Patent ID: 7742152

Claim:
A method for determining the distance to an object, comprising: intensity modulating a laser pulse with a chirp waveform u(t) having a frequency that varies linearly with time; splitting the modulated laser pulse into an optical transmit signal that is transmitted to the object and an optical local oscillator signal; receiving the optical transmit signal backscattered from the object; and, mixing the backscattered optical transmit signal and the optical local oscillator signal and detecting the difference in frequency between the modulating chirp waveform u(t) of the optical local oscillator signal and the modulating chirp waveform u(t−Δ) of the backscattered optical transmit signal as delayed by the transit time Δ in traveling to and from the object; and deriving the value of the transit time Δ of the backscattered optical transmit signal from the detected frequency difference and computing the distance to the object therefrom.