Compact Dual-Comb Absolute Distance Ranging With an Electric Reference

To exploit the potential of a dual-comb absolute distance ranging system outside a well-controlled laboratory, a compact dual-comb structure is proposed. A beat frequency generated by the repetition rates of two frequency combs serves as an electric reference, which is easily built and maintains a long range and high resolution compared with traditional dual-comb systems. The performance of the proposed method is compared with that of a heterodyne interferometer. The residuals range within -116.6 to 117.2 nm, the standard deviations vary from 46.3 to 137.9 nm, and the non-ambiguity range extension remains reliable throughout a 10-m test. Compared with Michelson-type dual-comb interferometers, this compact dual-comb system omits the redundant optical reference arm, promising practical applications of distance ranging.