Accurate and fast out-of-plane displacement measurement of flat objects using single-camera based on the sampling moiré method

Abstract

Abstract Out-of-plane displacement measurement is an important task not only to analyze the microelectronic device’s behavior at the micro-scale but also to evaluate the structural health monitoring (SHM) of infrastructures at the meter-scale. In this study, an accurate and fast out-of-plane displacement measurement method with a single camera is presented, including the theoretical equations, and calibration of phase-gradient to out-of-plane displacement. Since the proposed method requires only a single grating image before and after deformation and analyzes by the sampling moiré method, it yields high accuracy and speed. An experiment of out-of-plane displacement with three different focal length lenses has been conducted to verify the validity of this method. Experimental results indicated that both small and large out-of-plane displacement measurements could be performed accurately. This optical measurement technique will be of high value for SHM of various infrastructures under digital camera or video/cinema camera recording.