新世代的光儲存系統必定是往高紀錄密度的方向發展，但在縮小紀錄資料點的同時也提高了聚焦的困難度。資料讀取的過程中影響聚焦光點品質的因素很多，例如讀取頭的設計不當、讀取頭中光學元件的缺陷及碟片的傾斜晃動等等，這些因素都會改變聚焦光點的形狀及中心強度。基於此一觀點，本文將利用波動光學的純量繞射理論建構光碟機的數學模型及像差理論來分析聚焦物鏡的像差對聚焦光點的影響，同時我們也將探討碟片傾斜所導致的像差對聚焦伺服訊號(S-Curve)的影響。在模擬的部分我們使用自己的演算法計算光場及光強度再利用MATLAB將模擬結果以圖形的方式呈現，同時以另一套繞射軟體DIFFRACT來作模擬結果的驗證。

Reducing the size of data pattern on optical disk to increase the storage capacity is definitely a direction of development for storage medium. Therefore, high NA (Numerical Aperture) objective lens would be employed to generate tiny spot for the readout process. However, this would make the defocus tolerance rigorous at the same time. Therefore, focusing is still a critical issue in new generation optical storage system.
This thesis is devoted to investigate the effects of imperfect conditions within an optical pickup such as lens aberrations on the spot formation. Besides, the variation of focusing error signal (S-curve) due to the presence of disk tilt aberrations is also studied in this work. Wave optics and aberration theory are introduced in this thesis to calculate the optical field distribution and MATLAB is used to perform our own-developed program codes and plot the simulation results. On the other hand, a commercial software, DIFFRACT, is used to verify our simulation results.

[1]H.H. Hopkins, “Diffraction theory of laser read-out systems for optical video discs”, J. Opt. Soc. Am., Vol.69, No.1, pp.4-24, 1979.
[2]徐桂香, “光碟讀取頭光路之數學模型”, 清華大學動力機械工程學系碩士論文, 90年6月.
[3]B.E.A.Saleh, M.C.Teich, “Fundamentals of Photonics”, New York :Wiley, 1991.
[4]Miles V.Klein, Thomas E.Furtak, “Optics”, New York :Wiley, 1986.
[5]Joseph Braat, “Analytical expressions for the aberration coefficients of a tilted plane parallel plate.”, Applied Optics, Vol. 36, No. 32, p8459-8466, Nov, 1997.
[6]Frank L., Leno S., “Introduction to Optics”, Prentice Hall, Englewood Cliffs, 1993.
[7]P.W. Nutter, “Image Formation In The Scanning Optical Microscope”, Thesis submitted to the University of Manchester for the degree of Doctor of Philosophy in the Faculty of Science and Engineering, 1997.
[8]R.E. Gerber, M. Mansuripur, “Tilt correction in an optical disk system.”, Applied Optics., Vol. 35, No. 35, pp. 7000-7007, Dec, 1996.
[9]Jordan Isailovic, “Videodisc and optical memory systems”, New Jersey: Prentice-Hall, Inc., Englewood Cliffs, 1985.
[10]“Optical Pick-Up Specifications for DVD/CD: HOP-1000”, Hitachi. Ltd., October 1998.
[11]“CD-Audio Red Book”, PHIPLIS.
[12]“Guide to Program DIFFRACT 7.7”, MM Research, Jan 2002.
[13]Y. Li, E. Wolf, “Focal Shifts in Diffracted Converging Spherical Waves”, Optics Communications, Vol. 39, pp. 211-215, 1981.
[14]B. E. Bernacki, M. Mansuripur, “Investigation of substrate birefringence effects on optical-disk performance.” Applied Optics, Vol. 32, pp. 6547-6555, 1993.
[15]J. P. McGuire, R. A. Chipman, “Polarization aberrations Tilted and decentered optical systems.”, Applied Optics, Vol. 33, pp. 5101-5107, 1994.
[16]M. Born and E. Wolf, “Principles of Optics”, pp. 135-137, Oxford, 1980.