| 摘要 |
PURPOSE:To attain a high response speed of a change of reflectivity and to suppress deterioration due to repetition. CONSTITUTION:A reflecting film 3 is laminated on a transparent substrate 2 with a line of formed pits corresponding to an information signal to obtain a reflection type optical disk 1. The reflecting film 3 is made of amorphous Si or InSb having a tertiary nonlinear optical effect. Since the reflectance of the reflecting film 3 increases nearly in proportion to the light intensity of a projected beam spot, the effective spot diameter of a beam spot projected on the optical disk 1 can be reduced and an information signal having space frequency above the cutoff space frequency of a reproducing optical system can be read from the optical disk 1. |
