Simultaneous measurement of distance and speed via frequency-modulated continuous-wave LIDAR system based on H13C14N gas cell

Abstract

• Simultaneous and accurate measurement of distance and speed with frequency-modulated continuous-wave laser. • The traditional method of finding the measurement signal's frequency by Fourier transform is replaced. • Accurately fitting the relationship between the phase of the beat signal and the frequency of tunable laser according to the characteristics of the gas absorption cell. • Up and down-scanning frequency rate are obtained by Fabry Perot cavity. • The measurement signal's frequency is obtained by fitting relationship result and frequency rate. Traditional frequency-modulated continuous-wave lidar is to measure the distance of the target through the spectrogram of the beat signal. In this paper, we propose a lidar system to obtain distance and speed at the same time. The distance and speed of the moving target are extracted by product of the delay time obtained by H 13 C 14 N standard gas cell and the fitting frequency modulation rate obtained by Fabry Perot cavity, which can avoid spectral broadening. The experimental results show that the speed resolution of the system was 10µm/s, the mean error of the speed measurement from 0.1mm/s to 100mm/s was less than 162µm/s, and the mean standard deviation was less than 523µm/s. When the speed was less than 10mm/s and the distance was about 4.5m, the mean standard deviation of the distance was less than 163µm. With the advantages of light computation requirements, a simple optical path and measurement results with good repeatability and accuracy, this system has high practical value in precision industrial manufacturing.