Optical Technique for the Measurement of Surface Charges of Electrets

The paper reports a new technique for the measurement of surface charges of electrets which is based on optical measurements of the displacement of a reflecting membrane. The latter is used as the movable reflector in a Michelson interferometer. Simple calibration procedures and analyses allow calculation of the electret potential in terms of the displacement. Initial evaluation of the technique makes use of the electret material in the form of a membrane, specifically Mylar type S polyester film, 24 μ thick. Typical electret charge growth and decay data is presented which illustrates that the technique is simple, has high accuracy and resolution, and is reliable. Furthermore, the method is nondestructive.

Optical Technique for the Measurement of Surface Charges of Electrets Journal Articles