Low cost moire pattern sheet for the analysis of image unstability

Image unstability can be measured by simple, low cost moire pattern sheet. Two types of moire are suggested: the linear read out moire and the angular read out moire. A reference sheet with scale is placed on the screen, such that the moire fringes can be produced when the reference sheet is owerlapping with a grating or a Zone plate pattern which are projected from recorded film. Using this simple technique, the defect of the film flatness can be meas ured from the slope of the curved moire fringes, and the vibration of the film can be measured by measuring the moire shiftness. An automatic real time test method is also suggested for measuring the curved moire fringe and the moire shiftness.