| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens for an optical pickup, capable of forming a good spot by suppressing spherical and off-axis aberrations even during the recording or the reproducing of information in either of existing and new standard optical disks. <P>SOLUTION: The objective lens for an optical pickup is for an optical pickup device which recording/reproducing information in a plurality of optical disks by separately using three kinds of luminous fluxes. The luminous fluxes of first to third wavelengths are made incident as parallel lights on the objective lens, and at least one surface has a first area for securing a numerical aperture necessary during the use of a third optical disk, and a second area positioned its outside. The first area has an inside area intersecting an optical axis, and an outside area positioned its outside to converge the light of the third wavelength on the recording surface of the third disk. The valid radius h1 of the first area and the valid radius h1a of the inside area satisfy a conditional expression (1): 0.75<h1a/h1<0.87. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
