Patent ID: 8072868

Claim:
An optical pickup for recording or reproducing an information signal with respect to an optical disc comprising a plurality of recording layers, each recording layer having a recording track in which information pits are arranged, the information signal being recorded in the information pits, the optical pickup comprising: a light source for irradiating a laser beam; a diffracting device for diffracting the irradiated laser beam; an optical system for guiding the diffracted laser beam to one recording layer of the plurality of recording layers; an optical element for changing (i) a polarization direction in at least one portion of signal light generated in the one recording layer and (ii) a polarization direction in at least one portion of stray light generated in another recording layer of the plurality of recording layers, if the guided laser beam is focused on the one recording layer; and a plurality of light receiving devices for respectively receiving zero-order light, +first-order diffraction light and âˆ’first-order diffraction light, wherein one portion of the optical element sets the polarization direction in the one portion of the signal light and the one portion of the stray light to a first direction, and another portion of the optical element sets the polarization direction in another portion of the signal light and another portion of the stray light to a second direction, the light receiving devices are arranged so as to receive the one portion of the signal light with the another portion of the stray light, shapes of the one portion and the another portion of the optical element and a relative positional relationship between the one portion and the another portion of the optical element are defined on the basis of a width of a dead band which reduces an influence of a light interference of the signal light and the stray light, in an optical diameter of the signal light, and the optical element is disposed in a position in which optical diameters of a plurality of stray lights, generated in a plurality of recording layers other than the one recording layer, are all substantially equal, on an optical axis.