On the coupled focusing and tracking performances of a high-speed optical disk drive

The coupling dynamic between the focusing and tracking axis of a high speed optical disk drive system is exploited from the theoretical and experimental perspectives. By assuming the fact that the coupling dynamic is mainly due to the misalignment of the mass center and centroid of magnetic forces, a mathematical model of considered system is derived according to the first-principle method. Afterwards, experimental testings are carried out to identify some system coefficients and thereby verify the consistency of the theoretical model with practical system. The results turn out that the misalignment of mass center with centroid is not the only dominant reason for coupling, some other coupling mechanisms, such as stiffness coupling of the suspension wires, electro-magnet coupling and some nonlinearities in the system may also play some critical rule in the coupling dynamic. This analysis dedicates some deep insights of coupling phenomena for high speed disk drive, even though some phenomena could be roughly modeled by uncertainties insider the system.