Heterodyne grating interferometry based on sinusoidal phase modulation for displacement measurement

In this study, a heterodyne grating interferometer based on the sinusoidal phase modulation method for displacement measurements was proposed. The interference beams were modulated using a sinusoidal oscillating grating, and the proposed frequency-domain quadrature detection method was used to detect the optical phase of the interferometer and determine the displacement. Experimental results were consistent with the strain gauge results for several displacement ranges. When only high-frequency noise was considered, our method achieved a measurement resolution of approximately 2 nm.