Objective lens for optical receiver has refractive lens with area divided into common region via which low numerical aperture beam enters, exclusive region via large aperture beam enters

摘要

The objective lens (10) focuses light beams of at least 2 different wavelengths onto recording coatings of optical plates of different recording densities and has a refractive lens with at least one area divided into a common region through which a light beam with low numerical aperture enters and an exclusive region through which a beam with large numerical aperture enters. The beams are required for low and high recording densities respectively.