If we superimpose two grids of barely distinguishable alternating lines, the Moire effect shows that we can retrieve the period of one grid as a result of having knowledge of the final image (the central square in the picture) and of the period of the other grid. This effect is used in Structured Illumination Microscopy, where the use of an illumination grid of a known period allows researchers to increase the resolution of the acquired image.
Picture Courtesy: Rainer Heinztmann.
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