Enhanced high-resolution laser frequency-swept carrier ranging system for non-cooperative targets via dispersion compensation

High-precision, high-resolution ranging of long-distance non-cooperative targets presents significant challenges in industrial manufacturing and precision metrology, particularly due to weak optical feedback and dispersion mismatches. To address these issues, this paper proposes a dispersion-compensated laser frequency-swept carrier (LFSC) measurement system based on an external cavity tunable laser (ECTL). The system leverages the resonant cavity enhancement effect of the ECTL to amplify weak feedback signals from non-cooperative targets, forming the LFSC via intracavity interference. Furthermore, a rapid dispersion compensation method based on phase correction is integrated to ensure accurate distance demodulation. Experimental results demonstrate that the system can detect feedback signals as weak as 25.2 fW with a probe laser power of only 35 μ W. For an oxidized black aluminum plate positioned at distances of approximately 11 m and 28 m, measurement standard deviations of less than 7 µm and 16.13 µm were achieved, respectively. Additionally, step-displacement tests verified a practical resolution better than 100 µm with a residual error of less than 9.7 µm. This work provides a robust solution for static or quasi-static precision metrology in complex industrial environments.