Examples of random moiré
By Emin Gabrielyan
Superposition of two identical transparent layers comprising randomly located opaque dots produces moiré images. This phenomenon is called random moiré. Moiré superposition images are formed when the patterns of the layers are perfectly matched and one of the layers is slightly rotated. The figure below animates the superposition optical image of two layers with identical patterns of random dots. In this animation, one of the layers rotates, oscillating between 0 and 4 degrees:
Superposition of a transparent base layer where all opaque dots are replaced by a micro-shape (e.g. a given letter) with a revealing layer, which is completely opaque except tinny transparent holes, placed according the same random pattern as the pattern of the shapes in the base layer, forms a moiré image where the micro shape of the base layer appears magnified and rotated by +90 degree or by –90 degree.
The figure below animates superposition of a base layer comprising randomly scattered copies of the symbol “2” with an opaque revealing layer comprising similarly placed tinny holes. In this animation, the revealing layer oscillates between –2 degree and +2 degree. The diameter of holes of this sample is about 4 to 5 times smaller than the size of the shapes of the base layer.
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