Optical distance measuring device

Abstract

Embodiments describe an optical ranging device comprising: an optical transmission module comprising a transmitter layer comprising a plurality of optical transmitters; an optical sensing module comprising a sensor layer comprising a plurality of pixels, wherein each pixel of the plurality of pixels senses light from a different optical transmitter of the plurality of optical transmitters; a transmitter trigger circuit coupled to the plurality of optical transmitters and configured to activate only a subset of optical transmitters at a time; and a sensor array readout circuit coupled to the plurality of pixels and configured to synchronize the readout of each pixel within the plurality of pixels contemporaneously with the triggering of a corresponding optical transmitter, such that each optical transmitter of the plurality of individual optical transmitters can be activated and each pixel of the plurality of pixels can be read out over one emission cycle.

Description

[0001] This application is a divisional application of Chinese Patent Application for Invention entitled “Optical Ranging Device with Electronically Scanned Transmitter Array and Synchronized Sensor Array”, Application No. 201880053727.2.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 528,879, filed July 5, 2017, the disclosure of which is hereby incorporated by reference in its entirety and for all purposes. TECHNICAL FIELD

[0004] The present disclosure relates to optical ranging devices. BACKGROUND

[0005] Light imaging, detection, and ranging (LIDAR) systems measure distances to targets by illuminating the targets with pulsed laser light and measuring the reflected pulses with sensors. Time-of-flight measurements can then be used to produce a digital 3D representation of the targets. LIDAR systems can be used for various applications that require the use of 3D depth images, including archaeology, geography, geology, forestry, mapping, construction, medical imaging, and military applications, among others. Autonomous vehicles can also use LIDAR for obstacle detection and avoidance, as well as vehicle navigation.

[0006] Some LIDAR systems include mechanical, moving components that physically scan the transmitting and receiving elements through a rotational angle of less than or equal to 360° to capture images of scenery in a field. One example of such a system that can be used for obstacle detection and avoidance in vehicles is generally referred to as a rotating or spinning LIDAR system. In a rotating LIDAR system, a LIDAR sensor is mounted, typically within a housing, to a column that rotates or spins a full 360 degrees. The LIDAR sensor includes coherent light emitters (e.g., pulsed lasers in the infrared or near-infrared spectrum) to illuminate the scene around the vehicle as the LIDAR sensor continuously rotates through the scene. As the coherent light emitters rotate, they send pulses of radiation in different directions away from the LIDAR system in the scene. Portions of the radiation that are incident on surrounding objects in the scene are reflected from those objects around the vehicle, and then the reflections are detected by the imaging system portion of the LIDAR sensor at different time intervals. The imaging system converts the detected light into electrical signals.

[0007] In this way, information about objects surrounding the LIDAR system, including their distances and shapes, is collected and processed. The digital signal processing unit of the LIDAR system can process the electrical signals and reproduce the information about the objects in a depth image or 3D point cloud, which can be used as an aid for obstacle detection and avoidance, as well as vehicle navigation and other purposes. Additionally, image processing and image stitching modules can take the information and assemble a display of the objects surrounding the vehicle.

[0008] Another type of mechanical LIDAR system uses, for example, a galvanometer mirror to scan a laser beam along a predetermined scan pattern. Some such systems can include a two-dimensional array of photodetectors that are electronically scanned to coincide with the scan pattern of the laser beam. However, when a mechanical system is employed to control the beam, it is challenging to calibrate and synchronize the sensor array with the laser beam.

[0009] Solid-state LIDAR systems also exist that do not include any moving mechanical parts. Certain solid-state LIDAR systems do not rotate in the scene, but rather flash the entire portion of the scene that they intend to capture and sense light from. In such systems, the transmitter includes an array of emitters, all of which emit light at once to illuminate the scene, and are therefore sometimes referred to as "flash" LIDAR systems. Because of the lack of moving parts, flash LIDAR systems are less complex to manufacture; however, because all emitters are activated at once, they can require a large amount of power to operate, and they can require a large amount of processing power to process the signals from all pixel detectors at once. Reducing the number of light emitters can save power, but can sacrifice the quality and resolution of the final image. The large amount of emitted light can also cause unwanted stray light, which can create noise at the receiving end, reducing the signal-to-noise ratio of the sensed signal and causing blurring of the image. SUMMARY

[0010] Some embodiments of the present disclosure relate to stationary solid-state LIDAR systems, in which there is no rotating column or galvanometer mirror. Embodiments can capture images of a scene with high resolution and low power consumption, and with improved accuracy, reliability, size, integration, and appearance compared to currently available rotating LIDAR systems.

[0011] A light ranging device is disclosed, comprising: a light transmission module comprising a transmitter layer, the transmitter layer comprising a plurality of light emitters; a light sensing module comprising a sensor layer, the sensor layer comprising a plurality of pixels, wherein each pixel of the plurality of pixels senses light from a different light emitter of the plurality of light emitters; an emitter trigger circuit coupled to the plurality of light emitters and configured to activate only a subset of light emitters at a time; and a sensor array readout circuit coupled to the plurality of pixels and configured to synchronize the readout of each pixel within the plurality of pixels contemporaneously with the triggering of a corresponding light emitter, such that each light emitter of a plurality of separate light emitters can be activated and each pixel of the plurality of pixels can be read out over one emission cycle.

[0012] A light ranging device is disclosed, comprising: a two-dimensional array of light emitters aligned to project light beams into a field external to an optical system according to an illumination pattern, wherein each light beam in the illumination pattern represents a non-overlapping field of view within the field, the two-dimensional array of light emitters comprising a plurality of emitter groups aligned side-by-side, wherein each emitter group comprises a subset of emitters in the two-dimensional array of light emitters and is independently operable to emit light from its subset of emitters; a plurality of pixels operable to detect photons emitted from the two-dimensional array of light emitters that are reflected from a surface within the field, wherein each pixel of the plurality of pixels is aligned to sense light from a corresponding light emitter of the plurality of light emitters; an emitter array drive circuit coupled to the plurality of emitter groups, the emitter array drive circuit configured to activate one emitter group of the plurality of emitter groups at a time according to a trigger sequence, wherein each emitter group of the plurality of emitter groups is activated during one emission cycle; and a sensor array readout circuit coupled to the plurality of pixels and configured to synchronize the readout of each pixel within the plurality of pixels corresponding to emitters in the activated emitter group contemporaneously with the triggering of each emitter group, such that each light emitter of a plurality of separate light emitters can be activated and each pixel of the plurality of pixels can be read out over one emission cycle.

[0013] A light ranging device is disclosed, comprising: a light transmission module, comprising: an image space telecentric object transmitter optics; a semiconductor transmitter array comprising a two-dimensional array of light emitters aligned to project light beams through the object transmitter optics into a field outside the optical system according to an illumination pattern, wherein each light beam in the illumination pattern represents a non-overlapping field of view within the field, the two-dimensional array of light emitters comprising a plurality of emitter subsets, wherein each emitter subset comprises a plurality of emitters and is independently operable from other emitter subsets to emit light from its plurality of emitters; and a transmitter array drive circuit coupled to the plurality of emitter subsets, the transmitter array drive circuit configured to activate one of the plurality of emitter subsets at a time according to a firing sequence, wherein each of the plurality of emitter subsets is activated during one emission period; and a light sensing module disposed adjacent to the light transmission module, the light sensing module comprising: an image space telecentric object imaging optics; a sensor layer comprising an array of pixels operable to detect photons emitted from the two-dimensional array of light emitters received through the object imaging optics after reflection from a surface within the field, wherein each pixel comprises an array of single photon avalanche diodes (SPADs) and is paired with a corresponding light emitter in the two-dimensional array of light emitters; a light filter disposed between the object imaging optics and the sensor layer, wherein the light filter allows a narrow band of wavelengths of light to pass through the light filter while blocking light outside the narrow band from reaching the plurality of pixels, the narrow band comprising an operating wavelength of the transmitter array; and a sensor array readout circuit coupled to the array of pixels and configured to synchronize readout of individual pixels within the array simultaneously with firing of emitter subsets; wherein the light ranging device is operable to perform a plurality of emission periods, wherein the transmitter array drive circuit and sensor array read circuit operate to activate each emitter in the two-dimensional array of light emitters and read out each pixel in the array for each emission period.

[0014] According to some embodiments, a solid-state electronically scanned LIDAR system can include a scanning focal plane transmitting element and a scanning focal plane receiving element whose operations are synchronized such that a firing sequence of an array of emitters in the transmitting element corresponds to a capture sequence of an array of photosensors in the receiving element. The transmitting element and the receiving element can be coupled with image space telecentric bulk optics that respectively collimate fields of view of the transmitter and the receiver in object space.

[0015] During operation, the array of emitters can sequentially fire one or more light emitters to the scene and the reflected light can be received by a respective set of one or more photosensors through an aperture layer located in front of the photosensors. Each light emitter can correspond to an aperture in the aperture layer and each aperture can correspond to a photosensor in the receiving element, such that each light emitter corresponds to a specific photosensor in the receiving element. The aperture can mitigate exposure of stray light on adjacent photosensors and narrow the field of view range of the photosensor to a single point in the scene. By synchronously firing and capturing sequentially, a solid-state scanning LIDAR system can effectively capture an image by illuminating at a given point in time an amount of light from a set of emitters that can be effectively detected by a corresponding set of photosensors, thereby minimizing over-illumination of the scene and concentrating energy in a way that optimally utilizes the power available to the system. Furthermore, the electronically scanning LIDAR system in embodiments herein can also utilize micro-optics to further improve the efficiency of capturing images of the scene. The micro-optics can improve the brightness and intensity of the light emitted from the emitting element and minimize cross-talk between the sensor pixels of the receiving element of the electronically scanning LIDAR system.

[0016] A solid-state scanning LIDAR system according to some embodiments of the present disclosure can include a scanning focal plane array for the receiving element and a one-dimensional scanning mirror of a micro-electro-mechanical system (MEMS) coupled to the emitting element. In some embodiments, the emitter element can be a one-dimensional array of emitters oriented perpendicular to the scanning axis of the MEMS mirror and in some other embodiments, the emitter element can be a single emitter with another optical element to produce a laser line coupled with the MEMS mirror or multiple emitters behind multiple diffractive optical elements to achieve electronic scanning.

[0017] In some embodiments, a solid-state optical system includes a light transmission module including an emitter layer having an array of individual light emitters, a light sensing module including a sensor layer having an array of photosensors, an emitter array firing circuit coupled to the array of light emitters and configured to activate only a subset of the light emitters at a time, and a sensor array readout circuit coupled to the array of photosensors and configured to synchronize the readout of individual photosensors within the array with the firing of the corresponding light emitters. Each light emitter in the array of light emitters can be paired with a corresponding photosensor in the light sensing module.

[0018] In some further embodiments, a solid-state optical system for performing distance measurements includes a light-emission system including a bulk transmitter optic and an illumination source including a two-dimensional array of light emitters arranged and aligned according to an illumination pattern to project discrete beams of light through the bulk transmitter optic into a field in front of the optical system. The solid-state optical system further includes a light-detection system including a bulk receiver optic, an aperture layer including a plurality of apertures, and a photosensor layer including a two-dimensional array of photosensors configured to detect photons emitted from the illumination source and reflected from a surface within the field of view after passing through the bulk receiver optic. The aperture layer and the photosensor layer can be arranged to form a plurality of sensing channels arranged in a sensing pattern corresponding to the illumination pattern, and wherein each sensing channel of the plurality of sensing channels corresponds to an emitter of the emitter array and includes an aperture from the aperture layer and a photosensor from the photosensor layer. The solid-state optical system further includes an emitter array trigger circuit coupled to the two-dimensional array of light emitters and configured to activate only a subset of the light emitters at a time, and a sensor array readout circuit coupled to the two-dimensional array of photosensors and configured to synchronize the readout of each photosensor within the array with the triggering of the corresponding light emitter so that each light emitter of the array of light emitters can be activated and each photosensor of the array of photosensors can be read out through one emission cycle.

[0019] In some embodiments, a solid-state optical system for performing distance measurements includes a light emitting system comprising a body transmitter optics and an illumination source comprising a two-dimensional array of light emitters aligned to project discrete beams of light through the body transmitter optics into a field outside the optical system according to an illumination pattern, wherein each discrete beam in the illumination pattern represents a non-overlapping field of view within the field. The solid-state optical system also includes a light detection system configured to detect photons emitted from the illumination source and reflected from surfaces within the field. The light detection system includes a body receiver optics, an aperture layer comprising multiple apertures, and a photodetector layer comprising a two-dimensional array of photodetectors. The aperture layer and the photodetector layer are arranged to form a plurality of sensing channels having a sensing pattern in the field that substantially matches the illumination pattern of the light emitter array in size and geometry over a distance from the system. Each of the plurality of sensing channels corresponds to an emitter in the emitter array and includes an aperture from the aperture layer and a photodetector from the photodetector layer. The solid-state optical system also includes an emitter array triggering circuit coupled to an array of light emitters and configured to perform multiple image capture periods, wherein, for each image capture period, the emitter array triggering circuit sequentially triggers a subset of emitters within the emitter array according to a triggering order until an illumination pattern is generated, and a sensor array readout circuit coupled to an array of photoelectric sensors and configured to synchronize the readout of each light emitter within the array with the triggering of the corresponding photoelectric sensor within the light emitter array.

[0020] In some embodiments, a solid-state optical system for performing distance measurement includes: a first illumination source comprising a first two-dimensional array of light emitters aligned to project discrete light beams into a field outside the optical system according to a first illumination pattern; a second illumination source comprising a second two-dimensional array of light emitters aligned to project discrete light beams into the field according to a second illumination pattern, the second illumination pattern having the same size and geometry as the first illumination pattern; and a light detection module comprising a photodetector array configured to detect photons emitted from the first and second illumination sources and reflected from surfaces within the field, wherein each photodetector in the photodetector array has a field of view overlapping with the field of view of one emitter in the first light emitter array and one emitter in the second light emitter array. The first and second light emitter arrays and the photodetector array can operate synchronously such that when one or more light emitters are activated, the corresponding one or more photodetectors are read out.

[0021] In some other embodiments, a solid-state optical system for performing distance measurement includes: a first light emitting module including a first body-mounted transmitter optics and a first illumination source, the first illumination source including a first two-dimensional array of light emitters aligned to project discrete light beams through the first body-mounted transmitter optics into a field outside the optical system according to a first illumination pattern; and a second light emitting module including a second body-mounted transmitter optics and a second illumination source, the second illumination source including a second two-dimensional array of light emitters aligned to project discrete light beams through the second body-mounted transmitter optics into the field according to a second illumination pattern. The dimensions and geometry are identical to the first illumination pattern; and the light detection module includes a body receiver optics, an aperture layer comprising multiple apertures, and a photodetector layer. The photodetector layer includes a photodetector array configured to detect photons emitted from the first and second illumination sources and reflected from surfaces within the field through the body receiver optics. The aperture layer and photodetector layer are arranged to form a two-dimensional array of sensing channels. Each sensing channel includes an aperture from the aperture layer and a photodetector from the photodetector layer and has a field of view overlapping with the field of view of one emitter in the first emitter array and one emitter in the second emitter array. The first and second light emitter arrays and the photodetector array can operate synchronously such that when one or more light emitters are activated, a corresponding photodetector is read.

[0022] In some embodiments, a solid-state optical system for performing distance measurement includes a light detection system comprising a body receiver optics, an aperture layer including a plurality of apertures, and a photodetector layer including a two-dimensional array of photodetectors, wherein the aperture layer and the photodetector layer are arranged to form a plurality of sensing channels having a sensing pattern, wherein each of the plurality of sensing channels defines a discrete, non-overlapping field of view beyond a threshold distance in a field of view in front of the light detection system and includes an aperture from the aperture layer and a photodetector from the photodetector layer. The solid-state optical system also includes a light emitting system comprising a first body transmitter optics, a first two-dimensional array of light emitters aligned to project discrete beams of light through the first body transmitter optics into the field according to a first illumination beam, a second body transmitter optics, and a second two-dimensional array of light emitters aligned to project discrete beams of light through the second body transmitter optics into the field according to a second illumination pattern having the same size and geometry as the first illumination pattern, wherein the first and second illumination patterns are aligned such that a discrete beam of light from the first illumination pattern and a discrete beam of light from the second illumination pattern fall within the field of view of each of a plurality of sensing channels. The solid-state optical system also includes an emitter array scanning circuit coupled to first and second light emitter arrays and configured to perform multiple image capture periods, wherein, for each image capture period, the emitter array scanning circuit sequentially triggers a subset of emitters in the first emitter array, then triggers a subset of emitters in the second emitter array, until first and second illumination patterns are generated, and a sensor array scanning circuit coupled to a photoelectric sensor array and configured to synchronize the readout of each photoelectric sensor in the array with the triggering of the corresponding emitter in the first and second light emitter arrays.

[0023] In some embodiments, an optical system for performing distance measurements includes an illumination source having a column of light emitters aligned to project discrete beams of light into a field outside the optical system; a MEMS device configured to tilt along a scanning axis oriented perpendicular to the column of light emitters and reflect radiation from the column into the field to generate a two-dimensional illumination pattern, wherein discrete beams of light from the column of light emitters are repeated multiple times to form multiple non-overlapping columns within the pattern; and a light detection system configured to detect photons emitted from the illumination source and reflected from surfaces within the field, the light detection system including a photodetector layer comprising a two-dimensional photodetector array having a sensing pattern in the field substantially matching in size and geometry the two-dimensional illumination pattern created by the MEMS device within a distance range from the system. The optical system also includes circuitry coupled to the MEMS device and the array of light emitters and configured to perform multiple image capture periods, wherein for each image capture period, the array of light emitters is sequentially triggered as the MEMS device tilts along its axis until the illumination pattern is generated, and a sensor array scanning circuitry coupled to the array of photoelectric sensors and configured to synchronize the readout of each photoelectric sensor within the array with the triggering of the corresponding emitter in the array of light emitters.

[0024] In some other embodiments, an optical system for performing distance measurement includes: a light emitting system having a body transmitter optics and an illumination source, the illumination source including a column of light emitters aligned to project discrete beams of light through the body transmitter optics into a field outside the optical system; a MEMS device disposed between the body transmitter optics and the illumination source, the MEMS device being configured to tilt along a scan axis oriented perpendicular to the column of light emitters and reflect radiation from the column into a field outside the optical system to generate a two-dimensional illumination pattern, wherein discrete beams of light from the column of light emitters are repeated multiple times to form a plurality of non-overlapping columns within the pattern, to... The optical system includes a photodetector optics system that detects photons emitted from an illumination source and reflected from surfaces within a field. The photodetector system comprises a body receiver optics; an aperture layer including multiple apertures; and a photosensor layer including a two-dimensional photosensor array. The aperture layer and the photosensor layer are arranged to form multiple sensing channels with a sensing pattern in the field, the size and geometry of which substantially match the two-dimensional illumination pattern generated by a MEMS device within a distance range from the system. Each sensing channel corresponds to an emitter in an emitter array and includes an aperture from the aperture layer and a photosensor from the photosensor layer. The optical system also includes circuitry coupled to the MEMS device and the columns of light emitters and configured to perform multiple image capture periods, wherein for each image capture period, the columns of light emitters are sequentially triggered as the MEMS device tilts along its axis until the illumination pattern is generated; and a sensor array scanning circuitry coupled to the array of photosensors and configured to synchronize the readout of each photosensor within the array with the triggering of the corresponding emitter in the light emitter array.

[0025] In some embodiments, an optical system for performing distance measurement includes a light emitting system having a body transmitter optics and an illumination source, the illumination source including a single light emitter aligned to project discrete light beams through the body transmitter optics into a field outside the optical system, an optical element disposed between the body transmitter optics and the illumination source and configured to generate a light spot pattern from the single light emitter, and a MEMS device disposed between the optical element and the illumination source, the MEMS device being configured to tilt along a scanning axis and reflect radiation from the single light emitter into a field outside the optical system to produce a two-dimensional illumination pattern, wherein the light spot pattern is repeated multiple times to form a pattern. The system includes multiple non-overlapping columns within the field, and a light detection system configured to detect photons emitted from an illumination source and reflected from surfaces within the field. This light detection system includes a body receiver optics, an aperture layer comprising multiple apertures, and a photodetector layer comprising a two-dimensional photodetector array. The aperture layer and photodetector layer are arranged to form multiple sensing channels with a sensing pattern in the field, the size and geometry of which substantially match the two-dimensional illumination pattern generated by the MEMS device within a distance from the system. Each of the multiple sensing channels corresponds to a light spot within the two-dimensional illumination pattern and includes an aperture from the aperture layer and a photodetector from the photodetector layer. The optical system also includes circuitry coupled to the MEMS device and a single light emitter and configured to perform multiple image capture periods, wherein for each image capture period, the single light emitter is sequentially triggered as the MEMS device tilts along its axis until the illumination pattern is generated. A sensor array scanning circuitry is also included, coupled to the array of photodetectors and configured to synchronize the readout of each photodetector within the array with the triggering of the single light emitter.

