be heating resistor 751 configured to heat piezoelectric element 731 of actuator 721 when current passes through heating resistor 751. Similarly, heating resistors 752, 753, and 754 may be configured to heat piezoelectric elements 732, 733, and 734, respectively, when current passes through the corresponding heating resistor.

[0133] In some embodiments, for example, as shown in FIG. 7A , a MEMS mirror assembly may include multiple heating resistors, each configured to heat one component of the MEMS mirror assembly. Alternatively or additionally, a MEMS mirror assembly may include two or more heating resistors to heat one component. For example, MEMS mirror assembly 700A may include heating resistor 751 and another heating resistor (not shown) to heat piezoelectric element 731. Controller 761 may control the heating resistors to heat piezoelectric element 731, as described elsewhere in this disclosure. For example, controller 761 may determine to activate the heating resistors if the temperature of piezoelectric element 731 is below a threshold. Controller 761 may also control power source 771 to pass current through the circuit to each of the heating resistors. The heating resistors may be uniformly mounted on (or adjacent to) the component. Alternatively, the heating resistors may not be uniformly mounted on (or adjacent to) the component. For example, a first heating resistor may be mounted near the interconnection element 741 (i.e., the connection of the actuator 721 to the frame 711), and a second heating resistor 751 may be mounted on (or adjacent to) an arm of the actuator 721. In some embodiments, the first and second heating resistors may be the same type or different types. Alternatively or additionally, the controller 761 may control the power supply 771 to supply the same or different currents to the first and second heating resistors.

[0134] In some embodiments, the controller 761 may control the power supply 771 to supply different currents to different heating resistors. For example, the power supply 771 may supply a first current to the heating resistor 751 and a second current to the heating resistor 751 that is different from the first current (e.g., a larger or smaller current).

[0135] In some embodiments, the MEMS mirror assembly includes one heating element configured to heat two or more components. By way of example, as shown in FIG. 7B , the MEMS mirror assembly 700B may include a heating resistor 756 configured to heat the actuators 721, 722, 723, and 724 (or the piezoelectric elements 731, 732, 733, and 734) when a current flows through the heating resistor 756. In some embodiments, the heating resistors 751, 752, 753, and / or 754 may be configured to heat one or more components of the MEMS mirror assembly 700A (e.g., its actuator 721 and / or piezoelectric element 731) in response to information indicating the temperature of the component. For example, the controller 761 may receive information indicating that the temperature of the piezoelectric element 731 is below a threshold. The controller 761 may also control the power source 771 to supply current to the heating resistor 751 to heat the piezoelectric element 731.

[0136] In some embodiments, the heating resistors of MEMS mirror assembly 700A can be of the same type. Alternatively, MEMS mirror assembly 700A can include two or more different types of heating resistors. For example, heating resistor 751 can have a different total resistance, heating value, or the like, or a combination thereof, than heating resistor 752 (or other heating resistors).

[0137] In some embodiments, a heating resistor (e.g., one of heating resistors 751, 752, 753, 754, and 756) can have a total resistance in the range of ¼ to 5 kilohms. In some embodiments, the total resistance of the heating resistor can be limited to the following subranges: ¼ to 1 ohm, 1 to 10 ohms, 10 to 50 ohms, 50 to 100 ohms, 100 to 500 ohms, 500 to 1000 ohms, 1 to 2 kilohms, and 2 to 5 kilohms.

[0138] In some embodiments, the heating resistors (e.g., heating resistors 751, 752, 753, 754, and 756) can have a heating power in the range of 5 to 5000 milliwatts. In some embodiments, the heating power of the heating resistors can be limited to subranges of 5 to 10 milliwatts, 10 to 50 milliwatts, 50 to 100 milliwatts, and 100 to 500 milliwatts.

[0139] In some embodiments, the MEMS mirror assembly 700A may include various sensors (not shown) configured to monitor the conditions under which the MEMS mirror assembly 700A operates. For example, the MEMS mirror assembly 700A may include one or more temperature sensors configured to monitor the temperature of one or more components of the MEMS mirror assembly 700A. For example, a temperature sensor (e.g., a resistive temperature sensor) may be configured to measure the temperature of the actuator 721 (and / or the piezoelectric element 731). Alternatively or additionally, a temperature sensor may be configured to monitor the ambient temperature of the MEMS mirror assembly 700A.

[0140] The sensor may be configured to send signals and / or information related to the condition(s) it monitors to the controller 761. For example, the sensor may send information indicative of the temperature of the piezoelectric element 731 to the controller 761, and the controller 761 may determine whether to activate one or more heating resistors to heat the piezoelectric element 731 based on the received information. The measurement (or monitoring) of temperature by the sensor may be continuous or intermittent. Alternatively or additionally, the sensor may receive a control signal from the controller 761 to measure the temperature and send the temperature information it obtains to the controller 761. The sensor may measure the temperature directly or indirectly, for example, by measuring the effect of changing temperature on the operation of one or more components of the MEMS mirror assembly. As an example, the controller 761 may receive information indicative of the voltage for actuating the MEMS mirror 701 by the actuator 721 to generate a control signal that is sent to the sensor. The controller 761 may also use data from other sensors to generate data indicative of the temperature. For example, information regarding the voltage required to move the MEMS mirror may be used along with movement feedback data indicative of the degree of movement caused by the actuator to assess the temperature. After receiving the control signal, the sensor may measure the temperature of the actuator 721 (or piezoelectric element 731 ) and send the temperature information to the controller 761 .

[0141] In some embodiments, the sensor may be implemented as part of the MEMS mirror assembly 700A. For example, the sensor may be implemented on (or in proximity to) a component of the MEMS mirror assembly 700A. By way of example, the sensor may be implemented on the frame 711, the MEMS mirror 701, one of the actuators 721, 722, 723, and 724 (or piezoelectric elements thereof), the controller 761, or the like, or a combination thereof. In other embodiments, the sensor may be implemented external to the MEMS mirror assembly 700A (e.g., a temperature sensor external to the MEMS mirror assembly 700A configured to measure the ambient temperature around the MEMS mirror assembly 700A).

[0142] In some embodiments, the MEMS mirror assembly 700A may also include a controller 761 and a power supply 771. The controller 761 may include one or more processors, microprocessors, or the like, or a combination thereof. The controller 761 may be configured to control activation of one or more heating resistors 751, 752, 753, and 754. For example, the controller 761 may control a power supply 771 to supply current to one or more of the heating resistors. Alternatively or additionally, the controller 761 may control the actuation of one or more actuators 721, 722, 723, and 724. For example, the controller 761 may control an electric field applied to the actuators, thereby activating (or deactivating) the actuation of the actuators. In some embodiments, the controller 761 may be implemented on the same chip as at least one of the actuators, the heating resistors, and the power supply 771. In other embodiments, the controller 761 may be implemented as an external component of the MEMS mirror assembly (e.g., as part of the processor 118 of the LIDAR system).

[0143] The power source 771 may be configured to provide power to one or more heating resistors for heating. The power source 771 may be a battery, an AC power source, a DC power source, a rechargeable capacitor, or the like, or a combination thereof. In some embodiments, the power source 771 may include a power source that is part of the MEMS mirror assembly 700A (e.g., an internal power source). Alternatively or additionally, the power source 771 may include a power source external to the MEMS mirror assembly 700A.

[0144] In some embodiments, the power source 771 may be electrically coupled to various components of the MEMS mirror assembly 700A (e.g., the actuator, the heating resistor, the controller, various sensors). The power source 771 may be external to the controller 761. Alternatively, the power source 771 and the controller 761 may be integrated as a single unit. In some embodiments, the controller 761 and the power source 771 may be electrically coupled to the MEMS mirror assembly but external to the MEMS mirror assembly. For example, the controller 761 (and / or the power source 771) may be implemented external to the MEMS mirror assembly 700A (e.g., as a separate part of a LIDAR system that includes the MEMS mirror assembly).

