Abstract: In one embodiment, a lidar system includes a light source configured to emit a pulse of light and a scanner configured to direct the emitted pulse of light into a field of regard of the lidar system. The lidar system also includes a receiver configured to receive a portion of the emitted pulse of light scattered by a target located a distance from the lidar system. The receiver includes a digital micromirror device (DMD) that includes a two-dimensional array of electrically addressable micromirrors, where a portion of the micromirrors are configured to be set to an active-on state to direct the received pulse of light to a detector array. The detector array includes a two-dimensional array of detector elements, where the detector array is configured to detect the received pulse of light and produce an electrical signal corresponding to the received pulse of light.

Abstract: A detector system within a lidar receiver is configured to compensate for range walk error by detecting both the rising edge and the falling edge of a received light pulse as the envelope of the received light pulse passes through a particular detection (magnitude) threshold. Detection circuitry within the detector system then determines the center of the received light pulse as the point equidistant in time between the detected rising and falling edges of the received light pulse, and uses the time associated with the center of the received light pulse to determine the range to the target from which the scattered light pulse was received.

Abstract: A lidar system includes a transmitter that encodes successive transmit pulses with different pulse characteristics and a receiver that detects the pulse characteristics of each received (scattered or reflected) pulse and that distinguishes between the received pulses based on the detected pulse characteristics. The lidar system thus resolves range ambiguities by encoding pulses of scan positions in the same or different scan periods to have different pulse characteristics, such as different pulse widths or different pulse envelope shapes. The receiver includes a pulse decoder configured to detect the relevant pulse characteristics of the received pulse and a resolver that determines if the pulse characteristics of the received pulse matches the pulse characteristics of the current scan position or that of a previous scan position.

Abstract: A system includes a lidar, a camera, and a controller communicatively coupled to the camera and the lidar. The lidar includes a laser configured to emit pulses of light, a scanner configured to direct the emitted pulses in accordance with a scan pattern, and a receiver configured to detect the emitted pulse of light scattered by one or more remote targets to collect a set of lidar pixels of a scan frame, in a sequence defined by the scan pattern. The camera has a field of regard that at least partially overlaps the field of regard of the lidar. The controller is configured to cause the camera to capture images while the receiver of the lidar module collects the complete set of lidar pixels of the scan frame, and align lidar pixels with corresponding pixels in the captured images.

Abstract: A lidar system includes a lighting module configured to (i) select a wavelength from among a plurality of wavelength values, for a particular time period, and (ii) emit light at the selected wavelength. The lighting module emits light at different wavelengths during at least two adjacent periods of time. The lidar system further includes a scanner configured to direct the pulse of light to illuminate a respective region within a field of regard of the lidar system and a receiver module configured to (i) receive a light signal and (ii) determine whether the received light signal includes the light emitted by the lighting module and scattered by a remote target, based at least in part on the wavelength selected by the lighting module.

Abstract: To decrease the likelihood of a false detection when detecting light from light pulses scattered by remote targets in a lidar system, a receiver in the lidar system includes a photodetector and a pulse-detection circuit having a gain circuit with a varying amount of gain over time. The gain circuit operates in a low-gain mode for a time period T1 beginning with time t0 when a light pulse is emitted to prevent the receiver from detecting return light pulses during the threshold time period T1. Upon expiration of the threshold time period T1, the gain circuit operates in a high-gain mode to begin detecting return light pulses until a subsequent light pulse is emitted.

Abstract: A method in a lidar system comprises emitting a pulse of light, detecting at least a portion of the emitted pulse of light scattered by a target located a distance from the lidar system, and determining the distance from the lidar system to the target based at least in part on a round-trip time of flight for the emitted pulse of light to travel from the lidar system to the target and back to the lidar system. The method further comprises emitting a series of pulses of light having particular pulse-frequency characteristics, detecting at least a portion of the series of emitted pulses of light scattered by the target, and comparing the pulse-frequency characteristics of the series of emitted pulses of light with corresponding pulse-frequency characteristics of the detected series of scattered pulses of light to determine a velocity of the target with respect to the lidar system.

Abstract: In one embodiment, a lidar system includes a light source configured to emit pulses of light and a scanner configured to scan at least a portion of the emitted pulses of light across a field of regard. The lidar system also includes a receiver configured to detect at least a portion of the scanned pulses of light scattered by a target located a distance from the lidar system.

Abstract: A method in a lidar system comprises emitting a pulse of light, detecting at least a portion of the emitted pulse of light scattered by a target located a distance from the lidar system, and determining the distance from the lidar system to the target based at least in part on a round-trip time of flight for the emitted pulse of light to travel from the lidar system to the target and back to the lidar system. The method further comprises emitting a series of pulses of light having particular pulse-frequency characteristics, detecting at least a portion of the series of emitted pulses of light scattered by the target, and comparing the pulse-frequency characteristics of the series of emitted pulses of light with corresponding pulse-frequency characteristics of the detected series of scattered pulses of light to determine a velocity of the target with respect to the lidar system.

