# Law of Malus

The law of Malus (after Étienne Louis Malus ), more rarely also called Malus' law , describes the intensity I of a linearly polarized wave of the initial intensity I 0 after passing through an ideal polarizer as a function of the angle by which the optical axis of the polarizer relative to the The direction of polarization of the wave is twisted: ${\ displaystyle \ alpha}$

${\ displaystyle I = I_ {0} \ cos ^ {2} \ left (\ alpha \ right)}$

The transmitted radiation is polarized in the direction of the filter, the remaining intensity (proportional to ) is absorbed in the case of a polarization filter and reflected in the case of a polarizing beam splitter . ${\ displaystyle \ sin ^ {2} \ alpha}$

## literature

• Jürgen Hüttermann, Alfred Trautwein, Uwe Kreibig: Physics for doctors, biologists, pharmacists. 6., rework. Aufl. De Gruyter, Berlin / New York 2004, ISBN 3-11-017839-7 ( limited preview in the Google book search).