Rapid and Precise Distance Measurement Using Balanced Cross-Correlation of a Single Frequency-Modulated Electro-Optic Comb

Ultra-rapid, high-precision distance metrology is critical for both advanced scientific research and practical applications. However, current light detection and ranging technologies struggle to simultaneously achieve high measurement speed, accuracy, and a large non-ambiguity range. Here, a time-of-flight optical ranging technique based on a repetition-frequency-modulated femtosecond electro-optic comb and balanced nonlinear cross-correlation detection is presented. In this approach, a target distance is determined as an integer multiple of the comb repetition period. By rapidly sweeping the comb repetition frequency, absolute distance measurements within 500 ns and real-time displacement tracking at single-pulse resolution (corresponding to a refresh rate of 172 MHz) are achieved. Furthermore, the system attains an ultimate ranging precision of 5 nm (with 0.3 s integration time). This method uniquely integrates nanometer-scale precision, megahertz-level refresh rates, and a theoretically unlimited ambiguity range within a single platform, while also supporting multi-target detection. These advances pave the way for high-speed, high-precision ranging systems in emerging applications such as structural health monitoring, industrial manufacturing, and satellite formation flying.