Patent ID: 7313061

Claim:
An optical pickup, comprising: a first semiconductor laser for emitting a light beam of a first wavelength; a second semiconductor laser for emitting a light beam of a second wavelength, the second wavelength being different from the first wavelength; a hologram element for diffracting reflected light generated by reflecting any one of the light beam of the first wavelength and the light beam of the second wavelength by an optical information recording medium; and a plurality of photodetectors for receiving the diffracted light from the hologram element, wherein the hologram element is divided into two or more different diffraction regions by one or more dividing lines passing through a center of the hologram element, the plurality of photodetectors are provided away from the first semiconductor laser and the second semiconductor laser at both sides of a laser region including the first semiconductor laser and the second semiconductor laser, at least two or more of the plurality of the photodetectors being provided respectively at one side of the both sides and at the other side of the both sides opposite to the one side along an extended line of a line between a light emission position of the first semiconductor laser and a light emission position of the second semiconductor laser, each of the plurality of the photodetectors provided at the one side of the both sides and at the other side of the both sides is divided into at least four regions in a direction substantially parallel to the extended line, the diffracted light generated from the light beam of the first wavelength by the hologram element and the diffracted light generated from the light beam of the second wavelength by the hologram element are collected at substantially the same position in an area at the one side of the both sides, part of the plurality of photodetectors being provided at the position, signals obtained both from the four regions of the plurality of the photodetectors provided at the one side of the both sides and from the four regions of the plurality of the photodetectors provided at the other side of the both sides are used to obtain both a focus error signal and a tracking error signal, the second wavelength of the light beam of the second semiconductor laser is longer than the first wavelength of the light beam of the first semiconductor laser, the number of the photodetectors provided at the other side is greater than that of the photodetectors provided at the one side, the photodetectors provided at the one side are nearer to the first semiconductor laser than the second semiconductor laser, and the photodetectors provided at the one side are provided away from each other.