Objective lens element and optical pickup device provided with its object lens element

摘要

An optical pickup device has an optical source 101 for emitting an optical beam, an objective lens element 103 positioned to receive the optical beam for focusing the beam on a medium 104 , wherein a position of the optical source 101 relative to a position of the objective lens element 103 is fixed, a combined movement of the objective lens element 103 and the optical source 101 focuses the optical beam on the medium 104 ; and the objective lens element 103 satisfies the following condition: <?in-line-formulae description="In-line Formulae" end="lead"?>-0.300<=m<=-0.200, (1) <?in-line-formulae description="In-line Formulae" end="tail"?> where, m is an imaging magnification.