Patent ID: 7742384

Claim:
An optical head, comprising: a first light source for emitting a first laser beam having a first wavelength between 350 nm and 450 nm; a second light source for emitting a second laser beam having a first wavelength between 600 nm and 700 nm; an objective lens for focusing the first laser beam on a first information recording medium and focusing the second laser beam on a second information recording medium different from the first information recording medium; a beam splitting portion arranged on an optical path common to the first laser beam reflected and diffracted by the first information recording medium and the second laser beam reflected and diffracted by the second information recording medium for splitting the respective laser beams into a plurality of beams; and a light receiving portion for receiving the plurality of beams divided by the beam splitting portion, wherein: the beam splitting portion includes a first area and a second area divided by a first line passing through the optical axis of the objective lens and parallel to an information track of the first information recording medium in an area where the beam reflected and diffracted by the first information recording medium passes; the first area includes a first transmission area for transmitting many 1 st -order diffracted lights from the first information recording medium, a second transmission area adjacent to the first transmission area and closer to the optical axis than the first transmission area and a third transmission area adjacent to the first and second transmission areas; and the second area includes a fourth transmission area for transmitting many 1 st -order diffracted lights from the first information recording medium, a fifth transmission area adjacent to the fourth transmission area and closer to the optical axis than the fourth transmission area and a sixth transmission area adjacent to the fourth and fifth transmission areas.