Patent ID: 7068445
Filing Date: 2006-06-27
Classification: G11B

Abstract:
1. An optical pickup lens device used in an optical pickup device which performs at least one of reading, writing, and erasing of information by converging onto an information recording medium a bundle of rays with a wavelength range of 390 nm to 420 nm emitted from a light source, to form a spot, the optical pickup lens device comprising, in an order from a side of the light source: collimating means for converting the bundle of rays into parallel rays or predetermined convergent or divergent rays, the collimating means being movably held along a direction of an optical axis of the bundle of rays emitted from the light source; an aberration correcting element for allowing a bundle of rays emitted from the collimating means to be transmitted therethrough; and an objective lens element having a numerical aperture of 0.8 or more, and converging a bundle of rays coming from the aberration correcting element onto the information recording medium to form a spot, wherein the aberration correcting element and the objective lens element are integrally held together in a direction orthogonal to the optical axis so as to perform tracking on the information recording medium, and the optical pickup lens device satisfies the following conditions: where CAt: axial chromatic aberration (μm/nm) in an entire optical system, CAf: axial chromatic aberration (μm/nm) in the collimating means, CAm: axial chromatic aberration (μm/nm) in the aberration correcting element, θf: amount of change in an angle of a bundle of outgoing rays from the collimating means per unit wavelength (min/nm), and θm: amount of change in an angle of a bundle of outgoing rays from the aberration correcting element per unit wavelength (min/nm).