[0026] In some embodiments, an optical system for performing distance measurement includes a two-dimensional array of light emitters aligned to project discrete beams of light into a field outside the optical system according to an illumination pattern, wherein each discrete beam of light in the illumination pattern represents a non-overlapping field of view within the field, and a light detection system including a photodetector layer formed by a two-dimensional array of photodetectors, the two-dimensional array of photodetectors including a first subset of photodetectors positioned to correspond to a first light emitter in the light emitter array such that the field of view of the first light emitter overlaps with at least a portion of the field of view of each light emitter in the first subset of photodetectors, wherein each photodetector in the first subset of photodetectors is configured to receive at least a portion of the light emitted from the first light emitter.

[0027] In some other embodiments, an optical system for performing distance measurement includes a light emitting system configured to emit discrete beams of light into a field. The light emitting system includes a body transmitter optics and a two-dimensional array of light emitters aligned to project discrete beams of light through the body transmitter optics into a field outside the optical system according to an illumination pattern, wherein each discrete beam in the illumination pattern represents a non-overlapping field of view in the field. A light detection system is configured to detect photons emitted from an illumination source and reflected from surfaces within the field. The light detection system includes a body receiver optics and a photodetector layer formed by a two-dimensional array of photodetectors. This layer includes a first subset of photodetectors positioned to correspond to a first light emitter of the array of light emitters, such that the field of view of the first light emitter overlaps with at least a portion of the field of view of each photodetector in the first subset of photodetectors. Each photodetector in the first subset of photodetectors is configured to receive at least a portion of the light emitted from the first light emitter. The optical system also includes a transmitter array triggering circuit coupled to the array of light emitters and configured to perform multiple capture periods, wherein, for each capture period, the transmitter array triggering circuit sequentially triggers a subset of emitters within the transmitter array according to a triggering order until an illumination pattern is generated, and a sensor array readout circuit coupled to an array of photoelectric sensors and configured to synchronize the readout of each light emitter within the array with the triggering of the corresponding photoelectric sensor within the light emitter array.

[0028] In some embodiments, an optical system for performing distance measurement includes a light emitting system configured to emit discrete light beams into a field, the light emitting system including a body transmitter optics and a two-dimensional array of light emitters aligned to project discrete light beams through the body transmitter optics into a field outside the optical system according to an illumination pattern, wherein each discrete light beam in the illumination pattern represents a non-overlapping field of view within the field; and a light detection system configured to detect photons emitted from an illumination source and reflected from surfaces within the field, the light detection system including a body receiver optics and a photodetector layer formed by a two-dimensional array of photodetectors, the array including a first subset of photodetectors positioned to correspond to a first light emitter in the light emitter array such that the field of view of the first light emitter overlaps with at least a portion of the field of view of each photodetector in the first subset of photodetectors, each photodetector in the first subset of photodetectors being configured to receive at least a portion of the light emitted from the first light emitter. The optical system also includes a transmitter array triggering circuit coupled to the array of light emitters and configured to perform multiple capture periods, wherein, for each capture period, the transmitter array triggering circuit sequentially triggers a subset of emitters within the transmitter array according to a triggering order until an illumination pattern is generated, and a sensor array readout circuit coupled to an array of photoelectric sensors and configured to synchronize the readout of each light emitter within the array with the triggering of the corresponding photoelectric sensor within the light emitter array.

[0029] In some embodiments, an optical ranging device includes a semiconductor emitter array comprising a two-dimensional array of light emitters aligned to project discrete beams of light according to an illumination pattern into a field outside an optical system, wherein each discrete beam in the illumination pattern represents a non-overlapping field of view within the field. The two-dimensional array of light emitters includes a plurality of side-by-side aligned emitter groups, wherein each emitter group includes a subset of emitters in the two-dimensional array of light emitters and is independently operable to emit light from its emitter subset, and emitter array driving circuitry coupled to the plurality of emitter groups, the emitter array driving circuitry being configured to activate one of the plurality of emitter groups one at a time according to a triggering sequence, wherein the emitter subset in the activated group is triggered.

[0030] In some other embodiments, an optical ranging device includes an interconnect structure, a semiconductor emitter array coupled to the interconnect structure, the semiconductor emitter array comprising a two-dimensional array of body emitter optics and light emitters aligned to project discrete beams of light according to an illumination pattern through the body emitter optics into a field outside the optical system, wherein each discrete beam in the illumination pattern represents a non-overlapping field of view within the field, the two-dimensional array of light emitters comprising a plurality of side-by-side aligned emitter groups, each emitter group being independently operable to emit light, a plurality of drivers directly mounted on the surface of the semiconductor emitter array and electrically coupled to the light emitter array, each driver being configured to control the activation of a respective emitter group according to a trigger sequence, a heat sink coupled to a surface of the interconnect structure opposite to the surface coupled to the semiconductor emitter array, the heat sink comprising a plurality of fins and configured to dissipate heat generated by the semiconductor emitter array, and a thermoelectric cooler located between the interconnect structure and the heat sink, the thermoelectric cooler being configured to transfer heat from the interconnect structure to the heat sink.

[0031] In some embodiments, an optical ranging device includes an interconnect structure and an array of transmitters coupled to the interconnect structure. The transmitter array includes a two-dimensional array of body transmitter optics and light emitters aligned to project discrete beams of light according to an illumination pattern through the body transmitter optics into a field outside the optical system. Each discrete beam in the illumination pattern represents a non-overlapping field of view within the field. The two-dimensional array of light emitters includes a plurality of side-by-side aligned emitter groups, each emitter group being a semiconductor die on which a subset of light emitters of the light emitter array is constructed. A capacitor bank is mounted on the interconnect structure and connected via a first contact located between the capacitor bank and the light emitter array. An array is electrically coupled to an array of optical emitters. A capacitor bank includes multiple capacitors configured to charge and discharge their stored energy to activate the optical emitter array to project discrete beams. Each capacitor is coupled to a corresponding emitter bank and configured to activate a corresponding subset of optical emitters. Multiple drivers are mounted on an interconnect structure and electrically coupled to the optical emitter array via an array of second contacts located between the multiple drivers and the optical emitter array. Each driver is configured to control the activation of a corresponding subset of optical emitters. An electrical connector is mounted on the interconnect structure and electrically coupled to the multiple drivers. The electrical connector is configured to couple to an external device to allow the external device to control the operation of the optical emission system.

[0032] The nature and advantages of embodiments of this disclosure can be better understood by referring to the following detailed description and accompanying drawings. Attached Figure Description

[0033] Figure 1 This is a block diagram of an exemplary solid-state electronic scanning LIDAR system according to some embodiments of the present disclosure.

[0034] Figure 2A This is a simplified illustration of a transmitter array and sensor array for an exemplary solid-state electronically scanned LIDAR system according to some embodiments of the present disclosure.

[0035] Figures 2B-2D This is a simplified diagram illustrating exemplary trigger sequences for a transmitter array and sensor readout sequences for a sensor array according to some embodiments of the present disclosure.

[0036] Figure 3 These are illustrative examples of the optical transmission and detection operations of an electronically scanned LIDAR system in one embodiment according to some embodiments of the present disclosure.

[0037] Figure 4 This is a simplified illustration of an overlapping field of view for a transmitter array and a sensor array according to some embodiments of the present disclosure.

[0038] Figure 5 This is a simplified diagram showing a detailed side view of an exemplary solid-state electronic scanning LIDAR system according to some embodiments of the present disclosure.

[0039] Figure 6 This is a top-down system view of an exemplary transmitter drive system for a transmitter array in a solid-state electronically scanned LIDAR system according to some embodiments of the present disclosure.

[0040] Figure 7A This is a simplified illustration of an exemplary transmitter array according to some embodiments of the present disclosure, which is paired with a driver and arranged in a group that can be controlled individually.

[0041] Figure 7B This is a simplified illustration of an exemplary transmitter array according to some embodiments of the present disclosure, which is paired with a driver and arranged in columns that can be controlled individually.

[0042] Figure 8A This is a simplified illustration of an exemplary LIDAR system according to some embodiments of the present disclosure, which includes multiple independently operable transmitter arrays having non-overlapping fields of view, each transmitter array having its own set of drivers for emitting light that can be captured by a sensor array.

[0043] Figure 8B It is an overlay of some embodiments of this disclosure. Figure 8A A simplified illustration of a microlens array on a photoelectric sensor.

[0044] Figure 8C According to some embodiments of this disclosure Figure 8B A simplified cross-sectional view of the microlens array in the image, which is located when sensing light from the field. Figure 8A The front of the photoelectric sensor.

[0045] Figure 8D This is a simplified illustration of an exemplary LIDAR system according to some embodiments of the present disclosure, which includes multiple independently operable transmitter arrays with overlapping fields of view, each transmitter array having its own set of drivers for emitting light that can be captured by a sensor array.

[0046] Figure 8E This is a simplified illustration of overlapping fields of view for transmitter arrays and sensor arrays according to some embodiments of this disclosure, relative to... Figure 8D Let's have a discussion.

[0047] Figure 9A This is a simplified illustration of an exemplary optical transmission system including a one-dimensional transmitter array and a MEMS device, according to some embodiments of the present disclosure.

[0048] Figure 9B This is a simplified illustration of an exemplary optical transmission system including a single transmitter and a MEMS device, according to some embodiments of the present disclosure.

[0049] Figure 10 This is a simplified cross-sectional view of an exemplary enhanced light emission system according to some embodiments of the present disclosure.

[0050] Figure 11 This is a simplified diagram of a sensor control system for column-operating an m×n sensor array according to some embodiments of the present disclosure.

[0051] Figure 12 This is a simplified diagram of a sensor control system for row-by-row operation of an m×n sensor array, according to some embodiments of the present disclosure.

[0052] Figure 13A This is a simplified diagram of a control system for operating an m×n sensor array by photoelectric sensors using column and row control circuits according to some embodiments of the present disclosure.

[0053] Figure 13B This is a simplified diagram of a control system for operating an m×n sensor array by photoelectric sensor using a dedicated control circuit for each photoelectric sensor, according to some embodiments of the present disclosure.

[0054] Figure 14 This is a simplified illustration of some embodiments of the present disclosure in which the transmitter array and sensor array have a one-to-one correspondence configuration.

[0055] Figure 15 This is a simplified illustration of some embodiments of the present disclosure in which the transmitter array and sensor array have a one-to-one correspondence but a modified resolution in one dimension.

[0056] Figure 16 This is a simplified illustration of a configuration in which a sensor array has multiple photoelectric sensors, according to some embodiments of the present disclosure.

[0057] Figure 17 This is a cross-sectional view of the construction of an exemplary optical transmission module according to some embodiments of the present disclosure.

[0058] Figure 18 This is a simplified illustration of a solid-state electronic scanning LIDAR system implemented in the external area of ​​a highway vehicle according to some embodiments of the present disclosure.

[0059] Figure 19 This is a simplified illustration of a solid-state electronic scanning LIDAR system implemented on the roof of a highway vehicle according to some embodiments of the present disclosure.

[0060] Figure 20 This is a simplified top-down illustration of an exemplary solid-state electronically scanned LIDAR system according to some embodiments of the present disclosure, which includes more than one set of emission and detection systems to achieve an expanded field of view.

[0061] Figure 21A This is a simplified cross-sectional view of a part of an optical detection system, where there is no crosstalk between channels.

[0062] Figure 21B This is a simplified cross-sectional view of a part of an optical detection system, showing crosstalk between channels.

[0063] Figure 22 This is a simplified cross-sectional view of an exemplary micro-optical receiver channel structure according to some embodiments of the present disclosure.

[0064] Figure 23 This is a simplified cross-sectional view of an exemplary simplified receiver channel according to some embodiments of the present disclosure.

[0065] Figure 24 This is a simplified diagram of an enlarged portion of a sensor array according to some embodiments of the present disclosure.

[0066] Figure 25 This is a simplified diagram of an enlarged portion of a sensor array according to some embodiments of the present disclosure, wherein one or more components are mounted on the back side of a substrate. Detailed Implementation

[0067] Some embodiments of this disclosure relate to stationary solid-state LiDAR systems where there is no rotating column or galvanometer mirror. Embodiments can emit light into a field outside the LiDAR system and capture the emitted light after it has reflected away from objects in the field. The embodiments of this disclosure can then use the captured emitted light to create a three-dimensional image of the field. Compared to currently available rotating LiDAR systems, embodiments of this disclosure can have improved accuracy, reliability, size, integration, and appearance. Additionally, embodiments of this disclosure can use less power to capture images at a given resolution than solid-state flash LiDAR systems.

[0068] A solid-state array electronically scanned LiDAR system according to some embodiments of this disclosure may include an optical transmission module and an optical sensing module. The optical transmission module may include a transmitter layer comprising an array of individual transmitters, and the optical sensing module may include a sensor layer comprising an array of photodetectors. Each transmitter in the transmitter array may be paired with a corresponding sensor (i.e., a photodetector) in the photodetector array. In some embodiments, instead of flashing the entire transmitter group, only a subset of transmitters is activated at a time, and the corresponding subset of photodetectors is read out only at the same time as the transmitters are triggered. Then, different subsets of transmitters are activated at different times, while the corresponding subsets of photodetectors are read out simultaneously, so that all transmitters in the transmitter array can be activated, and all photodetectors in the sensor array can be read out in one transmission cycle.

[0069] As an example, for each emission cycle, the transmitter array of the optical transmission module can activate one column at a time and emit light in a sequential order from left to right. Similarly, the sensor array can be configured to sense (i.e., read out) the emitted light in a corresponding order. For example, the sensor array can be configured to measure light column by column at a time, from left to right, thereby enabling the transmitter and sensor array to operate synchronously. In this way, only those photoelectric sensors corresponding to the activated transmitters are read out to sense the light.

[0070] In some embodiments, the solid-state LIDAR system includes a micro-optical receiver layer formed above a sensor array. The micro-optical receiver layer may include optical elements in combination with the sensor array to form a two-dimensional array of micro-optical receiver channels. Each micro-optical receiver channel may include a photodetector from the sensor array, an aperture from the micro-optical layer configured to limit the field of view of its respective photodetector to match the field of view of a corresponding emitter, and a filter from the micro-optical layer configured to allow incident photons to pass through at wavelengths and passbands that include the operating wavelength of the emitter array. In some embodiments, the micro-optical receiver layer may further include one or more lens layers, additional aperture layers, and / or other optical structures.

[0071] In some cases, the micro-optical receiver channel structure has a columnar arrangement with a housing including absorptive and / or reflective sidewalls and / or a focusing funnel. The micro-optical receiver channel maximizes the collection of incident light through its aperture, collimates the light to make it perpendicular to the filter, and minimizes crosstalk with adjacent micro-optical receiver channels due to mixing of inputs from adjacent apertures, which will be discussed in detail below. In various cases, the light or other radiation of the entire emitter or photodetector array is modified according to the large imaging optics of this disclosure. The micro-optical structure can be part of an array and can modify the light in different ways for different emitters and / or photodetectors in the array. In some embodiments, one or more micro-optical elements are present for each individual array element (photodetector and / or emitter).

[0072] In some cases, the optical transmission module may include a micro-optical transmitter channel array to enhance the light output from the transmitter array. During operation, light output from the transmitter array (e.g., a laser pulse) passes through the micro-optical transmitter channel array and enters the main transmitter optics with a large numerical aperture to better capture the light from the micro-optical transmitter channel array. The light then exits the main transmitter optics and illuminates multiple spots at a distance. The micro-optical transmitter channel array can increase the brightness of the beam emitted from the main transmitter optics to provide enhanced spot illumination while improving the spatial resolution of the measured image, as will be discussed in further detail herein.

[0073] The body imaging optics defined herein can be one or more optical surfaces, possibly including multiple lens elements, having a transparent aperture greater than one millimeter, and positioned to receive light projected from a micro-optical transmitter / receiver layer or to focus received light onto a micro-optical transmitter / receiver layer. Body imaging optics that project light received from an optical transmitter (such as a micro-optical transmitter layer) are sometimes referred to herein as body transmitter optics or output body imaging optics. Body optical layers that focus light received from the field onto an optical detector, such as micro-optical receiver layers, are sometimes referred to herein as body receiver optics or input large imaging optics. Input image space telecentric body imaging optics allow the system to uniformly measure narrowband light within a wide field of view (FOV).

[0074] According to some embodiments of this disclosure, the light sensing module collects light from a wide field of view (FOV) within a limited wavelength range. For example, the sensing module can capture an image and detect light spanning at least 10 degrees of FOV. In some embodiments, the sensing module can capture an image and detect light spanning at least 20 degrees, at least 30 degrees, and in some embodiments at least 45 degrees or at least 90 degrees of FOV. Furthermore, the sensing module can detect light with narrow wavelengths of approximately 10 nanometers or less. This differs from conventional cameras, which detect light spanning the entire visible spectrum or three different wide RGB color bands, each band being 100 nanometers or wider. In some specific embodiments, the light sensing module can detect light with wavelengths of approximately 5 nanometers or less. In some embodiments, the sensing module can detect detection light with wavelengths less than 5 nanometers spanning approximately 32 degrees of FOV. The FOV can be vertical and / or horizontal, or any other angle in between.

[0075] It should be understood that the electronic scanning LIDAR system according to embodiments of the present disclosure can be configured and operated in various ways, as will be discussed in further detail herein.

[0076] I. Electronic Scanning LiDAR System

[0077] A better understanding of the solid-state electronic scanning LIDAR system according to some embodiments of the present disclosure can be determined with reference to FIG1.

[0078] Figure 1 A block diagram of an exemplary solid-state electronic scanning LiDAR system 100 according to some embodiments of the present disclosure is shown. The solid-state electronic scanning LiDAR system 100 may include an optical ranging device 102 and a user interface 150. The optical ranging device 102 may include a ranging system controller 104, an optical transmission (Tx) module 106, and an optical sensing (Rx) module 108. Ranging data may be generated by the optical ranging device 102 by transmitting one or more light pulses 110 from the optical transmission module 106 to objects in the field of view surrounding the optical ranging device 102. The reflected portion 112 of the transmitted light is then detected by the optical sensing module 108 after a delay time. Based on the delay time, the distance to the reflecting surface can be determined. Other ranging methods, such as continuous wave, optical demodulation, Doppler, etc., may also be used.

[0079] The optical transmission module 106 includes an emitter array 114 and a Tx optical system 116. The emitter array can be a one-dimensional or two-dimensional array of emitters, and the Tx optical system can form an optical emission system 138 together with the emitter array 114. The Tx optical system 116 may include a telecentric body emitter optics 144 in image space. In some embodiments, the Tx optical system 116 may further include one or more Tx optical components 146, such as aperture layers, collimating lens layers, and filters, which can be combined with the emitter array 114 to form a micro-optical emitter channel array, wherein each micro-optical emitter channel can increase the brightness of the beam emitted from the body emitter optics and / or be used for beam shaping, beam control, etc., as will be further discussed herein. The emitter array 114 or the individual emitters can be laser sources, such as vertical-cavity surface-emitting lasers (VCSELs), laser diodes, etc. The Tx module 106 may also include an optional processor 118 and memory 120, although in some embodiments these computing resources may be incorporated into the ranging system controller 104. In some embodiments, pulse decoding techniques, such as Barker code, may be used. In these cases, memory 120 may store pulse codes indicating when light should be transmitted. In some embodiments, the pulse codes are stored as integer sequences stored in memory.

[0080] The light sensing module 108 may include a sensor array 126, which may be, for example, a two-dimensional photoelectric sensor array. Each photoelectric sensor (sometimes referred to herein simply as a “sensor” or a “pixel”) may include a collection of photodetectors, such as a single-photon avalanche diode, or the sensor may be a single-photon detector (e.g., an APD). The light sensing module 108 includes a receiver optical sensing system 128, which, when combined with the sensor array 126, can form a light detection system 136. In some embodiments, the receiver optical sensing system 128 may include a receiver body receiver optics 140 and receiver optical components 142, such as an aperture layer, a lens layer, and a filter, which may be combined with the sensor array 126 to form a micro-optical receiver channel array, wherein each micro-optical receiver channel measures light in an image pixel corresponding to a different field of view of the surrounding field in which the light ranging device 102 is located. The following is in conjunction with... Figure 22 and 23 The discussion can be combined with further details of various examples of the micro-optical receiver channel in the optical ranging device 102 according to this disclosure.

