MAGNETIC FIELD DETECTOR UTILIZING NUCLEAR MAGNETIC RESONANCE

摘要

PURPOSE:To reduce the constitution of a detection terminal in size by imposing frequency modulation on the oscillation frequency of a sensor oscillator by a low-frequency signal, and eliminating the need for a magnetic field modulating coil. CONSTITUTION:The magnetic field detection terminal 1 consists of a container 10 which contains a material whose resonance absorption frequency depends upon a magnetic field H, e.g. water and a coil 11 wound around the container 10. The sensor oscillator 2 has varactor diodes 21 and 22 and capacitors 23- 25 and forms a tank circuit together with the coil 11. A low-frequency oscillator 13 is connected to the diode 22 and a function generator 4 is connected to the diode 21 to perform modulation and high-speed sweeping. A control means 5 detects the peak position of a frequency-modulated signal and performs control so that the oscillation frequency of the sensor oscillator coincides with the resonance absorption frequency. A display circuit 6 displays the oscillation frequency of the sensor oscillator 2 by a timing signal from a control circuit 50. The intensity of the magnetic field H at the detection terminal is known from the frequency.