Abstract
In this thesis, the tracking error signal generated by differential phase detection (DPD) is theoretically analyzed and numerically simulated. The tracking error signal is sensitive to the radial tilt angle but not to tangential tilt angle. A DVD-ROM model is built to simulate optical pickup in DVD drive and an overall tracking servo system is design to simulate tracking performance. Tilt effects on tracking error signal are analyzed and are compensated by a tilt compensator in tracking servo system. First, we propose the optical theory related to the mathematical model, and discuss the transfer function between the optical components in the system. Then, we propose the aberration theory resulted from the disk tilt. The tracking error influenced by different radial tilt angles will be simulated and analyzed, and the relations will be established. The tilt compensator will be designed using the relations. Finally, the performances of two tracking control system, one using the original model without tilt compensator and the other using modified model with tilt compensator, are compared while a 3-dimensional vibration model is built. It shows that the tilt compensator improves the tracking performance. The mathematical models of DVD-ROM and tracking servo system are built with the mathematical software, MATLAB.