A grating effect is an optical deflection grid, that multiplies the input rays. E.g. if you shoot a single laser beam to the grating, you get kind of a star effect (burst grating) or a "dotted line" (line grating) on the other side.
Every color spectrum is deflected in a different way, so if you have a multi color input, you get the colors split up as well. That's why it is physically not possible to generate a white star effect with the use of a deflection grating.
Simple grating effects are used in the very common Star Effect Lasers (like a Garden Effect Laser), but also in more professional systems like the Proline Series.
Grating effects can also be used with mirrors (BURST-10, LIN-10)
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