臺灣博碩士論文加值系統

本論文主要探討的方向，是利用外差干涉術，結合橢圓儀的觀念，在液晶前方放置一個四分之ㄧ波板，旋轉此波板造成入射至液晶的光偏振狀態改變，最後在光偵測器上得到不同的交流訊號。同時推導一個模擬理論，與得到的電壓比例值作曲線擬合，將TN-LC液晶的間隙、扭轉角以及方位角求出。

To compare with conventional method of measuring twisted nematic liquid crystal (TN-LC) cell parameters, this research proposes an amplitude–sensitive heterodyne interferometric ellipsometer to determine cell parameters precisely based on single wavelength at normal incidence. The advantage of this method is the capability of two dimensional (2-D) distribution measurement using CCD camera. We rotate a quarter wave plate (QWP) which is used to modulate the polarization state of incident laser beam prior to TN-LC in order to obtain a set of amplitude ratio of S- and P-waves versus rotation angle. Thus, the twisted angle Φ, untwisted phase retardation Γ, direction angleα and cell gap d of TN-LC are able to be obtained by using least square fitting algorithm. In this experiment, 0.25% of amplitude-ratio stability in 6 mins was achieved.

謝誌
目錄.....................................i
中文摘要................................iv
英文摘要.................................v
圖表索..................................vi
第一章 序論.............................1
1.1 研究背景.............................1
1.2 研究動機.............................1
1.3 文獻回顧.............................2
1.4 研究內容.............................3
第二章 外差干涉式橢圓儀.................5
2.1 干涉儀 (Interferometer).............5
2.1.1 麥克森干涉儀 (Michelson Interferometer)..........................6
2.1.2 馬克詹達干涉儀 (Mach-Zender Interferometer)..........................7
2.2 聲光調變器 (Acoustic-Optic Modulator)...............................8
2.2.1 聲波造成光的繞射效應..............8
2.2.2 粒子觀點來看頻率的改變...........11
2.3 鎖相放大器 (Lock-in Amplifier).....11
2.4 光學外差干涉式橢圓儀 (Optical Heterodyne Interferometric Ellipsometry)..........13
第三章 研究原理........................16
3.1 非均向性材料(Anisotropic Material) ..............................16
3.2 瓊斯向量 (Jones Vector..................................19
3.3 瓊斯矩陣 (Jones matrix).................................21
3.4 橢圓延遲片 (Elliptical Retardation Plate)..................................22
3.4.1 l四分之ㄧ波板的作用......................................24
3.4.2 l四分之ㄧ波板的作用......................................25
3.4.3 瓊斯矩陣表示式...................26
3.5 液晶 (Liquid Crystal)簡介......................................26
3.5.1 液晶的種類.......................27
3.5.2 熱致型液晶 (Thermotropic Liquid Crystal)................................29
3.5.3 液晶的物理性質...................33
3.5.3.1 液晶分子排列的變形......................................33
3.5.3.2 光學非均向性 (Anisotropic)...........................34
3.5.3.3 液晶的定向效應.................34
3.5.4 扭轉向列式液晶 (Twisted-Nematic Liquid Crystal, TN-LC) ....................................37
第四章 實驗系統架設與理論推導...........38
4.1 實驗架設............................38
4.2 實驗步驟............................39
4.3 理論推導............................40
4.3.1 扭轉相列式液晶......................................40
4.3.2 實際波長板.......................43
4.3.3 實驗模型.........................47
4.3.4 振幅比例及相位...................48
4.3.5 曲線擬合.........................49
第五章 數據分析........................51
第六章 結論與討論......................53
參考文獻................................56

1. C. C. Tsai, C. Chou, C. Y. Han, C. H. Hsieh, K. Y. Liao, and Y. F. Chao,” Determination of optical parameters of a twisted-nematic liquid crystal by phase-sensitive optical heterodyne interferometric ellipsometry”, Appl. Opt. 44, 7509-7514(2005)
2. F. Bruyneel, H. De Smet, J. Vanfleteren and A. V. Claster, “Method for measuring the cell gap in liquid-crystal displays”, Opt. Eng. 40, 259-267, 2001.
3. S. T. Wu and G. Xu, “Cell gap and twist angle determinations of a reflective liquid crystal display”, IEEE Trans. Electron Dev. 47, 2290-2293, 2000.
4. A. Lien and H. Takano, “Cell gap measurement of filled twisted nematic liquid crystal displays by a phase compensation method”, J. Appl. Phys. 69, 1304-1309.
5. Y. Zhou, Z. He, and S. Sato, “A novel method for determining the cell thickness and twist angle of a twisted nematic cell by Stokes parameters measurement”, Jpn. J. Appl. Phys 36, 2760-2764, 1997.
6. C. H. Lin, C. Chou, and K. S. Chang,“Real time interferometric ellipsometry with optical heterodyne and phase lock-in techniques”, Appl. Opt. 29, 5159-5162, 1990.
7. A. Yariv, Optical Electronics in Modern Communications, 5th ed., University Press, Oxford(1997)
8. Operating Manuel & Programming Reference of SRS830.
9. D. Goldstein, Polarized Light, 2nd ed., CRC(2003)
10. A. Yariv and P. Yeh, Optical Waves in Crystals, Wiley, New York, 1984.
11. P. G de Gennes and J. Prost, The Physics of Liquid Crystals, 2nd ed., Clarendon Press, Oxford(1993).
12. Chandrasekhar, S., Liquid Crystals, Cambridge University Press, New York(1997).
13. C. W Oseen, Trans, Faraday Soc., 29, 83(1993).
14. H. Zocher, Trans, Faraday Soc., 29, 19(1993).
15. F. C. Frank, Discuss, Faraday Soc., 25, 19(1958).
16. P. Yeh and C. Gu. Optics of Liquid Crystal Display, John Wiley & Sons, Inc, New York, pp.129-130.
17. I. Scierski, and F. Ratajczyk, Optik 68, 121-125(1984).
18. K. Pietraszkiewicz, W. A. Wozniak, and P. Kurzynowski, J. Opt. Soc. Am. A 12, 420-424(1995).
19. C. Chou, Y. C. Huang, and M. Chang, “Effect of elliptical birefringence on the measurement of the phase retardation of a quartz wave plate by an optical heterodyne polarimeter” J. Opt. Soc. Am. A 14, 1367-1372(1997).