| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens for optical pickup device in which a numerical aperture is large and an image height property is good, also an objective lens being suitable for use for a recording and reproducing device in which since thickness of a protective layer of the information recording medium has thinness of approximately 0.1 mm, working distance may be small, and an optical pickup device using these objective lenses. <P>SOLUTION: The objective lens for recording and reproducing of an information recording medium satisfies the following formula: 1.1≤d1/f≤3 (d1:lens thickness on axis, f:focal distance). Also, it is preferable to satisfy the following formulas: 1.2≤d1/f≤2.3, f/vd≤0.06 (vd:abbe number), 1.40≤n (n:refractive index in used frequency), 1.40≤n≤1.85, 0.40≤r1/(n×f)≤0.70 (r1: near axis curvature radius of light source side). <P>COPYRIGHT: (C)2009,JPO&INPIT |
