| 摘要 |
PURPOSE:To decrease the number of parts and the man-hours for assembly by fixing quadrisected photodetectors and other photodetectors on one substrate. CONSTITUTION:One of the quadrisected photodetectors 202 and the non-divided two photodetectors 203, 204 are fixed on the substrate 201. A flat plane optical element 205 is fixed thereabove by inclining this element 45 deg.. The optical element 205 is formed out of a crystalline material having double refractiveness to incident light. A half- transmittable film HM is formed on one surface thereof and a complete reflection film AM is formed on the rear surface thereof. This film HM reflects a specified ratio of the incident light quantity and allows the rest to transmit. This film AM totally reflects the incident light. The reflected light from an optical disk is condensed by a lens when the optical disk is irradiated with the laser beam at this time. The light during the course of the condensing is made incident on this photodetecting system. The incident light is partly reflected by the half-transmittable film HM and the reflected light is made incident as the light mixed with a P polarization component and an S polarization component on the quadrisected photodetectors 202. The magneto- optical signal MO expressing recording information is taken out by equation MO=e-f if the detection signal levels of the photodetectors 203, 204 are defined as e, f. |
