2D scanning high precision LiDAR using combination of rotating concave mirror and beam steering devices
The present disclosure describes a system and method for coaxial LiDAR scanning. The system includes a first light source configured to provide first light pulses. The system also includes one or more beam steering apparatuses optically coupled to the first light source. Each beam steering apparatus comprises a rotatable concave reflector and a light beam steering device disposed at least partially within the rotatable concave reflector. The combination of the light beam steering device and the rotatable concave reflector, when moving with respect to each other, steers the one or more first light pulses both vertically and horizontally to illuminate an object within a field-of-view; obtain one or more first returning light pulses, the one or more first returning light pulses being generated based on the steered first light pulses illuminating an object within the field-of-view, and redirects the one or more first returning light pulses.
1. A light detection and ranging (LiDAR) scanning system, comprising:
a first light source configured to provide one or more first light pulses;
one or more beam steering apparatuses optically coupled to the first light source, each beam steering apparatus comprising an oscillation mirror and a light beam steering device,
wherein the combination of the light beam steering device and the oscillation mirror, when moving with respect to each other, is configured to:
steer the one or more first light pulses both vertically and horizontally to illuminate an object within a field-of-view, wherein the light beam steering device is configured to steer the one or more first light pulses in either a horizontal or vertical direction, and the oscillation mirror is configured to steer the one or more first light pulses in the other direction,
obtain one or more first returning light pulses, the one or more first returning light pulses being generated based on the steered first light pulses illuminating an object within the field-of-view, and
redirect the one or more first returning light pulses to one or more receiving optical systems disposed in the LiDAR scanning system,
and wherein the oscillation mirror is configured to oscillate between two end vertical positions to obtain multiple scanlines in-between.
2. The system of claim 1 , wherein the light beam steering device includes flat or curved surfaces.
3. The system of claim 1 , wherein the light beam steering device comprises a rotatable polyhedron.
4. The system of claim 3 , wherein the rotatable polyhedron comprises a plurality of facets capable of reflecting or redirecting light pulses.
5. The system of claim 1 , wherein the light beam steering device is a one- or multi-facet oscillation mirror that is capable of oscillating back and forth.
6. The system of claim 5 , wherein the one- or multi-facet oscillation mirror comprises one or more facets capable of reflecting or redirecting light pulses.
7. The system of claim 1 , wherein the oscillation mirror includes flat or curved surfaces.
8. The system of claim 1 , wherein the oscillation mirror oscillates about a first axis and wherein the light beam steering device includes a pivot coaxially aligned with a second axis, the second axis being at an angle to the first axis.
9. The system of claim 8 , further comprising:
one or more actuators operatively coupled to the oscillation mirror and the light beam steering device, the one or more actuators being configured to oscillate the oscillation mirror about the first axis at a first velocity and rotate the light beam steering device around the second axis at a second velocity.
10. The system of claim 8 , wherein the angle between the first axis and the second axis is 90°.
11. The system of claim 1 , wherein the one or more first returning light pulses are substantially parallel to the steered first light pulses illuminating the object within the field-of-view.
12. The system of claim 1 , wherein the oscillation mirror is configured to:
generate a plurality of first redirected returning light pulses; and
redirect the first redirected returning light pulses to one or more facets of the light beam steering device.
13. The system of claim 12 , wherein the light beam steering device is configured to:
generate a plurality of second redirected returning light pulses based on the first redirected returning light pulses using the one or more facets of the light beam steering device; and
redirect the plurality of second redirected returning light pulses to the one or more receiving optical systems.
14. The system of claim 13 , wherein at least one of the plurality of second redirected returning light pulses is generated using the same facet of the light beam steering device as the facet that steers the first light pulses.
15. The system of claim 13 , wherein at least one of the plurality of second redirected returning light pulses is generated using a facet of the light beam steering device that is different from the facet that steers the first light pulses.
16. The system of claim 13 , wherein a portion of the light beam steering device that generates the plurality of second redirected returning light pulses has one or more of different flatness, different dimensions, and different number of facets from a portion that steers the one or more first light pulses to illuminate an object within a field-of-view.
17. The system of claim 1 , further comprising:
optical fibers and a beam collimating device, wherein the first light source is optically coupled to the one or more beam steering apparatuses using the optical fibers and the beam collimating device to enable delivering the one or more first light pulses to the light beam steering device.
18. The system of claim 1 , wherein the first light source is further configured to provide one or more second light pulses directed to the beam steering apparatus,
wherein the beam steering apparatus is configured to steer the first light pulses both vertically and horizontally along a first optical path and steer the one or more second light pulses both vertically and horizontally along a second optical path, and
wherein the beam steering apparatus is further configured to obtain, concurrently to the obtaining of the first returning light pulses, one or more second returning light pulses, the second returning light pulses being generated based on the steered second light pulses illuminating a second direction in the second optical path.
