| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high sensitivity magnetometer through a simple arrangement by detecting the phase difference between the oscillation waveform of an oscillator for exciting a resonance circuit and an waveform resonant to the resonance circuit. SOLUTION: The magnetometer has a resonance circuit 1 comprising a coil wound around a ferromagnetic, and a capacitor connected in series therewith. An AC high frequency power supply 3 (oscillator) having a frequency close to a resonance frequency for exciting the resonance circuit 1, a phase difference detection circuit 4 and a bias current source 2 for applying a bias field to the ferromagnetic are also provided. The AC high frequency power supply 3 excites the resonance circuit 1 and the phase difference detection circuit 4 detects the phase difference between the oscillation voltage waveform and the AC current waveform of the high frequency power supply 3 thus detecting variation of external field sensitively as the variation of inductance of the coil. Noise due to amplitude variation of the high frequency power supply 3 does not exist.
|
