Patent ID: 7280444

Claim:
An objective optical element to be used for an optical pickup device for performing reproducing and/or recording of information to a first optical information recording medium and a second optical information recording medium by converging a light beam having a wavelength λ 1 (640 nm≦λ 1 ≦670 nm) on an information recording surface of the first optical information recording medium having a protective substrate thickness t 1 (t 1 =0.6 mm), and by converging a light beam having a wavelength λ 2 (400 nm≦λ 2 ≦415 nm) on an information recording surface of the second optical information recording medium having a protective substrate thickness t 2 (t 2 =0.6 mm); wherein an optical system magnification m 2 of the objective optical element to the light beam having the wavelength λ 2 satisfies a relation of |m 2 |<0.01, and wherein an optical system magnification m 1 of the objective optical element to the light beam having the wavelength λ 1 satisfies a relation of − 1/20≦m 1 ≦− 1/200.