OBJECTIVE LENS FOR OPTICAL PICKUP DEVICE, AND OPTICAL PICKUP DEVICE

摘要

An objective lens for an optical pickup device. Said objective lens is characterized by making compatibility with three types of optical disc (Blu-ray Discs, DVDs, and CDs) possible with a shared objective lens. Said objective lens is further characterized in that in a basic structure superimposed on a center region and intermediate region of said objective lens, due to the size relationship between the pitch on the center-region side of a boundary and the pitch on the intermediate-region side of said boundary and also due to a relationship with a step direction, it is possible to apply over-corrected spherical aberration when using a third optical disc, thereby creating flare.