Patent ID: 8036093
Filing Date: 2011-10-11
Classification: G11B

Abstract:
1. An optical head device capable of recording and reproducing on and from a first optical information recording medium and a second optical information recording medium of different types, comprising: a first light source for emitting a first light beam having a wavelength λ a second light source for emitting a second light beam having a wavelength λ an optical system in which the first light beam and the second light beam share a same optical path; a luminous flux separating section for selectively separating the first light beam and the second light beam which enter from the shared optical path to a first optical path and a second optical path, respectively; a first objective lens for converging the first light beam separated to the first optical path by the luminous flux separating section onto the first optical information recording medium; a second objective lens made of resin for converging the second light beam separated to the second optical path by the luminous flux separating section onto the second optical information recording medium; and a first filtering section formed on a beam exit face of the second objective lens, for reducing a transmittance of the first light beam to be lower than a transmittance of the second light beam, wherein the first objective lens and the second objective lens satisfy the following condition (1): OL1_WDλ D: difference (mm) between a beam exit face position of the first objective lens and the beam exit face position of the second objective lens which are mounted to a biaxial actuator (the difference having a positive value when the beam exit face position of the first objective lens is higher (closer to the first optical information recording medium), and having a negative value when the beam exit face position of the second objective lens is higher (closer to the second optical information recording medium) OL2_t: thickness (mm) of the second objective lens OL2_nλ OL2_BFλ