| 摘要 |
An optical head is mounted in an optical disk apparatus that optically records or reproduces information on or from an information recording medium having a magnetooptical effect. The optical head includes a laser diode for emitting a P-polarized beam and a first hologram element on which the P-polarized beam is incident and which diffracts the P-polarized beam more in zeroth order than in higher orders but diffracts an S-polarized beam perpendicular to the P-polarized beam more in higher orders than in zeroth order. The zeroth order P-polarized beam emitted from the laser diode is focused on the information recording medium by the first hologram element or an objective lens interposed between the first hologram element and the information recording medium. One or more second hologram elements are placed between the first hologram element and the laser diode and split a beam reflected from the information recording medium and then diffracted by the first hologram element into beams having respective planes of polarization perpendicular to each other. A plurality of optical detectors for detecting the beams transmitted through the second hologram elements are disposed in line with the laser diode. |
