Laser Ranging With Micrometer Precision and kHz Rate via Joint Frequency-Phase Measurement

This is the authors' abstract. We don't add key points for this paper.

A joint frequency-phase measurement is proposed for high-precision and fast laser ranging, in which a frequency-modulated continuous-wave (FMCW) method is used for coarse long-distance ranging, while a phase-shift method is used for high-precision ranging. Since a low-duty-cycle linear-frequency-modulated (LFM) signal is used, the precision of the FMCW method can be reduced to be smaller than the unambiguous distance of the phase-shift method. Therefore, fast phase unwrapping can be achieved for the phase-shift method using a small bandwidth LFM signal. In the experiment, a lightwave is simultaneously modulated by a 1–7 GHz low-duty-cycle LFM signal and a 15 GHz single-tone signal, which are frequency-separated so that the FMCW ranging and the phase-shift ranging can be simultaneously achieved. The measurement precision and measurement rate are58~μ mand 1.7 kHz, respectively. The measurement range can be 300 m. Therefore, the proposed method can be used to achieve laser ranging with kHz rate and decades ofμ mprecision at hundreds of meters distance.