Patent ID: 7206276

Claim:
An optical element for use in an optical pickup apparatus which conducts reproducing and/or recording information for a first optical information recording medium having a first protective substrate with a first thickness t 1 by using a first light flux having a wavelength λ 1 from a first light source, conducts reproducing and/or recording information for a second optical information recording medium having a second protective substrate with a second thickness t 2 (t 1 ≦t 2 ) by using a second light flux having a wavelength λ 2 (λ 1 <λ 2 ) from a second light source, and conducts reproducing and/or recording information for a third optical information recording medium having a third protective substrate with a third thickness t 3 (t 2 ≦t 3 ) by using a third light flux having a wavelength λ 3 (λ 2 <λ 3 ) from a third light source, and uses a common objective lens for reproducing and/or recording information for the first, second and third optical information recording media, the optical element comprising: an entrance pupil surface; wherein when the entrance pupil surface is divided into three ring-shaped light flux regions of a first light flux region, a second light flux region and a third light flux region arranged in this order from an inner side near to an optical axis to an outer side, regions of the optical element through which light fluxes incident in each of the light flux regions passes are named as a first optical region, a second optical region and a third optical region from an inner side near to an optical axis to an outer side, wherein the first, second and third light fluxes incident into the first optical region are converged so as to form an appropriate wavefront on each information recording plane of the first, second and third optical information recording media, the first and second light fluxes incident into the second optical region are converged so as to form an appropriate wavefront on each information recording plane of the first and second optical information recording media and the third light flux incident into the second optical region does not form an appropriate wavefront on an information recording plane of the third optical information recording medium, and the first light flux incident into the third optical region is converged so as to form an appropriate wavefront on an information recording plane of the first optical information recording medium and the second and third light fluxes incident into the third optical region do not form an appropriate wavefront on each information recording plane of the second and third optical information recording media.