Patent ID: 7075055

Claim:
A measuring device for measuring an in-plane magnetization vector component of a magnetic substance to be measured, comprising: a light source; a focusing unit for focusing light flux from said light source and irradiating it to the magnetic substance to be measured; a polarization split detector for detecting a light amount of a polarization component in one direction or for separating each component of polarization components orthogonal to each other using a polarizer and photo-detectors in order to detect a change in polarization state or light amount of the light flux reflected by the magnetic substance to be measured due to a magneto-optical effect; and a half-turn asymmetric polarizing element acting only on the reflected light from the magnetic substance to be measured and acting in such a manner that its action on polarization distribution in a cross section of incident light flux has an asymmetric nature of about a half-turn around an optical axis.