MEASURING APPARATUS FOR BOTH AC AND DC MAGNETIC FIELDS

PURPOSE:To achieve a higher reliability with a better temperature characteristic by making a combined light of two kinds of lights different in the wavelength incident into a Faraday rotary type magnetic field sensor to separate the light emitted for photoelectric conversion. CONSTITUTION:Lights different in the wavelength from light sources 1a and 1b are combined with a wavelength synthesizer 2 and enters a Faraday rotary type magnetic field sensor with polarizing elements 4a and 4b and a Faraday element 5 via an optical fiber 3c so that the light different in the wavelength is rotated at the angle of Faraday rotation according to a magnetic field. Then, the light is separated with an optical fiber 3d and a wavelength separator 6 and converted into electricity with light receiving elements 7c and 7d. With such an arrangement, temperature characteristic or the like of fibers 3c and 3d and a magnetic sensor will be the same with respect to lights with a different wavelength and the number of the optical fibers also are reduced thereby improving the reliability with a better temperature characteristic of a measuring apparatus for both AC and DC magnetic fields.