Optical projector with off-axis diffractive element

1. An apparatus comprising:

a laser configured to produce a laser beam;

a collimating lens mounted to intercept the laser beam and produce a collimated beam;

a diffractive optical element (DOE) having an off-axis diffraction pattern and mounted to intercept the collimated beam and produce an off-axis diffracted beam pattern including an off-center 0th order beam; and

a projection element mounted to intercept the off-axis diffracted beam pattern and project a portion of the pattern excluding the 0th order beam;

wherein the projection element comprises:

a reflective component mounted at a non-45 degree angle to the 0th order beam; and

a block mounted to intercept the 0th order beam.

2. The apparatus of claim 1 wherein the block is mounted to intercept the 0th order beam before the reflective component.

3. The apparatus of claim 1 wherein the block is mounted to intercept the 0th order beam after the reflective component.

4. The apparatus of claim 1 wherein the DOE is integrated with the reflective component.

5. The apparatus of claim 1 wherein the projection component comprises a reflective component mounted to reflect a portion of the off-axis diffracted beam pattern but not reflect the 0th order beam.

6. The apparatus of claim 1 wherein the laser is an edge emitting laser.

7. The apparatus of claim 1 wherein the laser is a vertical cavity surface emitting laser (VCSEL).

8. The apparatus of claim 1 wherein the apparatus is mounted in a smartphone.

9. An apparatus comprising:

a laser configured to produce a laser beam;

a collimating lens mounted to intercept the laser beam and produce a collimated beam;

a diffractive optical element (DOE) having an off-axis diffraction pattern and mounted to intercept the collimated beam and produce an off-axis diffracted beam pattern including an off-center 0th order beam; and

a projection element mounted to intercept the off-axis diffracted beam pattern and project a portion of the pattern excluding the 0th order beam;

wherein the projection component includes an aperture positioned to not pass the 0th order beam.

10. An apparatus comprising:

a laser configured to produce a laser beam;

a collimating lens mounted to intercept the laser beam and produce a collimated beam;

a diffractive optical element (DOE) having an off-axis diffraction pattern and mounted to intercept the collimated beam and produce an off-axis diffracted beam pattern including an off-center 0th order beam; and

a projection element mounted to intercept the off-axis diffracted beam pattern and project a portion of the pattern excluding the 0th order beam;

wherein the projection element comprises:

a block mounted to intercept the 0th order beam, the block having a low reflective, light diffusing surface such that any reflected portion of the 0th order beam is less bright than a second order diffraction beam.

11. A method comprising:

producing a laser beam;

intercepting the laser beam and producing a collimated beam;

intercepting the collimated beam and producing an off-axis diffracted beam pattern including an off-center 0th order beam; and

intercepting the off-axis diffracted beam pattern and projecting a portion of the pattern excluding the 0th order beam

wherein the projecting step comprises:

reflecting a portion of the pattern excluding the 0th order beam using a non-45 degree angle to the 0th order beam; and

blocking the 0th order beam.

12. The method of claim 11 wherein blocking the 0th order beam is done before reflecting a portion of the pattern excluding the 0th order beam.

13. The method of claim 11 wherein blocking the 0th order beam is done after reflecting a portion of the pattern excluding the 0th order beam.

14. The method of claim 11 wherein both producing an off-axis diffracted beam pattern and reflecting a portion of the pattern excluding the 0th order beam are done using an integrated reflective and diffractive optical element component.

15. The method of claim 11 further comprising:

recording first positions of a plurality of elements of the off-axis diffraction pattern as reflected off a flat surface and detected by the a photodetector;

recording second positions of a plurality of elements of the off-axis diffraction pattern as reflected of a non-flat object to be measured;

determining the difference between the first and second positions for the plurality of elements of the off-axis diffraction pattern as reflected; and

generating a map of the depth of the non-flat object at different points based on the difference between the first and second positions for the plurality of elements of the off-axis diffraction pattern as reflected.

16. The method of claim 11 wherein the laser is an edge emitting laser.

17. The method of claim 11 wherein the step of projecting a portion of the pattern excluding the 0th order beam uses a mirror.