Abstract: This paper presents a large-range frequency-domain interferometric ranging method based on light-microwave mapping. Theoretical analysis shows that the frequency-domain interferometric signal can be periodically mapped from the optical frequency-domain to the microwave frequency-domain through photoelectric conversion, enabling high-resolution acquisition in the microwave frequency-domain. This overcomes the limitations caused by the relatively low spectral measurement resolution and provides the possibility to expand the measurement range of optical frequency-domain interferometry. A principle verification experiment is carried out, and absolute distance measurement with an accuracy of 11.1 μm is achieved within a range of 5 m. Compared with the existing optical frequency-domain interferometric ranging technology, this method expands the measurement range by about 30 times while maintaining a ranging accuracy of around 10 μm. In addition, a fast and high-fidelity sampling method for wide-spectrum frequency-domain interferometric signals is also studied. And it shows that within a range of 5 m, as the sampling time gradually increases to 10 μs, the ranging standard deviation ultimately remains within 200 μm. Finally, the kilometer-level ranging capability of this technology is experimentally investigated, and it shows that millimeter-level ranging accuracy can be achieved within the microsecond scale, providing a new solution for optical frequency-domain, interferometric, fast absolute distance measurement with high-precision and large-range.

Key words: optics, optical frequency-domain interference, light-microwave mapping, sensor design, signal processing, absolute distance measurement