Optical element, aberration correcting element, light converging element, objective optical system, optical pickup device, and optical information recording reproducing device

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 t1 by using a light flux having a first wavelength λ1 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 t2 (t2≧t1) by using a light flux having a second wavelength λ2 (λ2>λ1) 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 t3 (t3<t2) by using a light flux having a third wavelength λ3 (λ3>λ2) 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 λ1, and provides an optical path difference for the light flux having the second wavelength λ2 and the light flux having the third wavelength λ3.