Objective lens and optical pickup device

An optical pickup device for performing at least one of recording, reproduction and deletion of information on an optical information recording medium, comprising:

• a light source;
• and
• a converging optical system which includes an objective lens for converging a light beam emitted from the light source onto a recording surface of the optical information recording medium, wherein
• the objective lens is a bi-convex single lens having at least one aspheric surface, and satisfies the following conditions:
• 0.8<R1/r1<0.85 (4)
• 0.9<d/f<1.1 (3)
• (here, a numerical aperture NA on the optical information recording medium side of the objective lens satisfies NA≧0.85)
• where,
• R1 is a paraxial curvature radius [mm] on a light source side of the objective lens,
• r1 is an effective radius [mm] on the light source side of the objective lens,
• d is a thickness [mm] on the optical axis of the objective lens, and
• f is a focal length [mm] of the objective lens.