Patent ID: 7206274
Filing Date: 2007-04-17
Classification: G02B,G11B

Abstract:
1. A light converging optical system for use in an optical pickup apparatus which conducts reproducing and/or recording information for a first optical information recording medium by converging a light flux with a wavelength of λ 1 (350 nm≦λ 1 ≦450 nm) emitted from a first light source on an information recording surface of a first optical information recording medium having a protective substrate with a thickness of t 1 (0.5 mm≦t 1 ≦0.7 mm) and conducts reproducing and/or recording information for a second optical information recording medium by converging a light flux with a wavelength of λ 2 (650 nm≦λ 2 ≦700 nm) emitted from a second light source on an information recording surface of a second optical information recording medium having a protective substrate with a thickness of t 2 (0.5 mm≦t 2 ≦0.7 mm), the light converging optical system comprising: an objective optical element being a single lens and arranged to face directly the information recording surface of each of the first and second optical information recording media; a first optical element being a single lens and arranged to face directly a light source side optical surface of the objective optical element; and a phase difference giving structure formed on at least one optical surface of optical surfaces of the objective optical element and the first optical element and for giving a phase difference to a light flux with a wavelength λ