[0081] Each photodetector (e.g., a set of SPADs) in sensor array 126 may correspond to a specific transmitter in transmitter array 114, for example, as a result of the geometric configuration of light sensing module 108 and Tx module 106. As described herein, optical ranging device 102 may be an electronically scanned LiDAR device that can capture an image of a scene by activating only a subset of transmitters at a time and by reading out only the corresponding subset of photodetectors while triggering the transmitters. Different subsets of transmitters may be activated at different times, with corresponding subsets of photodetectors read out simultaneously, so that eventually all transmitters can be activated and all photodetectors in the sensor array can be read out in one emission cycle. As an example, the transmitter array may emit light by activating one column at a time in each emission cycle in a left-to-right order, while the sensor array may be configured to read out the corresponding photodetectors in the corresponding order. Therefore, embodiments of this disclosure may include one or more components to synchronize the emission and sensing of light.

[0082] In some embodiments, the light detection system 136 may include a sensor controller 125 coupled to the sensor array 126 and configured to control the operation of the sensor array 126. The sensor controller 125 may be any suitable component or group of components capable of selecting one or more photoelectric sensors to sense light, such as an ASIC, microcontroller, FPGA, or any other suitable processor coupled to selection circuitry (e.g., a multiplexer). Similarly, the light emission system 138 may include a transmitter controller 115 coupled to the transmitter array 114 and configured to control the operation of the sensor array 126. The transmitter controller 115 may also be any suitable processor mentioned above for the sensor controller 125 and includes one or more drive components for operating the transmitter array 114.

[0083] In some embodiments, sensor controller 125 and transmitter controller 115 are synchronized such that the light emission sequence in transmitter array 114 is synchronized with the sequence of readout photoelectric sensors in sensor array 126. As an example, both sensor controller 125 and transmitter controller 115 can be coupled to clock 117, allowing both controllers to operate based on the same timing scheme. Clock 117 may be an electronic component that generates a specific signal that oscillates between high and low states at a specific rate to coordinate the operation of digital circuitry. Alternatively, sensor controller 125 and transmitter controller 115 may include their own clock circuitry for coordinating their own operations. In such embodiments, sensor controller 125 and transmitter controller 115 may be communicatively coupled together via communication line 119, allowing sensor controller 125 to synchronize its clock with transmitter controller 115. In this way, sensor controller 125 and transmitter controller 115 can operate sensor array 126 and transmitter array 114 synchronously, respectively, to achieve image capture.

[0084] In some further embodiments, instead of or additionally to the sensor controller 125 and the transmitter controller 115, the ranging system controller 104 may be configured to synchronize the operation of the light sensing module 108 and the light transmission module 106 so that the light emission sequence of the transmitter array 114 is synchronized with the sensing light sequence of the sensor array 126. For example, the ranging system controller 104 may instruct the transmitter array 114 of the light transmission module 106 to emit light one column at a time in each emission cycle and in a left-to-right order, and accordingly instruct the sensor array 126 in the light sensing module 108 to sense light one column at a time in the same order. In such embodiments, the ranging system controller 104 may have its own clock signal, based on which its ranging commands are sent to the light sensing module 108 and the light transmission module 106. It should be understood that other forms of sequences for light detection are contemplated herein, and such sequences are not limiting, as will be discussed further herein.

[0085] In some embodiments, the sensor array 126 of the light sensing module 108 is fabricated as part of a monolithic device on a single substrate (using, for example, CMOS technology), the single substrate including a photodetector array, a processor 122, and a memory 124 for signal processing of measurement light from the individual photodetectors (or groups of photodetectors) in the array. The monolithic structure including the sensor array 126, processor 122, and memory 124 can be fabricated as a dedicated ASIC. In another embodiment, the sensor array 126 can be fabricated as a stack of two or more monolithic electronic devices (“semiconductor dies”) incorporated into a single light sensing module 108, with electrical signals passing between them. In this embodiment, the top array of photodetectors can be fabricated to maximize light sensing efficiency or minimize noise, while other dies are optimized for lower power, high-speed digital processing.

[0086] In some embodiments, the optical component 142 may also be part of a monolithic structure including a sensor array 126, a processor 122, and a memory 124. For example, the aperture layer, lens layer, and filter layer of the optical component 142 may be stacked on a semiconductor substrate and bonded to the semiconductor substrate with epoxy resin, the semiconductor substrate having multiple ASICs fabricated at the wafer level before or after dicing. For example, the filter layer may be a thin wafer placed against the photosensor layer and then bonded to the photosensor layer to combine the filter layer and the photosensor layer, thereby making the optical layer part of a monolithic structure; the collimating lens layer may be injection molded on the filter layer; and the aperture layer may be formed by stacking an opaque substrate on a transparent substrate or by coating the transparent substrate with an opaque film. Alternatively, the photosensor layer may be fabricated and diced, and the filter layer, collimating lens layer, and aperture layer may also be fabricated and diced. Then, each diced photosensor layer and optical layer may be combined to form a monolithic structure, wherein each monolithic structure includes a photosensor layer, a filter layer, a collimating lens layer, and an aperture layer. By incorporating these layers into the ASIC, the ASIC and the incorporated layers can form a monolithic structure. The wafer can then be diced into devices, each of which can be paired with a corresponding body receiver optics 140 to form a photosensing module 108. In other embodiments, one or more components of the photosensing module 108 may be external to the monolithic structure. For example, the porous layer may be implemented as a separate metal sheet with pinholes.

[0087] As described above, processor 122 (e.g., digital signal processor (DSP), microcontroller, field-programmable array (FPGA), etc.) and memory 124 (e.g., SRAM) can perform signal processing on the raw histograms of the individual photon detectors (or detector groups) in the array. As an example of signal processing, for each photon detector or photon detector group, memory 124 can accumulate the counts of detected photons over consecutive time bins, and these time bins can be combined to reconstruct the time series of the reflected light pulses (i.e., the photon counts versus time). This time series of the aggregated photon counts is referred to herein as an intensity histogram (or histogram only). Processor 122 can implement matched filtering and peak detection processing to timely identify the returned signal. Furthermore, processor 122 can implement specific signal processing techniques, such as multi-profile matched filtering, to help recover the photon time series that is less sensitive to pulse shape distortion that may be attributable to SPAD saturation and quenching. In some embodiments, all or part of this filtering can be performed by processor 122.

[0088] In some embodiments, the photon time series output from processor 122 is sent to ranging system controller 104 for further processing. For example, the data may be encoded by one or more encoders of ranging system controller 104 and then sent as data packets to user interface 150. Ranging system controller 104 can be implemented in various ways, including, for example, by using a programmable logic device such as an FPGA, as part of an ASIC, using a processor 130 with memory 132, and some combinations thereof. Ranging system controller 104 can control light sensing module 108 by sending commands including starting and stopping light detection and adjusting photodetector parameters. Similarly, ranging system controller 104 can control optical transmission module 106 by sending commands or relay commands, including, for example, controls to start and stop light emission and controls that can adjust other light emitter parameters (e.g., pulse codes). In some embodiments, ranging system controller 104 has one or more wired interfaces or connectors for exchanging data with light sensing module 108 and optical transmission module 106. In other embodiments, the ranging system controller 104 communicates with the light sensing module 108 and the light transmission module 106 via wireless interconnection, such as an optical communication link.

[0089] The solid-state electronic scanning LIDAR system 100 can interact with a user interface 150, which can be any suitable user interface that enables a user to interact with a computer system, such as a monitor, touchscreen, keyboard, mouse, and / or trackpad, for interacting with a laptop, tablet, and / or handheld computer system containing a CPU and memory. The user interface 150 can be local to the object on which the solid-state electronic scanning LIDAR system 100 is installed, but it can also be a remotely operated system. For example, commands and data sent to / from the solid-state electronic scanning LIDAR system 100 can be routed via cellular networks (LTE, etc.), personal area networks (Bluetooth, Zigbee, etc.), local area networks (WiFi, IR, etc.), or wide area networks such as the Internet.

[0090] The hardware and software user interface 150 can present imager data from the device to the user, but can also allow the user to control the solid-state electronic scanning LIDAR system 100 with one or more commands. Example commands may include commands to activate or deactivate the imager system, specify the photodetector exposure level, bias, sampling duration, and other operating parameters (e.g., emission pulse mode and signal processing), and specify light emitter parameters (such as brightness). Furthermore, commands may allow the user to select a method for displaying the results. The user interface can display imager system results, which may include, for example, a single-frame snapshot image, a continuously updated video image, and / or a display of other light measurements of some or all pixels.

[0091] In some embodiments, such as when the LIDAR system 100 is used for vehicle navigation, the user interface 150 may be part of a vehicle control unit that receives output from or communicates with the optical ranging device 102 and / or the user interface 150 via a network such as one of the wired or wireless networks described above. The vehicle control unit may modify one or more parameters associated with vehicle control based on the received LIDAR data. For example, in a fully autonomous vehicle, the LIDAR system 100 may provide real-time 3D images of the vehicle's surroundings to aid navigation in conjunction with GPS and other data. In other cases, the LIDAR system 100 may be used as part of an advanced driver assistance system (ADAS) or as part of a safety system that may provide 3D image data to any number of different systems, such as adaptive cruise control, automatic parking, driver drowsiness monitoring, blind spot monitoring, collision avoidance systems, etc. When the user interface 150 is implemented as part of a vehicle control unit, it may provide alerts to the driver or track the proximity of objects.

[0092] As described above, some embodiments of this disclosure relate to a solid-state LIDAR system, which includes an electronic scanning transmission element and an electronic scanning receiving element. Figure 2A This is a simplified illustration of a transmitter array 210 and a sensor array 220 for an exemplary solid-state electronically scanned LiDAR system 200 according to some embodiments of the present disclosure. The transmitter array 210 can be configured as a two-dimensional m×n array of transmitters 212 having m columns and n rows. In some embodiments, the sensor array 220 can be configured to correspond to the transmitter array 210 such that each photodetector 222 is mapped to a corresponding transmitter 212 in the transmitter array 210. Thus, the sensor array 220 can be configured as a corresponding two-dimensional m×n array of photodetectors 222. In some embodiments, the transmitter array 210 and sensor array 220 are typically large arrays, comprising more elements (i.e., more transmitters and more photodetectors) than typically used in rotating LiDAR systems. The size of the sensor array 220, i.e., the overall physical size (and therefore the corresponding transmitter array 210 for illuminating the field of view), together with the spacing of the photodetectors within the sensor array 220, determines the field of view and the resolution of the image that can be captured by the sensor array 220. Larger array sizes typically result in a larger field of view, while smaller spacing typically results in higher resolution captured images. In some embodiments, both the transmitter array 210 and the sensor array 220 are formed from a single semiconductor die, while in other embodiments, one or both of the transmitter array 210 and the sensor array 220 may be formed from multiple chips mounted on the same substrate, as described herein. Figure 6 As stated above.

[0093] Figures 2B-2D This is a simplified diagram illustrating the trigger sequence of the transmitter array 210 and the sensor readout sequence of the sensor array 220 according to some embodiments of the present disclosure. Figure 2B As shown, the first stage of the image capture sequence can be initiated by triggering the transmitter column 214(1) of the transmitter array 210 and simultaneously reading out the sensor column 224(1) of the sensor array 220. During this first stage, light pulses emitted from each individual transmitter in column 214(1) are emitted into the field. The emitted light can then be reflected from one or more objects in the field and captured by a corresponding subset of photoelectric sensors within the sensor column 224(1) of the sensor array 220. Next, in the second stage of the sequence, transmitters from the second column 214(2) of the transmitter array can be activated to emit light pulses that can be read out by the sensors in column 224(2) of the sensor array, such as... Figure 2CAs shown. The sequential triggering of the transmitter columns and the simultaneous readout of the photoelectric sensors in the corresponding columns continue until the last column 214(m) of the transmitter is activated, and simultaneously the last column 224(m) of the photoelectric sensors is read, as... Figure 2D As shown. When a complete cycle is completed (m stages of the image capture sequence), each column of the transmitter array 210 is activated, and each column of the sensor array 220 is read out to detect photons emitted from the corresponding column of the transmitter array 210. This cycle can then be repeated continuously while the LIDAR system 200 is running.

[0094] Although Figures 2B to 2D An image capture sequence is shown in which the transmitter advances one column per stage, but embodiments of this disclosure are not limited to any particular sequence. For example, in some embodiments, the following sequence may be used: for a first stage, the first column of transmitter array 210 is triggered; for stage 2, (m / 2 + 1) columns are triggered; for stage 3, column 2 is triggered; for stage 4, (M / 2 + 2) columns are triggered, and so on, until the m-th stage, the m-th column is triggered. Such embodiments may be advantageous in minimizing crosstalk within the sensor array because no adjacent sensor columns are read out in consecutive stages. As another example, two or more adjacent transmitter columns may be triggered simultaneously, with corresponding two or more adjacent sensor columns read out simultaneously. As an example where four columns are triggered and read out simultaneously, columns 1-4 of transmitter array 210 may be triggered in the first stage of the image capture sequence, columns 5-8 may be triggered in the second stage, and so on. These examples are merely some of many different possible trigger and readout sequences, and other trigger and readout sequences are possible in other embodiments.

[0095] As an example, instead of column-based operation—where a column of transmitters is triggered to simultaneously read the corresponding column of photoelectric sensors—the embodiment can operate row-based—where a row of transmitters is triggered to simultaneously read the corresponding row of photoelectric sensors. In some further embodiments, the LIDAR system can be transmitter-operated, where individual or groups of transmitters can be triggered to simultaneously read the corresponding photoelectric sensors or groups of photoelectric sensors. In such embodiments, each transmitter can be individually addressed with suitable transmitter-specific drive circuitry, allowing the embodiment to be operated to trigger and... Figure 13A and 13B The shown groupings are arbitrary transmitter groups that match the data. It should be understood that, according to some embodiments of this disclosure, any particular triggering arrangement of the transmitter may have a corresponding readout arrangement of the photoelectric sensor.

[0096] Figure 3This is an illustrative example of the optical transmission and detection operation of an electronically scanned LiDAR system in scheme 300 according to some embodiments of this disclosure. Specifically, Figure 3 A solid-state electronic scanning LIDAR system 200 is shown, which collects three-dimensional distance data around the system's volume or scene. Figure 3 This is an idealized diagram highlighting the relationship between the transmitter and the sensor; therefore, other components are not shown.

[0097] like Figure 2A The electronically scanned LiDAR system 200, as discussed, includes an emitter array 210 and a sensor array 220. The emitter array 210 may be an array of light emitters, such as a vertical-cavity surface-emitting laser (VCSEL) array, including columns of emitters 302 and 304. The sensor array 220 may be an array of photoelectric sensors including sensor columns 306 and 308. The photoelectric sensors may be pixelated photoelectric sensors, each employing a set of discrete photodetectors, such as single-photon avalanche diodes (SPADs). However, various embodiments may deploy other types of photoelectric sensors.

[0098] Each transmitter can be spaced apart from its neighboring transmitters by a distance and can be configured to transmit light pulses from its neighboring transmitters to different fields of view, thereby illuminating the corresponding field of view associated only with that transmitter. For example, a row of transmitters 302 emits illumination beams 310 (each formed by one or more light pulses) into region 312 of the field of view, and thus reflects them away from the trees 313 in that field. Similarly, a row of transmitters 304 emits illumination beams 314 into region 316 of the field of view. It should be understood that, in Figure 3 In the illustrated embodiment, the transmitter array 210 scans its columns in a left-to-right order. Therefore, Figure 3 The diagram shows the first instance of column 302 being triggered and the last instance of column 304 being triggered. Other columns can be moved sequentially from left to right between columns 302 and 304. Although Figure 3 An embodiment in which transmitter array 210 and sensor array 220 operate in columns and in sequence is shown, but the embodiment is not limited to such a configuration. In other embodiments, transmitter and sensor arrays 210 and 220 may operate in a non-sequential column order to minimize crosstalk, or in a sequential or non-sequential row order to minimize crosstalk, or transmit and receive light in any other suitable order, as above and will be discussed further herein. It should also be understood that, for ease of discussion, the columns of transmitters 302 and 304 and the columns of sensors 306 and 308 may represent only a portion of the many columns of transmitter array 210 and sensor array 220, respectively. Thus, although Figure 3For ease of illustration, only transmitters and sensors for 21 different points are shown, but it will be understood that many other implementations are possible. That is, denser point sampling can be achieved by having a denser array of transmitters and a correspondingly denser array of photoelectric sensors.

[0099] Each field of view illuminated by the emitter can be considered as a pixel or spot of light in the corresponding 3D image generated from the ranging data. Therefore, each emitter can be unique with respect to other emitters and does not overlap with other emitters, resulting in a one-to-one mapping between emitter groups and non-overlapping field of view groups. In some embodiments, both the emitter array 210 and the sensor array 220 are solid-state devices that can be very small and very close to each other. For example, according to embodiments of the invention, the size of the emitter or sensor array can range from a few millimeters to a few centimeters. Thus, the size of the two arrays and their separation distance (which can be approximately 1 cm) are negligible compared to the distance to objects in the scene. When this arrangement of the emitter and sensor arrays is paired with respective body optics in the sensor array that can be calibrated separately by the light emitted by the emitter array and focused onto the reflected light, the field of view of the sensor array and the emitter array can be very similar beyond a threshold distance, so that each emitter and the corresponding sensor observes substantially the same spot of light in the field of view. Reference Figure 4 This will help you better understand the concept.

[0100] Figure 4 This is a simplified illustration of the overlapping field of view for transmitter array 210 and sensor array 220 according to some embodiments of this disclosure. Each transmitter in transmitter array 210 can emit in a cone shape 402. Figure 4 The light pulse shown is collimated by the main transmitter optics 404 and output as emitted light 406 into the field. The emitted light 406 can then be reflected away from one or more objects in the field and propagate back to the sensor array 220 as reflected light 412. This reflected light 412 first propagates through the main receiver optics 410, which focuses the reflected light 412 downwards into a cone-shaped pulse 408, which then illuminates the corresponding photoelectric sensor in the sensor array 220. (See reference...) Figure 4 It is understood that the distance between the transmitter and receiver optics 404 and 410 can be between 1-3 cm, which is relatively small compared to the distance to the scene. Therefore, as the scene moves further away, the field of view of the transmitter array and the field of view of the sensor array overlap more and more. For example, as... Figure 4As shown, the overlapping regions 414, 416, and 418 of the field of view of the transmitter array 210 and the sensor array 220 increase with increasing distance from the scene. Therefore, at distances close to the scene, such as the end of an object in the field of view, the field of view of the transmitter array 210 can substantially overlap with that of the sensor array 220. Thus, even if the body receiver and the transmitter optics are separated by one or more centimeters, each corresponding transmitter and sensor can observe substantially the same points in the scene. That is, each illumination beam projected from the body transmitter optics 404 into the field of view in front of the system can have substantially the same size and geometry as the field of view of the corresponding photoelectric sensor (or the micro-optical receiver channel of the corresponding photoelectric sensor) at a certain distance from the system. In some embodiments, the transmitter array 210 can selectively project illumination beams into the field of view in front of the system 200 according to an illumination pattern that substantially matches the field of view of the input channel in size and geometry within the distance range of the system 200. By having substantially overlapping fields of view between the transmitter array and the sensor array, the solid-state electronically scanned LIDAR system 200 can achieve a high signal-to-noise ratio (SNR).

[0101] In some embodiments, the transmitter array and sensor array have matching geometries, and the body optics of the transmitter array are substantially identical to those of the sensor array. In other embodiments, the size and body optics of the sensor array 220 may differ from those of the transmitter array 210; however, they can be selected to ensure that corresponding columns of the transmitter array 210 and sensor array 220 have significantly identical fields of view. For example, the size of the sensor array 220 may be larger than that of the transmitter array 210. This means that the body receiver optics 410 of the sensor array 220 should be different from the body transmitter optics 404 of the transmitter array 210, and the two body optics should be carefully selected to ensure that the fields of view of corresponding columns in the two arrays are significantly identical. For example, a similar body optics with lens elements twice the size of those of the transmitter array 210 can be used. The focal length of the resulting body receiver optics will be twice the focal length of the body transmitter optics. In this case, the height and width of the sensor array 220 should be twice that of the transmitter array 210, and its receiving aperture diameter should be twice that of the transmitting diameter, thereby ensuring that the viewing angle range of each photoelectric sensor and transmitter is matched.

[0102] To ensure that corresponding columns of the transmitter array 210 and sensor array 220 see the same field of view, careful alignment of the LIDAR system 200 can be performed in the field previously, for example, by the manufacturer. Design features of some embodiments of this disclosure (e.g., a single semiconductor die or multi-chip module for the transmitter array and a single semiconductor die for the multi-chip module for the sensor array) allow the manufacturer to perform alignment only once, thereby simplifying the manufacturing and post-manufacturing maintenance of the LIDAR system 200. During optical alignment, the field of view of each pixel and each transmitter is measured to ensure they are identical. Alignment involves taking into account lens characteristics such as aberrations, distortions, and focal length, as well as adjusting the position and orientation of the lens elements relative to external components.

