Lidar scanning system
Embodiments include a LIDAR scanning system. A laser is configured to emit pulses of light. A transmit reconfigurable-metasurface is configured to reflect an incident pulse of light as an illumination beam pointing at a field of view. This pointing is responsive to a first holographic beam steering pattern implemented in the transmit reconfigurable-metasurface. A receive reconfigurable-metasurface is configured to reflect a return of the illumination beam to an optical detector. This pointing is responsive to a second holographic beam steering pattern implemented in the receiving reconfigurable-metasurface. An optical detector includes an array of detector pixels. Each detector pixel includes (i) a photodetector configured to detect light in the return of the illumination beam and (ii) a timing circuit configured to determine a time of flight of the detected light. The optical detector is also configured to output a detection signal indicative of the detected light and the time of flight.
1. A LIDAR scanning system comprising:
a laser configured to emit pulses of light at an operating wavelength;
a transmit reconfigurable-metasurface configured to reflect an incident pulse of light from the laser as an illumination beam pointing at a selected portion of a field of view (φ×θ), the pointing of the illumination beam responsive to a first selected holographic beam steering pattern implemented in the transmit reconfigurable-metasurface;
a receive reconfigurable-metasurface configured to reflect a return of the illumination beam from the selected portion of the field of view as a relay beam pointing at an optical detector, the pointing of the relay beam responsive to a second selected holographic beam steering pattern implemented in the receiving reconfigurable-metasurface; and
the optical detector comprising an array of detector pixels, each detector pixel including (i) a photodetector configured to detect light in the return of the illumination beam and (ii) a timing circuit configured to determine a time of flight of the detected light, the optical detector also configured to output a detection signal indicative of the detected light and a time of flight of the detected light for each pixel of the array.
2. The system of claim 1 , wherein the φ of the field of view is between 90 and 120 degrees.
3. The system of claim 1 , wherein the θ of the field of view is between 5 and 25 degrees.
4. The system of claim 1 , wherein the transmit reconfigurable-metasurface includes a dynamically reconfigurable-metasurface.
5. The system of claim 1 , wherein the pointing of the transmit reconfigurable-metasurface is reconfigurable on a time scale of less than 10 microseconds.
6. The system of claim 1 , wherein the pointing of the transmit reconfigurable-metasurface is reconfigurable on a time scale of between 1 microsecond and 1000 microseconds.
7. The system of claim 1 , wherein the transmit reconfigurable-metasurface includes a one-dimensional reconfigurable-metasurface.
8. The system of claim 1 , wherein the transmit reconfigurable-metasurface includes a two-dimensional reconfigurable-metasurface.
9. The system of claim 1 , wherein the transmit reconfigurable-metasurface includes a plurality of dynamically adjustable high-Q dielectric resonators arranged on the surface with inter-element spacing less than an operating wavelength of the laser.
10. The system of claim 9 , wherein the surface includes a conducting surface, and the plurality of resonators have a corresponding plurality of adjustable reflection phases providing a dynamically adjustable reflected wave responsive to an incident wave.
11. The system of claim 9 , wherein the inter-element spacing is less than one-half of the operating wavelength.
12. The system of claim 9 , wherein each of the plurality of dielectric resonators includes:
a pair of regions having a high refractive index; and
an electrically-adjustable material disposed in a gap between the regions.
13. The system of claim 12 , wherein the regions include semiconductor regions.
14. The system of claim 12 , wherein the regions include pillars oriented perpendicular to the surface.
15. The system of claim 9 , wherein each of the plurality of resonators further includes:
a pair of electrodes configured to apply an adjustable voltage across the electrically-adjustable material.
16. The system of claim 15 , wherein the plurality of resonators are arranged in a one-dimensional array, and each of the resonators further includes:
a first electrode in the pair of electrodes is connected to ground; and
a second electrode in the pair of electrodes is connected to a bias voltage for the resonator.
17. The system of claim 9 , wherein the plurality of resonators are arranged in a two-dimensional array indexed by row and column, and each of the resonators further includes:
a matrix circuitry indexed by row and column and connected to the pair of electrodes.
18. The system of claim 1 , wherein the selected portion of the field of view includes one selected field-of-view pixel.
19. The system of claim 1 , wherein the selected portion of the field of view includes a selected 1×4 field-of-view pixels.
20. The system of claim 1 , wherein the selected portion of the field of view includes a selected 2×2 field-of-view pixels.
21. The system of claim 1 , wherein the first selected holographic beam steering pattern is implemented in the transmit reconfigurable-metasurface in response to a first control signal.