[0145] In some embodiments, controller 761 may selectively cause power supply 771 to apply current through the heating resistor based on a temperature reading from the MEMS mirror assembly (or a component thereof). For example, controller 761 may be configured to control power supply 771 to selectively supply current to heating resistor 751 (but not to heating resistors 752, 753, or 754) based on a temperature reading from MEMS mirror assembly 700A (e.g., a temperature reading from piezoelectric element 731). As an example, controller 761 may selectively cause power supply 771 to apply current through heating resistor 751 if the temperature reading is below a threshold temperature.

[0146] In some embodiments, two or more components of the MEMS mirror assembly 700A (e.g., one or more of the frame 711, the MEMS mirror 701, the actuator 721, and the heating resistor 751) may be fabricated on a single wafer and may share a common layer (e.g., a common silicon layer, a common lead zirconate titanate (PZT) layer). For example, one or more of the heating resistors 751, 752, 753, and 754 may be implemented on a metal layer of the wafer of the MEMS mirror assembly 700A. Alternatively or additionally, one or more of the heating resistors 751, 752, 753, and 754 may be implemented on a doped region of a silicon-based layer of the wafer of the MEMS mirror assembly 700A. The silicon-based layer may be made of silicon, polysilicon, doped (or partially doped) silicon, doped (or partially doped) polysilicon, or any other silicon-based material, such as a silicide. As another example, at least one electrode used to apply an electric field to the piezoelectric element may be mounted on a metal layer of the wafer of MEMS mirror assembly 700A, and one or more of heating resistors 751, 752, 753, and 754 may be mounted on the same metal layer as the electrode used for piezoelectric actuation.

[0147] MEMS mirror assembly 700A may also include additional components, such as a controller 761, a power supply 771, sensors (e.g., temperature sensors), optical components, structural elements, a casing, etc. Such additional components may be implemented on the same wafer as the MEMS mirror, on a separate wafer, or may otherwise be integrated with the wafer of MEMS mirror 701.

[0148] In some embodiments, one or more heating resistors may be mounted on a component of the MEMS mirror assembly. For example, one or more heating resistors may be mounted on the actuator. Alternatively or additionally, one or more heating resistors may be mounted on the frame. For example, one or more heating resistors may be mounted on an edge of the frame adjacent to the actuator.

[0149] In some embodiments, the one or more heating resistors may be mounted on a non-moving portion of the MEMS mirror assembly, for example, adjacent to the actuator. For example, the MEMS mirror assembly may include one or more fixed silicon pieces, and the one or more heating resistors may be mounted on at least one of the fixed silicon pieces.

[0150] FIG. 8 shows an example MEMS mirror assembly 800 including four fixed silicon pieces. Similar to the MEMS mirror assembly 700A shown in FIG. 7A, the example MEMS mirror assembly 800 of FIG. 8 may include a MEMS mirror 802, a frame 804, and actuators 812A, 814A, 816A, and 818A. The actuator 812A of the MEMS mirror assembly 800 of FIG. 8 may include an actuation arm 824 and a silicon piece 825. The silicon piece 825 may be fixed and non-movable relative to the MEMS mirror assembly 800. The silicon piece 825 may be disposed adjacent to the actuation arm 824 and separated from the actuation arm 824 by a gap 828. The actuation arm 824 may be coupled to the MEMS mirror 802 using an interconnection element 830. However, the silicon piece 825 may not be mechanically or electrically coupled to the MEMS mirror 802. The silicon piece 825 of the MEMS mirror assembly 800 may be disposed between and spaced apart from the actuation arm 824 and the MEMS mirror 802. Furthermore, the silicon piece 825 may resemble a second actuation arm 826 of the MEMS mirror assembly 800 when not coupled to the MEMS mirror 802.

[0151] Similarly, actuators 814A, 816A, and 818A may each include one actuation arm 834, 844, and 854, respectively. As also shown in FIG. 8 , actuators 814A, 816A, and 818A may include silicon pieces 835, 845, and 855, respectively, separated from their respective actuation arms 834, 844, and 854 by gaps 838, 848, and 858, respectively. Additionally, actuation arms 834, 844, and 854 may be coupled to MEMS mirror 802 using interconnection elements 840, 850, and 860, respectively. Silicon pieces 835, 845, and 855 may be similar to actuation arms 836, 846, and 856, respectively, if actuation arms 836, 846, and 856 were not coupled to MEMS mirror 802. In some embodiments, one or more of the silicon pieces 825, 835, 845, and 855 may belong to the silicon layer on which the actuators and mirrors are implemented.

[0152] One or more heating resistors (e.g., heating resistors 862, 864, 866, and 868) may be mounted, and may be stationary, on each of silicon pieces 825, 835, 845, and 855. The heating resistors may be configured to heat the corresponding actuator (and / or its piezoelectric element) when a current flows through them.

[0153] 9 is a flowchart of an exemplary heating process 900 according to disclosed embodiments. One or more steps of the heating process 900 may be performed by the controller 761 (and / or other embodiments of a controller described herein, e.g., the processor 118 of a LIDAR system). Although the heating process is described herein using the components of the MEMS mirror assembly 700A shown in FIG. 7A, it may be applied to other exemplary MEMS mirror assemblies described in this disclosure.

[0154] In step 901, temperature information may be received. In some embodiments, step 901 may be performed by a controller (e.g., controller 761, processor 118). For example, controller 761 may receive the temperature information. In some embodiments, controller 761 may receive information indicative of a component of MEMS mirror assembly 700A from a temperature sensor. For example, a sensor proximate to actuator 721 may measure the temperature of actuator 721 (or piezoelectric element 731) and send information indicative of the temperature to controller 761. As another example, controller 761 may receive information indicative of the ambient temperature surrounding MEMS mirror assembly 700A from a sensor external to MEMS mirror assembly 700A.

[0155] In some embodiments, a sensor may continuously measure the temperature of one or more components (e.g., one or more actuators or their piezoelectric elements) and continuously transmit the information to the controller 761. Alternatively or additionally, the sensor may measure the temperature intermittently and transmit the temperature information to the controller 761 if the controller 761 is available. For example, the sensor may be configured to measure the temperature once over a predetermined period of time, which may range from 0.1 seconds to 10 minutes. In some embodiments, the period may be limited to sub-ranges of 0.1 to 1 second, 1 to 10 seconds, 10 to 60 seconds, and 1 to 10 minutes. Alternatively or additionally, the sensor may be configured to measure the temperature on demand. For example, the sensor may receive a control signal from the controller 761. In response, the sensor may measure the temperature (continuously or intermittently) and transmit the temperature information to the controller 761. In some embodiments, the sensor may continue measuring the temperature until it receives a second control signal to stop measuring.

[0156] In step 903, it may be determined whether to activate (or deactivate) one or more heating elements. In some embodiments, step 903 may be performed by a controller (e.g., controller 761, processor 118). For example, the controller 761 may be configured to determine whether to activate (or deactivate) one or more heating resistors 751, 752, 753, and 754 to heat one or more components of the MEMS mirror assembly 700A based on the received temperature information. For example, the controller 761 may determine whether the temperature of the piezoelectric element 731 is below an activation threshold, which may be the lower limit of the temperature range in which the component(s) optimally operate. If so, the controller 761 may determine to activate the heating resistor 751 to heat the piezoelectric element 731. On the other hand, if the controller 761 determines that the temperature of the piezoelectric element 731 is equal to or greater than the activation threshold, the controller 761 may determine that activation of the heating resistor 751 is not necessary (i.e., take no action). As another example, controller 761 may receive information indicative of the temperature of a first component from a first sensor and information indicative of the temperature of a second component from a second sensor. For example, controller 761 may receive information indicative of the temperature of MEMS mirror 701 from a first sensor and information indicative of the temperature of actuator 721 from a second sensor. Controller 761 may also determine that the temperature of MEMS mirror 701 is above a first activation threshold while the temperature of piezoelectric element 731 is below a second activation threshold (which may be the same as or different from the first threshold). Controller 761 may further determine to activate heating resistor 752 but not a heating resistor proximate to MEMS mirror 701 (not shown in FIG. 7A ). As a further example, the controller 761 may determine that the temperature of one of the components is below an activation threshold corresponding to the particular component (which may be the same or different for each component) and decide to activate some or all of the heating resistors 751, 752, 753, and 754.

