Beam walkoff mitigation for light detection and ranging

Abstract

A circuit module of a LIDAR system includes a transmit optical coupler, a first optical mixer, a second optical mixer, and an optical switch. The transmit optical coupler emits a transmit beam in response to a first portion of an optical signal. The transmit beam reflects from an object back to the circuit module as a returning beam. The first optical mixer is disposed on a first optical path to receive the returning beam in response to the returning beam having a first displacement. The second optical mixer is disposed on a second optical path to receive the returning beam in response to the returning beam having a second displacement. The optical switch is coupled to provide a particular portion of the optical signal to the first optical mixer or the second optical mixer based on whether the returning beam has the first displacement or the second displacement.

What is claimed is: 
     
         1 . A light detection and ranging (LIDAR) system comprising one or more circuit modules, wherein at least one of the one or more circuit modules includes:
 a transmit optical coupler configured to emit a transmit beam in response to a first portion of an optical signal, wherein the transmit beam is emitted into an environment and reflected from an object in the environment back to the at least one of the one or more circuit modules as a returning beam;   a first optical mixer disposed on a first optical path to receive the returning beam in response to the returning beam having a first displacement;   a second optical mixer disposed on a second optical path to receive the returning beam in response to the returning beam having a second displacement; and   an optical switch coupled to provide a particular portion of the optical signal to the first optical mixer or the second optical mixer based on whether the returning beam has the first displacement or the second displacement.   
     
     
         2 . The LIDAR system of  claim 1 , further comprising:
 a first receive optical coupler disposed on the first optical path and coupled to provide the returning beam to the first optical mixer in response to the returning beam having the first displacement; and   a second receive optical coupler disposed on the second optical path and coupled to provide the returning beam to the second optical mixer in response to the returning beam having the second displacement.   
     
     
         3 . The LIDAR system of  claim 2 , wherein the transmit optical coupler is disposed between the first receive optical coupler and the second receive optical coupler. 
     
     
         4 . The LIDAR system of  claim 3 , wherein the transmit optical coupler is disposed at a midpoint between the first receive optical coupler and the second receive optical coupler. 
     
     
         5 . The LIDAR system of  claim 2 , wherein the first receive optical coupler and the second receive optical coupler are non-coaxial with, and spaced apart from, the transmit optical coupler. 
     
     
         6 . The LIDAR system of  claim 1 , wherein the first displacement comprises displacement of the returning beam in a first direction, and wherein the second displacement comprises displacement of the returning beam in a second direction that is different from the first direction. 
     
     
         7 . The LIDAR system of  claim 1 , wherein the optical signal comprises infrared laser light or near-infrared laser light. 
     
     
         8 . The LIDAR system of  claim 1 , further comprising:
 a splitter configured to receive the optical signal and to provide the first portion of the optical signal to the transmit optical coupler and to provide the particular portion of the optical signal to the optical switch.   
     
     
         9 . An autonomous vehicle control system including a light detection and ranging (LIDAR) system, the LIDAR system comprising:
 a transmit optical coupler configured to emit a transmit beam in response to a first portion of an optical signal, wherein the transmit beam is emitted into an environment and reflected from an object in the environment back to the LIDAR system as a returning beam;   a first optical mixer disposed on a first optical path to receive the returning beam in response to the returning beam having a first displacement;   a second optical mixer disposed on a second optical path to receive the returning beam in response to the returning beam having a second displacement; and   an optical switch coupled to provide a particular portion of the optical signal to the first optical mixer in response to the returning beam having the first displacement and to provide the particular portion of the optical signal to the second optical mixer in response to the returning beam having the second displacement.   
     
     
         10 . The autonomous vehicle control system of  claim 9 , wherein the LIDAR system further comprises:
 a first receive optical coupler disposed on the first optical path and coupled to provide the returning beam to the first optical mixer in response to the returning beam having the first displacement; and   a second receive optical coupler disposed on the second optical path and coupled to provide the returning beam to the second optical mixer in response to the returning beam having the second displacement.   
     
     
         11 . The autonomous vehicle control system of  claim 10 , wherein the transmit optical coupler is disposed between the first receive optical coupler and the second receive optical coupler. 
     
     
         12 . The autonomous vehicle control system of  claim 11 , wherein the transmit optical coupler is disposed at a midpoint between the first receive optical coupler and the second receive optical coupler. 
     
     
         13 . The autonomous vehicle control system of  claim 10 , wherein the first receive optical coupler and the second receive optical coupler are non-coaxial with, and spaced apart from, the transmit optical coupler. 
     
     
         14 . The autonomous vehicle control system  claim 9 , wherein the first displacement comprises displacement of the returning beam in a first direction, and wherein the second displacement comprises displacement of the returning beam in a second direction that is different from the first direction. 
     
     
         15 . The autonomous vehicle control system of  claim 9 , wherein the optical signal comprises infrared laser light or near-infrared laser light. 
     
     
         16 . The autonomous vehicle control system of  claim 9 , wherein the LIDAR system further comprises:
 a splitter configured to receive the optical signal and to provide the first portion of the optical signal to the transmit optical coupler and to provide the particular portion of the optical signal to the optical switch.   
     
     
         17 . The autonomous vehicle control system of  claim 9 , wherein:
 the first optical mixer is configured to generate a first electrical signal that is representative of a first beat signal; and   the second optical mixer is configured to generate a second electrical signal that is representative of a second beat signal.   
     
     
         18 . An autonomous vehicle, comprising:
 a light detection and ranging (LIDAR) device including:
 a transmit optical coupler configured to emit a transmit beam in response to a first portion of an optical signal, wherein the transmit beam is emitted into an environment and reflected from an object in the environment back to the LIDAR device as a returning beam; 
 a first optical mixer disposed on a first optical path to receive the returning beam and generate a first electrical signal in response to the returning beam having a first displacement; 
 a second optical mixer disposed on a second optical path to receive the returning beam and generate a second electrical signal in response to the returning beam having a second displacement; and 
 an optical switch coupled to provide a particular portion of the optical signal to the first optical mixer or the second optical mixer based on whether the returning beam has the first displacement or the second displacement; and 
   one or more processors configured to control the autonomous vehicle in response to the first electrical signal and the second electrical signal.   
     
     
         19 . The autonomous vehicle of  claim 18 , wherein:
 the first electrical signal is representative of a first beat signal; and   the second electrical signal is representative of a second beat signal.   
     
     
         20 . The autonomous vehicle of  claim 19 , wherein the one or more processors are configured to determine at least one of a range or a velocity of the object in response to at least one of the first electrical signal or the second electrical signal.