[0103] Because the field of view of the transmitter overlaps with the field of view of its corresponding sensor, the photoelectric sensor can ideally detect reflected illumination beams originating from its corresponding transmitter, ideally without crosstalk, that is, no reflected light from other illumination beams is detected. For example, refer to... Figure 3 A column of emitters 302 emits illumination beams 310 into region 312 of the field of view, and some of the illumination beams are reflected from object 313 (i.e., a tree). Ideally, the reflection of light 318 is detected only by the column of photoelectric sensors 306. Therefore, the column of emitters 302 and the column of photoelectric sensors 306 share the same field of view. Similarly, the column of emitters 304 and the column of photoelectric sensors 308 can also share the same field of view. For example, during the last iteration of the emission cycle, a column of emitters 304 emits illumination beams 314 into region 316 of the field of view, and some of the illumination beams are reflected from an object, i.e., a car 315 parked next to object 313. In one cycle, Figure 3 The solid-state electronic scanning LiDAR system 200 can capture and generate images representing portions of a scene including tree 313 and car 315. Additional loops can further capture other areas of the scene, especially when the system 200 is moving (e.g., when the system 200 is mounted on a car), which will be referenced herein. Figure 18 Further discussion is needed. Although the corresponding transmitters and sensors are... Figure 3 The transmitters are shown in the same relative positions in their respective arrays, but depending on the design of the optics used in the system, any transmitter can be paired with any sensor.

[0104] During ranging measurements, reflected light from different fields of view around a volume distributed around the LIDAR system is collected and processed by various sensors to obtain distance information for any object in each corresponding field of view. As described above, time-of-flight techniques can be used, in which a light emitter emits precisely timed pulses, and the reflection of the pulses is detected by the corresponding sensors after a certain period of time. The distance to the reflecting surface is then calculated using the time elapsed between emission and detection, along with the known speed of light. In some embodiments, the sensors can obtain additional information to determine properties of the reflecting surface other than distance. For example, the Doppler shift of the pulse can be measured by the sensors and used to calculate the relative velocity between the sensors and the reflecting surface. Pulse intensity can be used to estimate target reflectivity, and pulse shape can be used to determine whether the target is a hard or diffuse material.

[0105] According to some embodiments, the LIDAR system 200 can transmit multiple pulses of light. In some embodiments, each coded pulse has an embedded positive pulse code formed by the light intensity. The system can determine the temporal position and / or amplitude of the light pulses in the presence of background light by creating intensity histograms of reflected light detected in different time slots. For each time slot, the system adds a weighted value to the intensity histogram, which depends on the intensity of the detected light. The weighted value can be positive or negative and has different amplitudes.

[0106] By selecting different combinations of positive pulse codes and applying different weights, the system can detect positive and negative codes suitable for standard digital signal processing algorithms. This method provides a high signal-to-noise ratio while maintaining low uncertainty in the measurement timing of the reflected light pulse.

[0107] II. Construction and Configuration of Solid-State Electron Scanning LiDAR Systems

[0108] Figure 5 This is a simplified diagram illustrating a detailed side view of an exemplary solid-state electronic scanning LiDAR system 500 according to some embodiments of the present disclosure. The solid-state electronic scanning LiDAR system 500 may include a light detection system 501 and a light emission system 503. The light emission system 503 provides active illumination of at least a portion of the field in which the system 500 is located using narrowband light 505. The light detection system 501 detects the narrowband light emitted from the light emission system 503, which has been reflected as reflected light 506 by objects within the field.

[0109] A. Optical detection system

[0110] The optical detection system 501 can represent the above reference. Figure 1The discussed light detection system 136. Light detection system 501 may include an optical sensing system and a sensor array. The optical sensing system may include a body receiver optics, an aperture layer, a collimating lens layer, and a filter layer; and the sensor array may include a photodetector array, wherein each photodetector may include one or more photodetectors for measuring light. According to some embodiments, these components operate together to receive light from a field. For example, light detection system 501 may include a body receiver optics 502 and a micro-optical receiver (Rx) layer 504. During operation, light rays 506 enter the body receiver optics 502 from multiple directions and are focused by the body receiver optics 502 to form a light cone 508. The micro-optical receiver layer 504 is positioned such that an aperture 510 coincides with the focal plane of the body receiver optics 502. In some embodiments, the micro-optical receiver layer 504 may be a one-dimensional or two-dimensional array of micro-optical receiver channels 512, wherein each micro-optical receiver channel 512 is formed by a respective aperture 510, collimating lens 514, and photodetector 516, which are positioned along the same axis in the direction of light transmission, for example, horizontally from left to right. Figure 5 As shown. Furthermore, each micro-optical receiver channel 512 can be configured in various ways to mitigate interference from stray light from between photoelectric sensors, which will be discussed further herein. During operation, each micro-optical receiver channel 512 measures the light information of different pixels (i.e., positions within the field).

[0111] At the focal point of the main receiver optics 502, light 506 is focused and passes through the aperture 510 in the aperture layer 511, entering the corresponding collimating lens 514. Each collimating lens 514 collimates the received light so that the light rays all enter the filter at approximately the same angle, for example, parallel to each other. The aperture and focal length of the main receiver optics 502 determine the cone angle of the corresponding light ray focused at the aperture 510. The aperture size and focal length of the collimating lens 514 determine the degree of collimation allowed, which in turn determines how narrow the bandpass can be achieved in the filter 518. During the operation of the light detection system 500, the aperture layer can perform various functions. For example, (1) aperture 510 can constrain the pixel field of view, thus exhibiting strict spatial selectivity despite large spacing on the photoelectric sensor plane; (2) aperture 510 can constrain the field of view to be similar or equal in size to the emitter field of view to effectively utilize the emitter light; (3) aperture can provide a small point light source at the focal plane of the collimating lens to achieve strict collimation of light before passing through the filter, wherein better collimation results in a tighter band that can pass through the filter; and (4) the aperture region surrounding the aperture layer of each aperture can block stray light. In some embodiments, collimating lens 514 is not included, and the passband of the bandpass filter is narrow.

[0112] Filter 518 blocks unwanted wavelengths of light. Interference-based filters tend to exhibit strong angle dependence in performance. For example, a 1-nanometer broadband pass filter with a center wavelength (CWL) of 900 nm at a zero-degree incident angle may have a CWL of 898 nm at a fifteen-degree incident angle. Imaging systems typically use filters tens of nanometers wide to accommodate this effect, resulting in a CWL shift much smaller than the bandpass width. However, the use of micro-optical layer 504 allows all light to enter filter 518 at approximately the same incident angle, thereby minimizing the CWL shift and allowing the use of very compact filters (e.g., less than 10 nm wide). Photodetector 516 generates a current or voltage in response to incident photons. In some embodiments, filter 518 is uniformly distributed throughout the array of micro-optical receiver channels 512, such that each individual micro-optical receiver channel 512 in the array receives light within the same wavelength range.

[0113] In some embodiments, the photodetector 516 is located on the opposite side of the collimating lens 514, such that light 506 first passes through the collimating lens 514 and the filter 518 before being exposed to the photodetector 516. Each photodetector 516 may be a miniature array of multiple photodetectors, such as multiple single-photon avalanche detectors (SPADs). Miniature SPAD arrays can be fabricated on a single monolithic chip, simplifying manufacturing. In some alternative embodiments, each photodetector 516 may be a single photodetector, such as a standard photodiode, an avalanche photodiode, a resonant cavity photodiode, or another type of photodetector.

[0114] B. Optical emission system

[0115] The light emitting system 503 may include a body transmitter optics 520 and a light emitting layer 522 formed by a one-dimensional or two-dimensional array of light emitters 524. Each light emitter 524 may be configured to generate a discrete beam of narrowband light. In some embodiments, the light emitting layer 522 is configured to selectively project the discrete beam through the body transmitter optics 520 according to an illumination pattern that spans a range of distances from the light emitting system 503 in size and geometry matching the field of view of the receiver channel in the micro-optical receiver layer 504. The light emitters 524 may be any suitable light emitting device, such as a vertical-cavity surface-emitting laser (VCSEL) integrated on one or more monolithic chips, or any other type of laser diode. The light emitters 524 may generate narrowband light cones 526 that are guided by the body transmitter optics 520, which may collimate the light cones 526 and then output the collimated light as an emitted ray 505 to a distant target within the field of view. In some embodiments, the body transmitter optics 520 is spatially telecentric.

[0116] from Figure 5 As can be clearly seen in the illustrations of parallel rays 505 and 506, each micro-optical receiver channel 512 has a non-overlapping field of view exceeding the threshold distance. For example... Figure 5 As shown, each micro-optical receiver channel 512 includes an aperture from multiple apertures, a lens from multiple lenses, and a photodetector from multiple photodetectors, wherein the aperture of each channel defines a discrete field of view for the pixels in the channel, the field of view not overlapping with the field of view of other micro-optical receiver channels beyond a threshold distance. Thus, each micro-optical receiver channel receives reflected light corresponding to discrete positions within the field that are not measured by any other micro-optical receiver channel in the micro-optical receiver layer 504.

[0117] In additional and alternative embodiments, the light rays 505 from the light cone 526 are first focused onto the mid-plane of space by a micro-optical transmitter layer (not shown) before being directed by the main transmitter optics 520 to a distant target to enhance the brightness and intensity of the light emitted from the light emitting system 503. In such embodiments, the light emitting system 503 and the light detection system 501 are configured such that each micro-optical transmitter channel (not shown) is paired with a corresponding micro-optical receiver layer 504, and their field centers are aligned to overlap at a distance from the sensor, or their principal rays are parallelized. In further additional and alternative embodiments, the far-field beam emitted by the light emitting system 503 has a size and divergence angle similar to the far-field field of view of each micro-optical receiver layer 504. Details of the light emitting system 503 with micro-optical transmitter layers for enhancing the brightness and intensity of the output light will be discussed in detail below.

[0118] 1. Drive system for electronic scanning LIDAR system

[0119] In some embodiments, the transmitter array may be operated by a drive system including various capacitors and control chips for operating the transmitter array. Figure 6 This is a top-down system view of an exemplary transmitter driving system 600 for a transmitter array 601 in a solid-state electronically scanned LiDAR system according to some embodiments of the present disclosure. The transmitter array 601 may include a plurality of light emitters 602 arranged in an m×n array to generate an illumination pattern. The transmitter array 601 may represent, for example, the above-described... Figures 2A to 2D The emitter array 210 discussed can be paired in a LIDAR system with an opto-sensor array such as one of the opto-sensor arrays described herein, which can represent sensor array 220 and include a sensing pattern having a geometry that matches the illumination pattern. The emitter array 601 can be divided into multiple individually driven emitter groups 604a-f, which are precisely aligned to form an m×n array.

[0120] In some embodiments, the transmitter array 601, comprising each transmitter group 604a-604f, may be formed on a single semiconductor die (e.g., a large single-chip VCSEL array). Each group may be driven by a separate driver circuit 612, 614, such that k driver circuits exist for a transmitter array having k groups. Each driver circuit 612, 614 is coupled to its corresponding group and can simultaneously excite all individual transmitters 602 in its group. The drivers 612, 614 may be activated according to a predetermined sequence by control circuitry as discussed herein, such that each group is triggered once or multiple times during an image capture period, and one or more columns (or other arrangements of individual photoelectric sensors) corresponding to the transmitters in a given triggered group are read out (e.g., according to the above regarding...). Figures 2B-2D (One or more similar scanning sequences as discussed) until the entire photoelectric sensor array is read out. This embodiment saves power compared to a flash LIDAR system that activates all transmitters at once.

[0121] For example, such as Figure 6 As shown, group 604a can be driven by its respective drivers 612 and 614 to emit light. When driven during the emission cycle, all four columns of group 604a can emit light simultaneously, while only one column of photosensors corresponding to one of the four emitters is read out. As an example, the column of the photosensor being read out can correspond to the leftmost column, for example, column 1 in group 604a (when the four columns in each group 604a-f are interpreted as columns 1-4 in left-to-right order). Therefore, during the entire emission cycle, columns 1-4 in group 604a can be driven while reading out the photosensor corresponding to column 1 of group 604a during the first image capture period, then columns 1-4 in group 604b can be driven while reading out the photosensor corresponding to column 1 of group 604b during the second image capture period, and so on, for groups 604c-f, until group 604a is activated again to emit columns 1-4, at which point the photosensor corresponding to column 2 of group 604a can be read out during the seventh image capture period. The sequence can continue until all photodetectors have been read out. In this example, each transmitter group can be activated four times for a complete transmission cycle, once per column of photodetectors for each corresponding image capture period.

[0122] In some alternative embodiments, the emission cycle can drive all four columns in each group while simultaneously capturing data on all four corresponding columns of the photodetectors in the receiver array. For example, group 604a can emit light, while the corresponding columns 1 to 4 of the corresponding group of photodetectors can all be enabled and read out during the first image capture before moving to the next group to repeat the sequence. The advantage of this approach is that laser energy is not wasted by triggering lasers that do not enable their corresponding photodetectors to detect reflected light.

[0123] In some embodiments, each group 604a-604f can be configured as a separate semiconductor die separated by a separation region 606. The separation region 606 can be any suitable electrical separator to isolate adjacent emitter groups from each other, such as an air gap. By dividing the emitter array 601 into different groups with separation regions 606, each group can be electrically isolated from each other and can form discrete circuits that are individually addressable to emit light during operation of the electronically scanned LiDAR system. In some embodiments, emitter groups 604a-f can be mounted on a support structure 605, which can be any suitable component configured to provide structural support for the emitter groups 604a-f. As an example, the support structure 605 can be a substantially flat component to ensure that the emitter groups 604a-f are also substantially flat and located in the same plane. Additionally, the support structure 605 can be a material with high thermal conductivity so that the heat generated by the activation of the emitter 602 can be quickly dissipated to avoid overheating and damage. In some embodiments, the support structure 605 is a ceramic substrate.

[0124] To generate light, current is driven through emitters 602 in emitter array 601. Therefore, emitter groups 604a-f can be coupled to capacitor group 608, which includes a plurality of capacitors configured to release current through emitter array 601. Each group 604a-f may include a respective array of contacts or vias 610a-f for coupling with capacitor group 608. Contact arrays 610a-f may be part of a semiconductor die on which the respective emitter group 604a-f is constructed. In some embodiments, contact arrays 610a-f are located between capacitor group 608 and light emitter 602 within their respective emitter groups 604a-f. One or more capacitors in capacitor group 608 can be charged before activating one or more emitters in emitter array 601, such that during activation of one or more emitters in emitter array 601, one or more charged capacitors can be discharged to drive current through one or more emitters to emit narrowband light. In some embodiments, the capacitors in capacitor bank 608 can be coupled to a power source (not shown) to charge the capacitors. The power source can be coupled to capacitor bank 608 via an array of electrical connections 618, where each electrical connection is a via coupled to a trace (not shown) wired to the power source. The electrical connections and traces can be part of or formed on an interconnect structure 622 (e.g., a printed circuit board (PCB)), on which capacitor bank 608 and emitter array 601 are mounted. Each pair of electrical connections can be associated with the positive and negative terminals of a corresponding capacitor in capacitor bank 608. Traces, capacitors, emitters, and drivers can be positioned to minimize loop inductance in the circuit discharge path, thereby minimizing the rise time of the drive current in the circuit.

[0125] In some embodiments, the drive system 600 may be implemented as a multi-chip module, wherein electrical inputs and outputs to and from the system (e.g., timing signals to drivers 612 and 614) may be sent to and from the drive system 600 via electrical connector 616 (e.g., a board-to-board connector). In this case, electrical connector 616 may be coupled to drivers 612 and 614 to enable the transmission of communication signals between them. Drivers 612 and / or 614 may be semiconductor devices that manage the current through the transmitter array 601, such as field-effect transistors (FETs), FPGAs, ASICs, etc. Thus, drivers 612 and 614 may control the sequence of light emission from the transmitter array 601 or cause a processing system (not shown) to emit light through connector 616. For example, drivers 612 and 614 may activate the transmitter array 601 sequentially from left to right and vice versa via the transmitter group. Therefore, in one emission cycle, drivers 612 and 614 can operate the transmitter array 601 by activating transmitter 602 in transmitter group 604a in a first time instance, transmitter 602 in transmitter group 604b in a second time instance, and so on, until the last transmitter group 604f is activated in the last time instance, wherein the light emission from the first to the last time instance together forms an emission cycle. In some embodiments, drivers 612 and 614 are coupled together via an electrical connection 624, which may be a trace plated on an interconnect structure 622. In this way, drivers 612 and 614 can communicate with each other to control the operation of transmitter array 601.

[0126] like Figure 6 As shown, each group 604a-f may include a corresponding contact array 611a-f for coupling with the driver 612. Like contact arrays 610a-f, contact arrays 611a-f may be part of a semiconductor die on which the corresponding emitter group 604a-f is constructed. In some embodiments, contact arrays 611a-f are located between the driver 612 and the light emitter 602, within their respective emitter groups 604a-f. It should be understood that in Figure 6 The reference numerals for contact arrays 611b-611e are not shown in the figures to avoid overlapping reference numerals. Furthermore, each driver 612 can be coupled to a corresponding electrical connector group 620, which, similar to electrical connector 618, can be part of or formed on interconnect structure 622, on which drivers 612 and 614 are mounted. Electrical connections 620 can couple drivers 612 to a power source or any other electrical component (not shown) on interconnect structure 622.

[0127] 2. Configuration of the transmitter array in the optical emission system

[0128] although Figure 6 The transmitter array 601 is shown divided into six distinct groups 604a-f, but the embodiments are not limited to this configuration, and other embodiments may have more or fewer than six groups and more or fewer transmitters in each group. That is, the transmitter array 601 may be formed from a single large group of transmitters, or the transmitter array 601 may be divided into 16, 32, 64, 128, or any other number of groups, each having any number of transmitter columns, without departing from the spirit and scope of this disclosure.

[0129] For example, Figure 7A This is a simplified illustration of an exemplary transmitter array 700 according to some embodiments of the present disclosure, paired with drivers 702 and arranged in individually controllable groups. The transmitter array 700 may be an m×n array of light emitters divided into k individually controllable emitter groups, where k is less than n. For example, each group may be configured to have four columns of light emitters, such that the number of groups is one-quarter of the number of columns n. Each driver 702 may activate the transmitter array 700 by group and in any order (such as from left to right, from right to left, every other group, etc.). An advantage of this embodiment is the simplification of the drive circuitry, thereby simplifying design and manufacturability. Furthermore, compared to a flash LIDAR system that uses a single drive circuit to power the entire transmitter array, dividing the transmitter array into multiple groups with independent drive circuits allows each channel in the system to operate with significantly lower current because each driver circuit drives fewer emitters. This can allow for a more powerful drive to the emitters in each channel, or it can employ different types of drive circuits that may not immediately provide the peak current required for the entire array to emit. Furthermore, the driving circuit can be separated from the light emitter, allowing for modular manufacturing using commercially available components.

[0130] In another example, Figure 7B This is a simplified illustration of an exemplary transmitter array 701 according to some embodiments of the present disclosure, which is paired with a driver 704 and arranged in individually controllable columns. The transmitter array 701 may be an m×n array of optical transmitters divided into n individually controllable transmitter groups (e.g., such as...). Figure 7BThe twenty-four groups shown are arranged such that each group has a single column of transmitters. In this embodiment, each driver 704 corresponds to a group of transmitters, and the group driver 704 can be combined with a multiplexer 706 to activate individual groups within the transmitter array in any order (e.g., from left to right, from right to left, every other group, etc.). That is, the multiplexer 706 can select the column to be activated by the driver 704. The advantage of such an embodiment is that dividing the transmitter array 701 into separate columns allows for interlaced modulation of the columns to minimize crosstalk from stray light emitted into adjacent sensor arrays and / or improve scan speed. For example, the driver 704 can activate all even groups (i.e., columns) in a first instance and then activate all odd groups in a second instance, thus completing one cycle in two iterations. Because emission occurs every other column, only those columns of the photosensors corresponding to the activated columns need to be operated to measure the emitted light, thereby minimizing the chance of crosstalk between columns of photosensors. The concept of interlaced scanning column modulation can be extended to other interlaced scanning schemes, such as transmitting once every third or fourth transmitter column, which can minimize crosstalk between the next two or three adjacent columns of the photoelectric sensor.

