| 摘要 |
PURPOSE:To exactly discriminate a defect by radiating a laser beam from an inclined direction and detecting it by dividing it into a diffracted and reflected light from the surface and the pit surface, a reflected light having the same polarization component as that of a light source and a reflected light having a different polarization component. CONSTITUTION:An optical disk 14 is rotated at constant speed, and the optical disk 14 is irradiated by a light beam from a laser light source 11 at a prescribed angle theta. In a position for receiving a reflected light from the surface of the optical disk 14, and a position for receiving a diffracted and reflected light in a reflected light from the pit surface 14b, photoelectric converting elements PD1, PD2 are arranged, respectively. A reflected light from the pit surface 14b is led to a polarization beam splitter 15, and in a light receiving position of a regularly reflected light in which a polarization component of the laser beam source 11 is reserved as it is, and in a position for receiving a reflected light of a polarization component being vertical to the light, photoelectric converting elements PD3, PD4 are arranged, respectively. Outputs of the photoelectric converting elements PD1-PD4 are inputted to AND circuits 29-32 through 1/V converters 21-24 and comparators 25-28, and the kind of a defect is discriminated. |
