| 摘要 |
PURPOSE:To obtain an information recording and reproducing device which provides easy rewriting by using metal or allow which has two kinds of phases, and forming recessed or projection parts on the base surface by utilizing volumetric variation based upon the variation of crystal structures due to phase transition and then recording and reproducing information such as signals, characters, graphic forms, and symbols. CONSTITUTION:A recording and reproducing medium is mad of the metal or alloy which has at least two kinds of crystal structures in a solid state, holds the crystal structure in one temperature range even in the other temperature range and has difference volumetric variation between the two different crystal states. For example, the recording medium 27 is formed of a Cu-Al-Ni alloy thin film on a glass plate 28 and an SiO2 film 26 is further formed on its surface. Grooves 29 for tracking are formed in the glass plate 28; the track width is, for example, 0.8mum, the track intervals is 1.6mum, and the depth is a quarter as large as the wavelength of a laser beam. This optical disk is used and the alloy thin film part is heated to 750 deg.C to record data is bits in brown; and information is erased by oscillating the laser light continuously and heating the film part at 500 deg.C, thereby changing the color into gold. |
