Scanning lidar with flood illumination for near-field detection
A LiDAR sensor includes a first lens, a first laser source configured to emit a plurality of first light pulses to be collimated by the first lens, a flood illumination source configured to emit a plurality of second light pulses as diverging light rays, a second lens configured to receive and focus (i) a portion of any one of the plurality of first light pulses and (ii) a portion of any one of the plurality of second light pulses that are reflected off of the one or more objects, a detector configured to detect (i) the portion of any one of the plurality of first light pulses and (ii) the portion of any one of the plurality of second light pulses, and a processor configured to construct a three-dimensional image of the one or more objects based on the detected portions of first light pulses and second light pulses.
1. A LiDAR sensor comprising:
a first lens defining a first optical axis;
a first laser source disposed substantially at a focal plane of the first lens, and configured to emit a plurality of first light pulses to be collimated by the first lens and directed toward a field of view of the LiDAR sensor;
a flood illumination source configured to emit a plurality of second light pulses as diverging light rays directed toward the field of view of the LiDAR sensor;
a second lens defining a second optical axis substantially parallel to the first optical axis, the second lens configured to:
receive and focus a portion of any one of the plurality of first light pulses that is reflected off of one or more objects in the field of view onto a focal plane of the second lens; and
receive and focus a portion of any one of the plurality of second light pulses that is reflected off of the one or more objects in the field of view onto the focal plane of the second lens;
a detector disposed substantially at the focal plane of the second lens, the detector configured to detect (i) the portion of any one of the plurality of first light pulses that is reflected off of the one or more objects, and (ii) the portion of any one of the plurality of second light pulses that is reflected off of the one or more objects; and
a processor communicatively coupled to the first laser source, the flood illumination source, and the detector, the processor configured to construct a three-dimensional image of the one or more objects based on the portion of any one of the plurality of first light pulses, emitted by the first laser source and reflected off the one or more objects in the field of view, and the portion of any one of the plurality of second light pulses, emitted by the flood illumination source and reflected off the one or more objects in the field of view, detected by the detector.
2. The LiDAR sensor of claim 1 wherein optical paths of the plurality of second light pulses emitted by the flood illumination source do not intercept the first lens or the second lens before being reflected off of the one or more objects.
3. The LiDAR sensor of claim 1 wherein the flood illumination source is disposed between the first lens and the second lens in a lateral direction perpendicular to the first optical axis.
4. The LiDAR sensor of claim 1 wherein the flood illumination source comprises a laser or a light-emitting diode (LED).
5. The LiDAR sensor of claim 1 wherein the portion of any one of the plurality of second light pulses includes a portion of at least one of the plurality of second light pulses that is reflected off of a first object among the one or more objects, and the first object is within about 10 meters from the LiDAR sensor.
6. The LiDAR sensor of claim 1 wherein the first laser source is configured to be translated in the focal plane of the first lens, and the detector is configured to be translated in the focal plane of the second lens synchronously with the translation of the first laser source, so as to scan the plurality of first light pulses across the field of view.
7. The LiDAR sensor of claim 1 further comprising:
a housing, wherein the first lens, the second lens, the first laser source, the flood illumination source, and the detector are attached to the housing; and
a drive mechanism configured to rotate the housing about one or two axes, so as to scan the LiDAR sensor across the field of view.
8. The LiDAR sensor of claim 1 further comprising:
a mirror configured to reflect the plurality of first light pulses emitted by the first laser source toward the field of view; and
a drive mechanism configured to rotate the mirror about one or two axes, so as to scan the LiDAR sensor across the field of view.
9. The LiDAR sensor of claim 8 wherein the mirror is further configured to reflect the plurality of second light pulses emitted by the flood illumination source toward the field of view.
10. The LiDAR sensor of claim 8 wherein the flood illumination source is disposed in a position so that the plurality of second light pulses emitted by the flood illumination source is directed toward the field of view without being reflected by the mirror.
11. A method of operating a LiDAR sensor, the method comprising:
emitting, using a first laser source, a plurality of first light pulses;
collimating, using a first lens, the plurality of first light pulses so that the plurality of first light pulses are directed toward a field of view of the LiDAR sensor, the first lens defining a first optical axis;
emitting, using a flood illumination source, a plurality of second light pulses as diverging light rays directed toward the field of view of the LiDAR sensor;
focusing, using a second lens defining a second optical axis substantially parallel to the first optical axis, (i) a portion of any one of the plurality of first light pulses that is reflected off of one or more objects in the field of view, and (ii) a portion of any one of the plurality of second light pulses that is reflected off of the one or more objects in the field of view, onto a detection plane;
detecting, using a detector positioned at the detection plane, (i) the portion of any one of the plurality of first light pulses emitted by the first laser source that is reflected off of the one or more objects, and (ii) the portion of any one of the plurality of second light pulses emitted by the flood illumination source that is reflected off of the one or more objects; and
constructing a three-dimensional image of the one or more objects based on the portion of any one of the plurality of first light pulses and the portion of any one of the plurality of second light pulses detected by the detector.
12. The method of claim 11 wherein optical paths of the plurality of second light pulses emitted by the flood illumination source do not intercept the first lens or the second lens before being reflected off of the one or more objects.
13. The method of claim 11 wherein the portion of any one of the plurality of second light pulses includes a portion of at least one of the plurality of second light pulses that is reflected off of a first object among the one or more objects, and the first object is within about 10 meters from the LiDAR sensor.
14. The method of claim 11 wherein the plurality of first light pulses and the plurality of second light pulses are emitted synchronously, so that each respective first light pulse and each corresponding second light pulse are emitted simultaneously.
15. The method of claim 11 wherein the plurality of first light pulses and the plurality of second light pulses are emitted synchronously, so that each respective second light pulse is emitted after each corresponding first light pulse is emitted with a time delay that is less than a detection time interval.
16. The method of claim 11 wherein the plurality of first light pulses and the plurality of second light pulses are emitted synchronously, so that each respective first light pulse is emitted after each corresponding second light pulse is emitted with a time delay that is less than a detection time interval.
17. The method of claim 11 wherein the plurality of first light pulses and the plurality of second light pulses are emitted in a timing pattern so that, in each detection time interval, only one of the plurality of first light pulses or one of the plurality of second light pulses is emitted.
18. The method of claim 11 further comprising:
translating the first laser source in an emission plane so as to scan the plurality of first light pulses across the field of view; and
translating the detector in the detection plane synchronously with the translation of the first laser source.
19. The method of claim 11 wherein the first lens, the second lens, the first laser source, the flood illumination source, and the detector are attached to a housing, and the method further comprising:
rotating the housing about one or two axes, so as to scan the LiDAR sensor across the field of view.
20. The method of claim 11 wherein the LiDAR sensor comprises a mirror configured to reflect the plurality of first light pulses toward the field of view, and the method further comprising:
scanning the mirror about one or two axes, so as to scan the LiDAR sensor across the field of view.