Magnetic field and electric current measuring device.

摘要

magnetic field and electric current measuring device which includes a Faraday cell (1) consisting of bismuth silicon oxide (Bi12SiO20) or bismuth germanium oxide (Bi12GeO20) as a Faraday cell is arranged that polarised light (13) which enters the cell is passed back and forth along the optical axis of the cell (1). This cancels any change in optical rotatory power caused by variations in temperature and also cancels any rotation caused by the latent rotary power of the cell. The magnetic field strength in the direction of the optical axis of the Faraday cell (1) is measured by monitoring the angle of rotation of the polarisation plane of the polarised light. Preferably the surface of the Faraday cell is coated with a transparent and electrically conducting thin film (15) to eliminate the effect of any external electric fields.