| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens for an optical pickup device having a large numerical aperture and an excellent image height characteristic; to provide an objective lens suitable for use in a recording/reproducing device, where working distance may be small, because thickness of a protection layer of an information recording medium is thin as around 0.1 mm; and to provide the optical pickup device using these objective lenses. <P>SOLUTION: An objective lens is a recording/reproducing objective lens of an information recording medium and satisfies the following expression. 1.1≤d1/f≤3 (where d1 represents on-axis lens thickness and f represents focal length). Furthermore, it is preferable to satisfy the following respective expressions. 1.2≤d1/f≤2.3, f/νd≤0.060 (where νd represents an Abbe number), 1.40≤n (where n represents a refractive index in use wavelength), 1.40≤n<1.85, and 0.40≤r1/(n×f)≤0.70 (where r1 represents a paraxial curvature radius of a light source side). <P>COPYRIGHT: (C)2013,JPO&INPIT |
