Synchronization of projected illumination with activation of sensing elements
Imaging apparatus includes an illumination assembly, including a plurality of radiation sources and projection optics, which are configured to project radiation from the radiation sources onto different, respective regions of a scene. An imaging assembly includes an image sensor and objective optics configured to form an optical image of the scene on the image sensor, which includes an array of sensor elements arranged in multiple groups, which are triggered by a rolling shutter to capture the radiation from the scene in successive, respective exposure periods from different, respective areas of the scene so as to form an electronic image of the scene. A controller is coupled to actuate the radiation sources sequentially in a pulsed mode so that the illumination assembly illuminates the different, respective areas of the scene in synchronization with the rolling shutter.
1. Optical apparatus, comprising:
an illumination assembly, comprising a plurality of radiation sources, mounted on a substrate and configured to emit pulses of optical radiation;
projection optics, which are configured to project the optical radiation from the radiation sources onto different, respective regions of a scene;
an imaging assembly, comprising an array of sensor elements and objective optics configured to form an optical image of the scene on the array, so that each of the respective regions of the scene is imaged onto a different, respective group of the sensor elements; and
a controller, which is coupled to actuate the radiation sources sequentially, so as to sweep the pulses of optical radiation across the scene, to activate the sensor elements to capture the optical radiation reflected from the respective regions of the scene in synchronization with actuation of the radiation sources, and to analyze signals output by the sensor elements in response to the captured optical radiation so as to generate a depth map of the scene.
2. The apparatus according to claim 1 , wherein the projection optics comprise an array of micro-optics, which are respectively aligned with the radiation sources.
3. The apparatus according to claim 1 , wherein the radiation sources comprise a matrix of light-emitting elements, which are arranged on the substrate and are configured to emit the optical radiation in a direction perpendicular to the substrate.
4. The apparatus according to claim 1 , wherein the radiation sources comprise a row of edge-emitting elements, which are arranged on the substrate and are configured to emit the optical radiation in a direction parallel to the substrate.
5. The apparatus according to claim 4 , wherein the projection optics comprise a reflector disposed on the substrate so as to turn the optical radiation emitted by the edge-emitting elements away from the substrate and toward the scene.
6. The apparatus according to claim 5 , wherein the reflector comprises a prism.
7. The apparatus according to claim 1 , wherein each group comprises one or more rows of the sensor elements, and wherein the regions define stripes that extend across the scene in a direction parallel to the rows.
8. The apparatus according to claim 7 , wherein the controller is configured to actuate the radiation sources so that the projected radiation sweeps across the scene in a direction perpendicular to the rows.
9. The apparatus according to claim 1 , wherein the controller is configured to activate each of the groups of the sensor elements only during a respective exposure period during which a radiation source that illuminates a respective region of the scene is actuated.
10. A method for imaging, comprising:
directing optical radiation emitted by an array of radiation sources, which are mounted on a substrate, toward projection optics, which are configured to project the optical radiation from the radiation sources onto different, respective regions of a scene;
actuating the radiation sources sequentially, so as to sweep the pulses of optical radiation across the scene;
forming an optical image of the scene on an array of sensor elements, so that each of the respective regions of the scene is imaged onto a different, respective group of the sensor elements;
activating the sensor elements to capture the optical radiation reflected from the respective regions of the scene in synchronization with actuation of the radiation sources; and
analyzing signals output by the sensor elements in response to the captured optical radiation so as to generate a depth map of the scene.
11. The method according to claim 10 , wherein directing the optical radiation comprises aligning an array of micro-optics with the radiation sources so as to direct the optical radiation from the radiation source via the micro-optics toward the scene.
12. The method according to claim 10 , wherein the radiation sources comprise a matrix of light-emitting elements, which are arranged on the substrate and are configured to emit the optical radiation in a direction perpendicular to the substrate.
13. The method according to claim 10 , wherein the radiation sources comprise a row of edge-emitting elements, which are arranged on the substrate and are configured to emit the optical radiation in a direction parallel to the substrate.
14. The method according to claim 13 , wherein directing the optical radiation comprises providing a reflector on the substrate so as to turn the optical radiation emitted by the edge-emitting elements away from the substrate and toward the scene.
15. The apparatus according to claim 14 , wherein the reflector comprises a prism.
16. The method according to claim 10 , wherein each group comprises one or more rows of the sensor elements, and wherein the regions define stripes that extend across the scene in a direction parallel to the rows.
17. The method according to claim 16 , wherein the controller is configured to actuate the radiation sources so that the projected radiation sweeps across the scene in a direction perpendicular to the rows.
18. The apparatus according to claim 10 , wherein activating the sensor elements comprises activating each of the groups of the sensor elements only during a respective exposure period during which a radiation source that illuminates a respective region of the scene is actuated.