Image processing applied to laser holographic interference fringes

Holographic interferogram of axisymmetric ethylene diffusion flame is obtained using double-exposure holographic interferometry. The distribution of infinitely wide fringes is recorded by digital camera. Image processing is completed employing all raw data including peak and valley data and transition point data for a given height of interference fringe pattern. The quantity of effective fringes is confirmed and fringes phase extraction is carried out. The analysis indicates that the observed fringes of holographic reproduction is not all interference fringes; In the central area of phase distribution, the gradient of interference fringes is so small that it is vulnerable to impact of noise; In the large gradient region of phase distribution, phase distribution is nearly linear. The effect of various extraction methods using all raw data is similar.