| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk having small noises during recording/ reproducing by providing a sectional structure where a pair of transparent substrates for a recording film double layer structure are stuck to each other by adhesive and setting a retardation value of a transparent replica layer equal to or lower than a specified value. SOLUTION: On a transparent substrate having the thickness of an information pattern surface set equal to or lower than 1.2 mm, a pair of transparent substrates of a recording film double layer structure where a recording film, a transparent replica layer and a recording layer are sequentially formed are stuck to each other by adhesive to form a sectional structure. Herein, the retardation of the transparent replica layer is set equal to or lower than 20 nm. This retardation indicates optical anisotropy, and as its value is larger, the optical distortion of a light is larger after transmitted through the transparent medium. Thus, based on the optical distortion of the transparent replica layer having a transferred information pattern, the degree of noise incursion during information recording/reproducing is understood. In the optical disk thus constructed, any recording/reproducing failures during its use are prevented. |
