diffraction grating films with 1000 lines/mm Project laser beams through the grating film, the single light source will be diffracted into several sub light source, with equal distance ( angle ) in between them.

Theorem behind it : Diffraction can create “rainbow” colors when illuminated by a wide spectrum (e.g., continuous) light source. This phenomenon is caused by the interference effects in reflections from the closely spaced transmissive layers. A grating has parallel lines, while a CD has a spiral of finely-spaced data tracks. Diffraction colors also appear when one looks at a bright point source through a translucent fine-pitch umbrella-fabric covering. Decorative patterned plastic films based on reflective grating patches are very inexpensive, and are commonplace.

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