Optical projector with beam monitor including mapping apparatus capturing image of pattern projected onto an object
Optical apparatus includes a device package, with a radiation source contained in the package and configured to emit a beam of coherent radiation. A diffractive optical element (DOE) is mounted in the package so as to receive and diffract the radiation from the radiation source into a predefined pattern comprising multiple diffraction orders. An optical detector is positioned in the package so as to receive and sense an intensity of a selected diffraction order of the DOE.
1. Mapping apparatus, comprising:
a projection subassembly, comprising:
a device package;
a radiation source, contained in the package and configured to emit a beam of coherent radiation;
a diffractive optical element (DOE), mounted in the package so as to receive and diffract the radiation from the radiation source into a predefined pattern comprising multiple diffraction orders; and
an optical detector, which is positioned in the package so as to receive a selected diffraction order of the DOE and to output a signal that is response to an intensity of the selected diffraction order;
an imaging subassembly, which is configured to capture an image of the pattern that is projected onto an object; and
processing circuitry, which is configured to process the image in order to produce a three-dimensional (3D) map of the object, and to process the signal in order to monitor a performance of the DOE.
2. The apparatus according to claim 1 , wherein the optical detector is configured to output a signal that is responsive to the intensity, and comprising a controller, which is coupled to receive and process the signal so as to monitor a performance of the apparatus.
3. The apparatus according to claim 2 , wherein the controller is configured to inhibit an operation of the apparatus when the signal is outside a predefined range.
4. The apparatus according to claim 1 , wherein the radiation source comprises a laser diode.
5. The apparatus according to claim 1 , wherein the selected diffraction order is a zero order of the DOE.
6. The apparatus according to claim 5 , wherein the optical detector is positioned so as to receive the zero order that is reflected back from the DOE.
7. The apparatus according to claim 6 , wherein the DOE is tilted relative to an axis of the beam emitted by the radiation source so as to direct the back-reflected zero order toward the optical detector.
8. The apparatus according to claim 1 , wherein the selected diffraction order is a high order of the DOE.
9. The apparatus according to claim 8 , wherein the apparatus is configured to project the pattern over a predefined angular range, and wherein the optical detector is positioned to receive the radiation transmitted through the DOE at an angle that is outside the angular range.