METHOD AND SYSTEM FOR DETECTING MAGNETIC FLUID

摘要

PROBLEM TO BE SOLVED: To provide a method and a system for detecting magnetic fluid using an excitation orthogonal magnetic field detection method which detects a reminding site of the magnetic fluid in a non-invasive manner without any affection of external magnetic noise. SOLUTION: This system comprises an excitation means 1 for exciting a direct- or alternate-current local magnetic field for a measurement site, a plurality of magnetic field detective means 2 and 3 disposed at positions in the proximity of the excitation means 1 for measuring a magnetic component orthogonal to an excited magnetic field, and a differential amplification means functioning to amplify the difference between two signals received from the detective means 2 and 3 to obtain the difference intensity of the magnetic field when the applied magnetic field is in the form of direct current, or the alternate current amplitude of the difference magnetic field when the applied magnetic field is in the form of alternate current.