US 11,698,444 B1
Techniques for enhancing LO and RX overlap in FMCW lidars using birefringent crystals
Ashwin Kumar Samarao, Sunnyvale, CA (US); Oguzhan Avci, San Francisco, CA (US); and Behsan Behzadi, Sunnyvale, CA (US)
Assigned to Aeva, Inc., Mountain View, CA (US)
Filed by AEVA, INC., Mountain View, CA (US)
Filed on Aug. 18, 2022, as Appl. No. 17/890,990.
Int. Cl. G01S 7/481 (2006.01)
CPC G01S 7/4815 (2013.01) [G01S 7/4817 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A frequency modulated continuous-wave (FMCW) light detection and ranging (LiDAR) system, comprising:
an optical source to emit an optical beam;
an optical window to reflect a first portion of the optical beam to generate a local oscillator (LO) signal;
an optical scanner to transmit a second portion of the optical beam to a target to scan the target to generate a target return signal;
a birefringent crystal plate to transmit the LO signal and the target return signal to a photodetector (PD) and shift the LO signal and the target return signal by different displacements to increase a percentage of an overlap of the LO signal and the target return signal on a detection plane of the PD, wherein an optical axis of the birefringent crystal plate is disposed to create a first angle with respect to a front surface of the birefringent crystal plate on a cross-section, and wherein the first angle is determined based on a scan speed of the optical scanner; and
the PD to mix the target return signal with the LO signal on the detection plane of the PD to extract range and velocity information of the target.