3D depth sensor and projection system and methods of operating thereof
A diffractive optical element includes: a first facet configured to perform an expansion optical function; and a second facet configured to perform a collimation optical function and a pattern generation function.
1. A projection system configured to emit patterned light along a projection optical axis, the projection system comprising:
a diffractive optical element having a first facet and a second facet, the first facet being configured to perform an expansion optical function and the second facet being configured to perform a collimation optical function and a pattern generation function; and
a light emitter configured to emit light toward the diffractive optical element,
wherein the collimation optical function is configured to collimate the light emitted from the light emitter, and
wherein the pattern generation function is configured to replicate the collimated light to produce the patterned light,
wherein the expansion optical function of the diffractive optical element defines an effective focal length (f) and a focal point at a distance (d) from the diffractive optical element, the effective focal length being larger than the distance, and
wherein the light emitter is located at the focal point at the distance (d) from the diffractive optical element.
2. The projection system of claim 1 , wherein the projection system has a thickness less than 3.2 mm and wherein the patterned light has a beam divergence less than 4.0×10 −3 radians.
3. The projection system of claim 1 , wherein the collimation optical function is spherical and wherein the patterned light comprises a plurality of points.
4. The projection system of claim 1 , wherein the collimation optical function is cylindrical and wherein the patterned light comprises a plurality of lines.
5. The projection system of claim 1 , wherein the light emitter is a coherent light source.
6. The projection system of claim 1 , wherein the light emitter is a light emitting diode.
7. The projection system of claim 1 , wherein the projection system is a component of a depth acquisition system, the depth acquisition system further comprising a camera configured to image a scene in a direction of the projection optical axis.
8. The projection system of claim 7 , wherein the camera is a stereo camera.
9. A diffractive optical element having:
a first facet configured to perform an expansion optical function; and
a second facet configured to perform a collimation optical function and a pattern generation function,
wherein the collimation optical function of the diffractive optical element is a bi-focal collimation function,
wherein the bi-focal collimation function generates optical aberrations, and
wherein the expansion optical function corrects the optical aberrations.
10. The diffractive optical element of claim 9 , wherein the pattern generation function and the collimation optical function are superimposed on the second facet.
11. A method for applying patterned light to a scene, the method comprising:
supplying power to a light emitter configured to emit monochromatic light toward a diffractive optical element, the diffractive optical element having a first facet and a second facet, the first facet being configured to perform an expansion optical function and the second facet being configured to perform a collimation optical function and a pattern generation function;
expanding, by the expansion optical function, the light emitted from the light emitter to generate divergent light;
collimating, by the collimation optical function, the divergent light to generate collimated light; and
replicating, by the pattern generation function, the collimated light to produce the patterned light,
wherein the expansion optical function of the diffractive optical element defines an effective focal length (f) and a focal point at a distance (d) from the diffractive optical element, the effective focal length being larger than the distance, and
wherein the light emitter is located at the focal point at the distance (d) from the diffractive optical element.
12. The method of claim 11 , wherein the collimation optical function of the diffractive optical element is a bi-focal collimation function.
13. The method of claim 12 , wherein the bi-focal collimation function generates optical aberrations, and
wherein the expansion optical function corrects the optical aberrations.
14. The method of claim 11 , wherein the collimation optical function is spherical and wherein the patterned light comprises a plurality of points.
15. The method of claim 11 , wherein the collimation optical function is cylindrical and wherein the patterned light comprises a plurality of lines.
16. The method of claim 11 , wherein the light emitter is a coherent light source.