Projector with spatial light modulation
A time of flight based depth detection system is disclosed that includes a projector configured to sequentially emit multiple complementary illumination patterns. A sensor of the depth detection system is configured to capture the light from the illumination patterns reflecting off objects within the sensor's field of view. The data captured by the sensor can be used to filter out erroneous readings caused by light reflecting off multiple surfaces prior to returning to the sensor.
1. A depth detection system, comprising:
a projection system, comprising:
a projector housing having a rigid substrate,
a first light source configured to emit light through a first plurality of light shaping components so as to produce a first illumination pattern, the first light source being mounted to the rigid substrate, and
a second light source configured to emit light through a second plurality of light shaping components so as to produce a second illumination pattern complementary to the first illumination pattern, the second light source being mounted to the rigid substrate adjacent to the first light source, wherein the first and second illumination patterns are configured to sequentially pulse such that only one of the first and second illumination patterns is active at any given time;
an imaging sensor proximate the projection system and configured to receive light emitted by the first and second light sources after being reflected off objects within a field of view of the imaging sensor; and
a processor configured to:
subtract a portion of light received by the imaging sensor when the first illumination pattern is active from light received by the imaging sensor when the second illumination pattern is active; and
calculate a distance between the depth detection system and the objects within the field of view of the imaging sensor by measuring an amount of time for light emitted by the first and second light sources to reflect off the objects within the field of view of the imaging sensor and return to the imaging sensor.
2. The depth detection system as recited in claim 1 , wherein the first and second light sources are infrared laser diodes.
3. The depth detection system as recited in claim 1 , wherein the imaging sensor has a global shutter.
4. The depth detection system as recited in claim 1 , wherein the first and second light illumination patterns are pulsed in an alternating pattern.
5. The depth detection system as recited in claim 1 , wherein the first plurality of light shaping components comprises a diffractive optical element and a micro-lens array.
6. The depth detection system as recited in claim 5 , wherein the first plurality of light shaping components shapes light emitted by the first light source into a first plurality of parallel light bars distributed across the field of view of the imaging sensor.
7. The depth detection system as recited in claim 6 , wherein the second plurality of light shaping components shapes light emitted by the second light source into a second plurality of parallel light bars covering gaps between the first plurality of parallel light bars.
8. The depth detection system as recited in claim 1 , wherein the first plurality of light shaping components comprises a collimating lens with folded optics.
9. The depth detection system as recited in claim 8 , wherein the second plurality of light shaping components comprises the collimating lens with folded optics.
10. The depth detection system as recited in claim 9 , wherein the light projected by the first and second light sources is reoriented by about 90 degrees by a reflective surface of the collimating lens.