the revealing layer traverses the distance equal to its period pr. Assuming that the base layer is immobile (vb=0), the following equation represents the ratio of the optical speed to the revealing layer’s speed: By replacing pm with its formula, we have In case the period of the revealing layer is longer than the period of the base layer, the optical image moves in the opposite direction. The negative value of the ratio computed according to this formula signifies a movement in the reverse direction. Superposition of layers with inclined lines Here we present patterns with inclined lines. When we are interested in optical speedup we can represent the case of inclined patterns such that the formulas for computing moiré periods and optical speedups remain valid in their current simplest form. For this purpose, the values of periods pr, pb, and pm correspond to the distances between the lines along the axis of movements (the vertical axis in the animated example of Figure 4). When the layer lines are perpendicular to the movement axis, the periods (p) are equal to the distances (denoted as T) between the lines (as in Figure 4). If the lines are inclined, the periods (p) along the axis of the movement are not equal to the distances (T) between the lines. Computing moiré lines’ inclination as function of the inclination of layers’ lines The superposition of two layers with identically inclined lines forms moiré lines inclined at the same angle. Figure 5 is obtained from Figure 1 with a vertical shearing. In Figure 5 the layer lines and the moiré lines are inclined by 10 degrees. Since the inclination is not a rotation, during the inclination the distance (p) between the layer lines along the vertical axis is conserved, but the true distance (T) between the lines (along an axis perpendicular to these lines) is changed. The difference between the vertical periods pb, pr, and the distances Tb, Tr is shown in the diagram of Figure 8. The inclination degree of layer lines may change along the horizontal axis forming curves. The superposition of two layers with identical inclination pattern forms moiré curves with the same inclination pattern. In Figure 6 the inclination degree of layer lines gradually changes according to the following sequence of degrees (+30, –30, +30, –30, +30). Layer periods pb and pr represent the distances between the curves along the vertical