System and Method for Increasing Coherence Length in Lidar Systems

Patent metadata

Field	Value
Publication number	US-2025035759-A1
Application number	US-202418600877-A
Country	US
Kind code	A1
Filing date	Mar 11, 2024
Priority date	Mar 15, 2013
Publication date	Jan 30, 2025
Grant date	—

Abstract

Various implementations of the invention compensate for “phase wandering” in tunable laser sources. Phase wandering may negatively impact a performance of a lidar system that employ such laser sources, typically by reducing a coherence length/range of the lidar system, an effective bandwidth of the lidar system, a sensitivity of the lidar system, etc. Some implementations of the invention compensate for phase wandering near the laser source and before the output of the laser is directed toward a target. Some implementations of the invention compensate for phase wandering in the target signal (i.e., the output of the laser that is incident on and reflected back from the target). Some implementations of the invention compensate for phase wandering at the laser source and in the target signal.

First claim

What is claimed is:

1 . A system for compensating for phase variance in a laser source comprising:
a phase difference detector configured to receive a reference arm signal and to detect a phase difference of the reference arm signal, the phase difference corresponding to a difference in the phase of the reference arm signal at two points in time; a phase correction estimator configured to receive the phase difference from the phase detector and to estimate a phase correction to be applied to a target arm signal, wherein the phase correction compensates for the phase variance of the laser source; a phase modulator configured to receive the phase correction from the phase correction estimator, to modulate the target arm signal with the phase correction, and to output a phase corrected target arm signal; and a delay coupled either to either the reference arm signal and configured to introduce a delay time into the reference arm signal prior to being received by the phase difference detector or to the target arm signal prior to being received by the phase modulator, wherein the delay time comprises at least a round trip path delay.

2 . The system of claim 1 , wherein the delay is coupled to the target arm signal prior to being received by the phase modulator.

3 . The system of claim 1 , wherein the delay time is adjustable.

Assignees

• Aeva Inc

Inventors

• Sebastian Richard L
• Belsley Kendall L
• Schulz Stephan

Classifications

• G01S17/34

  using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal · CPC title

• G02B26/06

  for controlling the phase of light (G02B26/08 takes precedence {, measuring optical phase difference G01J9/00}) · CPC title

• G01J9/00 Primary

  Measuring optical phase difference (devices or arrangements for controlling the phase of light beams G02F1/01); Determining degree of coherence; Measuring optical wavelength (spectrometry G01J3/00) · CPC title

• H01S3/0085

  Modulating the output, i.e. the laser beam is modulated outside the laser cavity · CPC title

• H01S3/1307

  Stabilisation of the phase · CPC title