# US 11,029,406 B2 · Lidar system with AlInAsSb avalanche photodiode > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,406 B2 - Document ID: US11029406B2 - Status: Granted - Kind: B2 - Application number: 15/947,308 - Filed: 2018-04-06 - Published: 2019-10-10 - Granted: 2021-06-08 - Earliest claimed: 2018-04-06 - Assignees: Luminar, LLC - Applicants: Luminar, LLC - Inventors: Joseph G. LaChapelle - Web page: https://patentgrep.com/patent/US11029406B2 ## CPC - G01S 17/08: for measuring distance only (indirect measurement G01S17/46; active triangulation systems G01S17/48) - G02B 26/101: {with both horizontal and vertical deflecting means, e.g. raster or XY scanners (colour television using laser beams scanning a display screen H04N9/3129)} - G01S 7/4817: {relating to scanning} - G01S 7/484: Transmitters - G01S 7/4861: Circuits for detection, sampling, integration or read-out - G01S 17/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) - G01S 17/93: for anti-collision purposes - G01S 17/931: of land vehicles - G02B 27/0977: {Reflective elements} - H10F 30/2255: {in which the active layers form heterostructures, e.g. SAM structures} - H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors - H10F 77/1248: {having three or more elements, e.g. GaAlAs, InGaAs or InGaAsP} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION ## Abstract In one embodiment, a lidar system includes a light source configured to emit pulses of light and a scanner configured to scan the emitted pulses of light across a field of regard of the lidar system. The lidar system also includes a receiver configured to detect a portion of the emitted pulses of light scattered by a target located a distance from the lidar system. The receiver includes an aluminum-indium-arsenide-antimonide (AlInAsSb) avalanche photodiode (APD) configured to: receive a pulse of light of the portion of the emitted pulses of light scattered by the target and produce an electrical-current pulse corresponding to the received pulse of light. The lidar system further includes a processor configured to determine the distance from the lidar system to the target based at least in part on a round-trip time of flight for the received pulse of light. ## Claims ### Claim 1 A lidar system comprising: a light source configured to emit pulses of light along a field of view of the light source; a scanner configured to scan the field of view of the light source and a field of view of a receiver across a field of regard of the lidar system, wherein: the light-source field of view and the receiver field of view are scanned in a scan direction across the field of regard at approximately equal scanning speeds; and the receiver field of view is offset from the light-source field of view in a direction opposite the scan direction; the receiver, wherein the receiver is configured to detect a portion of the emitted pulses of light scattered by a target located a distance from the lidar system, wherein the receiver comprises: an aluminum-indium-arsenide-antimonide (AlInAsSb) avalanche photodiode (APD) configured to: receive a pulse of light of the portion of the emitted pulses of light scattered by the target; and produce an electrical-current pulse corresponding to the received pulse of light; and a pulse-detection circuit configured to receive the electrical-current pulse from the AlInAsSb APD, wherein the pulse-detector circuit comprises: a transimpedance amplifier configured to produce a voltage pulse that corresponds to the electrical-current pulse; a voltage amplifier configured to amplify the voltage pulse to produce an amplified voltage pulse; and a comparator configured to produce a digital output signal when the amplified voltage pulse exceeds a particular threshold voltage; and a processor configured to determine the distance from the lidar system to the target based at least in part on a round-trip time of flight for the received pulse of light to travel from the lidar system to the target and back to the lidar system. ### Claim 2 (depends on 1) The lidar system of claim 1, wherein the AlInAsSb APD has an excess noise factor of less than three. ### Claim 3 (depends on 1) The lidar system of claim 1, wherein a reverse-bias voltage applied to the AlInAsSb APD is greater than 20 volts. ### Claim 4 (depends on 1) The lidar system of claim 1, wherein a gain of the AlInAsSb APD is greater than 10. ### Claim 5 (depends on 1) The lidar system of claim 1, wherein the AlInAsSb APD is configured to detect light having a wavelength between 900 nm and 1700 nm. ### Claim 6 (depends on 1) The lidar system of claim 1, wherein the pulse-detection circuit further comprises a time-to-digital converter (TDC) configured to: receive the digital output