Time of flight camera with rectangular field of illumination
View Patent ↗Improved field-of-illumination (FOI) and field-of-view (FOV) matching for 3D time-of-flight cameras is provided using light emitters with rectangular reflectors. A better adjustment of the FOI with the camera's FOV has the following advantages: optimal use of emitted light and reduced multi-path problems. Furthermore, embodiments bring the benefit for rather low-cost customization of the illumination to match the FOI to the specified FOV.
1. A time of flight camera, comprising:
a substrate;
one or more frustum shaped reflectors formed in a surface of the substrate, wherein each reflector includes a center port;
a respective light emitter located at a bottom of each reflector in the center port for producing light for illuminating a scene; and
an image sensor for detecting light from the scene;
wherein each reflector is arranged to direct light from the light emitter at the bottom of the reflector onto the scene so that a field of illumination substantially matches a field of view of the image sensor and light power at a periphery of the field of view is substantially the same as light power at a center of the field of view.
2. The camera as claimed in claim 1 , wherein each light emitter is a light emitting diode.
3. The camera as claimed in claim 1 , wherein each light emitter is a laser diode.
4. The camera as claimed in claim 1 , wherein each reflector is metal coated.
5. The camera as claimed in claim 1 , wherein each reflector has a rectangular cross-section.
6. The camera as claimed in claim 1 , wherein the image sensor includes an array of pixels that demodulate light returning from the scene synchronously with modulation of the light emitter.
7. The camera as claimed in claim 1 , further comprising a front cover, each reflector being formed in the front cover.
8. The camera as claimed in claim 1 , further comprising optical elements to shape the field of illumination.