19. The system of claim 18 , further comprising: a power controller configured to dynamically control power of the first light pulses according to a cross section area of an aperture associated with the first returning light pulses.
20. The system of claim 18 , further comprising a partial reflection mirror configured to generate the second light pulses using the first light source.
21. The system of claim 1 , wherein each of the one or more receiving optical systems is configured to focus the redirected returning light pulses to a focal point.
22. The system of claim 21 , wherein each of the receiving optical system comprises at least one of:
a refractive optical lens;
a parabolic mirror;
a concave mirror;
a compound optical lens including a plurality of optical elements; and
a compound focusing optics including a parabolic mirror and a refractive optical lens.
23. The system of claim 21 , wherein at least one of the one or more receiving optical systems comprises an optical sensitive device that is capable of detecting optical signals and converting optical signals to electrical signals.
24. The system of claim 23 , wherein the optical sensitive device comprises at least one of:
an optical detecting device configured to convert optical signal to electrical signal; and
an optical fiber configured to redirect the redirected returning light pulses to an optical detecting device that converts optical signal to electrical signal.
25. The system of claim 23 , wherein the optical sensitive device is shared among the one or more receiving optical systems.
26. The system of claim 25 , further comprising at least one of:
a first combination of one or more focusing optics and one or more mirrors; and
a second combination of at least one of a fiber bundle or a power combiner,
wherein the first and the second combination are both configured to redirect the redirected returning light pulses to the optical sensitive device.
27. The system of claim 23 , further comprising a refractive index matching material disposed on a surface of the optical sensitive device.
28. The system of claim 21 , wherein the first light source is configured to generate the one or more first light pulses based on an electrical trigger signal, wherein the electrical trigger signal enables determining of a reference time associated with the one or more steered first light pulses transmitted from the LiDAR scanning system.
29. The system of claim 21 , further comprising:
a reference pulse generation device configured to obtain and redirect one or more reference light pulses, wherein the one or more reference light pulses include a portion of the one or more first light pulses; and
an optical sensitive device configured to detect the redirected reference light pulses, wherein the redirected reference light pulses enable determining of a reference time associated with the one or more steered first light pulses transmitted from the LiDAR scanning system.
30. The system of claim 29 , where the reference pulse generation device is a partial reflection device that reflects a portion of the first light pulses to the optical sensitive device.
31. The system of claim 29 , where the reference pulse generation device is an optical splitter that splits a portion of the first light pulses and redirects a portion of the first light pulses to the optical sensitive device.
32. The system of claim 29 , further comprising:
one or more processors electrically coupled to the optical sensitive device, wherein one or more processors are configured to determine the time of flight based on a matching between the redirected reference light pulses and the redirected returning light pulses.
33. The system of claim 1 , further comprising a second light source, wherein the one or more receiving optical systems comprise a first receiving optical system and a second receiving optical system, wherein the second light source and the second receiving optical system are disposed at a different side of the light beam steering device from that of the first light source and the first receiving optical system, so that oscillation or rotation of the light beam steering device facilitates steering of second light pulses generated by the second light source in a different direction in the field-of-view from that generated by the first light source.
34. A method for performing LiDAR scanning using a LiDAR scanning system, comprising:
providing, by a first light source, one or more first light pulses;
performing, by one or more beam steering apparatuses optically coupled to the first light source, each beam steering apparatus comprising an oscillation mirror and a light beam steering device, wherein the combination of the light beam steering device and the oscillation mirror, when moving with respect to each other:
steering the one or more first light pulses both vertically and horizontally to illuminate an object within a field-of-view, wherein the light beam steering device is configured to steer the one or more first light pulses in either a horizontal or vertical direction, and the oscillation mirror is configured to steer the one or more first light pulses in the other direction,
obtaining one or more first returning light pulses, the one or more first returning light pulses being generated based on the steered first light pulses illuminating an object within the field-of-view, and
redirecting the one or more first returning light pulses to a receiving optical device in the LiDAR scanning system,
and wherein the oscillation mirror is configured to oscillate between two end vertical positions to obtain multiple scanlines in-between.
35. The method of claim 34 , further comprising:
forming one or more points of a point cloud based on calculating a distance of the object that scatters or reflects the steered first light pulses at one or more combinations of horizontal and vertical angles;
generating a sub-frame based on aggregating the one or more points corresponding to the steered first light pulses, the steered first light pulses being steered at least once in both horizontal and vertical directions; and
combining one or more sub-frames to form a frame, the frame representing motion correction of both the LiDAR scanning system's movement and the object's movement.