Electro-Optical Field Mapping

As a result of the discovery of an unusually large electro-optical effect in certain colloidal solutions of bentonite it has become possible to study and measure inhomogeneous electric fields by an optical method which is analogous to that of photoelasticity. Observations with crossed Polaroids show two orthogonal systems of lines. The isoclinic lines determine the field direction, the isochromatic lines give the field intensity in any point, of a plane field. The method employs a.c. potentials of less than 200 volts.