Lidar system

Abstract

A light detection and ranging (“LiDAR”) system includes a coherent light source that generates a frequency modulated optical signal comprising a series of optical chirps. A scanning assembly transmits the series of optical chirps in a scan pattern across a scanning region, and receives a plurality of reflected optical chirps corresponding to the transmitted optical chirps that have reflected off one or more objects located within the scanning region. A photodetector mixes the reflected optical chirps with a local oscillation (LO) reference signal comprising a series of LO reference chirps. An electronic data analysis assembly processes digital data derived from the reflected optical chirps and the LO reference chirps mixed at the photodetector to generate distance data and optionally velocity data associated with each of the reflected optical chirps.

What is claimed is: 
     
         1 . A light detection and ranging (LiDAR) system, comprising:
 a coherent light source that generates a frequency modulated optical signal comprising a series of optical chirps, wherein the coherent light source has a linewidth of about 100 kHz or less;   a scanning assembly that (a) transmits the series of optical chirps in a scan pattern across a scanning region and (b) receives a plurality of reflected optical chirps corresponding to the transmitted optical chirps that have reflected off one or more objects located within the scanning region;   a photodetector that mixes the reflected optical chirps with a local oscillation (LO) reference signal comprising a series of LO reference chirps; and   an electronic data analysis assembly that processes digital data derived from the reflected optical chirps and the LO reference chirps mixed at the photodetector to generate distance data associated with each of the reflected optical chirps;   wherein the coherent light source is configured such that a probability of interference between the transmitted optical chirps and other optical chirps transmitted by a second LiDAR system having a configuration of the LiDAR system is less than 1×10 −7.      
     
     
         2 . The LiDAR system of  claim 1 , wherein:
 the coherent light source comprises a source laser coupled to a resonator, wherein the resonator provides optical feedback to the source laser for linewidth reduction;   at least one optical property of the resonator is modulated to enable generation of the optical chirps; and   the resonator comprises a whispering gallery mode (WGM) resonator.   
     
     
         3 . The LiDAR system of  claim 1 , wherein each of the optical chirps has a chirp linearity of 80% or more. 
     
     
         4 . The LiDAR system of  claim 1 , wherein the optical chirps are transmitted at an optical power in a range of 10 mW to 3 W. 
     
     
         5 . A light detection and ranging (LiDAR) system, comprising:
 a coherent light source that generates a frequency modulated optical signal comprising a series of optical chirps, wherein the coherent light source has a linewidth of about 100 kHz or less;   a scanning assembly that (a) transmits the series of optical chirps in a scan pattern across a scanning region and (b) receives a plurality of reflected optical chirps corresponding to the transmitted optical chirps that have reflected off one or more objects located within the scanning region;   a photodetector that mixes the reflected optical chirps with a local oscillation (LO) reference signal comprising a series of LO reference chirps; and   an electronic data analysis assembly that processes digital data derived from the reflected optical chirps and the LO reference chirps mixed at the photodetector to generate distance data associated with each of the reflected optical chirps.   
     
     
         6 . The LiDAR system of  claim 5 , wherein the coherent light source has a linewidth of 10 kHz or less. 
     
     
         7 . The LiDAR system of  claim 5 , wherein the coherent light source has a linewidth of 1 kHz or less. 
     
     
         8 . The LiDAR system of  claim 5 , wherein the coherent light source has a linewidth of 100 Hz or less. 
     
     
         9 . The LiDAR system of  claim 5 , wherein the coherent light source has a linewidth of 1 Hz or less. 
     
     
         10 . The LiDAR system of  claim 5 , wherein the coherent light source is configured such that a probability of interference between the transmitted optical chirps and other optical chirps transmitted by a second LiDAR system having a configuration of the LiDAR system is less than 1×10 −7.    
     
     
         11 . The LiDAR system of  claim 5 , wherein the coherent light source comprises a source laser coupled to a resonator, wherein the resonator provides optical feedback to the source laser for linewidth reduction. 
     
     
         12 . The LiDAR system of  claim 5 , wherein each of the optical chirps has a chirp linearity of 80% or more. 
     
     
         13 . The LiDAR system of  claim 12 , wherein each of the optical chirps has a chirp bandwidth in a range of 1 GHz to 100 GHz. 
     
     
         14 . The LiDAR system of  claim 13 , wherein the optical chirps are generated at a chirp rate in a range of 1×10 14  Hz/s to 5×10 16  Hz/s. 
     
     
         15 . The LiDAR system of  claim 5 , wherein the optical chirps are transmitted at an optical power in a range of 10 mW to 3 W. 
     
     
         16 . The LiDAR system of  claim 5 , wherein the electronic data analysis assembly processes the digital data derived from the reflected optical chirps and the LO reference chirps mixed at the photodetector to also generate velocity data associated with each of the reflected optical chirps. 
     
     
         17 . The LiDAR system of  claim 5 , wherein the photodetector also detects incoherent light originating from one or more external light sources, wherein the incoherent light is filtered so as not to cause interference with the reflected optical chirps. 
     
     
         18 . A light detection and ranging (LiDAR) sensor, comprising:
 a single coherent light source that generates a frequency modulated optical signal comprising a series of optical chirps, wherein the coherent light source has a linewidth of 100 kHz or less;   a single scanner that (a) transmits the series of optical chirps in a scan pattern across a scanning region at an optical power in a range of 10 mW to 3 W and (b) receives a plurality of reflected optical chirps corresponding to the transmitted optical chirps that have reflected off one or more objects located within the scanning region;   a photodetector that mixes the reflected optical chirps with a local oscillation (LO) reference signal comprising a series of LO reference chirps, wherein the coherent light source generates the LO reference chirps; and   an electronic data analysis assembly that processes digital data derived from the reflected optical chirps and the LO reference chirps mixed at the photodetector to generate distance data associated with each of the reflected optical chirps.   
     
     
         19 . The LiDAR sensor of  claim 18 , wherein each of the optical chirps has a chirp linearity of 80% or more. 
     
     
         20 . The LiDAR sensor of  claim 18 , wherein the single coherent light source, the single scanner, the photodetector, and the electronic data analysis assembly are provided in a volume between 10 cm 3  and 500 cm 3 .