| 摘要 |
PURPOSE:To obtain a medium while the C/N is kept excellently without being subject to the effect of pre-group or information pit mutually by forming an information track of both sides of a medium in zigzag mutually so as not to be overlapped. CONSTITUTION:Pre-groups 12a/12b are formed at a prescribed interval concentrically in the radial direction of A/B sides of a disk base 10 or in zigzag and information pits 14a/14b are formed concentrically along the pre-groups 12a/12b on the face of dums 13a/13b of the A/B sides. Further, the pits 14a/14b are formed by focusing the laser luminous flux 18 of an optical disk head provided near the side A of the base 10 by an objective lens 16 onto the dums 13a, 13b and even when the luminous flux 18 is radiated onto the pit 14b, the light is reflected by the pit 14b and passes through the lens 16 again, and the reflected light is not interfered with the reflected light reflected by the pit 14a and the C/N is kept in an excellent way. |
