Patent ID: 7280444
Filing Date: 2007-10-09
Classification: G02B,G11B

Abstract:
1. 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 wherein an optical system magnification m