| 摘要 |
PURPOSE: To obtain an optical disk having a structure producing an effect similar to that in the case of an increased difference in reflectance of a VO2 film used as a reproduction assisting layer and varying reflectance even when laser beam of shorter wavelength than the conventional wavelength is used. CONSTITUTION: An underlayer 2, a VO2 film 3, a dielectric layer 4, a reflecting layer 5 and a protective film 6 are successively laminated on a transparent substrate 1 with previously formed information pits to obtain the objective optical disk 10. The dielectric layer 4 is made of a transparent dielectric material having a low complex index of refraction such as MgF2 or CaF2 . The real number part (n) of the complex index of refraction is 1.3-1.4 and the imaginary number part (k) is about 0. Since the dielectric layer 4 is formed, the reflectances of the high-temp. region and low-temp. region of the VO2 film 3 can be reduced as a whole and an effect similar to that in the case of an increased difference in reflectance can be produced. |
