Patent ID: 7304935

Claim:
An optical pickup device comprising: a first light source emitting a light flux with wavelength λ 1 (380 nm≦λ 1 ≦450 nm); a second light source emitting a light flux with wavelength λ 2 (600 nm≦λ 2 ≦700 nm); a light-converging optical element having a diffractive structure through which the light flux with wavelength λ 1 and the light flux with wavelength λ 2 pass; a first correcting element having a diffractive structure through which at least the light flux with wavelength λ 1 passes; a second correcting element having a diffractive structure through which at least the light flux with wavelength λ 2 passes; and a beam splitter that makes an optical path for the light flux with wavelength λ 1 and that for the light flux with wavelength λ 2 to agree with each other in terms of their positions; wherein reproducing and/or recording of information is conducted on the first optical information recording medium having protective substrate thickness t 1 (0 mm<t 1 ≦0.7 mm), by the use of the light flux with wavelength λ 1 , reproducing and/or recording of information is conducted on the second optical information recording medium having protective substrate thickness t 2 (0.5 mm≦t 2 ≦0.7 mm), by the use of the light flux with wavelength λ 2 , at least one of the first correcting element and the second correcting element is arranged between the beam splitter and the first light source or between the beam splitter and the second light source, the first light-converging spot formed on the first optical information recording medium by n 1 th diffracted light (n 1 is a natural number) of the light flux with wavelength λ 1 generated by diffractive effects of the light-converging optical element and the second light-converging spot formed on the second optical information recording medium by n 2 th diffracted light (n 2 is a natural number satisfying n 1 ≠n 2 ) of the light flux with wavelength λ 2 generated by diffractive effects of the light-converging optical element are controlled to be within a range necessary for reproducing and/or recording of information in terms of chromatic aberration, an absolute value of chromatic aberration owned by the light-converging optical element itself is controlled to be 0.15 μm/nm or less for the light flux emitted from the first light source, and an absolute value of chromatic aberration owned by the first correcting element itself is controlled to be 2.1 μm/nm or less for the light flux emitted from the first light source.