| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk which is good in S/N of the recording information to be reproduced and allows easy handling of focusing servo and tracking servo. SOLUTION: This optical disk is formed by laminating and depositing a mask layer 2 which is increased in light transmittance when the irradiation light intensity of a laser beam L increases, a reflection layer 4 which reflects the laser beam L for the purpose of reproducing the recording information and a protective layer 5 on a transparent disk substrate 1 turned around and formed with plural pits 1a corresponding to the recording information. The optical disk is so formed that the light spot diameter of the laser beam L cast from the transparent disk substrate 1 side is made into the substantially reduced spot diameter by transmitting the mask layer 2 and is made incident on the reflection layer 4. The optical disk D1 described above is deposited with a wavelength conversion layer 3 having a wavelength conversion function to the laser beam 1 between the mask layer 2 and the reflection layer 4. |
