| 摘要 |
PURPOSE:To contrive to make the optical head small in size and light in weight by providing a laser light source, an optical means for transforming a laser light cross sectional shape, and a movement or rotation driving means of the optical means. CONSTITUTION:An emitted light of a laser 5 is made parallel by a lens 7, made incident on a uniaxial optical member group 9, transformed to a desired cross sectional shape, and focused to the recording film surface of an optical disk 1 by an objective lens 13. At the time of reproduction, a reflected light is reflected to a detection lens 15 side by a beam splitter 11, and converted to an electric signal by a photodetector 17. The optical member group 9 consists of a cylindrical concave lens 9a and a cylindrical convex lens 9b, and a coil 9a moves. By a variation of a relative distance of the lenses, a cross section of a laser light emitted from the lens 9b is varied to circular and laterally long or longitudinally long elliptical shapes. The laser light of the laterally long elliptical shape, and the laser light of the longitudinally long elliptical shape are used for reading out a recording bit of plural tracks, and erasing the recording bit on the track, respectively, and at the time of recording data onto the track, the laser light is returned to a circular shape and used. By a magnet and the coil, the lens 9a is moved, and an optical head being light is weight and small in size is obtained. |
