| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens for an optical pickup device which can easily be manufactured in spite of a short focal distance and can record and/or reproduce information with high density, and to provide an optical pickup device and an optical information recording/reproducing apparatus. <P>SOLUTION: If the focal distance f of the objective lens is the upper limit of formula (1), that is, shorter than 1.3 mm, the optical pickup device can be downsized. If it is the lower limit, that is, longer than 0.41 mm, molding can be facilitated. In addition, if a value d/f is the upper limit of formula (2), that is, less than 2.1, the objective lens can obtain a sufficient operation distance (working distance), which does not interfere with the protective layer protecting the information recording face of an optical information recording medium. On the other hand, if the value d/f is the lower limit, that is, more than 1.0, the thickness of the peripheral part around the effective diameter of the objective lens in the axial direction is not too thin. Accordingly, molding can be facilitated. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
