| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently maintain the defocus tolerance of the laser light for recording or reproducing signals and to stably record and reproduce signals. SOLUTION: Grooves 2a are formed along recording tracks on a transparent substrate 2 and walls of the grooves 2a on both sides are formed as wobbling (meandering) into each independent form. The width W and depth D of the groove 2a are controlled to have the relation of 0.470<=W/ϕ<=0.610 and 0.120<=D/(A/n)<=0.142 and the angle θof the groove wall is 150 deg.+10 deg., wherein ϕis the spot diameter of the laser light L irradiating the groove, λ is the wavelength of the laser light in vacuum and n is the refractive index of the transparent substrate. |
