| 摘要 |
PURPOSE:To detect with high accuracy a DC magnetic field and an AC magnetic field containing a DC portion by making a light whose advance direction is opposite to each other pass through a polarizer which has installed each polarizing body by inclining, for instance, by 45 deg. on both sides of a Faraday element. CONSTITUTION:A light emitted from an LED light source 1 is divided equally into a straight direction and a vertical direction by a half mirror 21, and a transmitting light is reflected in the vertical direction by a half mirror 23 through a half mirror 22, an optical fiber 31, a polarizer 51, a Faraday element 6, a polarizer 52 and an optical fiber 32, and reaches a photodetector 72. On the other hand, a light of the opposite direction reflected in the vertical direction by the half mirror 21 is made incident to a photodetector 71 through the half mirror 23, the optical fiber 32, the polarizer 52, the Faraday element 6, the polarizer 51, the optical fiber 31 and the half mirror 22. Subsequently, outputs of the photodetectors 72, 71 are inputted to a subtracting amplifier 9 and an adding amplifier 10 through photoelectric converting amplifiers 81, 82, and an output of a divider 11 is converted to strength of a magnetic field by a converter 12 and outputted. |
