Patent ID: 8558993

Claim:
A method of comb-based coherent Light Detection and Ranging (LIDAR) comprising: generating a signal comb that transmits a signal pulse train reflected from a reference and a target to generate a target signal from the target and a reference signal from the reference; generating a local oscillator (LO) comb that transmits a LO pulse train at a slightly different repetition rate than the signal pulse train with a coherent optical carrier; detecting the reflected signal pulse train through linear optical sampling against the LO pulse train in which consecutive samples of an overlap between a signal pulse from the target signal and the references signal, and a LO pulse from the LO pulse train yields a high-resolution measurement of the target signal and reference signal; Fourier transforming the target signal to extract the optical phase vs. frequency of the target signal; Fourier transforming the reference signal to extract the optical phase vs. frequency of the reference signal; determining a frequency dependant optical phase difference between the optical phase of the target signal and the optical phase of the reference signal; fitting the optical phase difference to a straight line; obtaining a time-of-flight distance measurement from a slope of the straight light and the known group velocity of light at the frequency of the coherent optical carrier; obtaining an interferometric distance measurement between the target and the reference from an intercept of the straight line and the wavelength of the coherent optical carrier.