臺灣博碩士論文加值系統

目前在光碟機系統的設計中，因碟片晃動所造成的影響由於在規格規範下並不嚴重，所以並未將此影響列入考慮。然而由於縮小光點以提升容量這樣的作法很明顯的是將來光碟機系統的發展方向，隨著光波長的縮短及物鏡NA值的提高，碟片晃動所造成的效應將會嚴重地影響光碟機系統的性能。所以，為了未來的發展，前述的影響必定需要加以分析。
這篇論文將致力於研究當CD片放入光碟機之時，碟片晃動對光碟機系統聚焦動作方面所造成的影響。其中用來分析這些影響以及建立數學模型的光學理論將會被一一描述。最後將建立整個光碟機聚焦系統的數學模型，並對碟片晃動對這整個系統所造成的影響進行模擬及檢驗。之後，根據本論文所建立的光學系統而決定的適應性增益值將用於改善整體系統的性能。在本論文中，所有的模擬都是根據精確的數學模型所建立，而透過MATLAB這個軟體來加以實現。

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.

Contents Ⅰ
List of Figures Ⅲ
List of Tables Ⅵ
Chapter1 Preface 1
1.1 Introduction 1
1.2 Framework 2
Chapter2 Optics Theories 3
2.1 Ray optics 3
2.1.1 Postulates of ray optics 4
2.1.2 Properties of ray optics 5
2.2 Wave optics 7
2.2.1 Postulates of wave optics 7
2.2.2 Elementary waves 9
2.2.3 Effect of thin lens on incident light wave 11
2.3 Fourier optics 13
2.3.1 Transfer function of free space 14
2.3.2 Fresnel and Fraunhofer approximation of free space 16
Chapter3 Mathematical Model of the Optical Pickup 19
3.1 The ideal mathematical model of the optical pickup 19
3.1.1 System overview and free space approx. verification 21
3.1.2 Ideal mathematical model construction 24
3.2 Aberration theory 27
3.3 Expressions for aberration coefficients due to disk tilt 28
Chapter4 Influence of Disk Tilt on Optical Intensity 33
4.1 The pickup actuator 34
4.2 The compensator 35
4.3 The optical pickup 37
4.3.1 Examination of aberration coefficient due to disk tilt 40
4.3.2 Disk tilt effect on the focus error detection 49
Chapter5 Focusing Control under Disk Oscillation 54
5.1 Dynamics of disk oscillation 54
5.2 Simulation of the focusing control system 57
5.3 Improvement of system performance 61
5.3.1 Derivation of the adaptive gain 61
5.3.2 Simulation of the modified system 63
Chapter6 Conclusions and Research Prospects 69
6.1 Conclusions 69
6.2 Research Prospects 69
References 71
Appendix 73

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