Optical pick-up device and objective lens used therein

摘要

An optical pickup apparatus conducts recording or reproducing information for an information recording plane of a first or second optical information recording medium and comprises a first light source and a second light source mounted on a same base board; a converging optical system ; and a coupling lens. The converging optical system comprises an objective lens to converge a first or second light flux having passed through the coupling lens on a first or second optical information recording medium; and a diffractive structure to change a focal length in accordance with a wavelength of a light flux emitted from the first light source or the second light source.