OPTICAL PICKUP DEVICE, OBJECTIVE OPTICAL ELEMENT FOR OPTICAL PICKUP DEVICE AND OPTICAL INFORMATION RECORDER/REPRODUCER

摘要

An optical pickup device which can record and/or reproduce information appropriately on/from three kinds of discs having different recording densities while achieving simplification of configuration and cost reduction. An objective optical element and an optical information recorder/reproducer are also provided. During use of a BD, a first light beam enters an objective optical element (OBJ) under the state of infinite parallel light beam, but a second light beam during use of a DVD and a third light beam during use of a CD are made to enter the objective optical element (OBJ) under the state of finite divergence light beam. Consequently, the aberration correction amount required during compatible use of DVD and CD can be limited and the degree of contribution of the production error or transfer error of a die for molding the objective optical element (OBJ) can be limited by increasing the zone pitch (reducing the power of diffraction) of an optical path difference imparting structure. Furthermore, since the position where the third light beam is collected becomes distant from the objective optical element (OBJ), a long working distance can be assured or the zone pitch of the optical path difference imparting structure can be made small.