| 摘要 |
PURPOSE:To prevent the entrance of pulse noise and to perform optimum control over a wide range of magnetic field deviation by processing the detection signal of a nuclear magnetic resonance signal as required and controlling the power source for an electromagnet for magnetic field production. CONSTITUTION:The nuclear magnetic resonance signal passed through a probe 16 is detected by a detector 18 connected to a reference RF oscillator 11 and a phase shifter 19 with a reference RF signal and then applied to a control part 14 through an A/D converter 21. Then, a DC component is subtracted from the detection signal to integrate an AC component which improves integration precision for a specific time. The power source 23 for the electromagnet 15 is brought under the feedback control of the integral signal to perform control so that the AC component based upon the deviation between a reference signal frequency and a nuclear magnetic resonance signal frequency corresponding to the deviation between actual magnetic field intensity and reference magnetic field intensity, one to one, is eliminated. Therefore, the need for pulse excitation, etc., to magnetic field attenuation is eliminated and the entrance of pulse noise is eliminated to lock magnetic field intensity corresponding to optimum control over a wide range of magnetic field deviation. |
