| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that a reproduction light quantity per unit time is significantly decreased and reproduction quality (S/N) is drastically decreased since an actual reflectance of a medium is low and read-out time is short in a multilayer optical disk and in a high-speed optical disk. <P>SOLUTION: Reflection signal light from an optical disk and reference light, which is branched from the same light source and introduced into a detector without being applied to the optical disk, are made to interfere on the detector. At that time, four kinds of detection outputs, in which the reference light and the signal light are out of phase with one another by 90° each, are simultaneously obtained, and then computation is made to obtain reproduction signals which are always stable and amplified to high quality even if an optical path length varies due to the wobbling in the surface of the optical disk. <P>COPYRIGHT: (C)2008,JPO&INPIT |
