| 摘要 |
PURPOSE:To eliminate the generation of a false focusing signal by arranging an optical system so that the direction of two lattices, which generate a moire stripe, can be almost orthogonal with the direction of a pit string in an optical disk. CONSTITUTION:For two lattices 7 and 8 to make the moire stripe, a light transparent part and a light opaque part are respectively formed in a parallel stripe shape with a fixed interval. One lattice is arranged in front and back of an optical path with an interval in a condition to be rotated only by a fine angle. These two lattices 7 and 8 are arranged so as to be almost orthogonal with the pit string of an optical disk 6. Further, a second beam splitter 10 is arranged between the two lattices 7 and 8 and a beam is incident through a condenser lens 11 to a two-divided photo-detecting element (or a four-divided photo- detecting element) 14 to detect a tracking signal. This two-divided photo- detecting element (or four-divided photo-detecting element) 14 is used as the detecting means of a data (RF) signal as well. Thus, the false focusing signal is prevented from being generated. |
