Using ensemble empirical mode decomposition to improve the static fringe analysis in optical testing

Abstract

Static fringe analysis is an important skill to reconstruct the surface profile of the tested optics. The mixed image is simulated by the tilt aberration, and several methods of the reducing mixing fringe are utilized to reconstruct the optical paths difference (OPD) profile of the mixed image. In this paper, we propose the ensemble empirical mode decomposition (EEMD) method to decompose the mixed image into several intrinsic mode functions (IMFs), and then removing one or more IMFs to reduce the influence of the mixing fringe in the mixed image. The procedure of reducing mixing fringe can reconstruct the OPD profile of the mixed image easily. In the simulation, using EEMD to reduce the influence of the mixing fringe, the root mean square (RMS) value of the OPD is 0.081 waves as the residue image subtracted from the OPD profiles of original image. In the experiment, the EEMD method reducing the noise of the mixing fringe has the advantage on the high frequency as spherical aberration.