| 摘要 |
PURPOSE:To nearly flatten the percentage modulation of a bit signal within the range of a recording area by setting the width of the pits disposed on the inside circumferential side in the radial direction of the disk at the length equal to or larger than the width of the pits disposed on the outside circumferential side. CONSTITUTION:The pits are formed on the master disk of the optical disk while the width of the pits on the inside circumferential side in the radial direction of the disk is set larger than the width of the pits on the outside circumferential side and the pit area is maintained nearly constant. A glass plate 28 having a photoresist film 29 is disposed on the reading surface of a cutting machine and is rotated around a revolving center shaft 30 for the above- mentioned purpose. The photoresist film 29 is irradiated by laser light 20 from an He-Cd laser generator 21 via an irradiation power control part 22, a mirror 23, a collimating lens 24, an optical modulator 31, a collimating lens 32, a mirror 33, and a head moving part 25, by which the film is cut and the pits are formed thereon. The irradiation density is properly controlled by the control part 22 at this time. |
