Abstract
In current design of an optical readout system, the effect due to disk oscillation is not taken into consideration since it is insignificant under the specifications provided by the manufacturer. However, reducing the size of data pits on optical disk to increase the storage capacity is definitely the tendency for future optical readout system. In order to read data with such small size, the optical drive must have shorter wavelength for laser light and larger NA value for objective lens. However, such drive will be influenced by disk oscillation easily. Hence, how to analyze this effect due to disk oscillation becomes an important issue.This thesis will concentrate on the deviations of focusing behavior within an optical drive due to disk oscillation. Several optical theories used to analyze such deviations and establish the mathematical model of the optical pickup will be studied. Finally, a focusing control system of the optical drive will be constructed, and the effect due to disk oscillation on the overall system will be simulated and examined. In order to improve the performance against disk oscillation, an adaptive gain based on the optical model will be adopted. All simulations within this thesis are based on the accurate mathematical model and the MATLAB software.