Speckle-noise-reduction method of projecting interferometry fringes based on power spectrum density

Appl Opt. 2012 Oct 10;51(29):6974-8. doi: 10.1364/AO.51.006974.

Abstract

The fringe projection technique plays an important role in surface inspection, due to its noncontact, full-field acquisition and high resolution. When using projecting interferometry fringes, one of the basic problems encountered is the speckle noise existing in the fringe pattern. In this paper, a novel method is proposed to reduce the speckle noise based on power spectrum density (PSD) thresholding, which consists of three steps: first, PSD is calculated according to the frequency spectrum obtained by Fourier transform; second, a filter is constructed by a PSD thresholding to filter the frequency content of the speckle noise; and finally inverse Fourier transform is used to obtain the noise-reduction image. Experimental results prove the feasibility and effectiveness of the presented method.