Optical system for collecting distance information within a field
An optical system for collecting distance information within a field is provided. The optical system may include lenses for collecting photons from a field and may include lenses for distributing photons to a field. The optical system may include lenses that collimate photons passed by an aperture, optical filters that reject normally incident light outside of the operating wavelength, and pixels that detect incident photons. The optical system may further include illumination sources that output photons at an operating wavelength.
1. An optical system for performing distance measurements, the optical system comprising:
an optical imaging transmit module comprising:
a plurality of vertical-cavity surface-emitting lasers (VCSELs) arranged in a first array, each VCSEL of the plurality of VCSELs configured to project a discrete spot in a field ahead of the VCSEL and external to the optical imaging transmit module; and
bulk transmitter optics spaced apart from the plurality of VCSELs and characterized by a focal plane opposite the field; and
an optical imaging receive module comprising:
bulk receiver optics configured to receive light rays emitted by the plurality of VCSELs and reflected from surfaces and project the received light rays within the optical imaging receive module;
an aperture layer spaced apart from the bulk optics and coincident the focal plane, the aperture layer comprising a plurality of apertures corresponding in number to the plurality of lasers and arranged in a second array proportional to the first array;
a plurality of detectors corresponding in number to the plurality of apertures, each of the plurality of detectors aligned with a corresponding one of the plurality of apertures and including a plurality of single-photon avalanche diodes (SPADs);
a plurality of collimating lenses corresponding in number to the plurality of apertures, each lens in the plurality of collimating lenses disposed between one of the plurality of apertures and one of the plurality of detectors; and
an optical filter disposed between the plurality of collimating lenses and the plurality of detectors, the optical filter configured to receive light from the plurality of collimating lenses and pass light at the operating wavelength to the plurality of detectors.
2. The optical system of claim 1 wherein the optical imaging transmit module and the optical imaging receive module are disposed adjacent to each other.
3. The optical system of claim 2 wherein system is configured to be rotated about an axis parallel to a column of apertures in the plurality of apertures.
4. The optical system of claim 3 wherein the bulk transmitter optics and bulk receiver optics are substantially identical to each other in material, geometry and thermal isolation and are disposed adjacent to, and offset laterally from, each other.
5. The optical system of claim 1 wherein the optical imaging receive module includes a plurality of channels, corresponding in number to the plurality of detectors and arranged in an array, wherein each channel in the plurality of channels includes one aperture from the plurality of apertures, one collimating lens from the plurality of collimating lenses and one detector from the plurality of detectors.
6. The optical system of claim 1 wherein the plurality of SPADs included in each of the plurality of detectors is arranged in an array.
7. The optical system of claim 6 wherein the plurality of SPADs included in each of the plurality of detectors is arranged in two-dimensional array.
8. The optical system of claim 7 wherein each of the plurality of VCSELs and the plurality of SPADs are arranged in two-dimensional arrays.
9. The optical system of claim 1 wherein the bulk optics are configured to project the received light rays within the optical imaging receive module towards a focal plane and wherein each lens in the plurality of collimating lenses is characterized by a focal length and spaced apart from the focal plane by the focal length.
10. The optical system of claim 9 wherein the aperture layer is coincident to the focal plane and comprises a stop region around the plurality of apertures.
11. The optical system of claim 10 wherein the stop region is configured to absorb light rays reflected from surfaces.
12. An optical system for performing distance measurements, the optical system comprising:
an optical imaging transmit module comprising:
bulk transmitter optics; and
a plurality of lasers arranged in a first array spaced apart from the bulk transmitter optics, each of the plurality of lasers configured to project a discrete illuminating beam at an operating wavelength through the bulk transmitter optics; and
an optical imaging receive module comprising:
bulk receiver optics configured to receive light rays emitted by the plurality of lasers and reflected from surfaces and project the received light rays within the optical imaging receive module;
an aperture layer spaced apart from the bulk optics and comprising a plurality of apertures corresponding in number to the plurality of lasers and arranged in a second array proportional to the first array;
a plurality of detectors corresponding in number to the plurality of apertures, each of the plurality of detectors aligned with a corresponding one of the plurality of apertures;
a plurality of lenses corresponding in number to the plurality of apertures, each lens in the plurality of lenses disposed between one of the plurality of apertures and one of the plurality of detectors; and
an optical filter disposed between the plurality of lenses and the plurality of detectors, the optical filter configured to receive light from the plurality of lenses and pass light at the operating wavelength to the plurality of detectors.
13. The optical system of claim 12 wherein the optical imaging receive module includes a plurality of channels, corresponding in number to the plurality of detectors and arranged in an array, wherein each channel in the plurality of channels includes one aperture from the plurality of apertures, one collimating lens from the plurality of lenses and one detector from the plurality of detectors.
14. The optical system of claim 13 wherein each of the detectors in the plurality of detectors comprises a plurality of single-photon avalanche diodes (SPADs).
15. The optical system of claim 14 wherein each of the lasers in the plurality of lasers comprises a vertical-cavity surface-emitting laser (VCSEL).
16. The optical system of claim 14 wherein the optical image receive module further comprises a diffuser interposed between the optical filter and the plurality of detectors, the diffuser configured to spread collimated light output from each lens in the plurality of lenses across a width and height of a sensing area of SPADs in the same channel as the lens.
17. The optical system of claim 12 wherein system is configured to be rotated about an axis parallel to a column of apertures in the plurality of apertures.
18. The optical system of claim 12 wherein the bulk optics are configured to project the received light rays within the optical imaging receive module towards a focal plane and wherein each lens in the plurality of lenses is characterized by a focal length and spaced apart from the focal plane by the focal length.
19. The optical system of claim 18 wherein the aperture layer is coincident to the focal plane and comprises a stop region around the plurality of apertures and wherein the stop region is configured to absorb light rays reflected from surfaces.
20. The optical system of claim 12 wherein each lens in the plurality of lenses is configured to collimate light rays passed by its corresponding aperture in the plurality of apertures and to pass the collimated light rays into the optical filter.