[0157] In some embodiments, the activation temperature threshold may be related to the dew point at which the electro-optical system (or MEMS mirror assembly) operates. The dew point refers to the atmospheric temperature below which water droplets may begin to condense and form dew, which may vary depending on pressure and humidity. For example, the controller 761 may receive (or determine based on various factors such as pressure and humidity) the dew point at which the electro-optical system (or MEMS mirror assembly) operates. The controller 761 may set the dew point as the activation threshold. Alternatively, the controller 761 may set a certain degree Celsius below or above the dew point as the activation threshold. As an example, the controller 761 may set 3° C. below (or above) the dew point as the activation threshold.

[0158] In some embodiments, the activation temperature threshold may be related to the operating conditions of the MEMS mirror assembly. For example, the controller 761 may be configured to set the activation temperature high enough to maintain the temperature of the MEMS mirror assembly (and / or electro-optical system) within an operating range. By way of example, the activation temperature may be set by the controller 761 as the temperature below which the degree of movement of the mirror is limited, the voltage for operation is too high, one or more piezoelectric elements are damaged or behave abnormally, or the like, or a combination thereof. Alternatively or additionally, the controller 761 may receive an error signal from one or more components of the MEMS mirror assembly indicating that a component(s) is in a suboptimal state due to a low temperature. The controller 761 may activate one or more heating resistors, as described elsewhere in this disclosure.

[0159] The controller 761 may also be configured to deactivate one or more of the heating resistors 751, 752, 753, and 754 if a deactivation condition is met. For example, the controller 761 may deactivate the heating resistor 751 based on received temperature information. For example, the controller 761 may receive information from a sensor indicating the temperature of the piezoelectric element 731 after the heating resistor 751 is activated to heat the piezoelectric element 731 (as described elsewhere in this disclosure). The controller 761 may determine that the temperature of the piezoelectric element 731 is greater than or equal to a deactivation threshold. The controller 761 may decide to deactivate the heating resistor 751. The deactivation threshold of a component may be greater than or equal to its activation threshold. In some embodiments, the deactivation threshold may be related to the ambient temperature of the MEMS mirror assembly (e.g., 5, 10, or 15 degrees Celsius above ambient temperature). Alternatively or additionally, the controller 761 may deactivate the heating resistor after a predetermined heating period (e.g., 1, 5, or 10 minutes). In some embodiments, the deactivation threshold may be related to the dew point at which the electro-optical system (or MEMS mirror assembly) operates. For example, the controller 761 may receive (or determine based on various factors, such as pressure, humidity, etc.) the dew point at which the electro-optical system (or MEMS mirror assembly) operates. The controller 761 may set a certain degree Celsius above the dew point as the deactivation threshold. As an example, the controller 761 may set any number between 5 and 20 degrees Celsius above the dew point as the deactivation threshold.

[0160] In some embodiments, controller 761 may control activation of heating resistor 751 until a deactivation condition is met. For example, controller 761 may activate heating resistor 751 to heat piezoelectric element 731, and heating resistor 751 may be configured to heat piezoelectric element 731 when activated. Controller 761 may receive information from a sensor indicative of the temperature of piezoelectric element 731 after heating. Controller 761 may determine that the temperature of piezoelectric element 731 is higher than the ambient temperature around the MEMS mirror assembly by a temperature difference (e.g., 5 or 10 degrees Celsius). Controller 761 may then deactivate heating resistor 751. The temperature difference may be in a range of 1 to 30 degrees Celsius. In some embodiments, the temperature difference may be limited to subranges of 1 to 5 degrees Celsius, 5 to 10 degrees Celsius, 10 to 20 degrees Celsius, and 20 to 30 degrees Celsius. In some embodiments, the condition for deactivating the heating resistor may relate to reaching a deactivation temperature threshold after heating, reaching a period of time for heating by the heating resistor, or the like, or a combination thereof.

[0161] In some embodiments, the controller 761 may determine to activate (and / or deactivate) the heating resistor 751 to heat the component based on the temperature of the component and a reference temperature. The reference temperature may be the temperature of another component. For example, the controller 761 may receive information indicative of the temperature of the piezoelectric element 731 from a first sensor and information indicative of the temperature of the MEMS mirror 701 from a second sensor, which serves as the reference temperature. The controller 761 may determine to activate (and / or deactivate) the heating resistor 751 to heat the piezoelectric element 731 based on a comparison between the temperature of the piezoelectric element 731 and the reference temperature. As an example, the controller 761 may determine to activate the heating resistor 751 if the temperature of the piezoelectric element 731 is 5 degrees Celsius lower than the reference temperature.

[0162] In step 905, one or more heating elements may be activated (or deactivated). In some embodiments, step 905 may be performed by a controller (e.g., controller 761, processor 118). For example, controller 761 may be configured to activate (or deactivate) the heating elements (e.g., one or more of heating resistors 751, 752, 753, and 754) that it has determined to activate (or deactivate). For example, controller 761 may be configured to cause application of current to the heating resistors. As an example, controller 761 may control power supply 771 (e.g., by sending a control signal to power supply 771) to supply current to the heating resistors, which may heat one or more components when the current flows through them.

[0163] In some embodiments, the controller 761 may cause a current to be applied to the heating resistor based on the temperature of the component(s) that the heating resistor heats. For example, the controller 761 may control the power supply 771 to supply a first current to the heating resistor 751 when the piezoelectric element 731 is at a first temperature, and to supply a second current, greater than the first current, to the heating resistor 751 when the piezoelectric element 731 is at a second temperature that is lower than the first temperature.

[0164] In some embodiments, controller 761 may cause different currents to be applied to different heating resistors based on the difference between the temperatures of the components the heating resistors heat. For example, controller 761 may determine to activate heating resistors 751 and 752. Controller 761 may control power supply 771 to supply a first current to heating resistor 751 and a second current to heating resistor 752, which may be different from the first current (e.g., greater than or less than the first current). Alternatively or additionally, controller 761 may cause different currents to be applied to different heating resistors based on the type of heating resistor.

[0165] The power supply 771 may supply current to one or more heating resistors in a variety of ways (either under the direction of the controller 761 or independently). For example, the power supply 771 may supply a pulsed current to the heating resistors. Alternatively or additionally, the power supply 771 may supply current continuously to the heating resistors. Alternatively or additionally, the power supply 771 may supply current intermittently to the heating resistors. For example, the power supply 771 may continue to supply current to the heating resistors for a first period of time, cease supply for a second period of time, then resume supply for a third period of time, and so on. The periods for supplying and ceasing supply may be the same or different.

[0166] The power supply 771, under the direction of the controller 761 or independently, may supply currents to two or more heating resistors that cause the heating resistors to dissipate the same amount of heat (or have the same amount of heat). The amount of heat dissipated by a heating resistor may be proportional to the current flowing through the heating resistor and the voltage across the heating resistor. For example, the power supply 771 may supply currents to the heating resistors 751 and 752 that cause the heating resistors 751 and 752 to dissipate the same amount of heat. For example, the currents through the heating resistors may have the same flow, and the voltages across the heating resistors may be the same. Alternatively, the power supply 771 may supply currents to two or more heating resistors that cause the heating resistors to dissipate different amounts of heat. For example, the power supply 771 may supply a first current to the heating resistor 751. The power supply 771 may also supply a second current to the heating resistor 752, which may be different from the first current. For example, the second current may have a flow that is greater (or less) than the first current. Alternatively or additionally, power supply 771 may cause the voltage of heating resistor 751 to be different from the voltage of heating resistor 752 .

