| 摘要 |
PURPOSE:To eliminate the need for changing an original disk, a stamper, etc., and to easily cope with a change even when the using conditions of the disk is changed by changing the material quality of a refractive index adjusting film. CONSTITUTION:A refractive index adjusting film 4 having fixed thickness is formed on a surface where a bit 1a of a disk 1 is formed. A metallic reflecting film 5 and a protective film 6 such as aluminum are formed on the rear surface of the film 4. By such a constitution, when the depth (d) of the bit 1a is equal to a light wavelength lambda, and the refractive index of the film 4 are respectively set at (n) and (n'), since the conditions to obtain a maximum level difference for the light receiving quantity of a light receiving device is d=lambda/4(n-n'), by making (d) constant, and by suitably selecting the material of the film 4, the conditions can be satisfied. Consequently, the change of the using conditions such as the change of the light wavelength can be easily coped with by using the material at the desired refractive index without producing the original disk and the stamper again. |
