High-precision microdisplacement sensor based on zeroth-order diffraction using a single-layer optical grating

A high-precision microdisplacement sensor based on zeroth-order diffraction of a single-layer optical grating is reported. Laser grating interference occurs when part of the laser is reflected diffraction by the grating and another part is vertically reflected back by a mirror and diffracted again by the grating, thus generating optical interferometric detection. For the purpose of obtaining the optimal contrast of the optical interferometric detection, the duty cycle of the grating and the orders of diffraction were optimized by the diffraction scalar theory. The microdisplacement sensor demonstrates a sensitivity of 0.40%/nm, a resolution of 0.6 nm, and a full-scale range of up to 100 µm. This work enables a high-performance displacement sensor, and provides a theoretical and technical basis for the design of a displacement sensor with an ultracompact structure.