Patent ID: 7636290

Claim:
An optical element of an optical pickup device for at least one of reproducing and recording information on a first optical information recording medium having a protect substrate thickness t 1 by using a light beam having a first wavelength λ 1 emitted from a first light source, and for at least one of reproducing and recording information on a second optical information recording medium having a protect substrate thickness t 2 (t 2 ≧t 1 ) by using a light beam having a second wavelength λ 2 (λ 2 >λ 1 ) emitted from a second light source, comprising: an optical surface comprising a central region arranged around the optical axis and formed in an approximately circular shape, and a peripheral region arranged at a periphery of the central region; a diffractive structure having a plurality of diffracting ring-shaped zones arranged around an optical axis on at least one optical surface, the diffractive structure being provided in the central region; and an optical path difference giving structure for giving a prescribed optical path difference to a prescribed light beam passing through the diffracting ring-shaped zones, the optical path difference giving structure being provided in the central region, wherein the first wavelength λ 1 satisfies: 370 nm<λ1<430 nm, wherein the diffractive structure emits an L-th (L≠0) order diffracted light with a larger light amount than any other diffractive light, when the light beam having the first wavelength λ 1 passes through the diffractive structure, which emits an M-th (M≠0) order diffracted light with a larger light amount than any other diffractive light, when the light beam having the second wavelength λ 2 passes through the diffractive structure, and wherein the optical path difference giving structure is superimposed on the diffractive structure so that at least one stepped shape of the optical path difference giving structure is disposed on the optical surfaces of each of the plurality of diffracting ring-shaped zones.