What means "grating effect" and what is it for?

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, but also in more professional systems like the Proline Series.

Grating effects can also be used with mirrors (BURST-10, LIN-10)