This Demonstration illustrates the formation of time-averaged moiré fringes. The horizontal axis stands for the amplitude of harmonic oscillation ; the vertical axis represents the longitudinal coordinate . Stationary moiré grating is visualized at . Time-averaged images of the moiré grating are shown at increasing amplitudes of oscillation. The parameter controls the density of the moiré grating lines. The parameter controls the number of discrete time nodes in a period of the oscillation used to integrate the dynamical process. Double exposure fringes are produced at ; time-averaged fringes are produced at . One can observe the development of time-averaged fringes at increasing .