Method, system, and apparatus for a LiDAR sensor with varying grating pitch
A method, apparatus, and system for imaging a scene by flood illuminating the scene with a wavelength sweeping laser.
1. An apparatus for scanning a scene comprising:
a wavelength-sweeping laser arranged to flood illuminate the scene;
a photonic integrated circuit (PIC); the PIC including a plurality of gratings, wherein at least two gratings have a different pitch; a plurality of waveguides; a set of couplers; and a set of photodetectors; wherein each waveguide of the plurality of waveguides connects a grating of the plurality of gratings to a coupler of the set of couplers; wherein each coupler of the set of couplers is connected to a waveguide of the set of waveguides; wherein the PIC is arranged to capture light reflected from the scene from the wavelength-sweeping laser; and
a digital signal processor (DSP).
2. The apparatus of claim 1 wherein the plurality of gratings has a linear distribution in grating pitch.
3. The apparatus of claim 1 wherein the plurality of gratings has a stepwise distribution in grating pitch.
4. The apparatus of claim 1 wherein the plurality of gratings has a non-linear distribution in grating pitch.
5. The apparatus of claim 1 further comprising:
an analog digital converter (ADC); wherein the ADC is communicatively coupled to an output from the set photodetectors.
6. The apparatus of claim 5
wherein the digital signal processor is communicatively coupled to the ADC.
7. A method comprising:
illuminating a scene with flood illumination using light from a sweeping laser without scanning the scene;
receiving the light reflected off the scene from the sweeping laser at an array of gratings; wherein the received light substantially simultaneously travels down each waveguide of an array of waveguides on a PIC to a set of couplers; wherein each respective grating of the array of gratings has a respective waveguide of the array of waveguides connecting the each respective array of the array of gratings to a respective coupler of a set of couplers;
interfering, using each coupler of the set of couplers, the received light from the scene with light split from a wavelength-sweeping laser; and
measuring, using a set of photodetectors, the difference between the received light and the light split from the laser.
8. The method of claim 7 further comprising:
sending the measured difference to an analog digital converter; and
converting the measured difference to digital data.
9. The method of claim 8 further comprising:
sending the digital data to a digital signal processor (DSP); and
calculating a point cloud for the scene using the DSP.
10. A system comprising:
a wavelength-sweeping laser;
a photonic integrated circuit (PIC); the PIC including a plurality of gratings, wherein at least two gratings have a different pitch; a plurality of waveguides; a set of couplers; and a set of photodetectors; wherein each waveguide of the plurality of waveguides connects a grating of the plurality of gratings to a coupler of the set of couplers; wherein each coupler of the set of couplers is connected to a waveguide of the set of waveguides; wherein the PIC is arranged to capture light reflected from the scene from the wavelength-sweeping laser; wherein the PIC is enabled to:
receive the light reflected off the scene from the sweeping laser at an array of gratings; wherein the received light substantially simultaneously travels down each waveguide of an array of waveguides on a PIC to a set of couplers; wherein each respective grating of the array of gratings has a respective waveguide of the array of waveguides connecting the each respective array of the array of gratings to a respective coupler of a set of couplers;
interfere, using each coupler of the set of couplers, the received light from the scene with light split from the sweeping laser; and
measure, using a set of photodetectors, the interference between the received light and the light split from the wavelength-sweeping laser.
11. The system of claim 10 wherein the plurality of gratings has a linear distribution in grating pitch.
12. The system of claim 11 further comprising:
an analog to digital converter (ADC); wherein the PIC is enabled to send the measured difference to an analog digital converter; wherein the ADC is enabled to convert the measured difference to digital data.
13. The system of claim 12 further comprising:
a digital signal processor (DSP); wherein the ADC is enabled to send the digital information to the DSP; wherein the DSP is enabled to calculate a point cloud for the scene using the DSP.
14. The system of claim 13 wherein the wavelength-sweeping laser is enabled to project light on the scene using a sweeping laser.
15. The apparatus of claim 10 wherein the plurality of gratings has a step-wise distribution in grating pitch.
16. The apparatus of claim 10 wherein the plurality of gratings has a non-linear distribution in grating pitch.