The expanding cell

Abstract

In order to measure the three-dimensional profile of object's surface quickly, a shadow Moiré technique with phase shift based on varying light source positions was proposed. By switching two light sources the method used, the phase shift was introduced into measurement view. The two-dimension empirical mode decomposition was used to regularize the fringe pattern. Combining the spiral phase transform and two frames phase shift, the measurement height was estimated, the accurate measurement phase was picked up by using a new iterative adaptation algorithm. The results of the computer simulation and of the optical experiments indicate that the demodulation accuracy of the proposed methohd is better than the traditional two frames phase shift demodulation. Additionally, the proposed methohd greatly saves the measurement time by removing the mechanical motions in the process of measurement, since it only needs the two frames fringe pattern to demodulate the phase.