| 摘要 |
PURPOSE:To stabilize CN ratio and erasing rate and to improve reliability with simple constitution by increasing the rate of a change in the increase ratio of the melt width of a recording power with respect to an erasing power by combinations of the film thicknesses of heat insulating layers formed on the top and bottom of the optical recording layer. CONSTITUTION:The heat insulating layers A3, B5, the optical recording film 4 and a reflecting layer 6 are formed on a substrate 2 having optical guide grooves 1. A substrate 2a having optical guide grooves 1a are joined thereto by an adhesive agent 7. The film thicknesses of the two heat insulating layers A, B are so combined that the rate DELTAWerc of the change in the increase ratio of the melt width of the optical recording film with respect to the recording power attains the value larger than the rate >=Wera of the change in the increase ratio of the melt width with respect to erasing power. The power margins of the CN ratio and erasing rate stable to repetition of recording and erasure are obtd. by the combinations of the film thicknesses shifted to the lower sensitivity side to laser light irradiation, by which the reliability is improved. |
