Patent ID: 8395980

Claim:
An optical head device, comprising: a first laser light source which emits light at a wavelength λ 1 ; a second laser light source which emits light at a wavelength λ 2 longer than the wavelength λ 1 ; a focusing optical system which focuses the light at the wavelength λ 1 emitted from the first laser light source onto a recording layer of a first optical information medium through a base member having a first thickness t 1 or focuses the light at the wavelength λ 2 emitted from the second laser light source onto a recording layer of a second optical information medium through a base member having a second thickness t 2 larger than the first thickness t 1 ; a photodetector which receives the light at the wavelength λ 1 that has been reflected by the recording layer of the first optical information medium and the light at the wavelength λ 2 that has been reflected by the recording layer of the second optical information medium and outputs an electric signal in accordance with an amount of the received light at the wavelength λ 1 or the light at the wavelength λ 2 ; a branch element provided on a return optical path followed by the light at the wavelength λ 1 reflected by the recording layer of the first optical information medium and the light at the wavelength λ 2 reflected by the recording layer of the second optical information medium to guide the light at the wavelength λ 1 and the light at the wavelength λ 2 toward the photodetector; an optical element disposed between the branch element and the photodetector; and a wavelength selective light blocking region which blocks a center portion of a light flux of the light at the wavelength λ 1 to prevent the center portion from reaching the photodetector, and transmits the light at the wavelength λ 2 , wherein the wavelength selective light blocking region is disposed between the branch element and the photodetector and at a position intersecting at least the center portion of the light flux of the light at the wavelength λ 1 and a center portion of a light flux of the light at the wavelength λ 2 , and formed on the optical element.