| 摘要 |
PURPOSE:To improve erasability at the time of rewriting information and to make the amplitude of a reproducing signal larger by making the size of an energy beam spot on a recording film surface smaller at the time of a non- crystallizing and larger at the time of crystallizing. CONSTITUTION:A phase changing optical disk is formed by evaporating a crystal and non-crystal phase changing recording film 10 to a substrate 9 and evaporating a protecting film 11 on the recording film 10. The recording makes laser lights from a semiconductor laser 1 into circular parallel lines with a coupling lens 2 and a prism 3, makes the circular parallel lines pass through an optical system 4, which modulates a spot diameter hourly, makes the plane of polarization rotate at a 45 deg. angle with a polarizing prism 5, a wavelength board 6, and a galvanomirror 7, introduces an optical spot onto a track, and focuses on the film 10 with a converging lens 8. The reflected light is reversed, passed through the prism 5, divided into two with a polarizing prism 13, focuses with a signal detected by an automatic focusing detector 17, and made to follow the track with a detector 14. |
