Structured light projection using a compound patterned mask

1. A structured light projector comprising:

a light emitter; and

a compound patterned mask including:

a spacer substrate that is transparent to a wavelength of light emitted by the light emitter;

a first reflective surface on a first side of the spacer substrate, the first reflective surface having apertures therein to allow light emitted by the light emitter to pass through;

a plurality of lenses arranged to focus light, emitted by the light emitter, toward the apertures in the first reflective surface; and

a second reflective surface on a second side of the spacer substrate opposite the first side, wherein the second reflective surface has apertures therein to allow light emitted by the light emitter and passing through the apertures in the first reflective surface and through the spacer substrate to exit the compound patterned mask, wherein an arrangement of the apertures in the first reflective surface differs from an arrangement of the apertures in the second reflective surface.

2. The structured light projector of claim 1 wherein each of the first and second reflective surfaces comprises a metal.

3. The structured light projector of claim 1 wherein each of the first and second reflective surfaces comprises a reflective coating.

4. The structured light projector of claim 1 wherein each of the first and second reflective surfaces comprises at least one of gold, aluminum, chromium or a dichroic material.

5. The structured light projector of claim 1 wherein the plurality of lenses includes an array of micro lenses each of which is arranged to focus light emitted by the light emitter through a respective one of the apertures in the first reflective surface.

6. The structured light projector of claim 1 further including an optical collimator disposed between the light emitter and the compound patterned mask.

7. The structured light projector of claim 6 wherein the optical collimator is arranged to uniformly illuminate the compound patterned mask with light produced by the light emitter.

8. The structured light projector of claim 1 wherein an arrangement of the apertures in the first reflective surface matches an arrangement of the plurality of lenses.

9. The structured light projector of claim 1 wherein the light emitter comprises a plurality of vertical cavity surface emitting lasers.

10. An optoelectronic apparatus comprising:

a light projector operable to project a structured light pattern onto an object; and

an image sensor arranged to receive light reflected by the object;

wherein the light projector includes:

a light emitter; and

a compound patterned mask including:

a spacer substrate that is transparent to a wavelength of light emitted by the light emitter;

a first reflective surface on a first side of the spacer substrate, the first reflective surface having apertures therein to allow light emitted by the light emitter to pass through;

a plurality of lenses arranged to focus light, emitted by the light emitter, toward the apertures in the first reflective surface; and

a second reflective surface on a second side of the spacer substrate opposite the first side, wherein the second reflective surface has apertures therein to allow light emitted by the light emitter and passing through the apertures in the first reflective surface and through the spacer substrate to exit the compound patterned mask, wherein an arrangement of the apertures in the first reflective surface differs from an arrangement of the apertures in the second reflective surface.

11. The apparatus of claim 10 wherein the plurality of lenses includes an array of micro lenses each of which is arranged to focus light to a respective one of the apertures in the first reflective surface.

12. The apparatus of claim 10 wherein an arrangement of the apertures in the first reflective surface matches an arrangement of the plurality of lenses.

13. The apparatus of claim 10 wherein the light projector produces a structured pattern of light in the IR or near-IR region of the spectrum.

14. A method of producing structured light, the method comprising:

causing light of a particular wavelength to be emitted toward a plurality of lenses;

causing the light received by the lenses to be focused toward apertures in a first reflective surface;

allowing some of the light to pass through apertures in a second reflective surface spaced apart from the first reflective surface, and reflecting some of the light from the second reflective surface back toward the first reflective surface; and

subsequently reflecting, by the first reflective surface, some of the light reflected from the second reflective surface, back toward the second reflective surface such that at least some of the light previously reflected from the second reflective surface passes through the apertures in the second reflective surface.

15. The method of claim 14 further including:

generating the light of the particular wavelength using an array of vertical cavity surface emitting lasers; and

collimating the light emitted by the array of vertical cavity surface emitting lasers so as illuminate the plurality of lenses substantially uniformly.

16. The method of claim 14 including projecting the structured light onto one or more objects.

17. The method of claim 14 wherein the first and second reflective surfaces are separated from one another by a transparent spacer substrate such that light passing through the apertures in the first reflective surface transits the spacer substrate before reaching the second reflective surface.

18. The method of claim 14 wherein the particular wavelength is in the IR or near-IR region of the spectrum.

19. The method of claim 14 wherein the light that passes through the apertures in the second reflective surface produces a structured light pattern onto an object.

20. The method of claim 14 wherein an arrangement of the apertures in the first reflective surface differs from an arrangement of the apertures in the second reflective surface.