| 摘要 |
PURPOSE:To expand an area recordable a signal on an optical tape by forming a guide track on a medium in advance, and forming the track by using a master disk manufactured by an interference fringe generated by the interference of light. CONSTITUTION:When a beam 4 is separated into two beams by a half prism 5 and they are formed in flat beams by using beam expanders 10a and 10b and are superposed on a cylindrical lens 8, the interference fringe 9 is stopped on the master disk 2. When the master disk 2 is rotated for one revolution as changing the position of the fringe 9 by a phase shifter 6 at constant speed, the locus of the fringe 9 on the master disk 2 forms a pattern having a projecting groove 7 which forms an oblique concentric circular cylinder with a constant angle. Since plural grooves 7 are formed simultaneously by the fringe 9 arranged at constant intervals, pitch accuracy can be heightened. By transferring the groove 7 on the optical tape 1, plural guide grooves 11 can be formed. Stable tracking can be obtained at the time of performing the recording, the reproduction, and the erasure of a signal by using the groove 11 for the guide track of the tape 1, and the recording with high density can be realized due to high pitch accuracy. |
