Photonic approach for precise and efficient distance measurement via utilization of multi-frequency broadband optical carrier-based microwave signal

Distance measurement has received a growing demand with the development of scientific research and modern industry. However, most of the high-precision measure approaches hold stringent requirements on hardware equipment, manufacture accuracy, and operation environment. In this article, a photonic approach for distance measurement that utilizes broadband optical carrier-based microwave signal is proposed. Through switching between multiple modulation frequencies and applying the heterodyne process, a series of synthetic frequencies is constructed. Phase extraction is achieved based on all-phase fast Fourier transform (apFFT) for derivation of the distance. Moreover, we develop a phase unwrapping procedure to resolve phase ambiguity and derive the corresponding criterion for evaluation of reliability. The proposed method can realize tunable measurement range and high resolution within a relatively narrow bandwidth. Experiments verify the feasibility for distance measurement and align well with theoretical analysis. The results show good accuracy and stability with relative errors lower than 0.05%. Discussion demonstrates that apFFT is capable to suppress spectral leakage and mitigate the influence of signal truncation. As the presented approach maintains a simple configuration and competitive performance, it has great potential to become a useful tool for distance measurement in various practical applications. •A ranging approach that utilizes broadband optical carrier-based microwave signal is proposed.•An effective phase unwrapping procedure is implemented to resolve phase ambiguity with high efficiency.•Distance measurement results exhibit good accuracy and stability with relative errors lower than 0.05%.•The system setup is cost-effective, simple in structure, and suitable for integration.