PURPOSE: To obtain a stable output overcoming disturbance other than magnetic field, for example, light loss due to bending of an optical fiber and changes in the light transmissivity due to variation in the temperature by having a magnetic field detecting section made up of a polaroid element, a medium with a Faraday rotational capacity and an optical prism.
CONSTITUTION: Unpolarized light from an light source 1 is introduced into a magnetic field detecting section A through an optical fiber 2-1. The detecting section A is made up of a polariod element 3, a Faraday rotation element 4 and an optical prism 7, in such a manner that the vibration direction of light from the polaroid element 3 is set at 45° to the main axis of the prism 7. The prism 7 separates the incident light into two linear polarized waves which are separately detected with light detectors 6-1 and 6-2 through an optical fiber 2-2. The ratio is taken between the difference and sum of the intensities P1 and P2 of lights detected with the detectors 6-1 and 6-2 to perform a calculation. This provides only an output proportional to the magnetic field H thereby ensuring a stable output.
NAGATSUMA KAZUYUKI
SUGANUMA YASUO
| JP43016402A |