A Ranging System Integrating Time‐of‐Flight Approach With Optical‐Frequency‐Comb Interferometry for Ultra‐Precise Long‐Distance Measurements

Time‐of‐flight (TOF) ranging and pulse interference have been widely applied in high‐precision absolute ranging due to high robustness and low ambient noises. However, TOF is typically limited by low resolutions, whereas the absolute lengths determined using the pulse interference method are discrete. In this study, an absolute ranging system integrating TOF with OFC‐based interferometric modules was developed. In this system, the TOF module provides a rapid yet rough distance measurement, whereas the Michelson interferometry module significantly improves the ranging accuracy using interference techniques. First, the approximate distance was estimated using the TOF laser rangefinder. Then, the spatial position information of femtosecond pulse interference signals was determined through OFC‐based interferometric measurement. Finally, the exact distance was determined based on the rough measurement and the fine measurement. Sub‐meter simulations and practical measurements revealed that the t‐distribution‐based limit error were ± 1.3 and ± 2 μm within 50 m, respectively, demonstrating that the proposed ranging system integrating pulse coarse with OFC achieved a micron‐level absolute distance accuracy for 10‐m‐scale measurement tasks. The proposed system can be further optimized in terms of active frequency stabilization, extended TOF range, and full‐wave sampling and processing. This study paves the way for effective long‐distance ranging with ultra‐high precision requirements.