Depolarizer (optics)

A depolarizer or depolariser is an optical device used to scramble the polarization of light. An ideal depolarizer would output randomly polarized light whatever its input, but all practical depolarizers produce pseudo-random output polarization.

Optical systems are often sensitive to the polarization of light reaching them (for example grating-based spectrometers). Unwanted polarization of the input to such a system may cause errors in the system's output.