The selective absorption of one component of an electric field, resulting in polarization. For a crystal, the transmission axis is parallel to the principal axis of some crystals such as tourmaline, NaFe3B3Al6Si6O27(OH)4 and hypersthene. For a grid, the transmission axis is perpendicular to the wires. Polaroid consists of sheets of synthetic crystals (J-sheet) or polymers, in which the transmission is perpendicular to the chain axis.
