| 摘要 |
An optical head for a magneto-optical recording/ reproducing apparatus includes a semiconductor laser, an object lens for condensing a light beam from the laser onto a magneto-optical recording medium, an optical element disposed in an optical path from the laser to the lens, the optical element including three substantially right-angled prisms, and light detectors. The emitted light beam enters a first end face of a first substantially right-angled prism made of a uniaxial crystal of the optical element. Part of the light beam is reflected by a second end face of the first prism to exit from a third end face for separation into first and second light beams. These light beams are focused by the object lens as first and second light spots on the recording medium. Reflected light beams from the recording medium enter the first prism from the third end face thereof, partially pass through the second end face thereof to enter a second substantially right-angled prism made of a uniaxial crystal, emit from a second end face of the second prism, enter a third substantially right-angled prism from a first end face thereof which is joined to the second end face of the second prism, and then exit from the third prism almost perpendicularly to separate the first and second reflected light beams into first and second emergent light beams and third and fourth emergent light beams. The light detectors detect these emergent beams from the third prism. The optical head allocates the quantity of light from the semiconductor laser to the two spots.
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