초록 ▼

In an optical head, a laser beam L emitted from a semiconductor laser is collimated by a collimator lens and is incident on a beam splitter. The laser beam passing through the beam splitter is and a quarter wave plate converged by an objective lens onto an optical disk and reflected by the optical d

In an optical head, a laser beam L emitted from a semiconductor laser is collimated by a collimator lens and is incident on a beam splitter. The laser beam passing through the beam splitter is and a quarter wave plate converged by an objective lens onto an optical disk and reflected by the optical disk. The reflected laser beam passing through the objective lens and the quarter wave plate is returned to the beam splitter and is reflected from a polarizing surface of the splitter. The reflected laser beam is guided to a beam emerging surface of the prism, the surface being defined by a flat surface and a semicylindrical concave surface. The laser beam is separated at the surfaces and converged by a projection lens onto a photodetector.

대표청구항 ▼

An optical system for focusing a light beam onto an optical memory, comprising: means for generating a light beam; means for converging the generated light beam toward the optical memory, said converging means having an optical axis and being movable along the optical axis, the generated light beam

An optical system for focusing a light beam onto an optical memory, comprising: means for generating a light beam; means for converging the generated light beam toward the optical memory, said converging means having an optical axis and being movable along the optical axis, the generated light beam being focused on the optical memory when said converging means is in a focusing state, and the light beam being defocused on the optical memory when said converging means is in a defocusing state; means for guiding a light beam reflected from the optical memory and for separating the reflected light beam into first and second light beams, said reflected light beam guiding and separating means including first and second light beam emerging surfaces having different radii of curvature, the first and second light beams emerging from the emerging surfaces along first and second optical paths, respectively; means for detecting one of the first and second light beams to generate a focusing signal which indicates whether said converging means is in the focusing state or in the defocusing state; and means for driving said converging means in response to the focusing signal to maintain said converging means in the focusing state.