[0131] like Figure 7B As shown, driver 704 (and Figure 7A The driver 702 shown can be tightly integrated with the light emitter array, for example, by mounting the driver 704 directly onto the chip substrate containing the light emitter. This configuration can save space and help minimize the size of the overall design. However, in some other embodiments, the driver 704 can be positioned away from the chip substrate containing the light emitter to provide more space for additional light emitters, thereby increasing image resolution. In some embodiments, the driver 704 (and driver 702) can be implemented as part of a separate driver chip ASIC, while in other embodiments, the driver 704 can be a discrete component mounted on a ceramic or other die.

[0132] As understood through the embodiments herein, the number of pixels triggered by a single driver determines the amount of current required by the driver. For example, Figure 7A Each group in the transmitter array 700 comprises four times the number of optical transmitters in each group of the optical transmitter array 701 in Figure 7B. Therefore, Figure 7A Each driver 702 in the configuration needs to provide at least the following current: Figure 7BThe current required by the driver 704 is four times that of the standard driver. The difficulties associated with requiring a large current output from the driver can sometimes outweigh the benefits of simple manufacturing and design, which are often associated with having only one driver to activate a large number of transmitters. However, some embodiments can take advantage of the benefits offered by the two transmitter array configurations in 7A and 7B, which is achieved by using multiple transmitter arrays with multiple drive systems, as discussed herein. Figure 8A and 8B The discussion continues. Furthermore, photoelectric sensor arrays, where each photoelectric sensor typically uses a number of SPADs to increase dynamic range and include guard rings and other features in HVCMOS processes, are inherently limited by their resolution, posing a challenge to SPAD miniaturization. Consequently, some embodiments of this disclosure employ alternative methods to increase sensor resolution. Specifically, they employ a field-selective approach using a transmitter array instead of a receiver array. For example, some embodiments of this disclosure use a VCSEL array as the transmitter array. VCSEL arrays are not subject to the same size limitations as SPAD-based sensor arrays and, for example, can be used in some embodiments regarding… Figures 8A-8C The described approach aims to achieve a higher spatial resolution than the detector's original pixel resolution.

[0133] Figure 8A This is a simplified illustration of an exemplary LIDAR system 800 according to some embodiments of the present disclosure, comprising a plurality of independently operable transmitter arrays 802a-802d having non-overlapping field of view, each field of view having its own set of drivers 804a-d to emit light that can be captured by a sensor array 806. Each transmitter array 802a-802d may include m×n transmitter arrays, as described above in various embodiments, wherein the array relates to different corresponding field of view in the far field. For example, as... Figure 8A As shown, the first column and first row of transmitter array 802a are transmitters 812; the first column and first row of transmitter array 802b are transmitters 814; the first column and first row of transmitter array 802c are transmitters 816; and the first column and first row of transmitter array 802d are transmitters 818. Each of transmitters 812, 814, 816, and 818 can be aligned to project onto different discrete fields of view beyond a threshold distance.

[0134] Sensor array 806 may include an array of photoelectric sensors 808 arranged in the same m×n configuration as each emitter array and configured to capture light emitted from emitter arrays 802a-d. The aperture layer of the receiver channel array of sensor array 806 may define four distinct, non-overlapping fields of view for each photoelectric sensor 808, wherein each distinct field of view is aligned with a corresponding field of view from one emitter in each emitter array 802a-d. For example, photoelectric sensor 810 may have four distinct fields of view defined by the aperture layer, wherein each aperture (shown as a circle) is aligned to have the same field of view as one of: emitter 812 in emitter array 802a, emitter 814 in emitter array 802b, emitter 816 in emitter array 802c, and emitter 818 in emitter array 802d. Therefore, when emitters 812, 814, 816, and 818 are synchronized to emit light at their respective times to illuminate their respective locations (e.g., pixels) in the field, photodetector 810 will capture the emitted light through its respective aperture after it has been reflected by an object in the field. This concept can be understood with reference to an enlarged perspective view 801 of photodetector 810, where the fields of view (shown as circles) of each emitter 812, 814, 816, and 818 are superimposed on the field of view region (shown as a square) of photodetector 810. As shown, the field of view of each emitter 812, 814, 816, and 818 overlaps with a portion of the field of view of photodetector 810, allowing photodetector 810 to capture its emitted light after it has been reflected by an object in the field. In some embodiments, emitter arrays 802a-802d emit light separately and in sequence. For example, transmitter array 802a may first perform a transmission cycle (e.g., each group from left to right), then transmitter array 802b may next perform a transmission cycle, and so on, until transmitter array 802d has performed a transmission cycle. Once each transmitter array has completed a transmission cycle, the sequence order can be repeated to capture another image of the field.

[0135] like Figure 8AAs shown, by using multiple transmitter arrays 802a-d, the total number of transmitters capturing high-resolution images via sensor array 806 can be divided by the number of transmitter arrays, which is four in this case, resulting in fewer transmitters in the arrays and greater distances between them. Consequently, the power load required to illuminate the field with sensor array 806 to capture high-resolution images can be divided (e.g., divided by four) among the transmitter arrays 802a-d. Therefore, compared to a system with only one transmitter array, each transmitter array driver 804a-d only needs to provide one-quarter of the power (i.e., current) while still being able to capture high-resolution images of the scene. Alternatively, due to the reduced number of light emitters per driver, each driver can provide more current to the light emitters, resulting in the emitters outputting more light, thereby improving the image capture capability of the LIDAR system 800. During operation, each transmitter array 802a-d can perform one emission cycle, as described herein. Figures 6-7B The discussion proceeds in a sequential order, such that once all the transmitter arrays have completed their emission cycles, a complete scan of the scene is performed.

[0136] In some embodiments, each emitter array 802a-d and sensor array 806 is positioned behind its respective body imaging optics. When arranged in conjunction with the body imaging optics, each emitter array 802a-d can form a light emitting system, and the sensor array 806 can form a light sensing system. In some embodiments, the light emitting system can be arranged symmetrically around the light sensing system and can be positioned as close as possible to the light sensing system to minimize parallax. For example, as... Figure 8A As shown, the light emitter system (represented by emitter arrays 802a-d) can be symmetrically arranged above, below, and on both sides of the light sensing system (represented by sensor array 806).

[0137] although Figure 8A Only four light emitting systems arranged symmetrically are shown, but the embodiment is not limited to this configuration, and other embodiments may have more or fewer light emitting systems and be arranged asymmetrically. For example, some solid-state electronically scanned LIDAR systems may have three light emitting systems located above or below and on both sides of the light sensing system, or two light emitting systems located above or below and on the left or right side of the light sensing system. In embodiments with only two light emitting systems, a single sensor array may be configured to capture light from two emitter arrays. Therefore, the emitter array density of each emitter array may be half that of a LIDAR system with only one light emitting system. In such embodiments, each photodetector in the sensor array may correspond to only two light emitters, one in each light emitting array.

[0138] In some embodiments, an aperture layer and a microlens array may be implemented in front of the photodetector to enable an overlapping field of view between the photodetector and multiple light emitters. Each aperture may be aligned with a corresponding microlens, and both the aperture and the aligned microlens may correspond to a specific light emitter among the multiple light emitters. For example Figure 8B This is a simplified illustration of a microlens array 820 superimposed on a single photodetector 810 according to some embodiments of the present disclosure. Because a single photodetector 810 is shared across four different fields of view in a time-division multiplexing manner, this method allows more per-pixel processing logic to be adapted to each photodetector, since the spacing between photodetectors is four times the spacing between the emitter and the field-of-view detector. In this embodiment, it is feasible to embed the TDC, SRAM, and DSP directly into each photodetector 810 so that each photodetector can be read out individually. The field of view of each microlens in the microlens array 820 can be defined by a corresponding aperture in an aperture layer. In this example, the microlens array 820 includes four microlenses 822, 824, 826, and 828, which are aligned with their associated apertures, each aperture corresponding to and aligned to have the same field of view as the respective light emitters from each emitter array 802a-802d. For example, microlens 822 can correspond to and be aligned with emitter 812 to have the same field of view as emitter 812, and the same applies to microlens 824 and emitter 812, microlens 826 and emitter 816, and microlens 828 and emitter 818. The spacing of the microlens array 820 can be finer than the spacing of the sensor array 808, so that the microlens array 820 can be mounted on a single photoelectric sensor. For example, as Figure 8B As shown, the spacing of the microlens array 820 can be half the spacing of the photoelectric sensor array 808. Therefore, compared to a sensor array without such a microlens array, the microlens array enables the sensor array to capture a larger field of view (i.e., capture images at higher resolution).

[0139] Figure 8C This is a simplified cross-sectional view of a microlens array 820 positioned in front of a photodetector 810 when sensing light from a field, according to some embodiments of the present disclosure. In some embodiments, the microlens array 820 may be positioned between the body imaging optics 830 and the photodetector 810, such that light received from the field passes through the microlens array 820 before being exposed to the photodetector 810. Figure 8CAs shown, light 836 can be reflected light emitted from emitter 816, and light 838 can be reflected light emitted from emitter 818 at another time instance. After focusing light 836 onto a point at aperture layer 834 located along the focal plane of the body imaging optics 830, light 836 can pass through the body optics 830 and be exposed on microlens 826 to define a discrete field of view for photoelectric sensor 810 and reduce stray light, as described above regarding Figure 5 As discussed, once light 836 passes through the aperture and microlens 826 in the aperture layer 834, light 836 can be collimated and passed through auxiliary optics 832, which can be configured to redirect and refocus light 836 onto photodetector 810. In some embodiments, microlens array 820 and auxiliary optics 832 are implemented within a receiver channel for photodetector 810, such that microlenses 822, 824, 826, and 828 are positioned within sidewall 840, which forms a tunnel around the optical path to mitigate crosstalk between photodetectors. Auxiliary optics 832 can focus light passing through each microlens 822, 824, 826, and 828 onto photodetector 810. In some embodiments, photodetector 810 is formed by a plurality of SPADS, wherein a subset of the plurality of SPADS is positioned to receive light from the respective microlenses 822, 824, 826, and 828. In an alternative embodiment, the entire plurality of SPADS is positioned to receive light from each microlens 822, 824, 826 and 828, such that the entire plurality of SPADS is read out four times, once for each application to detect light passing through each microlens 822, 824, 826 and 828.

[0140] To further mitigate crosstalk, the MEMS device can be implemented above the aperture layer and along the light propagation path of each microlens to prevent crosstalk between microlenses. For example, an array of MEMS shutters (not shown) can be implemented between aperture 834 and the body imaging optics 830, with each shutter located above the corresponding aperture. The array of MEMS shutters can be operated such that light can pass through the MEMS shutters when the corresponding emitter emits light, and prevent light from passing through when the corresponding emitter does not emit light. By implementing such a MEMS shutter array, the signal-to-noise ratio of the photoelectric sensor 810 can be improved.

[0141] Instead of having a non-overlapping field of view for each transmitter array and increasing the resolution of the detector array, as described above relative to Figures 8A-8CAs discussed, in some embodiments of this disclosure, the fields of view of the transmitter arrays can overlap each other, thereby providing increased brightness and redundancy at each location within the field of view. Thus, if one transmitter in a transmitter array fails, or even if the entire transmitter array fails (e.g., due to damage from flying debris), the solid-state electronically scanned LIDAR system can still project emitted light into the field of view of a photoelectric sensor associated with the damaged transmitter, which has one or more other transmitters aligned with that field of view. Therefore, the resulting system can be more robust and reliable. Examples of this embodiment are shown in... Figure 8D As shown in the image.

[0142] Figure 8D This is a simplified illustration of an exemplary LiDAR system 850 according to some embodiments of the present disclosure, comprising a plurality of independently operable transmitter arrays 852a-b having overlapping fields of view, each transmitter array having its own set of drivers 854a-b for emitting light that can be captured by a sensor array 856. The transmitter arrays 852a, 852b and their respective drivers 854a, 854b may be arranged according to the groups discussed above with respect to Figures 6 and 7A, or as discussed above... Figure 7B The discussed arrangement is in independently addressable columns, or can be arranged in any arbitrary subset of the drive circuitry of the entire array. Each transmitter array 852a, 852b may include an m×n (equal-sized) transmitter array, as described above in the various embodiments, wherein the array relates to the same field of view in the far field. For example, as Figure 8D As shown, the first column and first row of transmitter array 852a contains transmitter 862, and the first column and first row of transmitter array 852b contains transmitter 864. Each transmitter 862 and 864 can be aligned to project onto the same different discrete field of view beyond a threshold distance.

[0143] Sensor array 856 may include an array of photoelectric sensors 858 arranged in the same m×n configuration as each emitter array 852a, 852b, and may be configured to capture light emitted from emitter arrays 852a, 852b. Specifically, each photoelectric sensor may have a one-to-one correspondence with a corresponding emitter in each emitter array 852a, 852b. For example, photoelectric sensor 860 may be associated with and aligned with emitter 862 in emitter array 852a and emitter 864 in emitter array 852b to have the same field of view. Therefore, when emitters 862 and 864 are triggered to emit light to illuminate the same location (e.g., discrete points) in the field, photoelectric sensor 860 will capture the light emitted from each emitter 862 and 864 after the light has been reflected by objects in the field. See reference... Figure 8E as well as Figure 8DThe enlarged perspective view 851 of the photoelectric sensor 860 shown illustrates this concept. First, refer to... Figure 8D The overlapping fields of view of each emitter 862 and 864 are shown as a single circle superimposed on the field of view (shown as a square) of the photoelectric sensor 860. As shown, the fields of view of emitters 862 and 864 overlap with the same portion of the field of view of the photoelectric sensor 860, such that after light is reflected by one or more objects in the field, the photoelectric sensor 860 can capture light from each emitter 862, 864.

[0144] Figure 8E This concept is further illustrated. Figure 8E This is a simplified illustration of the field of view of a single receiver channel in sensor array 856 and the overlapping field of view of the corresponding transmitters in transmitter arrays 852a and 852b. Each transmitter in transmitter arrays 852a and 852b can transmit... Figure 8E The light pulses shown are cones 870a and 870b, which are collimated by separate body transmitter optics 872a and 872b. Then, the collimated light from each transmitter array is output as pulsed discrete beams 874a and 874b to the field.

[0145] like Figure 8E As shown, emitter arrays 852a and 852b are co-aligned such that each discrete beam 874a and 874b has the same field of view 880 exceeding a threshold distance. In this way, the amount of light focused on a discrete point represented by the field of view 880 can be increased compared to a single beam, and multiple beams provide redundant illumination in each photodetector field of view. Each emitted beam 874a and 874b can reflect one or more objects in the field and propagate back as reflected light 882 to the sensor array 856. The reflected light 882 then propagates through a body receiver optics 884, which focuses the reflected light as a cone 886 of pulsed light to the corresponding photodetector (e.g., photodetector 860) within the sensor array 856. Since emitters 862 and 864 project light into the same field of view, if one of emitters 862 or 864 fails to operate, the photoelectric sensor 860 can still capture light emitted from the other emitter at specific locations (e.g., discrete points) in the field, thus providing a beneficial level of redundancy. Additionally, when both emitters are operating to emit light for a single photoelectric sensor, the photoelectric sensor exhibits improved sensing performance.

[0146] For reference Figure 8EUnderstandably, the distance between adjacent transmitter optics 872a, 872b and receiver optics 884 (e.g., in the range of 0.5 to 5 cm) is relatively small compared to the distance to the scene. Therefore, as the scene moves further away, the field of view of each transmitter array 852a, 852b increasingly overlaps with each other and with the field of view of the sensor array 856. For example, as... Figure 8E As shown, the overlap regions 890, 892, and 894 of the field of view of the transmitter array and the sensor array become larger with increasing distance from the scene. Therefore, at distances close to the scene, such as the end of an object in the field of view, the field of view of transmitter array 852a can substantially overlap with the field of view of sensor array 856, and the field of view of transmitter array 852b can also substantially overlap with the field of view of sensor array 856. Thus, even if the body receiver and transmitter optics are separated by one or more centimeters, each corresponding transmitter pair and sensor can observe essentially the same points in the scene. That is, the size and geometry of each illumination beam projected from the body transmitter optics 872a, 872b into the field outside the system can be substantially the same as the field of view of the corresponding photoelectric sensor (or the micro-optical receiver channel of the corresponding photoelectric sensor) at a certain distance from the system.

[0147] Although Figure 8D and Figure 8E An embodiment is shown in which two transmitter arrays 852a and 852b provide increased brightness and redundancy in the LIDAR system 850, but the embodiments disclosed herein are not limited to this configuration. Other embodiments may have two or more transmitter arrays to improve reliability. For example, some embodiments may have three, four, or more transmitter arrays with overlapping fields of view. This way, if one, two, or more transmitter arrays fail and one transmitter array remains operational, the LIDAR system can still operate to capture an image of that field. Alternatively, instead of simply having more transmitter arrays, other embodiments may have more than one sensor array with overlapping fields of view. These multiple sensor arrays can be synchronized in time, and their data can be combined in a downstream controller to improve sensor performance or redundancy. In such embodiments, the same concept from multiple transmitters can be applied to situations where multiple sensor arrays (and therefore multiple receivers) are present.

[0148] 3. MEMS devices used in optical emission systems

[0149] The above embodiments discussed a two-dimensional emitter array for a two-dimensional light pattern within a projection field. However, some embodiments of this disclosure may alternatively include a transmission element formed by a one-dimensional light emitter array or only a single light emitter. In such embodiments, one or more microelectromechanical systems (MEMS) devices may be modulated to reflect light from a one-dimensional light emitter array into a two-dimensional light pattern within the field, as described herein. Figure 9A and 9B The subject of discussion.

[0150] Figure 9A This is a simplified illustration of an exemplary optical transmission system 900 including a one-dimensional transmitter array 902 and a MEMS device 904, according to some embodiments of this disclosure. It should be understood that... Figure 9A Not drawn to scale, therefore in an actual implementation, the transmitter array 902 may not necessarily be larger than the MEMS device 904. The MEMS device 904 can be any suitable MEMS device capable of reflecting received light in any predetermined pattern. For example, the MEMS device 904 can be a tilting mirror that can be tilted / scanned in one or more dimensions. Figure 9A As shown, the MEMS device 904 can tilt / scan in a single horizontal direction (i.e., scan axis 918) to generate a light pattern 916 within the field. In such an embodiment, the emitter array 902 is oriented perpendicular to the scan axis 918. The resulting light pattern 916 can be a two-dimensional pattern projected onto the scene and reflected back to a sensor array configured to detect the two-dimensional pattern of reflected light. Therefore, the field of view of the emitter array 902 can be matched with the field of view of the corresponding sensor array, as described herein with respect to... Figure 4 The discussion is even conducted even though there is no one-to-one correlation between the transmitter array 912 and the sensor array.

[0151] In some embodiments, the transmitter array 902 and the MEMS device 904 can be controlled by circuitry, for example, under the control of the ranging system controller 104 of FIG. 1, to generate a light pattern 916, with the transmitter array 902 and the MEMS device 904 coupled to the control circuitry. The controller circuitry can be configured to execute multiple image capture periods (i.e., one emission cycle), wherein for each image capture period, the transmitter array 902 is sequentially triggered while the MEMS device 904 tilts along its scanning axis until a two-dimensional illumination pattern, i.e., the light pattern 916, is generated. In some instances, the transmitter array 902 is formed by n light emitters, which repeatedly emit m image capture periods while the MEMS device 904 tilts continuously along its scanning axis. Therefore, the resulting illumination pattern is an m×n array of discrete light beams.

[0152] Figure 9BThis is a simplified illustration of an exemplary light transmitting system 901 including a single transmitter 912 and a MEMS device 914, according to some embodiments of this disclosure. Instead of an array of transmitters, the light transmitting system 901 may include only one transmitter 912 that emits light into a field. When configured as a one-dimensional tilting mirror, the MEMS device 904 may project the emitted light into only a single dimension, rather than two dimensions, to match the sensor array. Therefore, the MEMS device 904 may be paired with an optical element that can diffract the received light into a second dimension. As an example, the MEMS device 904 may be paired with a diffractive optical element 926, which is positioned to receive light after it has been reflected back from the MEMS device 904. The diffractive optical element 926 may be configured to diffract the received light in a dimension in which the MEMS device 904 is not tilted. As an example, if the MEMS device 904 is tilted in the x-direction, the diffractive optical element 926 may diffract the received light in the y-direction. Therefore, when paired with MEMS device 904, the resulting light pattern can be a two-dimensional pattern of light emission (i.e., discrete beams of light).

