| 摘要 |
<p>An optical head for a magneto-optical recording/reproducing apparatus comprises a semiconductor laser, an object lens for condensing a light beam from the semiconductor laser onto a magneto-optical recording medium, an optical element disposed in an optical path from the semiconductor laser to the object lens, the optical element comprising three substantially right-angled prisms, and light detectors. The optical element is arranged such that the light beam emitted from the semiconductor laser enters a first end face of a first substantially right-angled prism made of a uniaxial crystal and part of the light beam is reflected by a second end face of the first prism to exit from a third end face substantially perpendicular to the first end face for separation into first and second light beams having their polarized directions orthogonal to each other, the uniaxial crystal of the first prism having an optical axis almost coincident with a propagating direction of the reflected light beam from the second end face, the light beam emitted from the semiconductor laser having its polarized direction inclined a predetermined angle from the optical axis of the uniaxial crystal; the first and second light beams exiting from the first prism are focused by the object lens as small first and second light spots on the magneto-optical recording medium; first and second 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 from a first end face thereof which is joined to the second end face of the first prism, emit from a second end face of the second prism almost perpendicular to the first end face thereof, enter a third substantially right-angled prism made of glass from a first end face thereof which is joined to the second end face of the second prism, and then exit from a second end face of the third prism almost perpendicularly, so that the first and second reflected light beams are respectively separated into first and second emergent light beams and third and fourth emergent light beams, each pair having their polarized directions orthogonal to each other; and the second prism has an optical axis inclined 45 DEG with respect to the polarized directions of the first and second light beams exiting from the third end face of the first prism. The light detectors detect the first, second, third and fourth emergent beams from the third prism. The optical head allocates the quantity of light from the semiconductor laser to two spots in predetermined amounts precisely. <IMAGE></p> |
