| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve spherical aberration and an image height characteristic, and to improve lightening of a lens and securing of operation distance when an objective lens performing recording or reproducing of information for an optical recording medium is used as a high NA lens of a single lens that converges short wavelength light on an optical recording layer. <P>SOLUTION: An objective lens 8 is a single lens, a surface 8a of a light source side is made a convex surface of strong curvature, a surface 8b of an optical recording medium side is made a surface of weak curvature, both surfaces include non-sphere. Also, Formulas (1) to (3) is satisfied. Formulas (1): 0.70<NA<0.98 Formulas (2): 0.70<d/f<1.40 Formulas (3): 0.48<X<0.55 where: NA: the number of aperture of optical recording medium side of objective lens 8 d:thickness (mm) on optical axis of objective lens 8 f: focal distance of objective lens 8 where: X: (X1-X2)(n-1)/(NA×f) X1, X2 : value about sag quantity in respective surfaces (n): refractive index. <P>COPYRIGHT: (C)2009,JPO&INPIT |
