A study for high track density recording on magneto-optical disks

Experiments were conducted to evaluate crosstalk due to jitter, mainly with the aim of raising the track density by electrical means. Clocking features of servo-based optical disks are used. Disks used in sample servo-based optical disk systems have prepits etched in the servo areas of the surface prior to use, to synchronize the clock used for data demodulation. The following advantages are also apparent when the system is viewed as a transmission path: (1) the clock channel and data channel can be regarded as independent; (2) the clock itself is extremely stable compared to self-clocking systems; (3) even at higher track densities, the clock transmission path is subject to virtually no crosstalk which might degrade the clock signal; and (4) as there are no self-clocking constraints, there is greater freedom in choosing the coding method. It is concluded that these features act to increase different margins of operation, and indirectly contribute to an increased track density.