| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the following problem: in an optical pickup for recording/reproducing information in/from different kinds of optical recording media such as a DVD and a CD, using light beams having different wavelengths, it is difficult for a polarizer used with two or more wavelengths in common to be compatible with both efficiency and measures against a birefringent disk with each other. <P>SOLUTION: About an area (area F) where an opening of a distributed wavelength plate 6 is large, areas (area D1 and area D2) with different properties in counter positions are arranged to oppose each other, and about an area (area E) where an opening is small, areas which have similarly the areas D1 and D2 and the same properties are arranged at counter angular positions. Thus, the efficiency is compatible with the measures against the birefringent disk without sacrificing a signal light quantity and signal quality. Moreover, since the arrangement requires only to change the arrangement pattern of the distributed wavelength plate, productivity is not spoiled either. <P>COPYRIGHT: (C)2008,JPO&INPIT |
