Coaxial lidar system using a diffractive waveguide
A coaxial lidar system includes one or more emitter channels and one or more sensor channels that share an optical module. A diffractive waveguide can be used to redirect received light from the shared optical module to the sensor channels.
1 . A lidar system comprising:
an emitter channel including a light source configured to produce light at an operating wavelength and a first micro-optic element configured to collimate the light produced by the light source;
a sensor channel including a photosensor, the sensor channel disposed at a lateral distance from the emitter channel;
a second micro-optic element configured to diverge the collimated light from the first micro-optic element and configured to collimate light received from an environment; and
a diffractive waveguide disposed between the first micro-optic element and the second micro-optic element, the diffraction waveguide including a diffraction grating that redirects received light having the operating wavelength from the second micro-optic element toward the sensor channel.
2 . The lidar system of claim 1 wherein the diffractive waveguide has a first surface and a second surface opposite the first surface and wherein the diffractive waveguide includes:
a first diffraction grating disposed at the first surface and configured to redirect received light having the operating wavelength from the second micro-optic element into the diffractive waveguide at an angle that produces total internal reflection at the second surface; and
a second redirection component positioned to redirect received light that has reflected off the second surface in a direction out of the diffractive waveguide and into the sensor channel.
3 . The lidar system of claim 2 wherein the first diffraction grating includes a non-diffractive opening sized and positioned such that the collimated light from the emitter channel passes through the non-diffractive opening.
4 . The lidar system of claim 2 wherein the first surface is oriented toward the second micro-optic element and the first diffraction grating is a transmissive grating.
5 . The lidar system of claim 2 wherein the first surface is oriented toward the first micro-optic element and the first diffraction grating is a reflective grating.
6 . The lidar system of claim 2 wherein the second redirection component includes a second diffraction grating.
7 . The lidar system of claim 2 wherein the second redirection component includes a mirror positioned at an angle to the first surface.
8 . The lidar system of claim 1 further comprising an aperture layer disposed between the first micro-optic element and the diffractive waveguide, the aperture layer having an opening to admit light output by the first micro-optic element into the diffractive waveguide.
9 . The lidar system of claim 1 further comprising:
a bulk optic module disposed between the second micro-optic element and the environment such that the emitter channel and the sensor channel have a common optical axis in the bulk optic module.
10 . A lidar system comprising:
an array of emitter channels, each emitter channel including a light source configured to produce light at an operating wavelength and a first micro-optic element configured to collimate the light produced by the light source;
an array of sensor channels arranged such that each sensor channel corresponds to a different one of the emitter channels, each sensor channel including a light detector;
an array of second micro-optic elements, each second micro-optic element configured to diverge the collimated light from a corresponding one of the emitter channels and to collimate light received from an environment; and
a diffractive waveguide disposed between the first micro-optic elements and the array of second micro-optic elements, the diffraction waveguide including a diffraction grating that redirects received light having the operating wavelength from the array of second micro-optic elements toward the array of sensor channels.
11 . The lidar system of claim 10 further comprising:
a bulk optic module disposed between the array of second micro-optic elements and the environment such that the emitter channels and the sensor channels have a common optical axis in the bulk optic module.
12 . The lidar system of claim 10 wherein the diffractive waveguide has a first surface and a second surface opposite the first surface and wherein the diffractive waveguide includes:
a first diffraction grating disposed at the first surface and configured to redirect received light having the operating wavelength from the array of second micro-optic elements into the diffractive waveguide at an angle that produces total internal reflection at the second surface; and
a second redirection component positioned to redirect received light that has reflected off the second surface in a direction out of the diffractive waveguide and into the sensor channels.
13 . The lidar system of claim 12 wherein the first diffraction grating includes an array of non-diffractive openings sized and positioned such that the collimated light from each of the emitter channels passes through one of the non-diffractive openings.
14 . The lidar system of claim 12 wherein the first surface is oriented toward the second micro-optic element and the first diffraction grating is a transmissive grating.
15 . The lidar system of claim 12 wherein the first surface is oriented toward the first micro-optic element and the first diffraction grating is a reflective grating.
16 . The lidar system of claim 12 wherein the second redirection component includes a second diffraction grating.
17 . The lidar system of claim 12 wherein the second redirection component includes a mirror positioned at an angle to the first surface.
18 . The lidar system of claim 10 wherein the array of emitter channels and the array of sensor channels are formed on the same substrate.
19 . The lidar system of claim 10 wherein the array of emitter channels and the array of sensor channels are one-dimensional arrays.
20 . The lidar system of claim 10 wherein the array of emitter channels and the array of sensor channels are two-dimensional arrays.