- For certain materials, such as transparent dielectrics, double refraction produced by an electric field. Also called Kerr electro-optic effect, or electro-optic Kerr effect.
- For plane-polarized light reflected from a highly-polished pole of a strong magnet, the rotation of the plane of polarization. The rotation is proportional to the strength of the magnetic field. Also called Kerr magneto-optic effect, or magneto-optic effect (2).