US Patent 7586819 Optical pickup device

An optical pickup device includes a two-wavelength composite light source that can emit laser beams for a CD and for a DVD, a light source that can emit a laser beam for a BD, a hologram element and a photo detector. When spots formed on the photo detector by 0 order light generated by diffraction of the three laser beams in the hologram element are first, second and third spots in the descending order of the wavelength of the laser beams, an attachment angle of the two-wavelength composite light source is adjusted so that positions of the third spot and the second spot match substantially each other while a position of the first spot is shifted from the position of the second spot in the same direction as a diffraction direction of +1st diffracted light.