OPTICAL ELEMENT, OBJECTIVE OPTICAL ELEMENT AND OPTICAL PICKUP DEVICE

摘要

a diffractive structure having a plurality of diffracting ring-shaped zones arranged around an optical axis on at least one optical surface; and an optical path difference giving structure arrranged on an optical surface of at least one of the plurality of diffracting ring-shaped zones, for giving a prescribed optical path difference to a prescribed light beam passing through the diffracting ring-shaped zone, wherein the optical surface of the diffractive structure is a structure having a diffracting function for setting L-th (L0) order diffracted light of the light beam having the first wavelength lambda1 to a maximum diffraction efficiency and for setting M-th (M0) order diffracted light of the light beam having the second wavelength lambda2 to a maximum diffraction efficiency in case of an assumption of no existence of the optical path difference giving structure.