| 摘要 |
PURPOSE:To obtain a photomagnetic sensor which operates even with a small light output by generating a signal synchronized with a photoelectric conversion signal obtained by rotating a polarizer or analyzer around an optical axis and a signal synchronized with the rotation of the polarizer or analyzer, and calculating an angle of Faraday rotation from the phase difference between those two synchronized signals. CONSTITUTION:Light from a light emitting diode 1 is passed through an optical fiber 2, lens 3, polarizer 4, Faraday rotating element 5, and analyzer 4 to convert the angle of polarization-directional rotation of the element 5 into the intensity of the light. Further, a signal indicating the angle of rotation of the analyzer 6 is supplied from a rotating device 60 to a generating circuit 14 for a polarization-directional position synchronizing signal and a signal synchronized with this signal is inputted from the circuit 14 to one input terminal of an arithmetic circuit 15. On the other hand, the electric signal converted by a photoelectric converting element 9 is inputted to the other input terminal of the circuit 15 through an AC amplifier 10 and a generating circuit 13 for a Faraday rotational angle synchronizing signal. Then the circuit 15 calculates the angle of Faraday rotation on the basis of the phase difference between the two inputted synchronized signals. Therefore, not only the intensity of an AC magnetic field, but also the intensity of a DC magnetic field are measured. |
