Optical pattern projection
Optical apparatus includes first and second diffractive optical elements (DOEs) arranged in series to diffract an input beam of radiation. The first DOE is configured to apply to the input beam a pattern with a specified divergence angle, while the second DOE is configured to split the input beam into a matrix of output beams with a specified fan-out angle. The divergence and fan-out angles are chosen so as to project the radiation onto a region in space in multiple adjacent instances of the pattern.
1. Optical apparatus, comprising first and second diffractive optical elements (DOEs) arranged in series to diffract an input beam of radiation,
wherein the first DOE is configured to diffract the input beam so as to generate a pattern of spots in a tile with a specified divergence angle, including spots corresponding to extreme diffraction orders of the first DOE at borders of the tile, while the second DOE is configured to split the input beam into a matrix of output beams with a specified fan-out angle, and
wherein the divergence and fan-out angles are chosen so as to project the radiation onto a region in space in multiple adjacent instances of the diffraction pattern, which tile the region, and
wherein the extreme diffraction orders of neighboring tiles are mutually adjacent in a spatial frequency space.
2. The apparatus according to claim 1 ,
wherein the divergence angle of each instance of the pattern is 2β Tile , and the fan-out angle between the adjacent instances is β FO , and wherein the divergence and fan-out angles are chosen so that sin(β FO )=2 sin(β Tile ).
3. The apparatus according to claim 2 , wherein a diffraction pattern of the apparatus includes a zero-order component, and wherein the first and second DOEs are configured to diffract the input beam so that the zero-order component contains no more than 1% of an energy of the input beam.
4. The apparatus according to claim 1 , wherein the first and second DOEs are configured so that the multiple adjacent instances of the pattern tile the region irrespective of a wavelength of the input beam.
5. The apparatus according to claim 1 , wherein the second DOE is configured to distribute an energy of the input beam among the output beams in accordance with a predefined non-uniform distribution.
6. The apparatus according to claim 1 , wherein the matrix of the output beams comprises at least a 3×3 matrix.
7. Mapping apparatus, comprising:
a projection subassembly, comprising:
a radiation source, which is configured to generate an input beam of radiation; and
first and second diffractive optical elements (DOEs) arranged in series to diffract the input beam, wherein the first DOE is configured to diffract the input beam so as to generate a pattern of spots in a tile with a specified divergence angle, including spots corresponding to extreme diffraction orders of the first DOE at borders of the tile, while the second DOE is configured to split the input beam into a matrix of output beams with a specified fan-out angle, so as to project the radiation onto a region in space,
wherein the divergence and fan-out angles are chosen so that the radiation is projected into multiple adjacent tiles containing the pattern of spots, which tile the region, such that the extreme diffraction orders of neighboring tiles are mutually adjacent in a spatial frequency space;
an image capture subassembly, which is configured to capture an image of the pattern appearing on an object in the region; and
a processor, which is configured to process the image so as to produce a three-dimensional (3D) map of the object.
8. The apparatus according to claim 7 ,
wherein the divergence angle of each instance of the pattern is 2β Tile , and the fan-out angle between the adjacent instances is β FO , and wherein the divergence and fan-out angles are chosen so that sin(β FO )=2 sin(β Tile ).
9. The apparatus according to claim 7 , wherein the first and second DOEs are configured so that the multiple adjacent instances of the pattern tile the region irrespective of a wavelength of the input beam.
10. The apparatus according to claim 7 , wherein the second DOE is configured to distribute an energy of the input beam among the output beams in accordance with a predefined non-uniform distribution.
11. The apparatus according to claim 7 , wherein the matrix of the output beams comprises at least a 3×3 matrix.
12. The apparatus according to claim 7 , wherein a diffraction pattern of the projection subassembly includes a zero-order component, and wherein the first and second DOEs are configured to diffract the input beam so that the zero-order component contains no more than 5% of an energy of the input beam.
13. A method for projection, comprising:
directing an input beam of radiation to pass in series through first and second diffractive optical elements (DOEs),
wherein the first DOE is configured to diffract the input beam so as to generate a pattern of spots in a tile with a specified divergence angle, including spots corresponding to extreme diffraction orders of the first DOE at borders of the tile, while the second DOE is configured to split the input beam into a matrix of output beams with a specified fan-out angle, and
wherein the divergence and fan-out angles are chosen so as to project the radiation onto a region in space in multiple adjacent tiles containing the pattern of spots, which tile the region, and
such that the extreme diffraction orders of neighboring tiles are mutually adjacent in a spatial frequency space.
14. The method according to claim 13 ,
wherein the divergence angle of each instance of the pattern is 2β Tile , and the fan-out angle between the adjacent instances is β FO , and wherein the divergence and fan-out angles are chosen so that sin(β FO )=2 sin(β Tile ).
15. The method according to claim 13 , wherein directing the input beam comprises arranging the first and second DOEs so that the multiple adjacent instances of the pattern tile the region irrespective of a wavelength of the input beam.
16. The method according to claim 13 , wherein the second DOE is configured to distribute an energy of the input beam among the output beams in accordance with a predefined non-uniform distribution.
17. The method according to claim 13 , wherein the matrix of the output beams comprises at least a 3×3 matrix.
18. The method according to claim 13 , wherein directing the input beam to pass through the first and second DOEs comprises generating a diffraction pattern that includes a zero-order component, and wherein the first and second DOEs are configured to diffract the input beam so that the zero-order component contains no more than 5% of an energy of the input beam.
19. The method according to claim 13 , and comprising capturing an image of the pattern appearing on an object in the region, and processing the image so as to produce a three-dimensional (3D) map of the object.