[0167] Electro-optical system with heating mechanism for solid-state photodetectors

[0168] To maintain an optimal environment in which the electro-optical system operates, it may be desirable to include one or more heating resistors integrated into the system to maintain the temperature of one or more components of the system within an operating range. Novel solid-state photodetectors, which may include integrated circuits, are described below. The solid-state photodetectors may be part of an electro-optical system, which may be part of a LIDAR system (e.g., LIDAR system 100). It is also contemplated that the principles described above may be applied to other types of electro-optical systems (e.g., cameras, rangefinders, electron microscopes). The electro-optical system may also include optics for directing light from the field of view (FOV) of the electro-optical system to the solid-state photodetector. In some embodiments, the electro-optical system may also include a current source for supplying current to one or more components of the solid-state photodetector (e.g., one or more heating resistors).

[0169] The integrated circuit may include one or more photosensitive photodiodes configured to generate an output signal indicative of light impinging on the photosensitive photodiode(s). The integrated circuit may also include one or more heating elements (e.g., heating resistors) configured to heat one or more components of the solid-state photodetector. The integrated circuit may further include circuitry for sending electrical current to the heating element(s).

[0170] 10A, 10B, and 10C show exemplary solid-state photodetectors according to examples of the disclosed subject matter. Although solid-state photodetectors 1000A, 1000B, and 1000C (and solid-state photodetectors 1100A and 1100B shown in FIGS. 11A and 11B) are described individually in some cases, one or more components of one solid-state photodetector may be used in other solid-state photodetectors described herein.

[0171] 10A, the solid-state photodetector 1000A may include, among other things, an integrated circuit 1001A, which may include a photosensitive photodiode 1011, a heating element (e.g., a heating resistor 1021), and circuitry for transmitting current from a power source (also called a current source) to the heating element. The photosensitive photodiode 1011 may be configured to sense light and generate an output signal indicative of the light impinging on the photosensitive photodiode. The heating resistor 1021 may be configured to heat the solid-state photodetector (or one or more components thereof). For example, the heating resistor 1021 may be configured to heat the photosensitive photodiode 1011 when current flows through the heating resistor 1021.

[0172] The integrated circuit may also include a sensor configured to monitor the temperature of the solid-state photodetector (or one or more components thereof). Figure 10B shows an example solid-state photodetector 1000B including an integrated circuit 1001B, which may include a sensor 1032 configured to monitor the temperature of the solid-state photodetector and / or photosensitive photodiode 1012. The integrated circuit 1001B may also include a heating resistor 1022 for heating the photosensitive photodiode 1012 based on the monitored temperature of the solid-state photodetector and / or photosensitive photodiode 1012.

[0173] The integrated circuit may further include a power supply configured to provide current to the heating elements via a controller and circuitry configured to control activation of the one or more heating elements. Figure 10C shows an exemplary solid-state photodetector 1000C including an integrated circuit 1001C, which may include a controller 1043, a power supply (not shown), a sensor 1033, photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018, and a heating resistor 1023. The sensor 1033 may be configured to monitor the temperature of the solid-state photodetector (and / or one or more components thereof). The controller 1043 may be configured to control activation of the heating resistor 1023 based on the monitored temperature of the solid-state photodetector and / or one or more components (e.g., one or more of the photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018). For example, the controller 1043 may receive information from the sensor 1033 indicative of the temperature of the photosensitive photodiode 1013. The controller 1043 may also determine that the temperature is below a threshold value. The controller 1043 may be further configured to control the power supply to supply a current to the heating resistor 1023, thereby heating the photosensitive photodiode 1013 (and / or one or more other components).

[0174] The photosensitive photodiodes may be configured to detect reflections from objects within the FOV of the electro-optical system. The photosensitive photodiodes may also generate output signals based on light impinging on the photosensitive photodiodes (e.g., intensity, timing, or the like, or a combination thereof). The electro-optical system may include one or more photosensitive photodiodes, each of which may include one or more detectors. The detectors (e.g., the detector of photosensitive photodiode 1011, one or more detectors of photosensitive photodiode 1012, one or more of photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018) may be photosensitive diode sensors, such as avalanche photodetectors (APDs), single-photon avalanche detectors (SPADs), silicon photomultiplier detectors (SiPMs), PIN photodiodes, etc.

[0175] In some embodiments, the solid-state photodetector may include a photosensitive photodiode that includes a detector. For example, as shown in FIG. 10A, an electro-optical system 1000A may include a photosensitive photodiode 1011 that includes a detector configured to detect light within the FOV of the electro-optical system. In other embodiments, the electro-optical system may include a photosensitive photodiode that includes multiple detectors. For example, a photosensitive photodiode may include a row or column of detectors. As another example, as shown in FIG. 10B, a solid-state photodetector (i.e., solid-state photodetector 1000B) may include a photosensitive photodiode 1012 that includes a matrix of 4×8 detectors (also called "pixels" or "detection cells"). In some embodiments, each of the pixels may be configured to detect light from a portion of the FOV. The size of the pixels may vary. For example, the pixel size may be approximately 100×100 μm. 2 or 1 x 1 mm 2The photosensitive photodiode 1012 may also include one or more outputs, each of which may correspond to a different portion (pixel) of the photosensitive photodiode 1012. The photosensitive photodiode 1012 may be two-dimensional in the sense that it has two or more sets of detectors (e.g., rows, columns) in two non-parallel axes. The number of detectors in the photosensitive photodiode 1012 may vary between different implementations (e.g., depending on the desired resolution, signal-to-noise ratio (SNR), and desired detection distance). For example, the photosensitive photodiode 1012 may have anywhere from 5 to 5,000 pixels. Fewer or higher pixel counts (e.g., megapixels) may also be implemented.

[0176] The detectors of light-sensitive photodiodes may be of the same type or may include different types. Alternatively or additionally, detectors of the same type may have different characteristics (e.g., sensitivity, size). Combinations of detectors of different types may be used for various reasons, such as, for example, to improve detection over a range of distances (e.g., close range), to improve the dynamic range of the detector, to improve the temporal response of the detector, and / or to improve detection in various environmental conditions (e.g., air temperature, rain, etc.).

[0177] In some embodiments, the electro-optical system may include multiple photosensitive photodiodes, each of which may include one or more detectors. For example, as shown in FIG. 10C , electro-optical system 1000C may include photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018. Each of photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018 may include multiple detectors. In some embodiments, the solid-state photodetector may also include readout circuitry associated with the photosensitive photodiodes (and / or detectors).

[0178] A solid-state photodetector may include one or more heating elements (e.g., heating resistors 1021, 1022, and 1023 shown in FIGS. 10A, 10B, and 10C, respectively). The heating resistors may be configured to heat one or more components of the solid-state photodetector (e.g., a photosensitive photodiode, a transparent layer, a controller, or the like, or a combination thereof). For example, as shown in FIG. 10A, heating resistor 1021 may be configured to heat photosensitive photodiode 1011. Alternatively or additionally, a solid-state photodetector may include two or more heating resistors to heat one component. For example, solid-state photodetector 1000A may include heating resistor 1021 and another heating resistor (not shown) to heat photosensitive photodiode 1011. Alternatively or additionally, a solid-state photodetector may include heating resistors configured to heat two or more photosensitive photodiodes. 10C, the solid-state photodetector 1000C may include a heating resistor 1023, which may be configured to heat the photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018. The heating resistor may be mounted on or in close proximity to the component. For example, the heating resistor may be mounted in close proximity to the photosensitive photodiode on a substrate on which the photosensitive photodiode is mounted. In some embodiments, one or more heating resistors may be mounted on a polysilicon or metal layer of an integrated circuit.

