Magneticfield and current measuring device using a Faraday cell with a thin electrically conductive film substantially covering the Faraday cell

摘要

A magnetic field and electric current measuring device which uses bismuth silicon oxide (Bi.sub.12 SiO.sub.20) or bismuth germanium oxide (Bi.sub.12 GeO.sub.20) as a Faraday cell, and which is so adapted that polarized light which enters the cell is passed back and forth through the cell along the optic axis thereof to cancel any change in optical rotatory power ascribable to a variation in temperature. A magnetic field applied in the direction of the optic axis of the Faraday cell is measured based on the angle of rotation of the polarization plane of the polarized light. The surface of the Faraday cell may be coated with a transparent and electrically conductive thin film to eliminate the effects of external electric fields.