Nanometer-Accuracy Two-Dimensional Targets Detection By Orthogonal Self-Mixed Laser Interferometry

Optical lithography or 3D printing operates on multi-dimensional movement at high resolution. Therefore, accurate position of both x-axis and y-axis deserves real-time measurement. Herein, we utilizes a half-external cavity orthogonal self-mixing laser interferometry for determining displacement of two independent targets. Synchronous detection of irrelevant displacements with nanometer accuracy (<10 nm) is realized here. Circularly polarized laser beam is optically-multiplexed into two polarization states for two additional external cavity. The laser system only needs a single-channel optical intensity to reflect the perpendicular displacement without reference path, which is conducive to simplify the acquisition channel and collimation.