Patent ID: 8077583

Claim:
A light converging element for use in an optical pickup apparatus in which reproducing and/or recording information is conducted for a first optical information recording medium equipped with a first protective layer having a thickness t 1 by using a light flux having a first wavelength λ 1 emitted from a first light source, reproducing and/or recording information is conducted for a second optical information recording medium equipped with a second protective layer having a thickness t 2 (t 2 ≧t 1 ) by using a light flux having a second wavelength λ 2 (λ 2 >λ 1 ) emitted from a second light source and reproducing and/or recording information is conducted for a third optical information recording medium equipped with a third protective layer having a thickness t 3 (t 3 <t 2 ) by using a light flux having a third wavelength λ 3 (λ 3 >λ 2 ) emitted from a third light source, comprising: an optical surface of the light converging element having a plurality of ring-shaped optical functional zones, wherein a superposition type diffractive structure is formed on one of the plurality of optical functional zones such that a plurality of ring-shaped zones are formed concentrically around an optical axis and plural stepped sections shaped stepwise are formed within each ring-shaped zone, and wherein the superposition type diffractive structure provides substantially no optical path difference for the light flux having the first wavelength λ 1 , and provides an optical path difference for the light flux having the second wavelength λ 2 and the light flux having the third wavelength λ 3 .