22. The system of claim 1 , wherein the first transmit reconfigurable-metasurface is reconfigurable in one-dimension.
23. The system of claim 1 , wherein the first transmit reconfigurable-metasurface is reconfigurable in two-dimensions.
24. The system of claim 1 , wherein the receive reconfigurable-metasurface includes a dynamically reconfigurable-metasurface.
25. The system of claim 1 , wherein the receive reconfigurable-metasurface includes a one-dimensional reconfigurable-metasurface.
26. The system of claim 1 , wherein the receive reconfigurable-metasurface includes a two-dimensional reconfigurable-metasurface.
27. The system of claim 1 , wherein the receive reconfigurable-metasurface includes a plurality of dynamically adjustable high-Q dielectric resonators arranged on a surface with inter-element spacing less than an optical operating wavelength of the laser.
28. The system of claim 1 , wherein the receive reconfigurable-metasurface includes a two dimensional field of view.
29. The system of claim 1 , wherein the receive reconfigurable-metasurface is configured to implement a specified beam steering hologram defined by a one-dimensional radiation pattern established in the receive reconfigurable-metasurface in response to a second control signal.
30. The system of claim 1 , wherein the array of detector pixels includes one or more detector pixels.
31. The system of claim 1 , wherein the array of detector pixels includes a 2×2 array of detector pixels.
32. The system of claim 1 , wherein the timing circuit of a pixel includes a timing circuit configured to determine a time of flight between a transmission of the pulse of light and a detection of the light of the return of the illumination beam.
33. The system of claim 1 , further comprising:
a scanning engine configured to implement a scan of the field of view by stepping the transmitted beam of the pulsed light over at least a portion of the field of view, the implementation including selecting for each pulse of light to be reflected by the transmit reconfigurable-metasurface (i) a first holographic beam steering pattern to be implemented in the transmit reconfigurable-metasurface and (ii) a second holographic beam steering pattern to be implemented in the receive reconfigurable-metasurface.
34. The system of claim 33 , wherein the scanning engine is configured to control a scan of the field of view at a first resolution.
35. The system of claim 34 , wherein the scanning engine is configured to control a scan of the field of view at a second resolution, the second resolution selected by the scanning engine in response to the outputted detection signal from the scan at the first resolution.
36. The system of claim 33 , wherein the scanning engine includes:
a metasurface controller circuit configured to implement the selected first holographic beam steering pattern using a first control signal and the selected second holographic beam steering pattern using a second control signal.
37. The system of claim 33 , wherein the scanning engine includes:
a hologram selector circuit configured to select (i) a first holographic beam steering pattern configured to reflect the light pulse as the illumination beam pointing at the selected portion of a field of view and (ii) a second holographic beam steering pattern configured to reflect the return of the illumination beam as the relay beam pointing at the optical detector.
38. The system of claim 33 , wherein the scanning engine includes a region of interest selector circuit, the region of interest selector circuit configured to:
recognize a pattern in a first outputted detection signal produced by a first scan of the field of view at a first resolution; and
select in response to the recognized pattern a region of interest in the field of view for a second scan at a second resolution higher than the first resolution.
39. The system of claim 1 , further comprising:
a data computation circuit configured to generate three-dimensional data indicative of at least a portion of the field of view in response to the outputted detection signal.
40. A LIDAR scanning system comprising:
a laser configured to emit pulses of light at an operating wavelength;
a transmit reconfigurable-metasurface configured to reflect an incident pulse of light from the laser as an illumination beam pointing at a selected portion of a field of view, the pointing of the illumination beam responsive to a first selected holographic beam steering pattern implemented in the transmit reconfigurable-metasurface;
a receive reconfigurable-metasurface configured to reflect a return of the illumination beam from the selected portion of the field of view as a relay beam pointing at an optical detector, the pointing of the relay beam responsive to a second selected holographic beam steering pattern implemented in the receiving reconfigurable-metasurface;
the optical detector comprising an array of detector pixels, each detector pixel including (i) a photodetector configured to detect light in the return of the illumination beam and (ii) a timing circuit configured to determine a time of flight of the detected light, the optical detector also configured to output a detection signal indicative of the detected light and a time of flight of the detected light for each pixel of the array;
a scanning engine configured to implement a scan of the field of view by stepping the transmitted beam of the pulsed light over at least a portion of the field of view, the implementation including selecting for each pulse of light to be reflected by the transmit reconfigurable-metasurface (i) a first holographic beam steering pattern to be implemented in the transmit reconfigurable-metasurface and (ii) a second holographic beam steering pattern to be implemented in the receive reconfigurable-metasurface.