Patent ID: 8044663

Claim:
An ultra-sensitive susceptibility detection apparatus of anharmonic resonance measurement type using an atomic magnetometer, in which a change in susceptibility by a specimen containing an object to be measured is detected, the apparatus comprising: an atomic magnetometer including: a cell containing an alkaline metallic atom, which is affected by a magnetic field caused by the specimen; a light source for magnetically polarizing the alkaline metallic atom of the cell; and a bias magnetic field applicator for applying a bias magnetic field Bo to adjust a measuring resonance frequency of the alkaline metallic atom; an excitation magnetic field applicator for applying an excitation magnetic field Bs to the specimen to magnetically excite the specimen, the excitation magnetic field Bs being comprised of a plurality of AC magnetic fields Bs 1 and Bs 2 having different frequencies, respectively and, in which a direct coupling of the excitation field with the atomic resonance is eliminated by matching the atomic resonance frequency not to the individual excitation field frequencies but to a linear combination of the two frequencies; and a measuring device for measuring a change in magnetic polarization of the alkaline metallic atom, which is affected by a magnetic field B caused by the specimen being magnetically excited by the excitation magnetic field Bs.