| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup device which appropriately records and/or reproduces information to/from three types of discs with different recording densities and improves light utilization efficiency with a simple configuration, and to provide an objective lens. <P>SOLUTION: A first optical path difference giving structure is formed on an optical surface of an objective lens. The first optical path difference giving structure is a step structure where a plurality of circular band like step units having the same number of steps are concentrically arranged around the optical axis. The width w1 of the highest step or the lowest step of at least one step unit of the step structure in a direction orthogonal to the optical axis is about a half of an average value w2 of two steps interposing the highest step or the lowest step in the direction orthogonal to the optical axis. <P>COPYRIGHT: (C)2010,JPO&INPIT |
