US 11,927,698 B2
System and method for increasing coherence length in lidar systems
Richard L. Sebastian, Frederick, MD (US); Kendall L. Belsley, Falls Church, VA (US); and Stephan Schulz, Bethesda, MD (US)
Assigned to Aeva, Inc., Mountain View, CA (US)
Filed by Aeva, Inc., Mountain View, CA (US)
Filed on Jan. 24, 2022, as Appl. No. 17/582,402.
Application 17/582,402 is a continuation of application No. 16/272,209, filed on Feb. 11, 2019, granted, now 11,231,488.
Application 16/272,209 is a continuation of application No. 14/795,059, filed on Jul. 9, 2015, granted, now 10,203,401.
Application 14/795,059 is a continuation of application No. 13/843,227, filed on Mar. 15, 2013, granted, now 9,081,090.
Prior Publication US 2022/0252704 A1, Aug. 11, 2022
Int. Cl. G01S 7/48 (2006.01); G01J 9/00 (2006.01); G01J 9/02 (2006.01); G01S 7/4911 (2020.01); G01S 7/4915 (2020.01); G01S 7/497 (2006.01); G01S 17/34 (2020.01); G02B 26/06 (2006.01); H01S 3/00 (2006.01); H01S 3/10 (2006.01); H01S 3/13 (2006.01)
CPC G01S 7/4911 (2013.01) [G01J 9/00 (2013.01); G01J 9/02 (2013.01); G01S 7/4915 (2013.01); G01S 7/497 (2013.01); G01S 17/34 (2020.01); G02B 26/06 (2013.01); H01S 3/0085 (2013.01); H01S 3/10053 (2013.01); H01S 3/1307 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A system for compensating fora phase variance of a laser source comprising:
a laser output path comprising:
a source delay line configured to delay an output of the laser source, and
a source phase modulator configured to receive an output of the source delay line and an output of a source phase corrector;
a phase error path comprising:
a source phase detector configured to determine an estimated phase error of the laser source based on not greater than one half of a coherence time of the laser source, and
the source phase corrector configured to receive the output of the source phase detector and determine a phase correction as the output of the source phase corrector, wherein the source phase modulator outputs a phase corrected laser output;
a target 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, the reference arm signal corresponding to a portion of the phase corrected laser output;
a target phase correction estimator configured to receive the phase difference from the target 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, the target arm signal corresponding to a portion of the phase corrected laser output incident on and reflected back from a target;
a target phase modulator configured to receive the phase correction from the target phase correction estimator, to modulate the target arm signal with the phase correction, and to output a phase corrected target arm signal; and
a target 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 target phase difference detector or to the target arm signal prior to being received by the target phase modulator, wherein the delay time comprises at least a round trip path delay to the target.