| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens having a thin axial thickness and high NA while securing a working distance, an excellent formability and assemblability; and an optical pickup device using the same. <P>SOLUTION: Using a glass material whose refractive index satisfies an inequality (1) enables securing of not only a working distance but also an area (width) of the end face where an inspection light is entered even if the outer diameter of a lens is reduced, therefore achieving an accurate adjustment of the objective lens attitude. Provided inequalities are (1) 1.55≥n1≥1.75 and (2) 0.8≥d/f≥1.1, where n1 is a refractive index of an objective lens material to a light flux having a wavelength λ1, d is a thickness of an objective lens on the optical axis (mm), and f is a focal distance of an objective lens material to a light flux having a wavelength λ1 (mm). <P>COPYRIGHT: (C)2012,JPO&INPIT |
