Study of plate vibrations by moire holography

Abstract

Advantages of moire holography with single illumination beam as a real-time method to detect vibrational modes of diffusing objects have been already experimentally demonstrated by several authors. The main obstacle to automatizing the analysis of the moire pattern is the difficulty in filtering the carrier pattern. At the present, it seems affordable to realize filtering in quasi-real time by means of a digital image-processing system. However, several problems arise in this operation, for example, the spread of the spatial frequency spectrum of the carrier fringes. Different filtering algorithms, with and without FFT, are compared. Different ways to combine both carriers are examined.