Coded light pattern having hermitian symmetry

1. An apparatus comprising:

a diffractive optical element (DOE) configured to generate an optical pattern,

wherein the optical pattern is hermitian symmetric, and

wherein the optical pattern comprises a tessellated codebook primitive generated to satisfy at least one codeword constraint.

2. The apparatus of claim 1 , wherein the DOE is manufactured based on the optical pattern using a single-mask photolithographic process.

3. The apparatus of claim 1 , further comprising a laser and a lens, wherein the laser is configured to emit light through the lens and the DOE to project the optical pattern onto a scene.

4. The apparatus of claim 1 , further comprising:

a second DOE configured to generate a second optical pattern; and

a controller configured to select the DOE or the second DOE based on one or more parameters.

5. An apparatus comprising:

means for emitting light;

means for focusing the light; and

means for diffracting the light to produce an optical pattern,

wherein the optical pattern is hermitian symmetric, and

wherein the optical pattern comprises a tessellated codebook primitive generated to satisfy at least one codeword constraint.

6. The apparatus of claim 5 , wherein the means for emitting, the means for focusing, and the means for diffracting are included in a transmitter device of a structured light depth sensing system.

7. The apparatus of claim 5 , wherein the means for emitting light comprises a laser, wherein the means for focusing the light comprises a lens, and wherein the means for diffracting the light comprises a diffractive optical element (DOE).

8. The apparatus of claim 1 , wherein the tessellated codebook primitive comprises a two-dimensional (2D) coded pattern.

9. The apparatus of claim 8 , wherein each point (x,y) of the 2D coded pattern corresponds to a point (−x,−y) of the 2D coded pattern, and wherein each point (−x,y) of the 2D coded pattern corresponds to a point (x,−y) of the 2D coded pattern.

10. The apparatus of claim 8 , wherein a plurality of codewords are encoded in the 2D coded pattern.

11. The apparatus of claim 10 , wherein the at least one codeword constraint comprises an average duty cycle constraint corresponding to an average ratio of a number of bits in each of the plurality of codewords having a value of 1 to a number of bits in each of the plurality of codewords having a value of 0.

12. The apparatus of claim 10 , wherein the at least one codeword constraint comprises a minimum duty cycle constraint corresponding to a lower limit ratio of a number of bits in each of the plurality of codewords having a value of 1 to a number of bits in each of the plurality of codewords having a value of 0.

13. The apparatus of claim 1 , wherein the at least one codeword constraint comprises a size constraint, an average duty cycle constraint, a minimum duty cycle constraint, a codebook cardinality constraint, a spatial representation constraint, a contour resolution constraint, an aliasing distance constraint, a phase shuffling constraint, a boundary constraint, or any combination thereof.

14. The apparatus of claim 1 , wherein the at least one codeword constraint comprises one or more duty cycle constraints, wherein the one or more duty cycle constraints comprise an average duty cycle constraint, a minimum duty cycle constraint, a maximum duty cycle constraint, or a combination thereof.

15. The apparatus of claim 1 , wherein the at least one codeword constraint comprises a codebook cardinality constraint, wherein the codebook cardinality constraint corresponds to a number of unique codewords in the tessellated codebook primitive.

16. The apparatus of claim 1 , wherein the at least one codeword constraint comprises a spatial representation constraint, wherein the spatial representation constraint indicates that the tessellated codebook primitive is to be represented using one or more dots, one or more lines, one or more grids, or a combination thereof.

17. The apparatus of claim 1 , wherein the at least one codeword constraint comprises a contour resolution constraint, wherein the contour resolution constraint indicates a shift amount associated with a codeword of the tessellated symmetric codebook primitive, and wherein, when the codeword is shifted by the shift amount, the codeword represents another codeword of the tessellated symmetric codebook primitive.

18. The apparatus of claim 1 , wherein the at least one codeword constraint comprises an aliasing distance constraint, wherein the aliasing distance constraint is associated with a distance between two codewords of the tessellated symmetric codebook primitive, and wherein that two codewords are the same.

19. The apparatus of claim 1 , wherein the at least one codeword constraint comprises a phase shuffling constraint, and wherein the phase shuffling constraint is associated with mapping one or more codewords of the tessellated symmetric codebook primitive to spatial symbols.

20. The apparatus of claim 1 , wherein the at least one codeword constraint comprises a boundary constraint, wherein the boundary constraint is associated with one or more codewords of the tessellated symmetric codebook primitive being recognizable at a boundary region of the tessellated codebook primitive.

21. A structured light depth sensing system comprising:

a transmitter configured to project an optical pattern onto a surface, wherein the optical pattern is hermitian symmetric, and wherein the optical pattern comprises a tessellated codebook primitive generated to satisfy at least one codeword constraint; and

a receiver configured to capture the optical pattern from the surface and to identify the at least one codeword constraint.

22. The structured light depth sensing system of claim 21 , wherein the transmitter comprises a projector and the receiver comprises a camera, and wherein the surface corresponds to a surface of an object or a scene.

23. The structured light depth sensing system of claim 21 , wherein the transmitter is located at a first point on a reference plane and the receiver is located at a second point on the reference plane, wherein the reference plane is substantially parallel to the surface.

24. The structured light depth sensing system of claim 21 , wherein the transmitter and the receiver are incorporated into a single device.

25. A diffractive optical element (DOE) comprising:

a first surface of a light diffracting material, the first surface comprising a pattern etched into the first surface; and

a second surface of the light diffracting material, the second surface comprising a substantially flat surface, and

wherein the light diffracting material is configured to generate an optical pattern onto a surface, wherein the optical pattern corresponds to the pattern etched into the first surface, wherein the optical pattern is hermitian symmetric, and wherein the optical pattern comprises a tessellated codebook primitive generated to satisfy at least one codeword constraint.

26. The DOE of claim 25 , wherein the light diffracting material includes glass or a polymer.

27. The DOE of claim 25 , wherein the pattern etched into the first surface comprises multiple channels recessed into the first surface, and wherein the light diffracting material is manufactured using a single-mask photolithographic process.

28. The DOE of claim 25 , wherein the light diffracting material is included in a transmitter device of a structured light depth sensing system.

29. The apparatus of claim 10 , wherein the at least one codeword constraint comprises a duty cycle constraint based on a first number of bits in each of the plurality of codewords having a value of 1 and a second number of bits in each of the plurality of codewords having a value of 0.

30. The apparatus of claim 29 , wherein the duty cycle constraint corresponds to a ratio of the first number of bits to the second number of bits.