Multiple pixel scanning LIDAR
Methods and systems for performing three dimensional LIDAR measurements with multiple illumination beams scanned over a three dimensional environment are described herein. In one aspect, illumination light from each LIDAR measurement channel is emitted to the surrounding environment in a different direction by a beam scanning device. The beam scanning device also directs each amount of return measurement light onto a corresponding photodetector. In some embodiments, a beam scanning device includes a scanning mirror rotated in an oscillatory manner about an axis of rotation by an actuator in accordance with command signals generated by a master controller. In some embodiments, the light source and photodetector associated with each LIDAR measurement channel are moved in two dimensions relative to beam shaping optics employed to collimate light emitted from the light source. The relative motion causes the illumination beams to sweep over a range of the three dimensional environment under measurement.
1. A light detection and ranging (LIDAR) device, comprising:
a plurality of pulsed illumination sources each emitting a pulse of illumination light from the LIDAR device in different directions into a three dimensional environment;
a plurality of photosensitive detectors each detecting an amount of return light reflected from the three dimensional environment illuminated by each pulse of illumination light and generating an output signal indicative of the detected amount of return light associated with each pulse of illumination light;
a beam scanning device disposed in an optical path between the plurality of pulsed illumination sources and the three dimensional environment under measurement and between the plurality of photosensitive detectors and the three dimensional environment under measurement, the beam scanning device configured to redirect each pulse of illumination light with respect to each of the plurality of pulse illumination sources and each of the plurality of photosensitive detectors in response to a command signal; and
a computing system configured to:
receive each output signal indicative of the detected amount of light; and
determine a distance between the LIDAR device and an object in the three dimensional environment based on a difference between a time when each pulse is emitted from the LIDAR device and a time when each photosensitive detector detects an amount of light reflected from the object illuminated by the pulse of illumination light.
2. The LIDAR device of claim 1 , further comprising:
one or more beam shaping optical elements disposed in the optical path between the beam scanning device and the plurality of pulsed illumination sources and between the beam scanning device and the plurality of photosensitive elements.
3. The LIDAR device of claim 1 , wherein the beam scanning device includes one or more beam shaping optical elements.
4. The LIDAR device of claim 1 , wherein a first range of the three dimensional environment measured by a sequence of pulses of illumination light emitted by a first pulsed illumination source of the plurality of pulsed illumination sources light and scanned over the first range by the beam scanning device spatially overlaps a second range of the three dimensional environment measured by a sequence of pulses of illumination light emitted by a second pulsed illumination source of the plurality of pulsed illumination sources light and scanned over the second range by the beam scanning device.
5. The LIDAR device of claim 1 , wherein the beam scanning device includes a mirror element rotated by an actuator about an axis of rotation.
6. The LIDAR device of claim 5 , wherein the mirror element is rotated about that axis of rotation with an oscillatory angular velocity.
7. The LIDAR device of claim 6 , wherein the oscillatory angular velocity tracks a sinusoidal profile.
8. The LIDAR device of claim 5 , wherein the plurality of pulsed illumination sources are disposed in a plane parallel to the axis of rotation.
9. The LIDAR device of claim 5 , wherein the plurality of pulsed illumination sources are disposed in a plane perpendicular to the axis of rotation.
10. The LIDAR device of claim 3 , wherein the one or more beam shaping optical elements are translated in a first direction parallel to an optical plane of the one or more beam shaping optical elements.
11. The LIDAR device of claim 10 , wherein the plurality of pulsed illumination sources are translated in a second direction parallel to the optical plane of the one or more beam shaping elements, wherein the first and second directions are different directions.
12. The LIDAR device of claim 1 , wherein the command signal is generated by the computing system.
13. A light detection and ranging (LIDAR) device, comprising:
a plurality of pulsed illumination sources each emitting a pulse of illumination light from the LIDAR device in different directions into a three dimensional environment;
a plurality of photosensitive detectors each detecting an amount of return light reflected from the three dimensional environment illuminated by each pulse of illumination light and generating an output signal indicative of the detected amount of return light associated with each pulse of illumination light;
a beam scanning device disposed in an optical path between the plurality of pulsed illumination sources and the three dimensional environment under measurement and between the plurality of photosensitive detectors and the three dimensional environment under measurement, the beam scanning device configured to redirect each pulse of illumination light with respect to each of the plurality of pulse illumination sources and each of the plurality of photosensitive detectors in response to a command signal; and
a non-transient computer-readable medium comprising computer-readable instructions that when read by a computing system cause the computing system to:
receive each output signal indicative of the detected amount of light; and
determine a distance between the LIDAR device and an object in the three dimensional environment based on a difference between a time when each pulse is emitted from the LIDAR device and a time when each photosensitive detector detects an amount of light reflected from the object illuminated by the pulse of illumination light.
14. The LIDAR device of claim 13 , further comprising:
one or more beam shaping optical elements disposed in the optical path between the beam scanning device and the plurality of pulsed illumination sources and between the beam scanning device and the plurality of photosensitive elements.
15. The LIDAR device of claim 13 , wherein the beam scanning device includes one or more beam shaping optical elements.
16. The LIDAR device of claim 13 , wherein a first range of the three dimensional environment measured by a sequence of pulses of illumination light emitted by a first pulsed illumination source of the plurality of pulsed illumination sources light and scanned over the first range by the beam scanning device spatially overlaps a second range of the three dimensional environment measured by a sequence of pulses of illumination light emitted by a second pulsed illumination source of the plurality of pulsed illumination sources light and scanned over the second range by the beam scanning device.
17. The LIDAR device of claim 13 , wherein the beam scanning device includes a mirror element rotated by an actuator about an axis of rotation.
18. The LIDAR device of claim 15 , wherein the one or more beam shaping optical elements are translated in a first direction parallel to an optical plane of the one or more beam shaping optical elements, and wherein the plurality of pulsed illumination sources are translated in a second direction parallel to the optical plane of the one or more beam shaping elements, wherein the first and second directions are different directions.
19. A method comprising:
emitting a plurality of pulses of illumination light into a three dimensional environment from a plurality of pulsed illumination sources, wherein each of the plurality of pulses of illumination light are incident on a beam scanning device;
redirecting each of the plurality of pulses in a different direction with respect to each of the plurality of pulse illumination sources in response to a command signal communicated to the beam scanning device based on an optical interaction between each pulse of illumination light and the beam scanning device;
redirecting an amount of return light reflected from the three dimensional environment illuminated by each pulse of illumination light based on an optical interaction between each amount of return light and the beam scanning device;
detecting each amount of return light reflected from the three dimensional environment illuminated by each pulse of illumination light;
generating an output signal indicative of the detected amount of return light associated with each pulse of illumination light; and
determining a distance between the plurality of pulsed illumination sources and an object in the three dimensional environment based on a difference between a time when each pulse is emitted from the LIDAR device and a time when each photosensitive detector detects an amount of light reflected from the object illuminated by the pulse of illumination light.
20. The method of claim 19 , wherein the redirecting of each of the plurality of pulses and the redirecting of each amount of return light reflected from the three dimensional environment involves a mirror element rotated by an actuator about an axis of rotation.