signal from the comparator; and determine an interval of time between an emission time when a pulse of light corresponding to the received pulse of light was emitted by the light source and a receipt time when the digital output signal was received by the TDC, wherein the interval of time corresponds to the round-trip time of flight for the received pulse of light to travel from the lidar system to the target and back to the lidar system. ### Claim 7 (depends on 6) The lidar system of claim 6, wherein the emission time when the pulse of light corresponding to the received pulse of light was emitted by the light source is determined from an optical trigger signal associated with detection by the receiver of a portion of the pulse of light which is scattered or reflected from a surface located within the lidar system prior to exiting the lidar system and propagating to the target. ### Claim 8 (depends on 1) The lidar system of claim 1, wherein the light source comprises: a pulsed laser diode configured to produce optical seed pulses; and one or more optical amplifiers configured to amplify the optical seed pulses to produce the emitted pulses of light. ### Claim 9 (depends on 1) The lidar system of claim 1, wherein the light source comprises a direct-emitter laser diode configured to produce the emitted pulses of light. ### Claim 10 (depends on 1) The lidar system of claim 1, wherein each emitted pulse of light has a pulse energy of less than 1 microjoule. ### Claim 11 (depends on 1) The lidar system of claim 1, wherein the emitted pulses of light have pulse characteristics comprising: a wavelength between 900 nm and 1700 nm; a pulse repetition frequency of less than 10 MHz; a pulse duration of less than 100 ns; and a duty cycle of less than 5%. ### Claim 12 (depends on 1) The lidar system of claim 1, wherein the scanner comprises one or more mirrors, wherein each mirror is mechanically driven by a galvanometer scanner, a resonant scanner, a microelectromechanical systems (MEMS) device, a voice coil motor, or a synchronous electric motor. ### Claim 13 (depends on 1) The lidar system of claim 1, wherein the scan direction is a second scan direction, and the scanner comprises: a first mirror driven by a first galvanometer scanner that scans the emitted pulses of light along a first scan direction; and a second mirror driven by a second galvanometer scanner that scans the emitted pulses of light along the second scan direction, wherein the second scan direction is substantially orthogonal to the first scan direction. ### Claim 14 (depends on 1) The lidar system of claim 1, wherein the scan direction is a second scan direction, and the scanner comprises: a first mirror configured to scan the emitted pulses of light along a first scan direction; and a polygon mirror configured to scan the emitted pulses of light along the second scan direction, wherein the second scan direction is substantially orthogonal to the first scan direction. ### Claim 15 (depends on 1) The lidar system of claim 1, wherein the lidar system is incorporated into a vehicle and configured to provide a greater than 60-degree view of an environment around the vehicle. ### Claim 16 (depends on 1) The lidar system of claim 1, wherein the lidar system is configured to generate point clouds at a rate between 0.1 frames per second and 1,000 frames per second. ### Claim 17 (depends on 1) The lidar system of claim 1, wherein the lidar system has a maximum range of greater than 50 meters. ### Claim 18 (depends on 1) The lidar system of claim 1, wherein the field of regard comprises: a horizontal field of regard greater than or equal to 25 degrees; and a vertical field of regard greater than or equal to 5 degrees. ### Claim 19 (depends on 1) The lidar system of claim 1, wherein the lidar system is a Class 1 or Class I laser product configured to operate in an eye-safe manner. ### Claim 20 (depends on 1) The lidar system of claim 1, wherein the comparator is further configured to produce another digital output signal when the amplified voltage pulse falls below the particular threshold voltage. ### Claim 21 (depends on 1) The lidar system of claim 1, wherein the AlInAsSb APD comprises an absorption layer with a composition AlxIn1-xAsySb1-y, wherein x and y each has a value from 0 to 1. ### Claim 22 (depends on 1) The lidar system of claim 1, wherein the AlInAsSb APD comprises an avalanche layer with a composition AlxIn1-xAsySb1-y, wherein x and y each has a value from 0 to 1. ### Claim 23 (depends on 1) The lidar system of claim 1, wherein the receiver field of view is offset from the light-source field of view so that the receiver field of view has an angular overlap with the light-source field of view of less than 50%.