Polarizers

Various materials may be used in optical polarization devices. Crystals, such as calcite, quartz and mica, exhibit different indices of refraction for different polarization orientations. These materials are referred to as being birefringent. Unpolarized light entering a birefringent crystal from the correct orientation is broken into two separate plane polarized beams. These are usually referred to as the ordinary (o-ray) and extraordinary (e-ray) rays.