Patent ID: 7995290

Claim:
An objective lens for converging light emitted from a light source onto an optical recording medium to record and reproduce information, the objective lens consisting of: a single lens having at least one aspheric surface, wherein the following conditional expressions (1) to (3) are satisfied: N≦ 1.75 (1) 0.5 <f/f 1 <0.6 (2) 0.8 <d /( NA·De )<1.0 (3) where N denotes a refractive index of the single lens, f denotes a focal length, in mm, of the single lens, f 1 denotes a focal length, in mm, of a light source side surface of the single lens, d denotes a thickness, in mm, of the single lens on an optical axis, NA denotes a numerical aperture of the single lens on an optical recording medium side, and De denotes an effective aperture, in mm, of the light source side surface of the single lens.