Abstract
Because optical disc systems use a laser light source, the systems can easily utilize a diffractive optical element. Accordingly, high function objective lenses for optical disc systems have been developed as hybrid elements having diffractive and refractive surface. Achromatic hybrid objective lenses for MO drives, and objective lenses for DVD/CD compatible drives, are practical examples of such elements. Especially, almost all DVD/CD drives use hybrid objective lenses. In addition, hybrid objective lenses are being considered for use in new optical disc systems using a blue-laser.
