Abstract: A lidar system comprises a light source configured to emit light, a scanner configured to direct the emitted light to scan a field of regard of the lidar system in accordance with a scan pattern, a receiver configured to detect the light scattered by one or more remote targets, and a controller configured to control motion of at least the second mirror to modify the scan pattern. The scanner includes a rotatable polygon mirror having a block having a first wall, a second wall, and reflective surfaces extending between the first and second walls, the reflective surfaces being angularly offset from one another along a periphery of the block. The scanner also includes a polygon mirror axle extending into the block through at least one of the first and second walls, about which the block rotates, and a second mirror pivotable along an axis orthogonal to the polygon mirror axle.

Abstract: To compensate for the uneven distribution of data points around the periphery of a vehicle in a lidar system, a light source transmits light pulses at a variable pulse rate according to the orientation of the light pulses with respect to the lidar system. A controller may communicate with a scanner in the lidar system that provides the orientations of the light pulses to the controller. The controller may then provide a control signal to the light source adjusting the pulse rate based on the orientations of the light pulses. For example, the pulse rate may be slower near the front of the lidar system and faster near the periphery. In another example, the pulse rate may be faster near the front of the lidar system and slower near the periphery.

Abstract: A lidar system is disclosed. The lidar system can include a light source to produce first and second sets of pulses of light. The system can also include a first lidar sensor with a first scanner to scan the first set of pulses of light along a first scan pattern, and a first receiver to detect scattered light from the first set of pulses of light. The system can also include a second lidar sensor with a second scanner to scan the second set of pulses of light along a second scan pattern, and a second receiver to detect scattered light from the second set of pulses of light. The first scan pattern and the second scan pattern can be at least partially overlapped in an overlap region. The lidar system can also include an enclosure to contain the light source, the first lidar sensor, and the second lidar sensor.

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 along a scan pattern contained within an adjustable field of regard. The scanner includes a first scanning mirror configured to scan the portion of the emitted pulses of light substantially parallel to a first scan axis to produce multiple scan lines of the scan pattern, where each scan line is oriented substantially parallel to the first scan axis. The scanner also includes a second scanning mirror configured to distribute the scan lines along a second scan axis that is substantially orthogonal to the first scan axis, where the scan lines are distributed within the adjustable field of regard according to an adjustable second-axis scan profile.

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.

Abstract: To detect light from light pulses at the operating wavelength of a light source in a lidar system, a thin-film notch filter is directly deposited on a photodetector or a lens via vacuum deposition or monolithic epoxy. The thin-film notch filter may include an anti-reflective coating such as a pattern-coated dichroic filter having an optical transmission of 90% or greater at in-band wavelengths and less than 5% at out-of-band wavelengths. To deposit the filter onto the photodetector without disrupting electronic connections between the photodetector and an application-specific integrated circuit, the area surrounding the electrodes on the photodetector is kept open using photolithography.

Abstract: To detect light from light pulses at the operating wavelength of a light source in a lidar system, a thin-film notch filter is directly deposited on a photodetector or a lens via vacuum deposition or monolithic epoxy. The thin-film notch filter may include an anti-reflective coating such as a pattern-coated dichroic filter having an optical transmission of 90% or greater at in-band wavelengths and less than 5% at out-of-band wavelengths. To deposit the filter onto the photodetector without disrupting electronic connections between the photodetector and an application-specific integrated circuit, the area surrounding the electrodes on the photodetector is kept open using photolithography.

Abstract: A lidar system operating in a vehicle comprising a first eye configured to scan a first field of regard and a second eye configured to scan a second field of regard. Each of the first eye and the second eye includes a respective optical element configured to output a beam of light, a respective scan mirror configured to scan the beam of light along a vertical dimension of the respective field of regard, and a respective receiver configured to detect scattered light from the beam of light. The field of regard of the lidar system includes the first field of regard and the second field of regard, combined along a horizontal dimension of the first field of regard and the second field of regard.

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: 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 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 compensate for the uneven distribution of data points around the periphery of a vehicle in a lidar system, a light source transmits light pulses at a variable pulse rate according to the orientation of the light pulses with respect to the lidar system. A controller may communicate with a scanner in the lidar system that provides the orientations of the light pulses to the controller. The controller may then provide a control signal to the light source adjusting the pulse rate based on the orientations of the light pulses. For example, the pulse rate may be slower near the front of the lidar system and faster near the periphery. In another example, the pulse rate may be faster near the front of the lidar system and slower near the periphery.

Abstract: A lidar system includes one or more light sources configured to emit light pulses, a scanner configured to direct the emitted light pulses as beams along one or more scan directions to illuminate, for each orientation of the scanner with each of the plurality of beams, a respective light-source field of view corresponding to a respective pixel, and a receiver configured to detect the light pulses scattered by one or more remote targets. The receiver includes a first, second, and third detectors to detect light pulses associated with respective beams. Each detector has a separate detector field of view within which the detector receives scattered light. A spatial separation between the first detector and the second detector is greater than a spatial separation between the second detector and the third detector.

Abstract: To compensate for motor dynamics in a scanner in a lidar system, a light source transmits light pulses at a variable pulse rate in accordance with a scan speed of the scanner. More specifically, the pulse rate may be directly related to the scan speed so that the light source transmits light pulses uniformly across a field of regard. A controller may determine the scan speed and provide a control signal to the light source adjusting the pulse rate accordingly.

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 lidar system includes a light source configured to emit light pulses and a receiver configured to detect light from some of the light pulses scattered by remote targets. The receiver includes an avalanche photodiode operating in the linear mode for detecting the light pulses. To prevent damage to the linear mode avalanche photodiode a quench circuit is coupled to the avalanche photodiode, where the quench circuit reduces a bias voltage applied to the avalanche photodiode, when an avalanche event occurs at the avalanche photodiode.