Optical ranging systems including optical cross-talk reducing features
An optical ranging system includes a support, a light emitter mounted on the support, and a time-of-flight (“TOF”) sensor chip mounted on the support. The TOF sensor chip, for example, includes at least one main pixel and at least one reference pixel in a semiconductor substrate. A barrier that is substantially non-transparent to light emitted by the light emitter separates the at least one reference pixel from the at least one main pixel. The optical ranging system also includes features for reducing optical cross-talk between the light emitter and the pixels of the TOF sensor.
1. An optical ranging system comprising:
a support;
a light emitter mounted on the support;
an optical time-of-flight (“TOF”) sensor chip mounted on the support, the TOF sensor chip including at least one main pixel and at least one reference pixel in a semiconductor substrate;
a first light barrier separating the at least one reference pixel from the at least one main pixel, wherein the barrier is substantially non-transparent to light emitted by the light emitter; and
further comprising a second light barrier between the light emitter and the reference and main pixels,
wherein the second light barrier is mounted on the support in a region separating the light emitter and the TOF sensor chip from one another,
wherein the light emitter is on a first side of the second light barrier,
wherein the reference and main pixels are on a second opposite side of the second light barrier, and
wherein the second light barrier is operable to absorb or attenuate light having a wavelength of light emitted by the light emitter.
2. The optical ranging system of claim 1 wherein the TOF sensor chip is mounted on the support by an adhesive, and wherein the means for reducing optical cross-talk includes a light reflective material on an edge of the adhesive.
3. The optical ranging system of claim 1 wherein the TOF sensor chip is mounted on the support by an adhesive, and wherein the means for reducing optical cross-talk includes a light absorptive material on an edge adhesive, the light absorptive material being operable to absorb or attenuate light having a wavelength of light emitted by the light emitter.
4. The optical ranging system of claim 1 wherein the means for reducing optical cross-talk includes a reflective material on an edge of the TOF sensor chip, the light reflective material reflecting operable to reflect light having a wavelength of light emitted by the emitter.
5. The optical ranging system of claim 1 wherein the means for reducing optical cross-talk includes a light absorptive material on an edge of the TOF sensor chip, the light absorptive material being operable to absorb or attenuate light having a wavelength of light emitted by the light emitter.
6. The optical ranging system of claim 1 wherein the means for reducing optical cross-talk includes a cavity containing a light blocking material, the cavity being in a region of the support separating a region where the light emitter is mounted from a region where the TOF sensor chip is mounted, and wherein the light blocking material is operable to absorb or attenuate light having a wavelength of light emitted by the light emitter.
7. The optical ranging system of claim 1 wherein the second light barrier is composed of one or more electronic components.
8. The optical ranging system of claim 7 wherein the second light barrier includes a resistor or capacitor.
9. The optical ranging system of claim 1 wherein the second light barrier has a height such that a top of the second light barrier is at the same height as a top of the TOF sensor chip.
10. The optical ranging system of claim 1 further including one or more lenses to direct incident light onto the at least one main pixel, the one or more lenses being contained in a lens holder having a sidewall that separates the light emitter and the TOF sensor chip from one another.
11. The optical ranging system of claim 10 wherein the lens holder laterally surrounds the TOF sensor chip.
12. The optical ranging system of claim 10 wherein the lens holder has a transparent window in a region over the at least one reference pixel.
13. The optical ranging system of claim 1 wherein the semiconductor substrate has a thickness in a range of 100-200 μm.
14. The optical ranging system of claim 1 wherein the light emitter is a light emitting diode.
15. The optical ranging system of claim 1 further including a light guide to direct some light generated by the emitter to the at least one reference pixel.
16. The optical ranging system of claim 1 wherein at least one main pixel includes a plurality of demodulation pixels.