Influence of the Interferometric Spectral Bandwidth on the Precision of Large-Scale Dual-Comb Ranging

In time-of-flight dual-comb ranging, the precision of distance measurement is affected by the state of the interferometric spectrum. This paper investigates the influence of spectral bandwidth for an optimized ranging precision. Firstly, a numerical simulation method is presented to analyze the ranging results of dual-comb signals in the frequency domain, and the optimal bandwidth range would be selected. After that, short-distance experiments were performed and the results are consistent with the trend of simulation. Large-scale experiments verified that the optimal interval is also valid in the range of 60m. In addition, the experiments indicate that narrow spectral bandwidth could improve the stability of the system in the optimal precision range. Finally, the 3 nm spectral bandwidth is considered suitable for our system and achieves a ranging precision of 4μm at a distance of 32.6 mm and around 11μm at a distance of 60m.