Dual-wavelength ranging accuracy enhancement based on improved gas absorption wavelength locking

In this letter, we propose and experimentally validate an improved method for high-precision locking of the laser center wavelength based on the absorption spectrum of saturated HCN gas, aiming to enhance the repeatability accuracy of dual-wavelength ranging. By combining with high-precision phase-generated carrier displacement measurement technology, we achieved real-time measurement of the target distance. Our experimental results demonstrate that this method achieves excellent stability for the laser center wavelength, with a wavelength uncertainty of only 1.05×10⁻⁸, a resolution better than 1 nm and a stability of 0.58 nm (1σ), nanoscale displacement measurement is achieved. These enhancements are significant in expanding the application of sine frequency modulation interferometry.