Fourier-transform moiré method with consideration of misalignment

We have previously proposed a moiré method using the Fourier transform of a fringe or grating line pattern recorded by a TV camera. It performs automated and accurate analysis of displacement, strain, strain rate and height distributions. In the method, the direction of the grating lines before deformation must co-incide with the direction of the scanning lines of the TV camera. In this paper, the method is extended to include the case of misalignment in which the direction of the grating lines is different from that of the scanning lines of the TV camera. By using this method, positioning of the TV camera is simplified because it does not require precise alignment of the TV camera. This method is useful to analyze fringe patterns with carrier fringes that are introduced to aid in the interpolation of brightness distribution.