| 摘要 |
PROBLEM TO BE SOLVED: To realize sufficient tilt margin, reduced crosstalk and sufficiently large reproduced output with the optical record medium adopting land-groove recording system. SOLUTION: The optical record medium has transparent substrate on which grooves exist and a groove and the area existing between the groove and its adjacent groove are used as a record track, and reproducing light is applied through the transparent substrate. In the optical record medium, -12.6T+15.6<=x<=25T-3.8 and 0.55<=T<=0.68 hold when T=PT/(λ/NA) where λis the wave length of reproducing light, n the refractive index, NA the numerical aperture of reproduction optical system, PT the record track pitch, and λ/(x.n) the depth of grooves. |