[0179] In some embodiments, the solid-state photodetector may include a controller configured to control one or more heating resistors to heat one or more components. For example, as shown in FIG. 10C , the solid-state photodetector 1000C may include an integrated circuit 1001C, which may include a controller 1043 configured to control activation of the heating resistor 1023. The controller 761 may control the heating resistor 1023 to heat at least one of the photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018. As an example, the controller 1043 may determine to activate the heating resistor 1023 if the temperature of the photosensitive photodiode is below a threshold. The controller 1043 may also control a power source (not shown) to pass current through the heating resistor.

[0180] In some embodiments, the solid-state photodetector may include two or more heating resistors configured to heat one or more components. The heating resistors may be uniformly mounted on (or adjacent to) the components. Alternatively, the heating resistors may not be uniformly mounted on (or adjacent to) the components. In some embodiments, the heating resistors may be the same type or different types. Alternatively or additionally, the controller may control the power supplies to supply the same or different currents to the heating resistors.

[0181] In some embodiments, the power supply may be controlled to supply different currents to different heating resistors, for example, the power supply may supply a first current to a first heating resistor and a second current to a second heating resistor that is different from the first current (e.g., a larger or smaller current).

[0182] In some embodiments, a solid-state photodetector may include one heating element configured to heat two or more components. By way of example, as shown in FIG. 10C, a solid-state photodetector 1000C may include a heating resistor 1023 configured to heat photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018 when a current is passed through the heating resistor 1023.

[0183] In some embodiments, the heating element may be configured to heat the solid-state photodetector (and / or one or more components thereof) in response to information indicative of the temperature of the solid-state photodetector (and / or one or more components thereof). By way of example, the controller 1043 may receive information indicating that the temperature of the photosensitive photodiode 1013 is below a threshold. The controller 1043 may control the power supply to provide current to the heating resistor 1023 to heat the photosensitive photodiode 1013.

[0184] In some embodiments, the heating resistors can be of the same type. Alternatively, the electro-optical system can include two or more different types of heating resistors. For example, a heating resistor can have a different overall resistance, heating value, or the like, or a combination thereof, from another heating resistor (or other heating resistors).

[0185] In some embodiments, the heating resistors (e.g., heating resistors 1021, 1022, and / or 1023) may have a total resistance in the range of ¼ to 5 kilohms. In some embodiments, the total resistance of the heating resistors may be limited to the following subranges: ¼ to 1 ohm, 1 to 10 ohms, 10 to 50 ohms, 50 to 100 ohms, 100 to 500 ohms, 500 to 1000 ohms, 1 to 2 kilohms, and 2 to 5 kilohms.

[0186] In some embodiments, the heating resistors (e.g., heating resistors 751, 752, 753, 754, and 756) can have a heating power in the range of 5 to 5000 milliwatts. In some embodiments, the heating power of the heating resistors can be limited to subranges of 5 to 10 milliwatts, 10 to 50 milliwatts, 50 to 100 milliwatts, 100 to 500 milliwatts, 500 to 1000 milliwatts, 1000 to 1500 milliwatts, 1500 to 2500 milliwatts, and 2500 to 5000 milliwatts.

[0187] In some embodiments, the solid-state photodetector may include various sensors (not shown) configured to monitor the conditions under which the solid-state photodetector operates. For example, the integrated circuit of the solid-state photodetector may include one or more temperature sensors configured to monitor the temperature of the solid-state photodetector (and / or one or more components thereof). For example, a temperature sensor (e.g., a resistive temperature sensor) may be configured to measure the temperature of the solid-state photodetector or its photosensitive photodiode. Alternatively or additionally, the temperature sensor may be configured to monitor the ambient temperature of the solid-state photodetector (or the electro-optical system including the solid-state photodetector). The sensor may include at least one of a feedback resistor, a diode, a transistor, or the like, or a combination thereof. The sensor may measure the temperature directly or indirectly, for example, by measuring the effect of changing temperature on the operation of one or more components of the solid-state photodetector.

[0188] The sensor may be configured to transmit signals and / or information related to the condition(s) it monitors to the controller of the solid-state photodetector. For example, the sensor may transmit information indicative of the temperature of one or more of the photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018 to the controller 1043, and the controller 1043 may determine, based on the received information, whether to activate one or more heating resistors to heat one or more of the photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018. The measurement (or monitoring) of temperature by the sensor may be continuous or intermittent. Alternatively or additionally, the sensor may receive a control signal from the controller 1043 to measure the temperature and transmit the temperature information it obtains to the controller 1043. As an example, the controller 1043 may receive information indicative of the operating state of one or more of the photosensitive photodiodes and generate a control signal to be transmitted to the sensor. After receiving the control signal, the sensor may measure the temperature of the light-sensitive photodiode and send the temperature information to the controller 1043 .

[0189] In some embodiments, the sensor may be implemented as part of a solid-state photodetector. For example, the sensor may be implemented on (or adjacent to) a component of a solid-state photodetector on an integrated circuit. As an example, the sensor may be implemented on a substrate on which a light-sensitive photodiode or controller 1043 is implemented. As another example, the sensor may be implemented adjacent to a transparent layer (e.g., window 124 shown in FIG. 1A, window 1131 shown in FIG. 11A, microlens 1152 shown in FIG. 11B, microlens 422 shown in FIG. 4D). In other embodiments, the sensor may be implemented external to the solid-state photodetector or the electro-optical system (e.g., a temperature sensor external to the electro-optical system configured to measure the ambient temperature around the electro-optical system).

[0190] In some embodiments, the solid-state photodetector may also include a controller (e.g., controller 1043) and a power supply. The controller 1043 may include one or more processors, microprocessors, or the like, or a combination thereof. The controller 1043 may be configured to control the activation of one or more heating resistors. For example, the controller 1043 may control a power supply (not shown) to supply current to one or more of the heating resistors.

[0191] The power source may be configured to provide power to one or more heating resistors for heating. The power source may be a battery, an AC power source, a DC power source, a rechargeable capacitor, or the like, or a combination thereof. In some embodiments, the power source may include a power source that is part of the solid-state photodetector or electro-optical system (e.g., an internal power source). Alternatively or additionally, the power source may include a power source external to the solid-state photodetector or electro-optical system.

[0192] In some embodiments, the power source may be electrically coupled to various components of the solid-state photodetector (e.g., the photosensitive photodiodes, the heating resistors, the controller, and various sensors). The power source may be external to the controller 1043. Alternatively, the power source and the controller 1043 may be integrated as a single unit. In some embodiments, the controller 1043 and the power source may be electrically coupled to the electro-optical system but external to the electro-optical system. For example, the controller 1043 (and / or the power source) may be implemented external to the electro-optical system (e.g., as a separate part of a LIDAR system that includes the electro-optical system).

[0193] In some embodiments, the controller 1043 may selectively cause the power supply to apply current through the heating resistor based on a temperature reading from the solid-state photodetector (or a component thereof). For example, the controller 1043 may be configured to control the power supply to selectively supply current to the heating resistor 1023 (but not to other heating resistor(s), if any) based on a temperature reading from the solid-state photodetector 1000C (e.g., a temperature reading from the photosensitive photodiode 1013). As an example, the controller 1043 may selectively cause the power supply to apply current through the heating resistor 1023 if the temperature reading is below a threshold temperature.

[0194] In some embodiments, the electro-optical system is a LIDAR system, which may further include a processor programmed to process the detection of the light-sensitive photodiode(s) to determine the distance to at least one object within the FOV. Other types of electro-optical systems (e.g., cameras, electro-optical microscopes) may also be contemplated.

[0195] In some embodiments, the solid-state photodetector may further include a transparent layer coupled to the solid-state photodetector, and the solid-state photodetector may include a heating resistor configured to reduce or prevent ice (or frost) buildup on the transparent layer. The transparent layer may be, for example, a window, a wedge, an array of microlenses, a prism, an array of prisms, an optical filter, or the like, or a combination thereof. The transparent layer may be transparent, partially transparent, or translucent.

