Patent ID: 7936658

Claim:
An optical pickup including a photo-detector to detect a light beam and a diffraction grating to split the light beam, the photo-detector comprising: a first light receiving area to receive the light beam emitted from a laser light source of a first wavelength and split by first and second diffraction grating pattern areas of the diffraction grating; and a second light receiving area to receive the light beam emitted from a laser light source of a second wavelength longer than said first wavelength and split by the first and second diffraction grating pattern areas of the diffraction grating; wherein said first light receiving area is disposed at a position where, when the light beam is emitted from said laser light source of the first wavelength, the light beam split by said first diffraction grating pattern area enters the first light receiving area and the light beam split by said second diffraction grating pattern area does not enter the first light receiving area, wherein said second light receiving area is disposed at a position where, when the light beam is emitted from said laser light source of the second wavelength, the light beam split by said first diffraction grating pattern area does not enter the second light receiving area and the light beam split by said second diffraction grating pattern area enters the second light receiving area, and the diffraction grating comprising said first and second diffraction grating pattern areas disposed at a same plane of the diffraction grating.