Flexible optical disk system with a sample servo format.
A high-capacity 90-mm flexible optical disk system with a phase-change rewritable disk is studied, aiming at low-cost recording media and small drives. The flexible disk rotates stably and is supported by two thrust air bearings fabricated in a plastic cartridge with a disk tilt of less than 5 mrad. A radial tracking-control precision of 0.2 microm is attained with a sample servo system by using photographically replicated square servo marks on the disk. The feasibility of this system is confirmed by write-erase operations in a 2-microm track pitch.