OBJECT OPTICAL SYSTEM, OPTICAL PICKUP DEVICE AND OPTICAL INFORMATION RECORDING/REPRODUCING DEVICE

摘要

The objective optical system of the present invention includes a first diffraction structure that applies diffraction to the light fluxes of wavelength »1, wavelength »2 and wavelength »3 so that the diffracted lights of the L-th order (L: odd number), M-th order (M: integer) and N-th order (N: integer) each will have the maximum diffraction efficiency, and a first optical path difference-generating structure that substantially provides a phase difference to one or two of the light fluxes of wavelength »1, wavelength »2 and wavelength »3.