Development of Two-Dimensional Scanning Moiré Method for Full-Field Micron/Nano-Scale Deformation Measurement

Abstract

A two-dimensional (2D) scanning moiré method was proposed to measure the micron/nano-scale deformation distributions in two dimensions using a single moiré pattern under a laser scanning microscope. The 2D scanning moiré pattern in a large view field (width is 500~2000 times the grating pitch) comes from the interference between a cross specimen grating and the 2D laser scanning dots which serve as the reference grating. The 2D scanning moiré fringes can be separated to two groups of parallel one-dimensional moiré fringes in two directions using complex Fourier transform. The full-field micron/nano-scale deformation distributions in the x and the y directions are measureable from the corresponding parallel moiré fringes, respectively. Consequently, the 2D displacement and strain distributions can be determined using a single 2D moiré pattern, instead of two moiré patterns in two directions. The proposed method possesses the advantages of time saving, large view field, non-destruction, and high accuracy for two-dimensional deformation measurement of various materials evaluation.