[0153] In operation, the transmitter 912 and the MEMS device 904 can control circuitry, for example in... Figure 1 A light pattern 916 is generated under the control of the ranging system controller 104, with the transmitter array 902 and the MEMS device 904 coupled to the control circuit. The controller circuit can be configured to execute multiple image capture periods, wherein for each image capture period, the transmitter 912 is sequentially triggered while the MEMS device 904 is tilted along its scanning axis. A diffractive optical element 926 can be located downstream of the MEMS device 904, such that light reflected by the MEMS device 904 passes through the diffractive optical element 926 and is diffracted into n discrete beams. While tilting the MEMS device 904, the n discrete beams can be repeatedly generated until a two-dimensional illumination pattern, i.e., light pattern 916, is generated. In some cases, the transmitter 912 is repeatedly emitted in m image capture periods, such that the resulting illumination pattern is an m×n array of discrete beams.

[0154] In some embodiments, the MEMS device 904 may be a tilting mirror that can be tilted / scanned in two dimensions to achieve the resulting emitted light pattern in two dimensions. That is, the MEMS device 904 can be tilted / scanned in both horizontal and vertical directions (i.e., scan axes 920 and 922) to generate a light pattern 924 within the field, thereby eliminating the need for a separate diffraction element (e.g., diffractive optics 926). Like pattern 916, the light pattern 924 may be a two-dimensional pattern projected onto the scene and reflected back to a sensor array configured to detect the two-dimensional pattern of the reflected light. Therefore, the field of view of the emitter array 912 can be matched to the field of view of the corresponding sensor array, as described herein with respect to...Figure 4 The discussion is even conducted even though there is no one-to-one correlation between the transmitter array 912 and the sensor array.

[0155] Although not shown, it should be understood that Figures 9A-9B The light emitter discussed can be paired with one or more corresponding microlenses that collimate the light and essentially guide it to the MEMS device. Alternatively, other diffractive elements or optical elements can be used to direct the emitted light toward the MEMS device 904.

[0156] 4. Enhanced optical emission system

[0157] Embodiments of this disclosure relate to LiDAR sensors, which, among other applications, can be used for obstacle detection and avoidance in autonomous vehicles. Some specific embodiments relate to LiDAR sensors with design features that make the sensor manufacturing cost sufficiently low and reliability sufficiently high, and achieve a sufficiently small footprint for use in mass-market cars, trucks, and other vehicles. For example, some embodiments include a set of vertical-cavity surface-emitting lasers (VCSELs) as an illumination source emitting radiation into the field, and include a single-photon avalanche diode (SPAD) detector array as a set of photoelectric sensors (detectors) for detecting radiation reflected back from surfaces within the field. Using VCSELs as emitters and SPADs as detectors allows for multiple measurements to be performed simultaneously (i.e., VCSELs can be excited simultaneously), and allows for the separate fabrication of a set of emitters and a set of photoelectric sensors on a single chip using standard CMOS processes, which greatly simplifies the manufacturing and assembly process.

[0158] However, using VCSELs and SPADs in certain embodiments presents certain challenges, which are overcome by various embodiments of this disclosure. For example, VCSELs have significantly lower power than typical lasers used in existing LiDAR structures, while SPADs are significantly less efficient than typical detectors used in existing LiDAR structures. To address these challenges, as well as the challenges of simultaneously exciting multiple emitters, certain embodiments of this disclosure include various optical components (e.g., lenses, filters, and aperture layers) that can work in conjunction with multiple SPAD arrays, each corresponding to a different pixel (e.g., location within the field), as described herein. Figure 1 As discussed, the optical system 128 of the light sensing module 108 may include a low-light receiver layer ( Figure 1 (Not shown in the image) is used to enhance the light detected by the sensor array 126, which may include an array of photoelectric sensors, each of which may be a SPAD array.

[0159] Because VCSELs are less powerful than typical lasers in existing LIDAR structures, in some embodiments, the optical emitting system can be configured to enhance the ability of a solid-state electronically scanned LIDAR system to perform optical ranging functions. That is, the quality of the light emitted by the optical emitting system can be improved to enhance optical ranging accuracy and efficiency. The quality of the transmitted light used for optical ranging and imaging purposes can be defined by its brightness and intensity. The brightness and intensity of the light emitted from the body transmitter optics can be enhanced by modifying and / or implementing one or more optical transmitter layers, which will be discussed further herein.

[0160] The brightness of transmitted light can be defined by the optical power (watts) per solid angle. Therefore, a light source that outputs light with tight collimation (i.e., low divergence) produces high-brightness light. Conversely, a light source that outputs highly divergent light produces low-brightness light. The intensity of light can be defined by the optical power per unit area; that is, if light emitted at a certain power is concentrated within a small area, its intensity will be higher. Therefore, even if both light sources output light with low divergence, the intensity of the light source outputting denser light will be higher than the intensity of the light source outputting less dense light. As will be understood herein, in embodiments of this disclosure, the transmitter component for a LIDAR system can be configured with micro-optical components that enable the transmitter to output light with enhanced brightness and intensity compared to a similar transmitter without micro-optical components.

[0161] Figure 10 This is a simplified cross-sectional view of an exemplary enhanced light emission system 1000 according to some embodiments of the present disclosure. The light emission system 1000 may include a light emitter array 1002 having light emitters 1004, which may include, for example, but not limited to, any light-emitting diode, laser diode, VCSEL, etc., for emitting light 1013. A VCSEL is a semiconductor laser diode that emits a laser beam vertically from its top surface. Note that... Figure 10 The linear array shown can be any geometrical transmitter array, including but not limited to circular, rectangular, linear, or any other geometric shape.

[0162] The enhanced optical emission system 1000 may include a micro-optical transmitter channel array 1006 separated from the optical transmitter array 1002 by an open space 1018. Each micro-optical transmitter channel 1008 may be associated with a corresponding receiver channel (e.g., Figure 5The receiver channels 512 in the optical imager system are paired, and their field centers are aligned to overlap at a distance from the optical imager system. The micro-optical transmitter channel array 1006 can be formed by a substrate 1019 sandwiched between a first optical surface 1020 located on the side facing the light emitter array 1002 and a second optical surface 1021 located on the opposite side facing away from the light emitter array 1002. Both the first optical surface 1020 and the second optical surface 1021 can be configured as convex micro-optical lens arrays, wherein each convex lens of the first optical surface 1020 is configured to be optically aligned with a corresponding convex lens of the second optical surface 1020, such that light transmitted through the first optical surface 1020 can subsequently transmit through the second optical surface 1021. Figure 10 As shown, the corresponding convex lenses from the first optical surface 1020 and the second optical surface 1021 may face away from each other. In some embodiments, the convex lens of the first optical surface 1020 has a first optical power, and the convex lens of the second optical surface 1021 has a second optical power different from the first optical power. For example, the second optical power may be greater than the first optical power, such that the focal length of the second optical power is shorter than the focal length of the first optical power. The substrate 1019 may be formed of any suitable material that is transmissive within the wavelength range of the light emitter 1004, such as silicon, silicon dioxide, borosilicate glass, polymers, etc. The first optical surface 1020 and the second optical surface 1021 may be formed of a transparent polymer imprinted on the respective opposing surfaces of the substrate 1019.

[0163] In some embodiments, the micro-optical transmitter channel array 1006 may be formed from a monolithic array of micro-optical transmitter channels 1008. Each micro-optical transmitter channel 1008 may include a first convex lens from a first optical surface 1020, a corresponding second convex lens from a second optical surface 1021, and a corresponding portion of a substrate 1019 located between the two convex lenses. Each micro-optical transmitter channel 1008 may correspond to a respective light emitter 1004, such that light emitted from the light emitter 1004 passes through the first convex lens, through a corresponding region of the substrate 1019, and then through the second convex lens during operation.

[0164] Once light exits from the second convex lens of the second optical surface 1021, the light forms a micro-spot image 1010, which is a true image of the corresponding light emitter 1004, but a scaled-down image of the corresponding light emitter 1004. In some embodiments, the micro-spot image 1010 is located between the micro-optical emitter channel array 1006 and the main emitter optics 1014. For example, the micro-spot image 1010 may be formed within a corresponding aperture of the aperture layer 1009. Each aperture may be a pinhole on a reflective layer or an opaque layer, wherein the emitted light is focused to form the micro-spot image 1010. It should be understood that the aperture layer 1009 is optional, and the light enhancement capability of the micro-optical emitter channel array 1006 can be achieved without the aperture layer 1009. In such an embodiment, the micro-spot image 1010 may be formed at the focal plane of the second convex lens of the second optical surface 1021. Continuing away from the light emitter and micro-optical channel, the light forms a light cone 1012, leading to the main emitter optics 1014.

[0165] According to some embodiments of this disclosure, the divergence of the emitted light 1013 can be less than the divergence of the light cone 1012. This difference in divergence can be generated by the micro-optical transmitter channel 1008, particularly by the optical power of the second optical surface 1021. Because the divergence of the light emanating from the micro-optical transmitter channel 1008 is greater than that of the light 1013 emitted from the light emitter 1004, the micro-spot image 1010 can be a true image of the light emitter 1004, but much smaller than the size of the light emitter 1004 and having the same number of photons as the emitted light 1013. Then, the final light cone 1012 formed after the formation of the true spot image is projected into the field as discrete beams of each light emitter 1004 after passing through the main transmitter optics 1014. The final light emitted from the light emitting system 1000 is a highly collimated beam with a small cross-sectional area, thereby enabling the light emitting system 1000 to output light with enhanced brightness and intensity. Conversely, a system that does not have a micro-optical channel array but has a light emitter array 1002 at the focal plane of the main transmitter optics 1014 will produce beams with significantly reduced collimation, and therefore these beams will have a larger cross-sectional area in the far field.

[0166] Please note that the main transmitter optics 1014 may include a single lens or a group of lenses, wherein two or more lenses together form the main transmitter optics 1014. Using multiple lenses in the main transmitter optics 1014 can increase the numerical aperture, reduce the RMS spot size, flatten the image plane, improve telecentricity, or otherwise improve the performance of the main transmitter optics 1014. Also note that, in some embodiments, the light cones 1012 may overlap to form a light cone overlap region 1016.

[0167] To better understand the operation and effectiveness of the micro-optical transmitter channel array 1006, a more detailed explanation of the operation of the optical emission system 1000 is discussed. For the enhanced optical emission system 1000 utilizing an array of optical transmitters formed by VCSEL transmitters, an exemplary initial radius of the transmitters can be 12.5 μm, where light is incident at a 10° half-cone. Such transmitters typically output 50 μW per square micrometer of active area. The diverging light cones from each transmitter 1004 are received in the micro-optical transmitter channel 1008, and then the converging light cones are output from the same micro-optical channel to produce a converging light cone with, for example, a 20° half-cone angle. Therefore, for some embodiments, the cone angle produced by the transmitter 1004 is smaller than the cone angle produced by the corresponding micro-optical transmitter channel 1008. The converging light cones emitted from the micro-optical transmitter channel 1008 then generate a micro-spot image 1010 of the transmitter. Figure 10 In this embodiment, the micro-spot image 1010 is a real image, smaller than the corresponding light emitter 1004. Note that all light rays from a given emitter may not be fully focused onto an arbitrarily small spot. The size of the micro-spot image is typically controlled by "optical invariants":

[0168] Θ_s*r_s>=Θ_e*r_e

[0169] Where Θ_s is the edge ray half-angle of the focused spot, r_s is the radius of the focused spot, Θ_e is the edge ray half-angle of the original emitter, and r_e is the radius of the original emitter. Therefore, in this example, the smallest possible micro-spot image radius that can be formed (while still capturing all rays from the emitter) is:

[0170] 10 / 20 * 12.5um = 6.25um

[0171] Please note that this smaller spot area will be one-quarter of the original emitter area, therefore the power density per square micrometer spot area is 200 μW. Each micro-optical emitter channel 1008 typically has one or more optical surfaces, characterized, for example but not limited to, a focal length of 50 μm and a lens diameter of 80 μm. In some embodiments, the distance between the light emitter 1004 and the corresponding micro-optical emitter channel 1008 can be, for example but not limited to, 150 μm. Figure 10 As shown, the open space 1018 between the transmitter array 1002 and the micro-optical transmitter channel array 1006 can be, for example, but not limited to, an air gap, such as an air gap created by methods commonly used in the manufacture of MEMS devices. The distance between the transmitter array 1002 and the micro-optical transmitter channel array 1006 can be, for example, 150 μm.

[0172] The main emitter optics 1014 is positioned in front of the micro-optics and the emitting layer, such that the focal plane of the main imaging optics coincides with the micro-spot image 1010. The main emitter optics 1014 receives the diverging light cone 1012 and outputs a collimated beam. Its numerical aperture can be at least large enough to capture the entire angular range in the diverging light cone; therefore, for example, but not limited to, in this example, the numerical aperture (NA) = 0.34. Furthermore, the main emitter optics 1014 can be telecentric in image space because the light cones 1012 exiting the micro-optics can all be parallel (rather than their central axes being aligned with the center of the main optics). In one embodiment, light can exit the main emitter optics 1014 approximately collimated. Note that the quality of beam collimation is related to the size of the “emitting object” (micro-spot image 1010) at the focal plane. Since the size of this “emitting object” has been reduced by using micro-optical stacking, a better collimation angle is obtained than simply imaging the emitting object directly.

[0173] although Figure 10 An enhanced light emitting system is illustrated, having an array of micro-optical channels formed by a substrate sandwiched between first and second optical surfaces, and positioned at a distance from the light emitter array via an open space to improve the brightness and intensity of the light output by the light emitting system. However, embodiments are not limited to this configuration. Rather, other embodiments do not necessarily have to implement an open space or two optical surfaces, as discussed in further detail in the relevant U.S. Patent Application 15 / 979,235, filed May 14, 2018, entitled "Optical Imaging Emitter with Brightness Enhancement," which is incorporated herein by reference in its entirety for all purposes.

[0174] III. Sensor Array Configuration and Operation

[0175] Once the light is reflected back to the electronically scanned LIDAR system, the light detection system receives the light by first passing it through a body-receiving optics, which then focuses the light downwards through an aperture layer and exposes it to multiple photodetectors in the sensor array. In some cases, the light may propagate through a filter before passing through the aperture layer. As the light is exposed to the sensor array, each photodetector detects a discrete amount of light, which, when analyzed together with all the photodetectors in the array, can be used to generate an image of the scene. That is, each photodetector can be read by external circuitry to construct the scene image. According to some embodiments, the sensor array can operate in various ways, as will be discussed herein. Figures 11-1 The three discussed.

[0176] Figure 11This is a simplified diagram of a sensor array control system 1100 for column-wise operation of an m×n sensor array 1102 according to some embodiments of the present disclosure. The sensor array control system 1100 may include column selection circuitry 1104, one or more time-digitized arrays 1106, and one or more static random access memory (SRAM) devices on a digital signal processor (DSP) array 1108. Column selection circuitry 1104 may be any suitable circuitry configured to select which column to read and in what particular order. In some embodiments, column selection circuitry 1104 may be configured to operate synchronously with a driver in a light-emitting system such that selected columns in sensor array 1102 may correspond to active columns in the emitter array, as discussed herein with respect to Figures 2 and 3. The TDC array 1106 may be configured to convert signals generated by photons detected at a photodetector into a digital time series of events. The time series may be a sequence of photon counts representing the relationship between the reflected photon flux returning to the photodetector and time, which can be used to determine the shape and distance of objects around the scene. The SRAM and DSP array 1108 can be any suitable microcontroller or processor configured to process signals received from the photoelectric sensors in the sensor array 1102.

[0177] In some embodiments where the sensor array is formed on a single ASIC, the time digitization array 1106 and the DSP 1108 can be pushed to the edge of the ASIC and positioned around the sensor array 1102. This design leaves ample space for photosensitive pixels (e.g., an array of SPADs) in the active region of the receiver ASIC, enabling the collection of more light and improved performance.

[0178] During operation, column selection circuit 1104 can select one or more columns to read, and the selected column can be read by the operation of TDC array 1106 and SRAM / DSP array 1108. For example, column selection circuit 1104 can select column 1110, and then column 1110 can be read by operating TDC array 1106 and SRAM / DSP array 1108. Figure 11As shown, each column of photosensitive sensors can be read by reading each row in sensor array 1102. In some embodiments, instead of reading only one row at a time, multiple rows can be read simultaneously. For example, sensor control system 1100 may include two TDC arrays 1106 and two SRAM / DSP arrays 1108, one on each side of sensor array 1102. Thus, during operation, column selection circuit 1104 can select two columns, such as 1110 and 1112, for reading, in which case the corresponding TDC array 1106 and SRAM / DSP array 1108 can read the column; for example, column 1110 can be read by the left arrays 1106 and 1108, while column 1112 can be read by the right arrays 1106 and 1108. This design allows simultaneous triggering of two emitters corresponding to two columns of photosensitive sensors that are read simultaneously. The time sequence of the pulse sequence detected by each photosensitive sensor can be stored in a group of SRAM memory in SRAM / DSP array 1108 so that the SRAM memory can provide this information to a DSP or any other processor, for example, Figure 1 The processor 122 or 130 is used in the system. In some embodiments, the SRAM capacity can be doubled, so that there are two identical groups instead of one for reading the sensor array 1102. Thus, while one group is reading data from a column of pixels, the other group can push the data to the digital signal processing system. This architecture allows for twice the data pipelined processing and twice the pixel capture rate in a system using a single SRAM group.

[0179] In addition to column-wise readout, some embodiments can also be configured to read out the sensor array row-wise, as described herein. Figure 12 As stated above. Figure 12 This is a simplified diagram of a sensor control system 1200 for row-by-row operation of an m×n sensor array 1202, according to some embodiments of the present disclosure. The sensor control system 1200 may include a row selection circuit 1204 and a TDC array and an SRAM / DSP array, shown as a single combined module labeled TDC and SRAM / DSP array 1206. The row selection circuit 1204 may have... Figure 11 The column selection circuit 1104 in the TDC and SRAM / DSP array 1206 has essentially the same configuration and operation, but its operation is to select the photoelectric sensor row by row instead of column by column. Figure 11 The TDC array 1106 and SRAM / DSP array 1108 have essentially the same configuration and operation, but their operation is to read the photoelectric sensor row by row instead of column by column. Therefore, the row selection circuit 1204 can select the row to be read, and the TDC and SRAM / DSP arrays 1206 can perform the read operation.

[0180] AlthoughFigure 11 and Figure 12 An embodiment is shown that reads an entire row or column at once, but the embodiment is not limited thereto. Instead, other embodiments can be configured to select one or more photoelectric sensors individually in the sensor array. Figure 13A This is a simplified diagram of a control system 1300 for operating an m×n sensor array 1302 by column and row control circuitry according to some embodiments of the present disclosure. Instead of having only one column or row selection circuit and only one corresponding TDC and SRAM / DSP array, the sensor control system 1300 may include both column selection circuit 1304 and row selection circuit 1306, as well as TDC and SRAM / DSP arrays 1308 and 1310 for row-by-row and column-by-column reading. In this way, the sensor control system 1300 can select a specific one-dimensional group of photoelectric sensors by selecting the specific row and column where the desired photoelectric sensor is located. As an example, the sensor control system 1300 may select only the group of photoelectric sensors 1312 and / or one-dimensional photoelectric sensors 1314 and 1316. Once those photoelectric sensors are selected, they can be read out by the corresponding column and / or row TDC and SRAM / DSP arrays 1308 and 1310.

[0181] In some other embodiments, instead of reading the TDC and SRAM at the end of the column or row of the photodetector, the photodetector can be read into the TDC and memory of each pixel, allowing the configuration of any one-dimensional or two-dimensional photodetector to be enabled at once. As an example, Figure 13BThis is a simplified diagram of a control system 1301 for operating an m×n sensor array 1302 per photosensor using dedicated control circuitry for each photosensor, according to some embodiments of this disclosure. Instead of merging TDC and SRAM / DSP arrays for rows and columns, separate TDC and SRAM devices can be implemented near the photosensors or on the underlying semiconductor die of each respective photosensor to enable simultaneous reading of any number and configuration of photosensors across the entire array. DSP arrays 1328 and 1330 can be implemented on one side of the sensor array 1302 and can serve as a shared resource for the TDC and SRAM devices under each photosensor, or the DSP can be incorporated into each pixel. In such embodiments, the sensor array 1302 can be fabricated as a stack of two or more monolithic electronic devices (“semiconductor dies”) integrated into a single structure, with electrical signals passing between them. The top semiconductor die may include the sensor array 1302, fabricated using a process that maximizes light sensing efficiency or minimizes noise, while other dies for the TDC and SRAM devices are optimized for lower power, higher speed digital processing. Using this configuration, sensor array 1302 can select any one-dimensional or two-dimensional group of photoelectric sensors in any arrangement by selecting the specific row and column where the desired photoelectric sensor is located and having the respective TDC and SRAM devices perform readouts of the selected photoelectric sensors. As an example, sensor control system 1301 can select two-dimensional groups 1334 and 1336 of photoelectric sensors in various arrangements. Once those photoelectric sensors are selected, they can be read out by the respective TDC and SRAM devices. Because the selection of these two two-dimensional photoelectric sensor groups can be completed in less than a microsecond, and the groups are continuously cycled through, the sensor control system can include configuration registers that predefine multiple photoelectric sensor groups corresponding to drive circuit groups on the respective transmitter arrays. For example, in some embodiments, there are 16 independent laser driver groups for a laser transmitter array and 16 independent configuration registers for defining photoelectric sensor groups, and these configurations can be determined by the ranging system controller or, as described herein, by reference to... Figure 1 Any other controller discussed is used to select which synchronizes the triggering of the transmitter array with the selection of its corresponding photoelectric sensor group. These group registers can be configured when the sensor array is turned on and can be reprogrammed to change the group order based on control input from the ranging system controller or based on information from the target environment.

