Patent ID: 7948855

Claim:
An optical pickup comprising a plurality of light emitting devices for projecting three kinds of laser beams with wavelengths of λ1, λ2 and λ3 (λ1>λ2>3), projecting an infrared laser beam having the wavelength of λ1 on an information recording surface of an optical disc for a CD (compact disc), projecting a red laser beam having the wavelength of λ2 on an information recording surface of an optical disc for a DVD (digital versatile disc), projecting a blue laser beam having the wavelength of λ3 on an information recording surface of an optical disc for a BD (Blu-ray Disc) or a HD-DVD (high definition digital versatile disc), and receiving the beam reflected at the information recording surface by a light receiving section through a diffractive optics and a beam splitter to read information on the optical disc, wherein the diffractive optics is a holographic element, the light receiving section includes a first light receiving section for receiving a zero-dimensional beam of the reflected beam, and a second light receiving section for receiving a diffraction one-dimensional beam of the reflected beam, when an incident angle of a central beam of the zero-dimensional beam into a beam splitter is defined as θ and variation in transmittance or reflectance of the beam splitter become a maximum with respect to change in the incident angle from θ to a plus side or a minus side in any one of the wavelengths λ1, λ2 and λ3 corresponding to the respective optical discs, the diffraction one-dimensional beam generated on an opposite side of the plus side or the minus side with respect to the zero-dimensional beam by the holographic element is received by the second light receiving section, and the received diffraction one-dimensional beam is used for detection of a signal for servo control.