| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup device compatible among three kinds of optical discs, BD, DVD and CD, with a common objective lens and capable of appropriately receiving light with a photodetector, an optical information recording and reproducing device and an objective lens suitable for the optical information recording and reproducing device. <P>SOLUTION: When actual measured values of diffraction efficiency is 60-80% in BD, 40-60% in DVD and 30-50% in CD, the flux of an optimum amount of light can be detected with the photodetector in consideration of respective optical discs. <P>COPYRIGHT: (C)2012,JPO&INPIT |
