diffraction grating

Definition: Optical component used to diffract light, consisting of transparent or reflective plate etched with lines which are very closely spaced -- 2-30micrometres apart: each pair of lines acts as slit through which light is diffracted, in proportion to wavelength. * Used as (a) special effects attachment in photography in which variation in diffraction with wavelength i.e. dispersion effects are exploited; (b) to disperse light for experimentation; (c) in camera viewfinder systems as beam-splitter. * Holograms systems are, in essence, complex diffraction gratings.
Free light shows
The wild colours visible on the active side of CDs are caused by the millions of microscopic pits and lands acting as diffraction gratings.

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