Patent ID: 6466536
Filing Date: 2002-10-15
Classification: G11B

Abstract:
An objective lens for a high-density optical recording medium, employed as an objective lens for an optical pickup for converging a luminous flux onto an optical recording medium;said objective lens comprising successively from a light source side, a first lens made of a biconvex lens having at least one surface formed as an aspheric surface, and a second lens having a convex surface directed onto the light source side, said second lens satisfying the following conditional expression (1): 0.5882&lE;0.676â€ƒâ€ƒ(1) where &bgr;2 is the imaging magnification of the second lens, andwherein said first lens is constituted by a lens whose aberration is corrected by itself and satisfies the following conditional expressions (2) and (3): NA1&gE;0.45â€ƒâ€ƒ(2) RMS1&lE;0.07&lgr;â€ƒâ€ƒ(3) whereNA1 is the numerical aperture of the first lens; RMS1 is the root mean square of the wavefront aberration of the first lens; and &lgr; is a reference wavelength.