OPTICAL PICKUP OBJECTIVE,OPTICAL PICKUP,AND DISK DRIVE

摘要

An objective for an optical pickup used for recording or reproducing an information signal on or from an optical disk. The objective comprises a resin layer (21) and a glass lens (22). The resin layer (21) has an aspherical first surface (S1) and an aspherical second surface (S2)in order from the object side. At least either of the surfaces includes a diffraction surface. The lens has a spherical second surface (S2) and an aspherical third surface (S3). The chromatic aberration to a wavelength range within several nanometers from a reference wavelength of 420 nm or less is corrected on the image surface on the optical axis is corrected. The objective has a numerical aperture (NA) of 0.8 or greater. The objective focuses a laser beam close to the diffraction limit on the image plane.