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 lens tubes that collimate collected photons, 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 collecting distance information, the optical system comprising:
a bulk transmitting optic;
an emitter array including a plurality of optical emitters having an operating wavelength, each optical emitter in the plurality of optical emitters configured to output an illuminating beam of the operating wavelength through the bulk transmitting optic into a field external to the optical system;
a bulk imaging optic;
a detector array comprising a plurality of pixels arranged behind the bulk imaging optic and operable to detect photons emitted from the emitter array and received through the bulk imaging optic after being reflected from surfaces within the field;
a plurality of lens tubes positioned between the bulk imaging optic and the detector array, wherein each lens tube in the plurality of lens tubes is aligned with a corresponding pixel in the plurality of pixels and is configured to pass light rays reflected into the bulk imaging optic from a discrete spot in the field to its corresponding pixel while absorbing incident light rays reflected into the bulk imaging optic from regions in the field outside the discrete spot, and wherein each lens tube comprises a transparent lens material extending from a first end adjacent to the bulk imaging optic to a second end adjacent to its respective pixel and an elongated opaque cylindrical wall disposed about the transparent lens material; and
one or more optical filters disposed in an optical path of the plurality of pixels and configured to allow a set of wavelengths of electromagnetic radiation, including the operating wavelength, to pass through the optical filter while blocking electromagnetic radiation outside the set of wavelengths from reaching the plurality of pixels.
2. The optical system set forth in claim 1 wherein the emitter array is arranged along a first plane and the elongated cylindrical wall of each lens tube defines an axis normal to an incidence plane of the one or more optical filters.
3. The optical system set forth in claim 2 wherein the cylindrical wall within each lens tube comprises a course or patterned opaque interface about a transparent lens material to increase absorption and decrease reflection of light rays incident on the cylindrical wall.
4. The optical system set forth in claim 1 wherein each optical emitter in the plurality of optical emitters is configured to output its illuminating beam of the operating wavelength towards a discrete spot in a field external to the optical system that is non-overlapping with the illuminating beams from all other optical emitters in the plurality of optical emitters.
5. The optical system set forth in claim 4 wherein each lens tube is configured to collimate light rays reflected into the bulk imaging optic from a discrete spot in the field illuminated by a corresponding optical emitter in the plurality of optical emitters.
6. The optical system set forth in claim 1 wherein the bulk image optic is characterized by a focal plane and each lens tube in the plurality of lens tubes is characterized by a focal length and offset from the focal plane of the bulk imaging optic by the focal length.
7. The optical system set forth in claim 1 wherein each pixel in the plurality of pixels comprises a set of subpixels.
8. The optical system set forth in claim 7 further comprising a diffuser interposed between the second end of each lens tube and the detector array, wherein the diffuser spreads collimated light from each lens in the plurality of lens tubes across the set of subpixels of a corresponding pixel in the plurality of pixels.
9. The optical system set forth in claim 7 wherein the set of subpixels in each pixel comprises a plurality of single photon avalanche diodes (SPADs).
10. The optical system set forth in claim 1 wherein each optical emitter in the plurality of optical emitters corresponds to one pixel in the plurality of pixels.
11. The optical system set forth in claim 1 wherein the plurality of lens tubes are arranged in a one-dimensional line array parallel to a first axis.
12. The optical system set forth in claim 1 wherein the plurality of lens tubes are arranged in a two-dimensional grid array.
13. An optical system for collecting distance information, the optical system comprising:
a bulk transmitting optic;
an emitter array including a plurality of optical emitters having an operating wavelength, each optical emitter in the plurality of optical emitters configured to output an illuminating beam of the operating wavelength through the bulk transmitting optic towards a discrete spot in a field external to the optical system that is non-overlapping with the illuminating beams from the other optical emitters in the plurality of optical emitters;
a bulk imaging optic;
a detector array comprising a plurality of pixels arranged behind the bulk imaging optic and operable to detect photons emitted from the emitter array and received through the bulk imaging optic after being reflected from surfaces within the field;
a plurality of lens tubes positioned between the bulk imaging optic and the detector array, wherein each lens tube in the plurality of lens tubes is aligned with a corresponding pixel in the plurality of pixels and is configured to pass light rays reflected into the bulk imaging optic from a discrete spot in the field to its corresponding pixel while absorbing incident light rays reflected into the bulk imaging optic from regions in the field outside the discrete spot, and wherein each lens tube comprises a transparent lens material extending from a first end adjacent to the bulk imaging optic to a second end adjacent to its respective pixel and an elongated opaque cylindrical wall disposed about the transparent lens material;
a plurality of shutters disposed between the plurality of lens tubes and the plurality of pixels, wherein each shutter in the plurality of shutters is aligned with a corresponding pixel in the plurality of pixels and is configured to open and close in conjunction with activation and deactivation of an optical emitter in the plurality of optical emitters that projects light into the field of view of the corresponding pixel; and
an optical filter disposed in an optical path of the plurality of pixels and operable to allow a set of wavelengths of electromagnetic radiation, including the operating wavelength, to pass through the optical filter while blocking electromagnetic radiation outside the set of wavelengths from reaching the plurality of pixels.
14. The optical system set forth in claim 13 wherein each shutter in the plurality of shutters is an electrochromic shutter.
15. The optical system set forth in claim 13 wherein each shutter in the plurality of shutters is a MEMS mechanical shutter.
16. The optical system set forth in claim 13 wherein each lens tube in the plurality of lens tubes comprises a lens characterized by a focal length and offset from a focal plane of the bulk imaging optic by the focal length.
17. The optical system set forth in claim 16 wherein the emitter array is arranged along a first plane and each lens tube in the plurality of lens tubes comprises the cylindrical wall extending from the lens opposite the focal plane defining a long axis substantially perpendicular to the first plane.
18. The optical system set forth in claim 17 wherein the cylindrical wall within each lens tube is configured to absorb incident light rays reflected into the bulk imaging optic from a region in the field outside the discrete spot illuminated by its corresponding optical emitter.
19. The optical system set forth in claim 13 wherein each pixel in the plurality of pixels comprises a plurality of single photon avalanche diodes (SPADs).
20. The optical system set forth in claim 19 further comprising a diffuser interposed between the second end of each lens tube and the detector array, wherein the diffuser spreads collimated light from each lens in the plurality of lens tubes across the plurality of SPADs of a corresponding pixel in the plurality of pixels.