Three-Dimensional Nano-displacement Measurement by Four-Beam Laser Interferometry

A 3D nano-displacement measurement method, where the difference in phase between the beams in a four-beam laser interference is changed, is proposed. Simulation results demonstrate that the variation of phase difference causes the deviation of the interference pattern in the laser interference system. Based on this theory, we design and build a four-beam laser interference system. The corner cube prism in the optical path is shifted, and the phase of the beam is changed by applying different voltages to a piezoelectric stage. The phase difference is obtained by analyzing the lattice pattern with subpixel precision, and then the displacement is determined by correlation operation. The experimental measurement results are consistent with the theoretical analysis, thereby verifying the feasibility of this measurement method. The four-beam laser interference lattice pattern can achieve higher precision displacement measurement.The 3D displacement measurement system of the four-beam laser interference can realize single-dimensional or multi-dimensional displacement measurement. At the same time, it provides a basis for micro-displacement measurement in various applications.The specific pixels of the interference pattern are accurately located using the correlation operation to achieve precise measurement results and minimize errors.