Optical pickup apparatus and objective lens

摘要

An optical pickup apparatus comprising: a laser diode; an objective lens made of synthetic resin arranged in an optical path of laser light between the laser diode and an optical disc so that the laser light from the laser diode is focused onto a signal recording layer through a protection layer of the optical disc; and an aberration correction element interposed in an optical path of the laser light between the laser diode and the objective lens, the aberration correction element configured to be operated so as to correct spherical aberration caused by moisture-absorption characteristics of the objective lens.