| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical disk which is capable of dealing with the shortening of a laser wavelength and the reduction in the thickness of a substrate by higher NA of a lens in good productivity. SOLUTION: This optical disk is constituted by having guide grooves or pits on the surface of a disk-shaped substrate, and further, forming a read-only pit recording surface of information or a reloadable recording surface capable of writing the information with a laser beam and posting a film via the adhesive layer of a tacky adhesive sheet to this recording surface. The pasted film is transparent to the laser beam and the double refraction to the laser beam is <=20 nm. The thickness of the parted film is 0.02 to 0.1 mm and the phase value of the tacky adhesive sheet is <=0.5%, and further, the refractive index difference between the tacky adhesive sheet and the pasted film is <=0.1. |
