Pseudo-random phase modulation-assisted dual comb ranging with an extended non-ambiguity range

Abstract

The invention of the laser has greatly facilitated the ranging needs in production and scientific research. Dual comb ranging has attracted the attention of the academic community in recent years due to its high precision and rapid measurement speed. However, the non-ambiguity range of conventional dual comb ranging systems is usually short, which can hinder their broader practical application. In this work, we introduce a novel approach that involves phase modulating the signal beam with a pseudo-random noise, allowing the non-ambiguity range of dual comb ranging system to be extended by adjusting the repetition period of the pseudo-random noise. Furthermore, based on the algorithm we have developed, the pseudo-random noise can be effectively removed from the phase, so as not to degrade the measurement precision. Through our experimental validation, we demonstrated that the proposed method effectively extends the non-ambiguity range while maintaining high precision. In this study, the NAR is equal to the adjustable repetition length of the PRN, which can theoretically extend to infinity. The measurement uncertainty can be within ±0.5

, which can further decrease to ±0.2

by reducing the modulation depth. The Allan deviation can reach 0.4

at 10

, and further 80 nm at 0.2 ms averaging time. The enhancements proposed here are simple to implement, necessitating only the addition of a single electro-optic modulator. This cost-effective solution holds promise for more extensive applications in practice.