Measurement of pure twist fringe distribution by using a double whole-field filtering technique

A double whole-field filtering technique to measure pure twist fringe distribution of a deformed object is proposed. In this method, the slope fringes which are contained in the pattern of twist fringes can be completely eliminated from the twist fringes. Thus a pattern of pure twist fringes with a good contrast can be obtained. Theoretical analysis and experimental results are given in this paper.