[0182] As discussed in this paper, the emitter array and sensor array, and therefore the corresponding micro-optical emitter and receiver channels for manipulating light, can correspond to each other, allowing the sensor array to detect light from the emitter array. To help illustrate the correspondence between the emitter and the photoelectric sensor, the aperture array of the micro-optical emitter channels can be superimposed on the pixel array of the micro-optical receiver channels, such as... Figures 14-16 As shown.

[0183] Figures 14-16 An exemplary configuration of a sensor array relative to an emitter array is shown, wherein, for clarity and ease of understanding, the light emitter is represented by a circle (which in some embodiments may further represent the aperture of a micro-optical emitter channel), and the photodetectors of the micro-optical receiver channels are represented by their own geometric contours (i.e., squares / rectangles). It should be understood that... Figures 14-16 The transmitter and sensor array shown may represent only a portion of the actual transmitter and sensor array, and could include more transmitters and photoelectric sensors than shown in the figure. Furthermore, Figures 14-16 Each photodetector shown can be a single photodetector or multiple SPADS.

[0184] Figure 14 This is a simplified illustration of a configuration 1400 in which the emitter array and sensor array have a one-to-one correspondence according to some embodiments of the present disclosure. As shown, each light emitter 1402 can correspond to a corresponding photoelectric sensor 1404, such that the light emitted by the emitter 1402 can be detected by its corresponding photoelectric sensor 1404 after the emitted light has been reflected away from an object in the field. Horizontal and vertical sidewalls 1406 and 1408 can mitigate crosstalk between adjacent photoelectric sensors. In such embodiments, the horizontal and vertical pixel pitch dimensions can be the same. For example, the horizontal and vertical pixel pitch of the sensor array used for configuration 1400 can be 100µm × 100µm.

[0185] In some embodiments, the size of the photoelectric sensor can be changed to modify the resolution of the sensor array in one or more orientations. For example, Figure 15 This is a simplified illustration of a configuration 1500 according to some embodiments of the present disclosure, in which the transmitter array and sensor array have a one-to-one correspondence but a modified resolution in one dimension. As shown, each photoelectric sensor 1504 can have a greater length, making it more compatible with... Figure 14Compared to the resolution of the sensor array in configuration 1400, the vertical resolution is reduced. In such an embodiment, each photoelectric sensor 1504 may be rectangular in shape. By reducing the resolution in one or more dimensions, more space can be provided to mount electrical components. In such an embodiment, the horizontal and vertical pixel pitch dimensions may be different. For example, the horizontal and vertical pixel pitch of the sensor array used for configuration 1500 may be 100µm × 200µm.

[0186] Figure 16 This is a simplified illustration of a configuration 1600 in which a sensor array has multiplexed photoelectric sensors according to some embodiments of the present disclosure. In a multiplexed photoelectric sensor arrangement, one or more photoelectric sensors may correspond to a single transmitter in a transmitter array, and some photoelectric sensors may correspond to more than one transmitter. For example, the transmitter array in configuration 1600 may include transmitters 1602a-h, characterized by being indicated by circles, which represent the field of view of the transmitter defined by the aperture of the transmitter. Each transmitter 1602a-h may correspond to a plurality of photoelectric sensors 1604a-f in the sensor array. As an example, transmitter 1602a may correspond to four photoelectric sensors, photoelectric sensors 1604a-d, each photoelectric sensor having at least a portion capable of capturing light emitted from transmitter 1602a after being reflected by an object in the field. Although Figure 16 Only emitters corresponding to four photoelectric sensors are shown, but other embodiments may have emitters corresponding to any other suitable number of photoelectric sensors, such as six, eight, or even sixteen. Having a greater number of photoelectric sensors for detecting the light from a single emitter provides a larger dynamic range for each pixel measured in the field and allows for more closely packed sensor arrays, thereby improving resolution.

[0187] In some embodiments, one or more photoelectric sensors can be configured to sense light from multiple light emitters. As an example, the field of view of emitter 1602c can overlap with that of photoelectric sensors 1602c-f; therefore, since the field of view of emitter 1602a overlaps with that of photoelectric sensors 1602a-d, photoelectric sensors 1602c-d can correspond to emitters 1602a and 1602c. By enabling this sensing overlap, photoelectric sensor resources can be shared, thereby providing a more efficient sensor array. (As in...) Figure 16It is understandable that, in order for multiplexed photodetectors to operate, the sidewalls between photodetectors in adjacent columns may not exist; instead, only the sidewalls between rows 1606 may be present. Besides the overlap of photodetectors used for different transmitters, the lack of column walls can lead to crosstalk. Therefore, it may be beneficial to modulate the transmitter array in a way that mitigates crosstalk between adjacent photodetectors while still allowing photodetector resources to be shared. For example, if Figure 16 The transmitter array in the diagram can be a column-modulated transmitter array as discussed herein with reference to Figure 2—where transmitters 1602a-b are immediately activated (and so are transmitters 1602c-d, 1602e-f, and 1602g-h). The transmitter array can then be configured to activate transmitters 1602a-b and 1602e-f in a first time instance, and then activate transmitters 1602c-d and 1602g-h in a second time instance. Transmitters 1602a-b and 1602e-f can be transmitters from the same transmitter array or from different transmitter arrays, as referred to herein. Figure 8A and 8D A discussion was held.

[0188] although Figure 16 Each dotted square is referred to as a separate photodetector, but it should be understood that the embodiments are not limited to this implementation, and each dotted square can represent other sensing elements. For example, in some embodiments, each dotted square can represent an array of SPADS or a single SPAD. In this example, the array of dotted squares as a whole in configuration 1600 can be used as an amorphous sensing array that dynamically selects one or more SPADS arrays or a single SPADS array for readout based on which emitter 1602a-h is emitting light. For example, when emitter 1602a is activated during a first capture, arrays 1604a-d of SPADS can be readout, and arrays 1604c-f of SPADS can be readout when emitter 1602a is activated during a second capture. Each array of SPADS 1604a-d can correspond to a sub-region of the photodetector, as described herein relative to... Figure 8C As discussed similarly, each array of SPADS 1604a-d can correspond to a single photoelectric sensor.

[0189] IV. Solid-state construction of electronically scanned LiDAR systems

[0190] Figure 17This is a cross-sectional view of the construction of an exemplary optical transmission module 1700 according to some embodiments of the present disclosure. The optical transmission module 1700 may include a transmitter array 1702 formed on a substrate 1704. For example, in some embodiments, the transmitter array 1702 may be a VCSEL array formed directly on a semiconductor chip. The transmitter array 1702 may be mounted together with driver circuitry (not shown) on a structure 1706 (e.g., a ceramic plate), as referenced herein. Figure 6 and Figures 7A-7B The discussed structure 1706 can be mounted on the interconnect structure 1708, such as a printed circuit board (PCB). In some embodiments, the structure 1706 can be a driver circuit capable of operating the transmitter array 1702, such as a driver ASIC. When configured as a driver circuit, the structure 1706 can be flip-chip bonded to the underside of the substrate 1704. Various other electrical components (not shown) can also be mounted on the interconnect structure 1708 to operate the transmitter array 1702. Therefore, the interconnect structure 1708 can be electrically coupled to the substrate 1704 by any suitable method such as wire bonding (not shown).

[0191] In some embodiments, the optical transmission module 1700 may include a heat sink 1716 coupled to the side of the interconnect structure 1708 opposite to the side coupled to the transmitter array 1702. In this way, the heat sink 1716 can absorb heat from the transmitter array 1702 during operation to prevent overheating. To provide this functionality, various components may include thermal routing structures to allow heat to be transferred from the transmitter array 1702 to the heat sink 1710. For example, the optical transmission module 1700 may include a thermoelectric cooler (TEC) 1712 between the heat sink 1710 and the interconnect structure 1708 to transfer heat generated by the transmitter array 1702 to the heat sink 1710 or to regulate the temperature of the transmitter array 1702. The TEC 1712 may include two plates sandwiching a plurality of thermally conductive vias, such as... Figure 17 As shown. The heat sink 1710 can be any suitable heat sink capable of dissipating heat to the surrounding environment, such as a metal structure with fins. In some embodiments, the interconnect structure 1708 may include an array of thermal vias 1714 extending between the top and bottom surfaces of the interconnect structure 1708 to thermally couple the support structure 1706, the substrate 1704, and the emitter array 1702 to the heat sink 1710. The thermal vias 1714 can be formed of any suitable high thermal conductivity material, such as tungsten, copper, aluminum, or any other metallic material.

[0192] V. Exemplary Implementations of Scanning LiDAR Systems

[0193] According to some embodiments of this disclosure, an electronically scanned LiDAR system can be configured as a solid-state system with a fixed structure. This type of LiDAR system does not rotate, thus eliminating the need for separate motors to rotate the sensor and transmitter modules. Example solid-state LiDAR systems include... Figure 18 and 19 As shown.

[0194] Figure 18 and 19 This is a simplified illustration of an exemplary implementation of a solid-state electronic scanning LiDAR system. Specifically, Figure 18 The embodiments 1800 according to some embodiments of the present disclosure are shown, wherein solid-state electronic scanning LIDAR systems 1802a-d are implemented in the external region of a road vehicle 1805, such as an automobile; Figure 19 Embodiment 1900 according to some embodiments of the present disclosure is shown, wherein a solid-state electronically scanned LiDAR system 1902a-b is implemented on top of a road vehicle 1905. In each embodiment, the number of LiDAR systems, the location of the LiDAR systems, and the field of view of each LiDAR system can be selected to obtain a majority (if not all) 360-degree field of view of the environment surrounding the vehicle. The automotive embodiment of the LiDAR system chosen here is merely illustrative; the sensors described herein can be used in other types of vehicles, such as ships, airplanes, trains, etc., and in a variety of other applications using 3D depth imagery, such as medical imaging, mobile phones, augmented reality, geodesy, geographic information science, archaeology, geography, geology, geomorphology, seismology, forestry, atmospheric physics, laser guidance, airborne laser strip mapping (ALSM), and laser altimetry.

[0195] Referring to Figure 1800, solid-state electronic scanning LIDAR systems 1802a-d can be mounted on the exterior of the vehicle, near the front and rear fenders. Each LIDAR system 1802a-d can be positioned at a corresponding corner of the vehicle 1805, such that they are positioned near the outermost corner of the vehicle 1805. This allows the LIDAR systems 1802a-d to better measure the distance between the vehicle 1805 and objects in the field at regions 1806a-d. Each solid-state LIDAR system can face a different direction (there may be partial overlap and / or non-overlapping fields of view between units) to capture a larger composite field of view than each unit can capture on its own. Objects in the scene can reflect portions of the light pulses 1810 emitted from the LIDARTx module 1808. One or more reflected portions 1812 of the light pulses 1810 then propagate back to the LIDAR system 1802a and can be received by the Rx module 1809. The Rx module 1809 can be housed in the same housing as the Tx module 1808. As discussed herein, electronically scanned LIDAR systems 1802a-d can electronically scan a scene to capture an image of the scene. Thus, LIDAR system 1802a can scan between points 1820 and 1822 to capture objects in the field in region 1806a, and the same applies to systems 1802b-d and regions 1806b-d.

[0196] Although Figure 18 Four solid-state electronic scanning LiDAR systems are shown mounted at the four corners of a vehicle, but the embodiment is not limited to this configuration. Other embodiments may have fewer or more solid-state electronic scanning LiDAR systems mounted in other areas of the vehicle. For example, the electronic scanning LiDAR systems may be mounted on the roof of the vehicle, such as... Figure 19 As shown. In such an embodiment, the electronically scanned LIDAR system 1902a-b can have a higher vantage point for better observation of the area 1907a-b surrounding the vehicle 1905. In some embodiments, scanning can be performed in other ways, such as chip-based beam steering techniques, for example, by using a microchip employing one or more MEMS-based reflectors, such as a digital micromirror device (DMD), a digital light processing (DLP) device, etc., as will be stated here relative to... Figures 9A-9B Further discussion is needed.

[0197] As mentioned herein, the number of LiDAR systems, their locations, and the field of view of each LiDAR system can be selected to obtain a majority (if not all) 360-degree field of view of the environment surrounding the vehicle. Therefore, each LiDAR system 1802a-d can be designed with a field of view of approximately 90 degrees, such that when all four systems 1820a-d are implemented, the vast majority of the 360-degree field of view around the vehicle 1805 can be observed. In embodiments where each LiDAR system 1802a-d has a field of view of less than 90 degrees, such as 45 degrees, one or more additional LiDAR systems can be implemented to extend the field of view to achieve a combined field of view that is larger than the field of view of a single LiDAR system, as will be described herein relative to... Figure 20 Further discussion is needed.

[0198] Figure 20 This is a simplified top-down illustration of an exemplary solid-state electronic scanning LIDAR system 2000 according to some embodiments of the present disclosure, the system including more than one set of emission and detection systems to achieve an expanded field of view. Figure 20 As shown, the solid-state electronic scanning LIDAR system 2000 may include emission and detection system groups 2002a-i mounted on a central support structure 2004, wherein each emission and detection system group includes its own optical emission system, for example... Figure 5 The light emitting system 503, and the light detection system, for example in Figure 5 The light detection system 501 is configured such that each group can be arranged radially outward from the center of the support structure 2004 and placed side by side, so that their fields of view can be adjacent to each other to form a combined field of view 2006, which is many times larger than the field of view of any single single emission and detection system. Multiple emission detection systems can be synchronized and controlled by a common LIDAR controller, allowing the end user to interact with what appears to be a single system. Furthermore, each emission detection system can be aligned to a fixed pixel grid to simulate a wider field of view, higher resolution system operating on a fixed field of view grid.

[0199] VI. Reduce receiver channel crosstalk

[0200] As can be understood from the disclosure herein, adjacent channels in a receiving element can be positioned very close to each other (e.g., within 100 micrometers of each other). Some embodiments of this disclosure include one or more structures that minimize crosstalk that may occur between adjacent channels due to the close spacing of the receiving elements. Ideally, such as Figure 21A As shown, no channel should receive stray light.

[0201] Figure 21AThis is a simplified cross-sectional view of a portion of the optical detection system 2100, where there is no crosstalk between channels. During operation, the perpendicular ray 2102 and the principal ray 2104 enter the body imaging optics 2106 and produce a light cone 2108. Rays 2102 and 2104 enter the aperture of the aperture layer 2110 and then enter the collimating lens 2111. The collimating lens 2111 accepts a limited range of incident light angles. For example, the collimating lens 2111 can accept rays with incident angles of +25 to -25 degrees relative to the vertical. Figure 21A The light cone 2108 is shown with an angle of incidence between +25 and -25 degrees. The principal ray 2104 is the ray that passes through the center of the aperture. In this example, the principal ray 2104 has an angle of incidence of 0 degrees on the collimating lens 2111.

[0202] Figure 21B This is a simplified cross-sectional view of a portion of the photodetector system 2101, where crosstalk exists between channels. In this case, during operation, the tilted ray 2112 and the main ray 2114 enter the body receiver optics 2116 and then the collimating lens 2121. In this example, the collimating lens 2121 belongs to a micro-optical channel corresponding to the photodetector located away from the image center. In this example, the main ray 2114 has an incident angle of -12 degrees, and the focusing cone has an incident angle between +12 and -35 degrees. The collimating lens 2121 blocks some light because it only accepts light with an incident angle between +25 and -25 degrees. Furthermore, light outside the collimating lens receiving cone can propagate to other optical surfaces and become stray light. Therefore, the signal photons transmitted to the photodetector by the non-telecentric body imaging optics will be significantly fewer, while potentially contaminating other channels with deviated rays 2122. On the other hand, telecentric body imaging optics will produce a light cone with an incident angle of approximately +25 to -25 degrees and a principal ray with an incident angle of approximately 0 degrees on the collimating lens, regardless of the angles of the tilted ray 2112 and the principal ray 2114. When the laser is telecentric (its principal rays are all parallel), telecentric body imaging optics have similar benefits for the transmitter, as in the case of VCSELs or side-emitting diode laser bars.

[0203] In some embodiments, the light detection system of the light sensing module uses an input image space telecentric body imaging optics. In some other embodiments, such as when cost or a larger field of view is more important than performance, the light detection system may use more standard input body imaging optics, such as biconvex lenses. For any given input field of an image space telecentric lens, the generated principal rays are parallel to the optical axis, and the image-side ray cones all span approximately the same set of angles. This allows micro-optical channels in the light detection system that are far from the optical axis to achieve similar performance to coaxial micro-optical channels. The light detection system does not require perfect image space telecentricity to operate, but the closer to perfect telecentricity, the better. For micro-optical receiver lens layers that can only accept + / -25 degrees of light, it is preferable that the input body imaging optics generate image-side rays of no more than 25 degrees for each point on the focal plane.

[0204] In some embodiments, a specific light detection system with a wide field of view and narrow bandgap imaging may have a telecentric body imaging optics for the input image space, with a numerical aperture of 0.34 and a focal length of 20 mm. Similarly, some other embodiments may have a 1 nm wide bandpass filter, enabling the detection of very specific wavelengths of light. The light detection system is capable of supporting a field of view greater than 30 degrees.

[0205] According to some embodiments of this disclosure, each channel of the micro-optical receiver channel array can be specifically configured to have features that minimize stray light intrusion into the corresponding photodetector, thereby reducing or eliminating any harmful effects caused by the presence of stray light. Figure 22 This is a simplified cross-sectional view of an exemplary micro-optical receiver channel structure 2200, also referred to herein as a micro-optical receiver channel. Receiver channel 2200 can represent... Figure 5 The micro-optical receiver channel 512 is configured to receive an input light cone encompassing a wide range of wavelengths, filtering out all wavelengths outside a narrow band centered on the operating wavelength, and allowing the photoelectric sensor 2202 to detect only or substantially only photons within the aforementioned narrow band of wavelengths. According to some embodiments of this disclosure, a micro-optical receiver channel structure such as receiver channel 2200 may include the following layers:

[0206] • Input aperture layer 2204, including optically transparent aperture 2206 and optically opaque stop region 2208, is configured to be placed on imaging optics such as Figure 5 The main receiver optical device 502 shown is shown. Figure 22A narrow field of view is defined when the focal plane (not shown) is used. Aperture layer 2204 is configured to receive input edge rays 2210. The term "optically transparent" herein refers to allowing most or all of light to pass through. Light here refers to electromagnetic radiation in the near-ultraviolet, visible, and near-infrared range (e.g., 300 nm to 5000 nm). Optically opaque herein refers to allowing little or no light to pass through, instead absorbing or reflecting light. Aperture layer 2204 may comprise an array of optically transparent apertures of uniform area spaced apart from each other by optically opaque aperture regions (e.g., each aperture may be a pinhole with the same diameter). The apertures and aperture regions may be constructed on a single monolith, such as an optically transparent substrate. Aperture layer 2204 may optionally include a one-dimensional or two-dimensional aperture array 2206.

[0207] The optical lens layer 2212 includes a collimating lens 2214, characterized by a focal length offset from the plane of aperture 2206 and stop region 2208, aligned axially with aperture 2206, and configured to collimate photons passing through the aperture such that they travel approximately parallel to the axis of collimating lens 2214, which is aligned with the optical axis of receiver channel 2200. The optical lens layer 2212 may optionally include an aperture, an optically opaque region, and a tubular structure to reduce crosstalk.

[0208] The filter layer 2216 includes filters 2218, typically Bragg reflector type filters, adjacent to the collimating lens 2214 and opposite to the aperture 2206. The filter layer 2216 can be configured to allow normal incident photons at a specific operating wavelength and passband to pass through. The filter layer 2216 can contain any number of filters 2218. The filter layer 2216 may optionally include an aperture, optically opaque regions, and tubular structures to reduce crosstalk.