[0196] 11A shows an exemplary solid-state photodetector 1100A including a photosensitive photodiode 1111 and heating resistors 1121 and 1122. The photosensitive photodiode 1111 may be similar to a photosensitive photodiode as described elsewhere in this disclosure. The heating resistors 1121 and 1122 may be similar to heating resistors as described elsewhere in this disclosure. The solid-state photodetector 1100A may also include a window 1131 coupled to the photosensitive photodiode 1111. Ice or frost (e.g., ice 1141) may accumulate on the window 1131 under certain conditions (e.g., when the exterior and / or interior of a LIDAR system, including an electro-optical system, may fall below freezing in the presence of moisture or steam). The ice or frost may form an optical block (or filter) and / or alter the optical properties of the window 1131 (e.g., alter the light intensity of a lens). To reduce or prevent ice buildup, heating resistor 1122 (and / or heating resistor 1121) may be configured to heat window 1131 (and / or photosensitive photodiode 1111). The heating process may be similar to heating processes described elsewhere in this disclosure (e.g., according to process 1200). FIG. 11B shows an example solid-state photodetector 1100B including a photosensitive photodiode 1111 and heating resistors 1121 and 1124. The photosensitive photodiode 1111 may be similar to a photosensitive photodiode as described elsewhere in this disclosure. The heating resistors 1123 and 1124 may be similar to heating resistors as described elsewhere in this disclosure. The solid-state photodetector 1100B may also include an array of microlenses 1152 coupled to the photosensitive photodiode 1112. Ice or frost (e.g., ice 1142) may accumulate on the microlens 1152 (or one or more of its microlenses) under certain conditions (e.g., the exterior and / or interior of a LIDAR system including the solid-state photodetector may fall below freezing in the presence of moisture or steam). The ice or frost may form an optical block (or filter) and / or alter the optical properties of the microlens 1152 (e.g., altering the light intensity of the lens). To reduce or prevent ice buildup, heating resistor 1124 (and / or heating resistor 1123) may be configured to heat microlens 1152 (and / or photosensitive photodiode 1112). The heating process may be similar to heating processes described elsewhere in this disclosure (e.g., according to process 1200).

[0197] In some embodiments, two or more components of the solid-state photodetector (e.g., one or more of the photosensitive photodiode, the heating resistor, the controller, and the power supply) may be fabricated on a single chip (or circuit). For example, the heating resistor 1023 and one or more of the photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018 (and circuitry for delivering current to the heating resistor 1023) may be implemented on an integrated circuit. Alternatively or additionally, the electrodes of the heating resistor and the photosensitive photodiode may be implemented on the same metal layer of the integrated circuit. Alternatively or additionally, the heating resistor may be implemented on a doped region of a silicon-based layer of the integrated circuit. In some embodiments, the heating resistor and the photosensitive photodiode may be mechanically and / or electrically isolated from each other even if implemented on the same metal layer (e.g., in the same metal application process). In other embodiments, the heating resistor and the photosensitive photodiode may be mechanically and / or electrically coupled.

[0198] A solid-state photodetector may also include additional components, such as a controller, a power supply, a sensor (e.g., a temperature sensor), optical components, structural elements, a transparent layer, etc. One of the additional components may be implemented on the same chip as the heating resistor and / or the photosensitive photodiode, on a separate chip, or may be otherwise integrated.

[0199] In some embodiments, one or more heating resistors may be mounted on a location proximate to a component of a solid-state photodetector. For example, one or more heating resistors may be mounted proximate to a light-sensitive photodiode.

[0200] 12 is a flowchart of an exemplary heating process 1200 according to disclosed embodiments. One or more steps of the heating process 1200 may be performed by a controller of the solid-state photodetector or a controller external to the solid-state photodetector (e.g., processor 118). The heating process is described herein using the components of the solid-state photodetector 1000C shown in FIG. 10C, but it may be applied to other exemplary solid-state photodetectors described in this disclosure.

[0201] In step 1201, temperature information may be received. Step 1201 may be performed by the controller and / or processor 118 of the solid-state photodetector. For example, the controller 1043 may receive the temperature information. In some embodiments, the controller 1043 may receive information indicative of the solid-state photodetector 1000C (or one or more components thereof, such as one or more photosensitive photodiodes, transparent layers, or the like, or a combination thereof) from a temperature sensor. For example, a sensor proximate to the photosensitive photodiode 1013 may measure the temperature of the photosensitive photodiode 1013 and send information indicative of the temperature to the controller 1043. As another example, the controller 1043 may receive information indicative of the ambient temperature surrounding the solid-state photodetector 1000C from a sensor external to the solid-state photodetector 1000C.

[0202] In some embodiments, the sensor may continuously measure the temperature of a solid-state photodetector (or one or more components thereof, such as one or more light-sensitive photodiodes, a transparent layer, or the like, or a combination thereof) and continuously transmit the information to the controller 1043. Alternatively or additionally, the sensor may intermittently measure the temperature and transmit the temperature information to the controller 1043 if the controller 1043 is available. For example, the sensor may be configured to measure the temperature once over a predetermined period of time, which may range from 0.1 seconds to 10 minutes. In some embodiments, the period may be limited to sub-ranges of 0.1 to 1 second, 1 to 10 seconds, 10 to 60 seconds, and 1 to 10 minutes. Alternatively or additionally, the sensor may be configured to measure the temperature on demand. For example, the sensor may receive a control signal from the controller 1043. In response, the sensor may measure the temperature (continuously or intermittently) and transmit the temperature information to the controller 1043. In some embodiments, the sensor may continue measuring the temperature until it receives a second control signal to stop the measurement.

[0203] In step 1203, it may be determined whether to activate (or deactivate) one or more of the heating resistors. Step 1203 may be performed by the solid-state photodetector's controller and / or processor 118. For example, the controller 1043 may be configured to determine whether to activate (or deactivate) one or more of the heating resistors (e.g., including heating resistor 1023) to heat the solid-state photodetector or one or more components of the solid-state photodetector (e.g., an integrated circuit, one or more photosensitive photodiodes, a sensor, a controller, a transparent layer, or the like, or a combination thereof) based on the received temperature information. For example, the controller 1043 may determine whether the temperature of one or more of the photosensitive photodiodes 1013, 1014, 1015, 1016, 1017, and 1018 is below an activation threshold, which may be the lower limit of a temperature range at which the component(s) optimally operate. If so, the controller 1043 may determine to activate the heating resistor 1023 to heat the photosensitive photodiode(s). On the other hand, if the controller 1043 determines that the temperature of the photosensitive photodiode(s) is equal to or greater than the activation threshold, the controller 1043 may determine that activation of the heating resistor 1023 is not necessary (i.e., take no action). As another example, the controller 1043 may receive information indicative of the temperature of a first component from a first sensor and information indicative of the temperature of a second component from a second sensor. As an example, the controller 1043 may receive information indicative of the temperature of the photosensitive photodiode 1013 from the first sensor and information indicative of the temperature of the photosensitive photodiode 1014 from the second sensor. The controller 1043 may also determine that the temperature of the photosensitive photodiode 1013 is above a first activation threshold, while the temperature of the photosensitive photodiode 1014 is below a second activation threshold (which may be the same as or different from the first threshold).The controller 1043 may further determine to activate the heating resistors proximate the photosensitive photodiode 1014, but not the heating resistors proximate the photosensitive photodiode 1013 (not shown in FIG. 10A ). As a further example, the controller 1043 may determine that the temperature of one of the components is below an activation threshold corresponding to the particular component (which may be the same or different for each component) and decide to activate some or all of the heating resistors.

[0204] In some embodiments, the activation temperature threshold may be related to the dew point at which the electro-optical system (or solid-state photodetector) operates. For example, the controller 1043 may receive (or determine based on various factors, such as pressure, humidity, etc.) the dew point at which the electro-optical system (or solid-state photodetector) operates. The controller 1043 may set the dew point as the activation threshold. Alternatively, the controller 1043 may set a certain degree Celsius below or above the dew point as the activation threshold. As an example, the controller 761 may set 3° C. below (or above) the dew point as the activation threshold.

