FIELD OF TECHNOLOGY

This disclosure generally relates to lidar systems and, more particularly, photodetectors that can be used in such systems.

BACKGROUND

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Light detection and ranging (lidar) is a technology that can be used to measure distances to remote targets. Typically, a lidar system includes a light source and an optical receiver. The light source can be, for example, a laser which emits light having a particular operating wavelength. The operating wavelength of a lidar system may lie, for example, in the infrared, visible, or ultraviolet portions of the electromagnetic spectrum. The light source emits light toward a target which then scatters the light. Some of the scattered light is received back at the receiver. The system determines the distance to the target based on one or more characteristics associated with the returned light. For example, the system may determine the distance to the target based on the time of flight of a returned light pulse.

SUMMARY

According to the techniques of this disclosure, a light source, a scanner, and a receiver with a light detector in a lidar system are configured to define certain advantageous relationships between the light-detector field of view (FOV), which corresponds to an area illuminated by the light source, the instantaneous light-detector field of view (FOV), which corresponds to an area illuminated by the light source at a time when the light source emits a pulse of light, and the detector FOV, which corresponds to an angular region over which the detector is configured to receive scattered light. The techniques can include sizing the detector FOV relative to the light-source FOV in a certain manner, moving the detector FOV relative to the instantaneous light-source FOV according to a particular scheme, controlling the overlap between the detector FOV and the light-source FOV in a certain manner, etc.

In one implementation, a lidar system includes a light source configured to emit pulses of light along a light-source field of view (FOV), a scanner configured to scan a field of regard (FOR) of the light source and direct the pulses of light along a scan direction, where each of the pulses illuminates a respective instantaneous light-source FOV which corresponds to the light-source FOV at a time when the pulse is emitted, and a receiver configured to detect the pulses of light scattered by one or more remote targets. The receiver includes a detector with a detector field of view that corresponds to an angular region over which the detector is configured to receive scattered light. The light-source field of view is smaller than the detector field-of view. The system is configured to detect remote targets located up to RMAXmeters away. The scanner causes the detector field of view to move relative to the instantaneous light-source field of view along the scan direction, so that (i) when a pulse of light is emitted, the instantaneous light-source field of view is approximately centered within the detector field of view, and (ii) when a scattered pulse of light returns from a target located RMAXmeters away, the instantaneous light-source field of view is located near an edge of the field of view of the detector.

Another implementation of these techniques is a method in a lidar system for scanning a field of regard of the lidar system configured to detect remote targets located up to RMAXmeters away. The method includes generating a light pulse for each of multiple different scanning positions of scanner along a scan direction, where each of the generated pulses illuminates a respective instantaneous light-source field of view (FOV) which corresponds to a light-source FOV at a time when the pulse is emitted. The method also includes receiving scattered light pulses scattered from one or more remote targets in at least some of the different scanning positions, using a detector with a detector FOV that corresponds to an angular region over which the detector is configured to receive scattered light. The light-source FOV is smaller than the detector FOV. Receiving the scattered light pulses includes causing the detector FOV to move relative to the instantaneous light-source FOV along the scan direction, so that (i) when a pulse of light is emitted, the instantaneous light-source FOV is approximately centered within the detector FOV, and (ii) when a scattered pulse of light returns from a target located RMAXmeters away, the instantaneous light-source FOV is located near an edge of the detector FOV.

Yet another embodiment of these techniques is a lidar system including a light source configured to emit pulses of light along a light-source field of view (FOV), a scanner configured to scan a field of regard (FOR) of the light source and direct the pulses of light along a scan direction, where each of the pulses illuminates a respective instantaneous light-source FOV which corresponds to the light-source FOV at a time when the pulse is emitted, and a receiver configured to detect the pulses of light scattered by one or more remote targets. The receiver includes a detector with a detector FOV that corresponds to an angular region over which the detector is configured to receive scattered light. The system is configured to detect remote targets located up to RMAXmeters away. The scanner causes the detector FOV to move relative to the instantaneous light-source FOV along the scan direction so that an amount of overlap between the instantaneous light-source FOV and the detector FOV is different at two or more instances of time in an interval between (i) when a pulse of light is emitted and (ii) when a scattered pulse of light returns from a target located RMAXmeters away.

Still another embodiment of these techniques is a method in a lidar system for scanning a field of regard of the lidar system configured to detect remote targets located up to RMAXmeters away. The method includes generating a light pulse for each of multiple different scanning positions of scanner along a scan direction, where each of the generated pulses illuminates a respective instantaneous light-source field of view (FOV) which corresponds to a light-source FOV at a time when the pulse is emitted. The method also includes receiving scattered light pulses scattered from one or more remote targets in at least some of the different scanning positions, using a detector with a detector FOV that corresponds to an angular region over which the detector is configured to receive scattered light. Receiving the scattered light pulses includes causing the detector FOV to move relative to the instantaneous light-source FOV along the scan direction, so that an amount of overlap between the instantaneous light-source FOV and the detector FOV is different at two or more instances of time in an interval between (i) when a pulse of light is emitted and (ii) when a scattered pulse of light returns from a target located RMAXmeters away.

