Radiation source with a small-angle scanning array

• US 20180062345A1
• Filed: 08/30/2016
• Published: 03/01/2018
• Est. Priority Date: 08/30/2016
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Bills, Richard E., Sutton, Andrew J., Niclass, Cristiano L., Rezk, Mina A.
• Granted Patent: US 10,305,247 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 26/0891 forming an optical wedge
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: H01S 5/0071 for beam steering, e.g. using a mirror outside the cavity to change the beam direction
• CPC Class Codes: H01S 5/042 Electrical excitation ; Circuits therefor monolithically integrated laser drive components H01S5/0261
• CPC Class Codes: H01S 5/423 having a vertical cavity

Abstract

An optical apparatus includes an array of lasers, which are arranged in a grid pattern having a predefined spatial pitch and are configured to emit respective beams of pulses of optical radiation. Projection optics having a selected focal length project the beams toward a target with an angular pitch between the beams defined by the spatial pitch and the focal length. A scanner scans the projected beams over a range of scan angles that is less than twice the angular pitch. Control circuitry drives the lasers and the scanner so that the pulses cover the target with a resolution finer than the angular pitch. A receiver receives and measures a time of flight of the pulses reflected from the target.

Claims

1. Optical apparatus, comprising:

an array of lasers, which are arranged in a grid pattern having a predefined spatial pitch and are configured to emit respective beams of pulses of optical radiation;

projection optics having a selected focal length and configured to project the beams toward a target with an angular pitch between the beams defined by the spatial pitch and the focal length;

a scanner, which is configured to scan the projected beams over a range of scan angles that is less than twice the angular pitch;

control circuitry, which is coupled to drive the lasers and the scanner so that the pulses cover the target with a resolution finer than the angular pitch; and

a receiver, which is configured to receive and measure a time of flight of the pulses reflected from the target.

2. The optical apparatus according to claim 1, wherein the array of lasers comprises:

a semiconductor substrate; and

an array of vertical-cavity surface-emitting lasers (VCSELs) formed on the substrate, which are configured to emit the optical radiation.

3. The optical apparatus according to claim 1, wherein the projection optics comprise a lens, and wherein the scanner is configured to scan the projected beams by translating the lens transversely with respect to the beams.

4. The optical apparatus according to claim 1, wherein the scanner is configured to scan the projected beams by applying a motion to the array of lasers relative to the projection optics.

5. The optical apparatus according to claim 4, wherein the motion comprises translating the array of lasers transversely relative to a direction of the beams.

6. The optical apparatus according to claim 4, wherein the motion comprises rotating the array of lasers around a rotational axis in a plane of the array of the lasers.

7. The optical apparatus according to claim 1, wherein the scanner comprises a rotating mirror positioned to deflect the projected beams at a variable deflection angle.

8. The optical apparatus according to claim 1, wherein the scanner comprises a grating positioned to diffract the beams at a variable diffraction angle.

9. The optical apparatus according to claim 7, wherein the grating comprises an electro-optical spatial light modulator, which is configured to generate the grating with a variable period and orientation.

10. The optical apparatus according to claim 1, wherein the scanner comprises at least one prism, which is positioned to intercept and refract the beams and is movable relative to the array so as to vary an angle of deviation of the refracted beams.

11. The optical apparatus according to claim 10, wherein the at least one prism comprises a pair of wedge prisms configured as a Risley prism.

12. The apparatus according to claim 1, wherein the control circuitry is configured to drive the lasers to emit the pulses in a pseudo-random spatio-temporal pattern.

15. The method according to claim 12, wherein the beams are projected by projection optics, and wherein scanning the projected beams comprises applying a motion to the array of lasers relative to the projection optics.

16. The method according to claim 15, wherein applying the motion comprises applying at least one of a translation and a rotation to the array of the leasers.

20. The method according to claim 12, wherein projecting the respective beams comprises driving the lasers to emit the pulses in a pseudo-random spatio-temporal pattern.

13. A method of scanning, comprising:

projecting, toward a target from an array of lasers arranged in a grid pattern, respective beams of pulses of optical radiation with a predefined angular pitch between the beams;

scanning the projected beams over a range of scan angles that is less than twice the angular pitch, while driving the lasers so that the pulses cover the target with a resolution finer than the angular pitch; and

receiving and measuring a time of flight of the pulses reflected from the target.

14. The method according to claim 13, wherein the beams are projected through a lens, and wherein scanning the projected beams comprises translating the lens transversely with respect to the beams.

17. The method according to claim 13, wherein scanning the projected beams comprises deflecting the beams at a variable deflection angle using a rotating mirror.

18. The method according to claim 13, wherein scanning the projected beams comprises diffracting the beams using a grating configured to diffract the beams with a variable diffraction angle.

19. The method according to claim 13, wherein scanning the projected beams comprises moving at least one prism through which the beams are transmitted so as to vary an angle of deviation of the beams.