Zhi Jiawen, Xu Mingyang, Liu Yang, Shao Chenggang, Wu Hanzhong
Author Affiliations
Huazhong University of Science and TechnologyNational Institute of Metrology ChinaChinashow less
Abstract
Length/distance is of fundamental importance in both science and technology. In this work, we describe a ranging scheme based on chirped pulseinterferometry. In contrast to the traditional spectral interferometry, the local oscillator is strongly chirped which isable to meet the measurement pulses at arbitrary distances, and therefore the dead zones can be removed. The distancescan be precisely determined via two measurement steps based on time-of-flight method and synthetic wavelength interferometry, respectively. To overcome the speed limitation of the optical spectrum analyzer, the spectrograms arestretched and detected by a fast photodetector and oscilloscope, and consequently mapped into the time domain in real
time. The experimental results indicate that the measurement uncertainty can be well within ±2 µm, compared withthe reference distance meter. The Allan deviation can reach 0.4 µm at averaging time of 4 ns, 25 nm at 1 µs, and canachieve 2 nm at 100 µs averaging time. We also measure a spinning disk with grooves of different depths to verify themeasurement speed, and the results show that the grooves with about 150 m/s line speed can be clearly captured. Our
method provides a unique combination of non-dead zones, ultrafast measurement speed, high precision and accuracy,large ambiguity range, and with only one single comb source.