LIDAR waveform generation system
A light detection and ranging (LIDAR) system includes a LIDAR measurement unit, a reference measurement unit, and a phase cancellation unit. The LIDAR measurement unit estimates a time for which a laser beam travels. The reference measurement unit determines a phase of a laser source. The phase cancellation unit identifies phase noise and cancels the phase noise from the laser beam, at least partially based on the phase of the laser source and the time for which the laser beam travels. The denoised signal is used to determine the range between a laser source and a target.
1. A light detection and ranging (LIDAR) system comprising:
a laser configured to generate a laser beam based on a particular laser waveform that is associated with at least one parameter of a plurality of parameters; and
a calibration unit configured to reduce distortion in the laser using a derivative of a merit function with respect to the at least one parameter of the plurality of parameters to update the at least one parameter of the plurality of parameters with a value that reduces a value of the merit function, wherein the merit function is a function of a time-dependent frequency of the laser beam, wherein the calibration unit is configured to update the particular laser waveform with the at least one parameter of the plurality of parameters.
2. The LIDAR system of claim 1 further comprising:
an interferometer configured to provide a reference signal,
wherein the calibration unit is configured to receive an in-phase signal and a quadrature signal from the interferometer,
wherein the calibration unit is configured to determine the time-dependent frequency of the laser beam based on the in-phase signal and the quadrature signal.
3. The LIDAR system of claim 1 , wherein the plurality of parameters have initial values and one or more of the initial values are superseded by one or more updated values.
4. The LIDAR system of claim 1 , wherein the calibration unit is configured to evaluate the merit function with updated values of the plurality of parameters.
5. The LIDAR system of claim 4 , wherein to evaluate the merit function, the calibration unit is configured to load the particular laser waveform into a digital to analog converter, measure an output from an interferometer, and calculate the time-based frequency of the laser beam based on the output from the interferometer.
6. The LIDAR system of claim 1 , wherein the calibration unit is configured to calculate a gradient of the merit function with respect to the at least one parameter of the plurality of parameters.
7. The LIDAR system of claim 1 , wherein a first parameter of the plurality of parameters includes a shape of the particular laser waveform and a second parameter of the plurality of parameters includes a behavior of the particular laser waveform.
8. The LIDAR system of claim 1 , wherein the calibration unit is configured to update the plurality of parameters based on a partial derivative of the merit function with respect to at least one parameter of the plurality of parameters.
9. The LIDAR system of claim 1 , wherein the calibration unit is configured to update the plurality of parameters to compensate for distortion characteristics of the laser.
10. An autonomous vehicle control system comprising:
a light detection and ranging (LIDAR) system including:
a laser configured to generate a laser beam based on a particular laser waveform that is associated with at least one parameter of a plurality of parameters; and
a calibration unit configured to reduce distortion in the laser using a derivative of a merit function with respect to the at least one parameter of the plurality of parameters to update the at least one parameter of the plurality of parameters with a value that reduces a value of the merit function, wherein the merit function is a function of a time-dependent frequency of the laser beam, wherein the calibration unit is configured to update the particular laser waveform with the at least one parameter of the plurality of parameters; and
one or more processors to control the autonomous vehicle control system in response to the particular laser waveform at least partially updated by the calibration unit.
11. The autonomous vehicle control system of claim 10 further comprising:
an interferometer,
wherein the calibration unit is configured to receive an in-phase signal and a quadrature signal from the interferometer,
wherein the calibration unit is configured to determine the time-dependent frequency of the laser beam based on the in-phase signal and the quadrature signal.
12. The LIDAR system of claim 10 , wherein the plurality of parameters have initial values and one or more of the initial values is superseded by one or more updated values.
13. The LIDAR system of claim 10 , wherein the calibration unit is configured to evaluate the merit function with updated values of the plurality of parameters.
14. The LIDAR system of claim 13 , wherein to evaluate the merit function, the calibration unit is configured to load the particular laser waveform into a digital to analog converter, measure an output from an interferometer, and calculate the time-based frequency of the laser beam based on the output from the interferometer.
15. The LIDAR system of claim 10 , wherein the calibration unit is configured to calculate a gradient of the merit function with respect to the at least one parameter of the plurality of parameters.
16. An autonomous vehicle comprising:
a light detection and ranging (LIDAR) system including:
a laser configured to generate a laser beam based on a particular laser waveform that is associated; with at least one parameter of a plurality of parameters; and
a calibration unit configured to reduce distortion in the laser using a derivative of a merit function with respect to the at least one parameter of the plurality of parameters to update the at least one parameter of the plurality of parameters with a value that reduces a value of the merit function, wherein the merit function is a function of a time-dependent frequency of the laser beam, wherein the calibration unit is configured to update the particular laser waveform with the at least one parameter of plurality of parameters; and
one or more processors to control the autonomous vehicle in response to the particular laser waveform at least partially updated by the calibration unit.
17. The autonomous vehicle of claim 16 , wherein the calibration unit is configured to evaluate the merit function of the laser with updated values of the plurality of parameters.
18. The autonomous vehicle of claim 16 , wherein the calibration unit is configured to calculate a gradient of the merit function with respect to the at least one parameter of the plurality of parameters.