Polarizer#Malus.27 law and other properties

The Law of Malus (after Étienne Louis Malus ) I describes the intensity of a linearly polarized wave of the initial intensity I0 after passing through an ideal polarizer, depending on the angle at which the polarizer is rotated:

The transmitted radiation is polarized in the direction of the filter, the remainder of the intensity (proportional to ) is absorbed in the case of a polarization filter, reflecting in the case of a polarizing beam splitter.