A nanometer-resolution displacement measurement system based on laser feedback interferometry

Based on laser feedback interferometry (LFI) combined with phase-freezing technology (PFT), a novel displacement measurement system is demonstrated, which improves the measurement resolution to nanometer scale. The phase modulator is added to modulate the external cavity phase, and the PFT is used for sampling and demodulation. The displacement information of the external target is reconstructed. The signal modulation, sampling, reconstruction technology is researched and the simulation results show the feasibility of the method. Error analysis is made for searching the influence of modulation frequency, sampling frequency and reflector vibration frequency. Verification experiment is made to check the accuracy of the system with appropriate parameters. It provides a displacement and vibration measurement method for MEMS elements.