Analysis of tracking performance in optical data storage systems under eccentricity

In the paper, we analyze the tracking performance of the optical storage systems in the presence of the disc eccentricity. Eccentricity is the amount of the radial deviation of the circular tracks to the rotating center, which results from the geometric distortion of the data tracks (or the unbalanced loading of the disc). The eccentricity is inevitable in practice and significantly degrades the system performance such as the stable data access. Two performance issues - the pull-in capability and the steady track following ability - are discussed. It will be shown that the multiplication of the eccentricity and the rotating frequency does affect the pull-in performance. Also, to tackle the steady track following performance, the simplest form of the 2 DOF compensator is proposed.