[0205] In some embodiments, the controller 1043 may be configured to determine to activate the heating resistor based on a temperature reading from a chip on which the light-sensitive photodiode is implemented. For example, the controller 1043 may be configured to receive a temperature reading from a chip on which the light-sensitive photodiode is implemented and determine that the temperature is below a threshold. The controller 1043 may be configured to determine to selectively activate the heating resistor to heat the light-sensitive photodiode.

[0206] The controller 1043 may also be configured to deactivate one or more heating resistors if a deactivation condition is met. For example, the controller 1043 may deactivate a heating resistor based on received temperature information. As an example, the controller 1043 may receive information from a sensor indicating the temperature of the photosensitive photodiode 1013 after the heating resistor 1023 is activated to heat the photosensitive photodiode 1013 (as described elsewhere in this disclosure). The controller 1043 may determine that the temperature of the photosensitive photodiode 1013 is equal to or greater than a deactivation threshold. The controller 1043 may decide to deactivate the heating resistor 1023. A component's deactivation threshold may be equal to or greater than its activation threshold. In some embodiments, the deactivation threshold may be related to the ambient temperature of the solid-state photodetector (e.g., 5, 10, or 15 degrees Celsius above ambient temperature). Alternatively or additionally, the controller 1043 may deactivate the heating resistor after a predetermined heating period (eg, 1, 5, or 10 minutes).

[0207] In some embodiments, the controller 1043 may control activation of the heating resistor 1023 until a deactivation condition is met. For example, the controller 1043 may activate the heating resistor 1023 to heat the photosensitive photodiode 1013, and the heating resistor 1023 may be configured to heat the photosensitive photodiode 1013 when activated. The controller 1043 may receive information from the sensor indicating the temperature of the photosensitive photodiode 1013 after heating. The controller 1043 may determine that the temperature of the photosensitive photodiode 1013 is higher than the ambient temperature around the solid-state photodetector (or its photosensitive photodiode) by a temperature difference (e.g., 5 or 10 degrees Celsius). The controller 1043 may then deactivate the heating resistor 1023. The temperature difference may be in a range of 1 to 30 degrees Celsius. In some embodiments, the temperature difference may be limited to a subrange of 1 to 5 degrees Celsius, 5 to 10 degrees Celsius, 10 to 20 degrees Celsius, or 20 to 30 degrees Celsius. In some embodiments, the condition for deactivating the heating resistor may relate to reaching a deactivation temperature threshold after heating, reaching a period of time for heating by the heating resistor, or the like, or a combination thereof.

[0208] In some embodiments, the deactivation threshold may be related to the dew point at which the electro-optical system (or solid-state photodetector) operates. For example, the controller 1043 may receive (or determine based on various factors, such as pressure, humidity, etc.) the dew point at which the electro-optical system (or solid-state photodetector) operates. The controller 1043 may set the deactivation threshold to a certain degree Celsius above the dew point. As an example, the controller 1043 may set the deactivation threshold to any number between 5 and 20 degrees Celsius above the dew point.

[0209] In some embodiments, the controller 1043 may determine to activate (and / or deactivate) the heating resistor to heat the component based on the temperature of the component and a reference temperature. The reference temperature may be the temperature of another component. For example, the controller 1043 may receive information indicative of the temperature of the photosensitive photodiode 1013 from a first sensor and information indicative of the temperature of the photosensitive photodiode 1014 from a second sensor, which serves as the reference temperature. The controller 1043 may determine to activate (and / or deactivate) the heating resistor 1023 to heat the photosensitive photodiode 1013 based on a comparison between the temperature of the photosensitive photodiode 1013 and the reference temperature. As an example, the controller 1043 may determine to activate the heating resistor 1023 if the temperature of the photosensitive photodiode 1013 is 5 degrees Celsius lower than the reference temperature.

[0210] In step 1205, one or more heating elements may be activated (or deactivated). Step 1205 may be performed by a controller of the solid-state photodetector or a controller external to the solid-state photodetector. For example, the controller 1043 may be configured to activate (or deactivate) heating elements that it has determined to activate (or deactivate). For example, the controller 1043 may be configured to cause a circuit to apply a current to a heating resistor. As an example, the controller 1043 may control a power supply (e.g., by sending a control signal to the power supply) to cause a circuit to supply a current to a heating resistor, which may heat one or more components when the current flows through it. In some embodiments, the heating may reduce or prevent ice buildup on the photosensitive photodiode and / or transparent layer of the solid-state photodetector.

[0211] In some embodiments, given that a photosensitive photodiode may operate better (e.g., have lower noise) at lower temperatures, heating the photosensitive photodiode may affect the performance of the photosensitive photodiode. For example, heating the photosensitive photodiode may reduce the sensitivity of the power supply. The controller 1043 may deactivate a heating resistor that heats the photosensitive photodiode if the heating may adversely affect the performance of the photosensitive photodiode. For example, the controller 1043 may receive information related to the performance of the photosensitive photodiode after the photosensitive photodiode has been heated or is being heated. The controller 1043 may determine whether to deactivate the heating resistor based on the received information. The controller 1043 may also deactivate the heating resistor if it determines that the heating is adversely affecting the performance of the photosensitive photodiode. As another example, the controller 1043 may receive information related to the temperature of the photosensitive photodiode after the photosensitive photodiode has been heated or is being heated. The controller 1043 may determine that the temperature is above a deactivation threshold. The controller 1043 may further determine to deactivate the heating resistor so that the photosensitive photodiode can operate at an optimal temperature, thereby maintaining the optical transparency or optical efficiency of the path from the FOV to the photosensitive photodiode.

[0212] In some embodiments, the controller 1043 may be configured to cause the heating resistor to heat the photosensitive photodiode to a temperature at least some degree Celsius above the ambient temperature surrounding the solid-state photodetector (or photosensitive photodiode). For example, the controller 1043 may be configured to cause the heating resistor to heat the photosensitive photodiode to a temperature at least any number between 5 and 20 degrees Celsius above the ambient temperature surrounding the solid-state photodetector (or photosensitive photodiode).

[0213] In some embodiments, the controller 1043 may cause a current to be applied to the heating resistor based on the temperature of the component(s) that the heating resistor heats. For example, the controller 1043 may control the power supply to supply a first current to the heating resistor 1023 when the photosensitive photodiode 1013 is at a first temperature, and to supply a second current, greater than the first current, to the heating resistor 1023 when the photosensitive photodiode 1013 is at a second temperature, lower than the first temperature.

[0214] In some embodiments, the controller 1043 may cause different currents to be applied to different heating resistors based on the difference between the temperatures of the components the heating resistors heat. For example, the controller 1043 may determine to activate a first heating resistor and a second heating resistor. The controller 1043 may control the power source to supply a first current to the first heating resistor and a second current to the second heating resistor, which may be different from the first current (e.g., greater than or less than the first current). Alternatively or additionally, the controller 1043 may cause different currents to be applied to different heating resistors based on the type of heating resistor.

[0215] The power supply may supply current to one or more heating resistors in a variety of ways (under the direction of the controller 1043 or independently). For example, the power supply may supply a pulsed current to the heating resistor. Alternatively or additionally, the power supply may supply current continuously to the heating resistor. Alternatively or additionally, the power supply may supply current intermittently to the heating resistor. For example, the power supply may continue to supply current to the heating resistor for a first period of time, cease supply for a second period of time, then resume supply for a third period of time, and so on. The periods for supplying and cessation of supply may be the same or different.