[0209] The photodetector layer 2220 includes a photodetector 2202 adjacent to the filter layer 2216 and is configured to detect photons incident on the photodetector 2202. The photodetector 2202 herein refers to a single photodetector capable of detecting photons, such as an avalanche photodiode, a single-photon avalanche detector (SPAD), a resonant cavity photodiode (RCP), etc., or several photodetectors, such as a SPAD array, which cooperate to act as a single photodetector, typically having a higher dynamic range, lower dark count rate, or other beneficial characteristics compared to a single large photon detection area. Each photodetector can be an active region capable of sensing photons, i.e., light. In some embodiments, the photodetector layer includes an array of photodetectors, each photodetector having a substantially uniform sensing area larger than the area of ​​its corresponding aperture in the aperture layer 2204. In embodiments where each photodetector is an array of SPADs or other photodetectors, the SPADs or other photodetectors of a given photodetector are distributed across the entire sensing area. The photoelectric sensor layer 2220 refers to a layer made of a photodetector and includes optional structures to improve detection efficiency and reduce crosstalk with adjacent receiver structures. The photoelectric sensor layer 2220 may optionally include a diffuser, a converging lens, an aperture, an optically opaque tube spacer structure, an optically opaque conical spacer structure, etc.

[0210] Stray light can be caused by roughness of optical surfaces, defects in transparent media, back reflections, etc., and can be generated at many features inside or outside receiver channel 2200. Stray light can be guided: through filter region 2218 along a path not parallel to the optical axis of collimating lens 2214; reflected between aperture 2206 and collimating lens 2214; and generally takes any other path or trajectory that may involve many reflections and refractions. If multiple receiver channels are arranged adjacent to each other, stray light in one receiver channel may be absorbed by the photodetector in another channel, thereby contaminating the inherent timing, phase, or other information of the photons. Therefore, receiver channel 2200 can have several structures to reduce crosstalk between receiver channels.

[0211] According to some embodiments, each layer of the micro-optical channel layer structure can be designed in a specific way to mitigate the harmful effects of stray light. Various different designs for each layer are discussed in U.S. Patent Application 15 / 979,295, filed May 14, 2018, entitled “Micro-optics for Imaging Module with Multiple Converging Lenses per Channel,” and are incorporated herein by reference for all purposes.

[0212] Each such layer can be configured in various ways to mitigate crosstalk, i.e., expose stray light to adjacent receiver channels, as discussed in this paper. Figure 22 The embodiments discussed herein are not limited to this particular configuration, and other embodiments may be configured in different ways using different embodiments of the various layers disclosed in U.S. Patent Application 15 / 979,295.

[0213] As in Figure 22 Understandably, a receiver channel can include multiple layers that perform specific functions. However, each layer has associated manufacturing costs. Therefore, a greater number of layers can sometimes lead to higher manufacturing costs. In some cases, it may be desirable to remove one or more layers or simplify the structure of the receiver channel to save costs without significantly affecting its sensing capabilities. (See reference here.) Figure 23 Let's discuss an example of this simplified receiver channel.

[0214] Figure 23 This is a simplified cross-sectional view of an exemplary simplified receiver channel 2300 according to some embodiments of the present disclosure, which is well-suited for embodiments in which photoelectric sensors (e.g., arrays of SPADs) are very tightly packaged together and the aperture of the receiver channel is reduced due to the tight packaging. For example, in rotating LiDAR applications where the photoelectric sensor array includes a SPAD array, the array can be designed with a pixel pitch of 200 micrometers or even 400 micrometers. To achieve competitive resolution in some solid-state LiDAR designs, pixels are packaged together at a tighter pitch (e.g., 100 micrometers or less). For larger 200-400 micrometer channels, in some cases, the diameter of the aperture (e.g., aperture 2304) for each sensor channel can be about 25-30 micrometers. As the sensor channels are compressed to a smaller pitch (e.g., 100 micrometers), the aperture diameter can also be compressed. The combination of reduced pitch and smaller aperture makes the benefits of including a lens layer to collimate light passing through the aperture may not outweigh the additional processing steps of manufacturing the lens.

[0215] like Figure 23 As shown, receiver channel 2300 may include an aperture layer 2302, which includes an aperture 2304 formed in a non-transparent layer 2306. In some embodiments, the aperture 2304 may be formed by a void space defined by an opening in layer 2306, while in some other embodiments, the aperture 2304 may be formed of an optically transparent material.

[0216] Receiver channel 2300 may also include filter layer 2314, which, as in Figure 23The filter layer 2314 is positioned directly above the aperture layer 2302, or between the aperture 2302 and the photoelectric sensor 2326. The filter layer 2314 may include a filter 2316, which is directly located on the optically transparent substrate 2318 that structurally supports the filter 2316. This is achieved through... Figure 14 and 15 A comparison reveals that receiver channel 2300 does not include an optical lens layer for collimating light entering aperture 2304. By removing the optical lens layer, receiver channel 2300 can have a simpler design with fewer layers. The sacrifice in optical performance due to the absence of the optical lens layer may not outweigh the cost savings and the simplicity of manufacturing the receiver channel. Furthermore, one or more other layers of receiver channel 2300 can be modified to compensate for the absence of the optical lens layer. For example, filter 2316 can be modified to be more... Figure 22 The filter 2218 is a wider bandpass filter. Because there is no optical lens layer, the angle of incident light is larger, thus encompassing a wider wavelength spectrum. Therefore, by having a wider bandpass filter, which has a wider passband, a wider spectrum of light can be allowed to pass through filter 2316. In some embodiments, the passband width of filter 2316 is an order of magnitude larger than that of filters 1416 and 1516, for example, between the orders of 9x and 11x in some particular embodiments, and especially between the orders of 10x. Thus, as an example, filter 2316 may have a 10nm wide passband instead of the 1nm passband of filters 1416 and 1516.

[0217] Immediately below the aperture layer 2302 may be a photodetector layer 2320. In some embodiments, the photodetector layer 2320 of the receiver channel 2300 may include an optically opaque spacer structure 2322, a converging lens group 2324, and a photodetector 2326. The converging lens group 2324 may be located directly above the photodetector 2326, and each discrete photodetector 2328 within the photodetector 2326 includes a converging lens, wherein each lens of the converging lens group 2324 is configured to focus incident photons passing through the filter layer 2314 and the aperture 2304 onto the corresponding discrete photodetector 2328 instead of the inactive region 2330. Furthermore, the optically opaque spacer structure 2322 may be formed of an optically opaque material (e.g., black chrome). The optically opaque spacer structure 2322 forms a tube that prevents any light from propagating outside the receiver channel 2300 in the region between the photodetector 2326 and the aperture layer 2302.

[0218] According to some embodiments of this disclosure, by positioning an aperture 2304 in front of its respective photodetector, the aperture 2304 constrains the field of view detected by the photodetector 2326, thereby improving the spatial sensitivity of the photodetector 2326, because the aperture 2304 forces the photodetector 2326 to observe only a single point in the field of view. The aperture 2304 also provides a filtering function to allow only light propagating at a specific angle to enter the receiver channel and be exposed on the photodetector 2326 or all SPADS (if the photodetector 2326 is arranged as a SPADS array). In some embodiments, the size of the aperture 2304 is smaller than the size of the photodetector 2326.

[0219] By implementing according to relative Figure 23 The receiver channel in any of the embodiments discussed can prevent deviated light from being exposed on adjacent receiver channels, thereby improving the accuracy of each photoelectric sensor's ability to capture photons for imaging.

[0220] VII. Specifications of Electronic Scanning LiDAR System

[0221] As can be understood from the embodiments of this disclosure, the field of view and resolution of a particular LiDAR system can depend on several interrelated factors, such as, but not limited to, the size of the sensor array, the spacing between the photodetectors in the sensor array, the spacing between the transmitter arrays, the size of the transmitter array, and the spacing of the SPADs within a single photodetector. A larger sensor array can result in a larger field of view, where the sensor spacing is constant. Conversely, with a constant sensor array size, a smaller photodetector spacing can produce a higher resolution image, but can result in a smaller field of view.

[0222] To meet the requirements of some commercial LiDAR specifications, electronic scanning LiDAR systems can be designed in different ways. For example, some commercial LiDAR specifications require a minimum horizontal field of view of approximately 45 degrees, a minimum vertical field of view of approximately 22.5 degrees, and a minimum resolution of approximately 256 pixels by 128 pixels. Therefore, some scanning LiDAR systems can meet these requirements by configuring a sensor array with a 256 x 128 sensor array. To keep the array size compact, the spacing between photodetectors can be between 50 and 70 μm in both the vertical and horizontal dimensions, particularly 60 μm in some embodiments; and in embodiments where each photodetector is formed by an array of SPADS, the SPAD spacing can be between 5 and 15 μm, particularly 10 μm in some embodiments. In such embodiments, each photodetector can have 16 SPADS. The final size of the sensor array can be approximately 15 mm x 7.6 mm.

[0223] To ensure the sensor array receives sufficient light, the transmitter array can be designed to complement the sensor array's specifications. For example, the transmitter array can consist of two transmitter arrays (resulting in a LIDAR system with two light-emitting systems), each of which is a sparse transmitter array, which can be combined to achieve a greater resolution than either one alone, as discussed in this paper. Figure 8A As discussed, the transmitter array can generate an illumination pattern that matches the photoelectric sensor arrangement of the sensor array. Therefore, each transmitter can have a size of approximately 7.6 mm × 3.8 mm.

[0224] VIII. Position of the readout lines of the sensor array

[0225] As in Figures 11-1 As shown in Figure 3, the readout lines (indicated by arrows in the respective sensor arrays 1102, 1202, and 1302) overlap with the photoelectric sensors. However, in other embodiments, these readout lines can be rearranged to maximize the space available for the photoelectric sensors. For example, Figure 24 This is a simplified diagram of a magnified portion 2400 of a sensor array 2402 according to some embodiments of the present disclosure. Multiple column enable lines 2404 and readout lines 2406 may exist to enable operation of the photodetector 2408. Instead of routing the column enable lines 2404 and readout lines 2406 through the sensor array 2402 and between the photodetectors 2408, the column enable lines 2404 and readout lines 2406 can be routed around the sensor array 2402, i.e., near or outside the outer periphery of the sensor array 2402. Additionally, when the photodetector 2408 is a SPAD, each SPAD requires an analog front-end component 2410, which can be a solid-state device configured to bias, quench, and charge the photodetector 2408 during operation; the readout lines 2406 can also be routed outside the front-end component 2410. By routing the column enable lines 2404 and readout lines 2406 around the sensor array 2402, the photodetector 2408 can be positioned to maximize the fill factor in its local area. When used in conjunction with microlens arrays, this can achieve a high optical fill factor at the photoelectric sensor level.

[0226] To provide even more space for the photoelectric sensor 2408, one or more components may be mounted on the back side of the silicon substrate on which the sensor array is disposed, or mounted together on different substrates. As an example, FIG25 is a simplified diagram of a magnified portion 2500 of a sensor array 2502 according to some embodiments of the present disclosure, wherein one or more components are mounted on the back side of the substrate. Multiple column enable lines 2504 and readout lines 2506 may be present to enable operation of the photoelectric sensor 2508 and are located around the sensor array 2502. Instead of placing the front-end components together with the sensor array 2502 on the front side of the substrate, the front-end components can be mounted on the back side, thus freeing up more space for the photoelectric sensor 2508. In this way, Figure 24 The front-end component 2410 seen in the image does not exist. Figure 25 The area occupied by the sensor array 2502 is increased. Therefore, the resolution of the sensor array can be improved and the chip size can be reduced, thereby saving costs.

[0227] Although this disclosure has been described with reference to specific embodiments, it should be understood that this disclosure is intended to cover all modifications and equivalents within the scope of the following claims.

Claims

1. A solid-state electronic scanning optical ranging device, wherein the solid-state electronic scanning optical ranging device does not include a rotating column or a galvanometer mirror, and the solid-state electronic scanning optical ranging device comprises: An optical transmission module, comprising a transmitter layer and a main transmitter optics, wherein the transmitter layer comprises a plurality of optical emitters arranged in a two-dimensional array, the plurality of optical emitters being aligned to project an illumination beam into a field outside the optical ranging device according to an illumination pattern; A light sensing module, the light sensing module including a sensor layer and a body receiver optics, wherein the sensor layer includes a plurality of pixels having a non-overlapping field of view, wherein each of the plurality of pixels senses light from a different light emitter among the plurality of light emitters; A transmitter triggering circuit coupled to the plurality of light emitters and configured to electronically scan the two-dimensional array of the plurality of light emitters to perform a plurality of emission cycles, wherein during each emission cycle, the transmitter triggering circuit activates only a subset of the light emitters at a time until the illumination pattern is generated; as well as A sensor array readout circuit, coupled to the plurality of pixels and configured to synchronize the readout of each pixel within the plurality of pixels simultaneously with the triggering of the corresponding light emitter, such that each pixel in the plurality of pixels can be read out through one emission cycle. Multiple individual light emitters are arranged in a two-dimensional array having a first dimension and configured to project discrete light beams through the optics of the main emitter into the field outside the optical ranging device; The plurality of pixels are arranged in a two-dimensional array having a second size and configured to detect photons reflected from the surface in the field after photons have passed through the body receiver optics; and the combination of the first size, the second size, the body transmitter optics and the body receiver optics is designed such that the field of view through each transmitter column of the body transmitter optics is significantly the same as the field of view through the corresponding pixel column of the body receiver optics.

2. The solid-state electronic scanning optical ranging device according to claim 1, wherein each of the plurality of pixels has a one-to-one correspondence with each of the plurality of light emitters, and the field of view of each of the plurality of light emitters is aligned with the field of view of its corresponding pixel among the plurality of pixels.

3. The solid-state electronic scanning optical ranging device according to claim 2, wherein the main body transmitter optics are telecentric in image space and the main body receiver optics are telecentric in image space.

4. The solid-state electronic scanning optical ranging device according to claim 1, wherein the plurality of optical emitters are arranged in a two-dimensional array, and the emitter triggering circuit activates a subset of the emitters by column or by row.

5. The solid-state electronic scanning optical ranging device according to claim 1, wherein the system calculates the distance to an object in the field based on the time elapsed between the reflection of an optical pulse emitted from the plurality of optical emitters and the reflection of a pulse detected by a pixel among the plurality of pixels.

6. The solid-state electronic scanning optical ranging device according to claim 5, wherein the photosensitive module is capable of measuring the Doppler frequency shift of the emitted light pulse detected by the pixel, and the system further calculates the relative velocity between the photosensitive module and the reflective surface based on the measured Doppler frequency shift.

7. The solid-state electronic scanning optical ranging device of claim 5, wherein the system is further configured to estimate the reflectivity of the reflective surface based on the pulse intensity detected by a pixel among the plurality of pixels.

8. The solid-state electronic scanning optical ranging device of claim 5, wherein the system is further configured to determine whether the reflective surface is a hard material or a diffuse material based on the shape of the detected pulse.

9. The solid-state electronic scanning optical ranging device according to any one of claims 1 to 8, wherein each of the plurality of pixels comprises a plurality of single-photon avalanche diodes (SPADs).

10. A solid-state electronic scanning optical ranging device, wherein the solid-state electronic scanning optical ranging device does not include a rotating column or a galvanometer mirror, and the solid-state electronic scanning optical ranging device comprises: A two-dimensional array of light emitters, the two-dimensional array of light emitters being aligned to project light beams into a field outside an optical system according to an illumination pattern, wherein each light beam in the illumination pattern represents a non-overlapping field of view within the field, the two-dimensional array of light emitters comprising a plurality of emitter groups aligned side-by-side, wherein each emitter group comprises a subset of emitters in the two-dimensional array of light emitters and is capable of operating independently to emit light from its emitter subset; Multiple pixels having non-overlapping fields of view, the multiple pixels being operable to detect photons emitted from a two-dimensional array of light emitters and reflected from a surface within the field, wherein each of the multiple pixels is aligned to sense light from a corresponding light emitter among the multiple light emitters; A transmitter array driving circuit coupled to the plurality of transmitter groups is configured to electronically scan a two-dimensional array of the light emitters to perform a plurality of emission cycles, wherein during each emission cycle, the transmitter array driving circuit activates only one of the plurality of transmitter groups at a time according to a triggering order, wherein each of the plurality of transmitter groups is activated during one emission cycle until the illumination pattern is generated; and A sensor array readout circuit, coupled to the plurality of pixels and configured to synchronize the readout of each pixel within the plurality of pixels corresponding to the transmitters in the activated transmitter group simultaneously with the triggering of each light transmitter group, such that each pixel of the plurality of pixels can be read out over one emission cycle.

11. The solid-state electronic scanning optical ranging device according to claim 10, wherein each of the plurality of pixels comprises a plurality of single-photon avalanche diodes (SPADs), and wherein the two-dimensional array of the optical emitter comprises a plurality of vertical-cavity surface-emitting lasers (VCSELs).

12. The solid-state electronic scanning optical ranging device of claim 10, wherein the two-dimensional array of the optical emitter is formed by a plurality of semiconductor dies, and the emitter array driving circuit includes a plurality of drivers, wherein each of the plurality of drivers is directly mounted to the surface of one of the semiconductor dies.

13. The solid-state electronic scanning optical ranging device according to claim 10, wherein the two-dimensional array of the optical emitters is formed by a single semiconductor die, and the emitter array driving circuit is directly mounted to the semiconductor die.

14. The solid-state electronic scanning optical ranging device according to claim 10, wherein: Each of the multiple groups comprises x columns, and the transmitter array drive circuit is configured to activate each of the multiple groups x times during a single transmission cycle; as well as Each time a specific group is activated in a single transmission cycle, the sensor array readout circuit synchronizes with the transmitter array drive circuit to read out the column in the sensor array corresponding to the activated group.

15. The solid-state electronic scanning optical ranging device according to any one of claims 10 to 14, wherein the system calculates the distance to an object in the field based on the time elapsed between the reflection of an optical pulse emitted from the plurality of optical emitters and the reflection of a pulse detected by a pixel of the plurality of pixels.

16. A solid-state electronic scanning optical ranging device, wherein the solid-state electronic scanning optical ranging device does not include a rotating column or a galvanometer mirror, and the solid-state electronic scanning optical ranging device comprises: An optical transmission module, the optical transmission module comprising: The main body emitter optics are telecentric in the image space; A semiconductor emitter array comprising a two-dimensional array of light emitters aligned to project light beams through body emitter optics into a field outside an optical system according to an illumination pattern, wherein each light beam in the illumination pattern represents a non-overlapping field of view within the field, the two-dimensional array of light emitters comprising a plurality of emitter subsets, wherein each emitter subset comprises a plurality of emitters and is operable independently of other emitter subsets to emit light from its plurality of emitters; and A transmitter array driving circuit coupled to the plurality of transmitter subsets, the transmitter array driving circuit being configured to electronically scan a two-dimensional array of the light emitters to perform a plurality of emission cycles, wherein during each emission cycle, the transmitter array driving circuit activates only one subset of the plurality of transmitter subsets at a time according to a triggering sequence, wherein each subset of the plurality of transmitter subsets is activated during one emission cycle until the illumination pattern is generated; and A light sensing module, wherein the light sensing module is configured to be adjacent to the light transmission module, the light sensing module comprising: A body imaging optics device, wherein the body imaging optics device is telecentric in image space; A sensor layer comprising an array of pixels having a non-overlapping field of view, the array of pixels being operable to detect photons emitted from a two-dimensional array of light emitters, reflected from a surface within the field, and received by a body imaging optics, wherein each pixel comprises an array of single-photon avalanche diodes (SPADs) and is paired with a corresponding light emitter in the two-dimensional array of light emitters. A filter, disposed between the body imaging optics and the sensor layer, wherein the filter allows a narrow band of light wavelengths to pass through while blocking light outside the narrow band from reaching multiple pixels, the narrow band including the operating wavelength of the emitter array; and A sensor array readout circuit, coupled to the array of pixels and configured to synchronize the readout of each pixel in the array simultaneously with the triggering of a subset of transmitters, such that each pixel in the array of pixels is read out only once in each emission cycle.

17. The solid-state electronic scanning optical ranging device according to claim 16, wherein, During each emission cycle, each subset of the transmitter is activated x times, and each time a subset of the transmitter is activated, 1 / x of the pixels corresponding to the subset of the transmitter in the activated group are read out.

18. The solid-state electronic scanning optical ranging device according to claim 16, wherein the two-dimensional array of the optical emitter comprises a plurality of vertical cavity surface emitting lasers (VCSELs).

19. The solid-state electronic scanning optical ranging device according to any one of claims 16 to 18, wherein the system calculates the distance to an object in the field based on the time elapsed between the reflection of an optical pulse emitted from the plurality of optical emitters and the reflection of a pulse detected by a pixel of the plurality of pixels.

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