| 摘要 |
PURPOSE:To improve an information recording density by alternately forming grooves and lands with spiral, concentrical or parallel rugged shapes on an optical information recording surface and setting the effective depth of the ruggedness at the specific ratios of the wavelength of a laser beam. CONSTITUTION:The magneto-optical recording film 2 which consists of metals, such as Te and Bi or the alloy thereof and is formed on a transparent substrate 1 consisting of a transparent material, such as glass, is alternately formed with the grooves 4, 5 and the lands 7 with the spiral, concentrical or parallel rugged shapes. The depth of the grooves 4, 5 is set at 3/8 to 5/8 of the wavelength of the laser beam used so that the pitch between the tracks in the case of formation of a plane by elongating the grooves is increased. The grooves are formed as the guide grooves at the time of the execution of the tracking control of an optical pickup. The arrival of the condensed beam at the adjacent land an the interference thereof by the setting of the above-mentioned depth are prevented by increasing the distance between the tracks. The crosstalks between the tracks is decreased in this way and the quality of reproduced signals and the information recording density are improved. |