Abstract: A lidar system includes a transmitter that encodes successive transmit pulses with different pulse characteristics and a receiver that detects the pulse characteristics of each received (scattered or reflected) pulse and that distinguishes between the received pulses based on the detected pulse characteristics. The lidar system thus resolves range ambiguities by encoding pulses of scan positions in the same or different scan periods to have different pulse characteristics, such as different pulse widths or different pulse envelope shapes. The receiver includes a pulse decoder configured to detect the relevant pulse characteristics of the received pulse and a resolver that determines if the pulse characteristics of the received pulse matches the pulse characteristics of the current scan position or that of a previous scan position.

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.

Abstract: In one embodiment, a method for dynamically varying receiver characteristics in a lidar system includes emitting light pulses by a light source in a lidar system. The method further includes detecting, by a receiver in the lidar system, light from one of the light pulses scattered by one or more remote targets to identify a return light pulse. The method also includes determining an atmospheric condition at or near a geolocation of a vehicle that includes the lidar system. The method further includes providing a control signal to the receiver adjusting one or more characteristics of the receiver to compensate for attenuation or distortion of the return light pulses associated with the atmospheric condition.

Abstract: A light source includes a laser configured to emit a ranging pulse including a sequence of fast pulses. A lidar system uses one or more properties of the sequence of fast pulses to determine a signature of the ranging pulse. A receiver includes a detector element configured to detect a light signal and a signature detection circuitry configured to determine whether the detected light signal corresponds to the signature of the emitted ranging pulse. The lidar system is configured to generate a pixel value based on the detected light signal if the detected light signal corresponds to the signature of the emitted ranging pulse.

Abstract: A lidar system identifies anomalous optical pulses received by the lidar system. The lidar system includes a light source configured to output a plurality of transmitted pulses of light, each transmitted pulse of light having one or more representative characteristics, a scanner configured to direct the plurality of transmitted pulses of light to a plurality of locations within a field of regard, and a receiver configured to detect a plurality of received pulses of light from the field of regard. The lidar system is configured to identify an anomalous pulse amongst the plurality of received pulses of light based on its having at least one characteristic that does not correspond to the one or more representative characteristics of the plurality of transmitted pulses of light.

Abstract: A scanning system includes a light source configured to emit light as a series of one or more light pulses, a scanner configured to direct the one or more light pulses towards a remote target, and a receiver configured to detect light scattered by the remote target. The receiver includes a light detector element disposed on an ASIC that includes multiple comparators disposed in parallel with one another, and corresponding time-to-digital converters (TDCs) coupled to the comparator. Each of the comparators processes a received electrical signal from the light detector element to produce a digital edge signal when the amplitude of the received electrical signal reaches a particular threshold. A corresponding TDC outputs a time delay value associated with a time at which the received electrical signal reaches the particular threshold.

Abstract: To detect an atmospheric condition at the current location of a lidar system, a receiver in the lidar system detects a return light pulse scattered by a target and analyzes the characteristics of the return light pulse. The characteristics of the return light pulse include a rise time, a fall time, a duration, a peak power, an amount of energy, etc. When the rise time, fall time, and/or duration exceed respective thresholds, the lidar system detects the atmospheric condition such as fog, sleet, snow, rain, dust, smog, exhaust, or insects. In response to detecting the atmospheric condition, the lidar system adjusts the characteristics of subsequent pulses to compensate for attenuation or distortion of return light pulses due to the atmospheric condition. For example, the lidar system adjusts the peak power, pulse energy, pulse duration, inter-pulse-train spacing, number of pulses, or any other suitable characteristic.

Abstract: A method for calibrating lidar systems operating in vehicles includes detecting a triggering event, causing the lidar system to not emit light during a calibration period, determining an amount of noise measured by the lidar system during the calibration period, generating a noise level metric based on the amount of noise detected during the calibration period, and adjusting subsequent readings of the lidar system using the noise level metric. The adjusting includes measuring energy levels of return light pulses emitted from the lidar system and scattered by targets and offsetting the measured energy levels by the noise level metric.

Abstract: To decrease the likelihood of a false detection when detecting light from light pulses scattered by remote targets in a lidar system, a receiver in the lidar system includes a photodetector and a pulse-detection circuit having a gain circuit with a varying amount of gain over time. The gain circuit operates in a low-gain mode for a time period T1 beginning with time t0 when a light pulse is emitted to prevent the receiver from detecting return light pulses during the threshold time period T1. Upon expiration of the threshold time period T1, the gain circuit operates in a high-gain mode to begin detecting return light pulses until a subsequent light pulse is emitted.

Abstract: In one embodiment, a lidar system includes a light source configured to emit pulses of light and a scanner configured to scan at least a portion of the emitted pulses of light across a field of regard. The lidar system also includes a receiver configured to detect at least a portion of the scanned pulses of light scattered by a target located a distance from the lidar system.

Abstract: To decrease the likelihood of a false detection when detecting light from light pulses scattered by remote targets in a lidar system, a receiver in the lidar system includes a photodetector and a pulse-detection circuit having a gain circuit with a varying amount of gain over time. The gain circuit operates in a low-gain mode for a time period T1 beginning with time t0 when a light pulse is emitted to prevent the receiver from detecting return light pulses during the threshold time period T1. Upon expiration of the threshold time period T1, the gain circuit operates in a high-gain mode to begin detecting return light pulses until a subsequent light pulse is emitted.