OBJECTIVE OPTICAL ELEMENT AND OPTICAL PICKUP DEVICE

摘要

An optical pickup device which can correctly perform information recording/reproduction, for instance, to all of the high density DVDs and conventional DVDs and CDs. Concerning that in an objective optical element OBJ, it is difficult to perform aberration correction to all of the light fluxes having three different wavelengths for correct information recording and/or reproduction by using a single diffraction structure, a first diffraction structure (10) is used to previously introduce an optical path difference to only a light flux having a wavelength of lambda3 so as to change the phase, and a spherical aberration or wave aberration is corrected. Then, a second diffraction structure (50) is used to introduce mainly an optical path difference to light fluxes having wavelengths of lambda1 and lambda2, and a spherical aberration or wave aberration is corrected so as to reduce the burden. Thus, aberration correction is performed to all of the light fluxes having three different wavelengths in total, and correct information recording and/or reproduction is performed.