Patent ID: 7903528
Filing Date: 2011-03-08
Classification: G02B,G11B

Abstract:
1. An optical pickup apparatus for conducting recording and/or reproducing information for a first optical information recording medium including at least a transparent protective substrate, a first information recording surface, and a second information recording surface which are laminated in this order from a light source side along an optical axis, comprising: a first light source to emit a light flux having a wavelength of λ an objective lens to converge the light flux onto the first optical information recording medium; a spherical aberration correcting structure to correct a spherical aberration caused in a converged spot on the first and second information recording surfaces due to a difference in thickness between the thickness from the surface of the transparent protective substrate to the first information recording surface and the thickness from the surface of the transparent protective substrate to the second information recording surface when the objective lens converges a light flux emitted from the first light source on the first information recording surface and the second information recording surface, wherein the objective lens is a single lens, wherein the spherical aberration correcting structure comprises optical elements including a positive lens and a negative lens, and wherein at least one of the optical element moves along the optical axis when the position of the converged spot of the light flux with a wavelength of λ