Patent ID: 7301882
Filing Date: 2007-11-27
Classification: G11B

Abstract:
1. An optical pickup device which selectively records or reproduces a first optical recording medium, and a second optical recording medium having a recording density lower than that of the first optical recording medium and a substrate thickness larger than that of the first optical recording medium, comprising: a first laser light source which emits a first laser light whose wavelength is not more than 450 nm in accordance with the first optical recording medium; a second laser light source which emits a second laser light whose wavelength is longer than that of the first laser light in accordance with the second optical recording medium; a chromatic aberration correction element which corrects a chromatic aberration with respect to the first laser light; first and second laser light separating means for separating the first laser light and the second laser light from each other; a diffractive optical element which corrects a spherical aberration generated due to a difference in substrate thickness between the first and second recording mediums; and an objective lens which has a numerical aperture (NA) set to 0.75 or above for the first optical recording medium, in which at least one of respective surfaces thereof backing onto each other is formed into an aspherical surface and which converges the first and second laser lights on the respective signal surfaces of the first and second optical recording mediums, wherein, when a wavelength having the same value as a reference wavelength λ