We need to add the controller in order to enhance the control precision and response speed of DVD focus servo system,and then a new emendation arithmetic was put forward.

The evaluation technologies include the theoretical analysis and evaluation methodsresearch of characteristic parameter, DVD servo system research and engineeringrealization technology research of test equipment.

Research on the focus servo system due to the disc oscillation;

The focus servo system of the OM is analyzed and the mathematical model of the voice-coil motor is presented.

To implement dual-pickup-head multilayer data storage system,it is necessary to measure the synchronizing focus error of the two pickup heads to validate the feasibility of the focus servo method.

This paper presents a technique on the control system constructing and the single-chip compute r programtheng of an auto-focusing servo laser micrometer.