| 摘要 |
PROBLEM TO BE SOLVED: To improve reliability for heat resistance, wear resistance and information record preservable property by forming a rugged bit corresponding to recorded information on the surface of a substrate consisting of inorganic crystal material having light transmissivity. SOLUTION: A laser beam 10 is converged by a condenser lens 11, and is made incident from a surface opposite to the surface formed with the rugged pits 2 of the rotating substrate 1 to arrive at the rugged pits 2, and is abutted on a reflection film layer 3 to be reflected and to be returned. A protection film layer 4 is formed on the reflection film layer 3. A single crystal sapphire substrate having an optical axis in the direction perpendicular to the substrate 1 is used as the inorganic crystal material having light transmissivity, and the surface is optically ground to be made the substrate 1 for optical recording medium. Although the substrate 1 is inserted into a furnace in the air atmosphere to be heated to a maximum temp. 1000 deg.C, the rugged pits 2 are not changed, and when the recorded information is reproduced using a laser beam of wavelength 780 nm, a excellent reproducing signals without noise due to birefringence and with a small jitter component is obtained. |