[0216] The power supply, under the direction of the controller 1043 or independently, may supply currents to two or more heating resistors that cause the heating resistors to dissipate the same amount of heat (or have the same amount of heat). The amount of heat dissipated (heat) by the heating resistors may be proportional to the generation of current through the heating resistors and the voltage of the heating resistors. For example, the power supply may supply currents to a first heating resistor and a second heating resistor that cause the heating resistors to dissipate the same amount of heat. For example, the currents through the heating resistors may have the same flow, and the voltages of the heating resistors may be the same. Alternatively, the power supply may supply currents to two or more heating resistors that cause the heating resistors to dissipate different amounts of heat. For example, the power supply may supply a first current to the first heating resistor. The power supply may also supply a second current to the second heating resistor, which may be different from the first current. For example, the second current may have a flow greater (or less) than the first current. Alternatively or additionally, the power supply may cause the voltage of the first heating resistor to be different from the voltage of the second heating resistor.

[0217] In some embodiments, the electro-optical system can be configured to detect light from the FOV of the electro-optical system by a light-sensitive photodiode (after and / or before heating from one or more heating resistors). For example, at least one instance of heating the light-sensitive photodiode (or transparent layer) can precede the detection of light. In some embodiments, detection can be performed continuously (e.g., to scan the FOV of a solid-state photodetector), while heating is performed when a heating condition is satisfied (e.g., when the temperature falls below a threshold temperature).

[0218] The foregoing description has been presented for purposes of illustration. It is not exhaustive or limited to the precise form or embodiment disclosed. Modifications and adaptations will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed embodiments. Furthermore, while aspects of the disclosed embodiments are described as being stored in memory, those skilled in the art will recognize that these aspects can also be stored in other forms of computer-readable media, such as, for example, a hard disk or CD ROM, or other forms of RAM or ROM, secondary storage devices such as USB media, DVD, Blu-ray, or other optical drive media.

[0219] Computer programs based on the written descriptions and disclosed methods are within the skill of an experienced developer. Various programs or program modules can be created using any of the techniques known to those skilled in the art, or designed in conjunction with existing software. For example, program sections or program modules can be designed in or with the .Net framework, the .Net Compact Framework (and related languages ​​such as Visual Basic and C), Java, C++, Objective-C, HTML, a combination of HTML / AJAX, XML, or HTML, including Java applets.

[0220] Furthermore, while exemplary embodiments have been described herein, the scope of any and all embodiments, having equivalent elements, modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations, and / or variations, will be recognized by those of ordinary skill in the art based on this disclosure. Any limitations in the claims shall be interpreted broadly based on the language used in the claims and not limited to the examples described herein or during prosecution of this application. These examples are to be construed non-exclusively. Furthermore, the steps of the disclosed methods may be modified arbitrarily, including by changing the order of steps and / or inserting or deleting steps. Accordingly, it is intended that the specification and examples be considered merely as illustrative, with a true scope and spirit being indicated by the following claims and their full scope of equivalents.

Claims

1. 1. A solid-state photodetector comprising: an integrated circuit including at least one photosensitive photodiode configured to generate an output signal indicative of light impinging on the photosensitive photodiode; at least one heating resistor configured to heat the solid-state photodetector when a current is passed through the at least one heating resistor; a circuit for delivering the current of a current source to the at least one heating resistor; Equipped with the electrodes of the at least one heating resistor and the at least one photosensitive photodiode are mounted on the same metal layer of the integrated circuit; A solid-state photodetector, wherein the at least one heating resistor and the at least one photosensitive photodiode are not electrically connected through the metal layer.

2. 1. A solid-state photodetector comprising: an integrated circuit including at least one photosensitive photodiode configured to generate an output signal indicative of light impinging on the photosensitive photodiode; at least one heating resistor configured to heat the solid-state photodetector when a current is passed through the at least one heating resistor; a circuit for delivering the current of a current source to the at least one heating resistor; Equipped with the at least one heating resistor is mounted on a doped region of a silicon-based layer of the integrated circuit; A solid-state photodetector, wherein the at least one heating resistor and the at least one photosensitive photodiode are not electrically connected through the silicon-based layer.

3. 3. The solid-state photodetector of claim 1, further comprising a controller configured to control activation of the at least one heating resistor in response to information related to a temperature of the solid-state photodetector.

4. The solid-state photodetector of any one of claims 1 to 3, further comprising a temperature sensor mounted on the integrated circuit.

5. The solid-state photodetector of claim 4 , wherein the temperature sensor includes at least one of a feedback resistor, a diode, or a transistor.

6. A solid-state photodetector according to any one of claims 1 to 5, wherein said heating prevents ice build-up on said solid-state photodetector.

7. 7. The solid-state photodetector of claim 1, further comprising a transparent layer coupled to the solid-state photodetector, and wherein the heating prevents ice buildup on the transparent layer.

8. The solid-state photodetector of claim 7 , wherein the transparent layer comprises a plurality of microlenses.

9. 9. A solid-state photodetector according to claim 7 or 8, wherein the transparent layer comprises a window.

10. A solid-state photodetector according to any preceding claim, wherein the heating reduces the sensitivity of the solid-state photodetector.

11. A solid-state photodetector according to any one of claims 1 to 10, wherein said at least one heating resistor emits an amount of heat having a range between 250 and 2,000 milliwatts.

12. 1. An electro-optical system comprising: The solid-state photodetector according to any one of claims 1 to 11, an optical system for directing light from a field of view (FOV) of the electro-optical system to the solid-state photodetector; current source and Equipped with The electro-optical system is a LIDAR system, and the system further includes a processor programmed to process detections by the solid-state photodetector to determine a distance to at least one object within the FOV.

13. An electro-optical system comprising: a solid-state photodetector; optics for directing light from a field of view (FOV) of an electro-optical system to the solid-state photodetector; current source and Equipped with The solid-state photodetector comprises: an integrated circuit including at least one photosensitive photodiode configured to generate an output signal indicative of light impinging on the photosensitive photodiode; at least one heating resistor configured to heat the solid-state photodetector when a current is passed through the at least one heating resistor; a circuit for delivering the current of the current source to the at least one heating resistor; Equipped with the solid-state photodetector includes a plurality of sensor pixels, each of the sensor pixels configured to detect light from a different portion of the FOV of the electro-optical system; The electro-optical system further includes a processor programmed to process detection by the solid-state photodetector to determine a distance to at least one object within the FOV.

14. The electro-optical system described in claim 13, wherein the electro-optical system is a LIDAR system.

15. 1. A method for operating an electro-optical system, comprising: passing a current through at least one heating resistor of the electro-optical system to heat a photosensitive photodiode, the at least one heating resistor being mounted on an integrated circuit on which the photosensitive photodiode is mounted; detecting light from a field of view (FOV) of the electro-optical system with the light-sensitive photodiode of the electro-optical system; Including, the at least one heating resistor and the electrodes of the photosensitive photodiode are mounted on the same metal layer of the integrated circuit; The method, wherein the at least one heating resistor and the photosensitive photodiode are not electrically connected through the metal layer.

16. A method for operating an electro-optical system, comprising: passing a current through at least one heating resistor of the electro-optical system to heat a photosensitive photodiode, the at least one heating resistor being mounted on an integrated circuit on which the photosensitive photodiode is mounted; detecting light from a field of view (FOV) of the electro-optical system with the light-sensitive photodiode of the electro-optical system; Including, the at least one heating resistor is mounted on a doped region of a silicon-based layer of the integrated circuit; The method, wherein the at least one heating resistor and the photosensitive photodiode are not electrically connected through the silicon-based layer.

17. 17. The method of claim 15 or 16, further comprising selectively applying the current based on a temperature reading from the chip.

18. 18. The method of claim 17, further comprising selectively passing the current if the temperature reading indicates a temperature below a threshold temperature.

19. The method of any one of claims 15 to 18, further comprising passing different currents through the at least one heating resistor based on different temperatures of a solid-state photodetector of the electro-optical system.

20. 20. The method of any one of claims 15 to 19, wherein the heating comprises heating a solid-state photodetector of the electro-optical system to a temperature at least 5 degrees Celsius above an ambient temperature around the solid-state photodetector.

Images