| This thesis concerns a study of the application, and performance optimization, of standard lead-lag compensation techniques to improve the closed loop performance of a focus servo system for an optical data storage device. Only with proper application of these compensation techniques will it be possible to meet the sub-micrometer focus error tolerances while maintaining the stability of the closed loop system. The performance indices used in this optimization study are the Integral of the Squared Error (ISE), the Integral of the Absolute Error (IAE), and the Integral of the Time multiplied by the Absolute Error (ITAE) as defined below, with the error function e(t) being the focus error of the closed loop servo system in response to a step input. ISE=OT e2t dt IAE=OT ∣et∣ dt ITAE=OT t∣et∣ dt . |
