Patent ID: 8345356

Claim:
An objective lens for converging light emitted from a light source onto an optical recording medium which information is recorded in or reproduced from, the objective lens comprising: a single lens that has at least one aspheric surface, wherein the following conditional expressions (1) and (2) are satisfied: −0.90 <R 1 /R 2 <−0.45 (1) 0.70 <d/f <1.40 (2) where R 1 denotes a radius of curvature, in mm, of a light source side surface of the single lens near an optical axis, R 2 denotes a radius of curvature, in mm, of an optical recording medium side surface of the single lens near the optical axis, d denotes a thickness, in mm, of the single lens on an optical axis, and f is a focal length, in mm, of the single lens, a mass of the objective lens is equal to or less than 0.5 grams the following conditional expression (6) is satisfied: 0.50 <g/d <0.80 (6) where g denotes a distance, in mm, from a tangential plane that is a plane perpendicular to the optical axis and is tangent to a vertex of the light source side surface of the single lens to a center of gravity of the single lens.