the base layer lines with a long period advance faster than the revealing layer lines with a short period. At the halfway of the distance pm, the base layer lines are ahead the revealing layer lines by a half a period (pr/2) of the revealing layer lines, due to which the lines are interleaving, forming a dark moiré band. At the full distance pm, the base layer lines are ahead of the revealing layer lines by a full period pr, so the lines of the layers again overlap. The base layer lines gain the distance pm with as many lines (pm/pb) as the number of the revealing layer lines (pm/pr) for the same distance minus one: pm/pr = pm/pb + 1. From here we obtain the well known formula for the period pm of the superposition image: For the case when the revealing layer period is longer than the base layer period, the distance between moiré bands is the absolute value computed by the formula. The superposition of two layers comprising parallel lines forms an optical image comprising parallel moiré lines with a magnified period. According to the formula for computing pm, the closer the periods of the two layers, the stronger the magnification factor is. The thicknesses of layer lines affect the overall darkness of the superposition image and the thickness of the moiré bands, but the period pm does not depend on the layer lines’ thickness. Speedup of movements with moiré The moiré bands of Figure 1 will move if we displace the revealing layer. When the revealing layer moves perpendicularly to layer lines, the moiré bands move along the same axis, but several times faster than the movement of the revealing layer. The GIF animation shown in Figure 4 corresponds to a slow movement of the revealing layer. The GIF file repeatedly animates an upward movement of the revealing layer (perpendicular to layer lines) across a distance equal to pr. The animation demonstrates that the moiré lines of the superposition image move up at a speed, much faster than the movement speed of the revealing layer. When the revealing layer is shifted up perpendicularly to the layer lines by one full period (pr) of its pattern, the superposition optical image must be the same as the initial one. It means that the moiré lines traverse a distance equal to the period of the superposition image pm while