High-precision short-distance dual-comb ranging system without carrier-envelope-offset locking

In this paper, we propose a high-precision dual-comb ranging (DCR) method for short-distance measurement, avoiding carrier-envelope-offset locking. Cross-polarization detection is introduced, which makes better use of the intrinsic coherence of interferogram pairs over a short distance. We analyze the noise in the DCR system and propose a carrier-wave phase difference (CPD) calculation algorithm based on centroid extraction. The standard deviation of CPD is eight times less than that of the method we had proposed in a previous work, and the dynamic distance resolution is less than 10 nm at a distance of 10 µm. Besides, we compare the DCR result with the He-Ne laser interferometer from 0 to 4.8 mm, and the residual is found to be less than ±40 nm.