Producing illumination beams using micro-lens arrays
A device includes an illumination device for emitting an illumination beam. The illumination device includes an emitter array including multiple light emitters; and a micro-lens array (MLA) including multiple micro-lenses. The MLA is positioned to receive light emitted from the emitter array. Light from the MLA forms the illumination beam. A first region of the MLA is offset from the emitter array by a first offset amount, and a second region of the MLA is offset from the emitter array by a second offset amount different than the first offset amount.
1. A device comprising:
an illumination device for emitting an illumination beam, the illumination device comprising:
a substrate;
an emitter array comprising multiple light emitters, wherein the emitter array is positioned in an emission layer of the substrate;
an optical layer transparent to the wavelength of light at which the light emitters are configured to emit light, wherein the optical layer is epitaxially grown onto the emission layer of the substrate, wherein the optical layer comprises GaAs or AlGaAs, wherein the optical layer has a thickness of more than 10 μm and less than 20 μm; and
a micro-lens array (MLA) comprising multiple micro-lenses configured to deflect light of the multiple light emitters, the MLA being positioned to receive light emitted from the emitter array, wherein the MLA is positioned in the optical layer,
wherein the multiple micro-lenses of the MLA are arranged at different offsets to the corresponding multiple light emitter such that sub-beams are formed with adjacent sub-beams overlapping at their FWHM point and forming an illumination beam having a uniform intensity and a steep rollover at the edges of the illumination beam.
2. The device of claim 1 , in which the light emitters comprise vertical cavity surface emitting lasers (VCSELs).
3. The device of claim 1 , in which the optical layer has a refractive index of at least 1.5.
4. The device of claim 1 , in which each light emitter emits a single beam of light, and in which a divergence of the illumination beam is greater than a divergence of each of the single beams of light emitted from the light emitters.
5. The device of claim 4 , in which the divergence of the illumination beam is between 20° and 180°.
6. The device of claim 5 , in which the divergence of the illumination beam is between 60° and 70°.
7. The device of claim 4 , in which the divergence of the illumination beam in a first direction is different than the divergence of the illumination beam in a second direction.
8. The device of claim 7 , in which the divergence of the illumination beam in the first direction is between 50° and 60° and the divergence of the illumination beam in the second direction is between 60° and 70°.
9. The device of claim 1 , in which each of the micro-lenses at least partially overlaps a corresponding one of the light emitters.
10. The device of claim 9 , in which each of the micro-lenses at least partially overlaps multiple corresponding light emitters.
11. The device of claim 1 , wherein a first sub-beam output from a first region of the MLA has a different angle of deflection than a second sub-beam output from a second region of the MLA.
12. The device of claim 1 , in which the illumination device comprises an illumination device of a mobile computing device.
13. The device of claim 1 , in which the illumination device comprises a LIDAR device.
14. The device of claim 13 , in which the device comprises a vehicle and the illumination device comprises a LIDAR device for the vehicle.
15. The device of claim 13 , in which the LIDAR device comprises a component of a three-dimensional mapping system.
16. A 3-D imaging system comprising:
an illumination device in accordance with claim 1 , the illumination device being configured to illuminate an object with a pattern of light;
a sensor configured to receive reflected light from the illuminated object; and
one or more computing devices configured to determine a 3-D shape of the object based on the reflected light.
17. The 3-D imaging system of claim 16 , in which the sensor comprises a camera.
18. The 3-D imaging system of claim 16 , in which the one or more computing devices are configured to determine a 3-D mapping of an area based on the reflected light.
19. The 3-D imaging system of claim 16 , in which the one or more computing devices are configured to perform a facial recognition process based on the determined 3-D shape of the object.
20. A method of making an illumination device, comprising:
forming an emitter array in an emission layer of a substrate, the emitter array comprising multiple light emitters; and
forming an optical layer transparent to the wavelength of light at which the light emitters are configured to emit light on the substrate by:
epitaxially growing the optical layer comprising GaAs or AlGaAs on the emission layer of the substrate; and
forming an MLA comprising multiple micro-lenses in the optical layer, wherein the multiple micro-lenses are configured to deflect light of the multiple light emitters,
in which forming the MLA includes forming the MLA
such that the multiple micro-lenses of the MLA are arranged at different offsets to the corresponding multiple light emitter forming sub-beams with adjacent sub-beams overlapping at their FWHM point forming an illumination beam having a uniform intensity and a steep rollover at the edges of the divergent illumination beam,
wherein the optical layer has a thickness of more than 10 μm and less than 20 μm.
21. The method of claim 20 , in which forming the emitter array and the MLA comprise forming the emitter array and the MLA using semiconductor fabrication processes.
22. A device comprising:
an illumination device for emitting an illumination beam, the illumination device comprising:
a substrate;
an emitter array comprising multiple light emitters, wherein the emitter array is positioned in an emission layer of the substrate;
an optical layer transparent to the wavelength of light at which the light emitters are configured to emit light, wherein the optical layer is epitaxially grown onto the emission layer of the substrate, wherein the optical layer comprises GaAs or AlGaAs, wherein the optical layer has a thickness of more than 10 μm and less than 20 μm; and
a micro-lens array (MLA) comprising multiple micro-lenses configured to deflect light of the multiple light emitters, the MLA being positioned to receive light emitted from the emitter array, wherein the MLA is positioned in the optical layer,
wherein the multiple micro-lenses of the MLA are arranged at offsets to the corresponding multiple light emitter such that sub-beams are formed with adjacent sub-beams overlapping at their FWHM point and forming an illumination beam having a uniform intensity and a steep rollover at the edges of the illumination beam;
wherein the light emitters comprise vertical cavity surface emitting lasers (VCSELs), the VCSELs having a diameter of 7.5 μm and arranged in an array with a pitch of 28 pm;
wherein the multiple lenses in the MLA have a diameter of 25 μm and a height of 8 μm; and
wherein each lens in the MLA is offset from its corresponding VCSEL by an offset of 8.5 μm.