Optoelectronic modules operable to recognize spurious reflections and to compensate for errors caused by spurious reflections
An optoelectronic module including a light emitter to generate light to be emitted from the module, a plurality of spatially distributed light sensitive elements arranged to detect light from the emitter that is reflected by an object outside the module, and one or more dedicated spurious-reflection detection pixels.
1. An optoelectronic module comprising:
a light emission chamber and a light detection chamber;
a first passive optical element disposed over the light emission chamber and a second passive optical element disposed over the light detection chamber;
a light emitter in the light emission chamber operable to emit light toward the first passive optical element;
a plurality of demodulation pixels in the light detection chamber arranged to detect light from the emitter that is reflected by an object outside the module; one or more spurious-reflection detection pixels in the light detection chamber; and
one or more light absorbing regions in or on the second passive optical element for defining a narrow straight path from a predefined area on a surface of a transmissive cover of a host device to the one or more spurious-reflection detection pixels, wherein the one or more light absorbing regions are substantially non-transparent to light at a wavelength emitted by the light emitter.
2. The optoelectronic module of claim 1 including a plurality of the light absorbing regions in or on the second passive optical element.
3. The optoelectronic module of claim 2 wherein a first one of the light absorbing regions is on a surface of the second passive optical element facing the demodulation pixels, and a second one of the light absorbing regions is on a surface of the second passive optical element facing away the demodulation pixels.
4. The optoelectronic module of claim 1 wherein the light emitter is operable to emit infra-red light and wherein the one or more light absorbing regions are substantially nontransparent to the infra-red light.
5. The optoelectronic module of claim 1 wherein each of the one or more light absorbing regions comprises a black chrome coating.
6. The optoelectronic module of claim 1 wherein each of the one or more light absorbing regions is a laser blackened region of the second passive optical element.
7. An optoelectronic module comprising:
a light emission chamber and a light detection chamber;
a first passive optical element disposed over the light emission chamber and a second passive optical element disposed over the light detection chamber;
a light emitter in the light emission chamber operable to emit light toward the first passive optical element;
a plurality of demodulation pixels in the light detection chamber arranged to detect light from the emitter that is reflected by an object outside the module;
one or more spurious-reflection detection pixels in the light detection chamber; and
one or more light absorbing regions in or on the second passive optical element arranged to block emitter light reflected from one or more pre-defined areas of a transmissive cover of a host device from reaching the demodulation pixels.
8. The optoelectronic module of claim 7 wherein the one or more light absorbing regions are disposed so as to allow emitter light reflected by an object outside the module back toward the module to pass through the second passive optical element to the demodulation pixels.
9. The optoelectronic module of claim 7 wherein each of the one or more light absorbing regions comprises a black chrome coating.
10. The optoelectronic module of claim 7 wherein each of the one or more light absorbing regions is a laser blackened region of the second passive optical element.