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研究生：	陳園迪 Chen, Yuan-Di
論文名稱：	偶氮染料摻雜液晶中橢圓偏振激發光引致偶氮染料吸附效應之研究 Studies of azo dye adsorption effect induced by elliptically polarized light in azo dye-doped liquid crystals
指導教授：	傅永貴 Fuh, Ying-Guey Andy
學位類別：	碩士 Master
系所名稱：	理學院 - 光電科學與工程研究所 Institute of Electro-Optical Science and Engineering
論文出版年：	2009
畢業學年度：	97
語文別：	中文
論文頁數：	138
中文關鍵詞：	橢圓偏振光、偶氮染料
外文關鍵詞：	adsorption, MR
相關次數：	點閱：72 下載：2
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本論文探討有關利用不同橢圓率偏振光激發摻雜於向列相液晶中的偶氮染料-甲基紅(methyl red，簡稱MR)之吸附效應。首先利用橢圓偏振之長軸平行液晶導軸的綠光雷射進行實驗，實驗結果發現由於MR吸收光能量的對稱性會導致多區域(multi-domain)吸附結果，為克服多區域吸附之現象，我們將橢圓偏振光之長軸更改為與液晶導軸夾+45o的橢圓偏振光，並分別利用固定橢圓偏振光之總光強度或固定其長軸方向光強度的方式來討論，結果發現利用不同橢圓率之橢圓偏振光所得之MR吸附所產生的液晶分子轉向效應，即扭轉角(twisted angle)，會隨著橢圓率越接近1(圓偏振)而越小，而傾角(tilted angle)則幾乎都為零，兩部分的實驗都有同樣的結果。再利用不同光強度的圓偏振綠光雷射激發MR，觀察並探討MR吸附的結果，實驗結果顯示在圓偏振光各方向能量均等的情況之下，不會有扭轉角跟傾角產生，且在吸附面上有不均勻的成核(nucleation)現象發生。接著探討左右旋橢圓偏振光對MR吸附結果的影響，選取兩組橢圓率的左右旋橢圓偏振光，結果發現MR吸附的結果與左右旋橢圓偏振光無關，僅與橢圓長短軸方向有關。最後利用SEM觀察MR吸附的結果，實驗結果顯示該MR吸附並無波紋(ripple)結構的產生。

This thesis studies the alignment properties of liquid crystals by the adsorbed azo dyes (methyl red; MR) excited by elliptically polarized green laser beams with various ellipticities in azo dye-doped liquid crystals (ADDLCs). Firstly, an elliptically polarized green laser beam with its major axis being parallel to the liquid crystal director was used as the pump beam. Experimental results showed that MR molecules were adsorbed along multiple directions due to the symmetry light-absorbance by MR molecules. In other words, multi-domain adsorption was generated. Secondly, by overcoming the shortage of multi-domain adsorption, the major axis of the pump beam was changed to make an angle of +45o with the liquid crystal director. In this part, the alignment properties of the adsorbed MRs generated by illuminating elliptically polarized green laser beams with various ellipticities having a fixed light intensity or a fixed light component along the direction of major axis were studied. The experimental results indicated that the light-induced MR molecular reorientation effect, the so-called twisted angle, caused by the adsorbed MR, decreased with increasing ellipticity of the elliptically polarized green light. Notably, zero pre-tilt angle of LC alignment was achieved in this experiment. Thirdly, the MR adsorption effect recorded by circularly polarized green laser beams with various intensities was studied. Experimentally, neither the twisted angle nor the tilt angle was produced using circularly polarized green light. Additionally, the nucleation phenomenon, which caused a nonuniform adsorption layer was observed. Finally, the direction of the MR adsorption was found to be independent of the sign of the light ellipticity, but dependent on the direction of the major or minor axis of the elliptically polarized green pump beam. Moreover, the ripple structures of the adsorbed dyes, which were observed using a linearly polarized green pump beam were not observed in the cases pumped by elliptically or circularly polarized beam.

摘要......................................................................Ⅰ
Abstract..................................................................Ⅱ
致謝......................................................................Ⅲ
目錄......................................................................Ⅳ
表目錄...................................................................Ⅸ
圖目錄...................................................................Ⅹ
第一章 簡介.............................................................1
1前言....................................................................1
2液晶簡介...............................................................3
2.1何謂液晶...........................................................3
2.2液晶的分類........................................................5
3 液晶物理.............................................................12
3.1液晶的折射率異向性.............................................12
3.2連續彈性體理論..................................................16
3.3電場對絕緣的向列型液晶的影響.................................17
3.4溫度對向列相液晶的影響........................................19
第二章 理論介紹................................................... 20
1光引致分子轉向效應................................................. 20
1.1正力矩效應：Jánossy Mode.....................................20
1.2 負力矩效應：Gibbons Model...................................22
1.3 光激發之同素異構化反應(Photoisomerization) ................23
1.4 吸附引致液晶轉向之效應 (Adsorption Effect) ................25
1.5 光致熱效應 (Light-Induced Thermal Effect) ...................28
2溝槽理論.............................................................29
3雷射引致細微波紋 (Ripple Structure) ...............................29
第三章 實驗準備與過程.........................................32
1 樣品製作.............................................................32
1.1材料介紹.........................................................32
1.2樣品製程.........................................................35
2 光學顯微鏡目測法檢測配向.........................................39
3 樣品微觀圖像觀察及結構分析儀器..............................39
3.1 偏光顯微鏡 (Polarizing Optical Microscope，簡稱POM) ........40
3.2 扭轉角（twisted angle）量測實驗架設........................41
3.3 傾角（tilted angle）量測實驗架設...............................42
3.3.1 電壓穿透曲線(transmittance vs. voltage curve，T-V curve)量測.............................................................42
3.3.2模擬軟體(1D-Dimos) ........................................44
3.4 液晶盒厚度(cell gap)量測........................................46
3.5 橢圓率量測................................................47
3.6 掃瞄式電子顯微鏡(Scanning Electron Microscope, 簡稱SEM) ..........................................................49
3.7 原子力顯微鏡(Atomic Force Microscope, 簡稱AFM) .........50
4 實驗裝置.............................................................52
4.1橢圓偏振光長短軸方向在0o跟90o................................53
4.2 橢圓偏振光長短軸方向在正負45o...............................54
5 實驗圖型編排........................................................55
第四章 結果與討論................................................57
1 各種不同橢圓率光的選取............................................57
1.1橢圓長短軸位於0o與90o..........................................58
1.2橢圓長短軸位於+45o及-45o.......................................59
2 各種不同橢圓率偏振光激發偶氮染料 (橢圓長短軸分別於0o及90o) ..........................................................61
2.1 偏光顯微鏡觀測結果............................................62
2.2 分析結果與討論..................................................68
3 各種不同橢圓率偏振光激發偶氮染料 (橢圓長短軸位於+45o及-45o) ................................................................69
3.1 固定激發光總光強...............................................69
3.1.1 動態圖形量測...............................................70
3.1.2 偏光顯微鏡(POM)觀測......................................74
3.1.3 扭轉角量測..................................................82
3.1.4 傾角量測....................................................83
3.1.5 分析結果與討論.............................................89
3.2 固定長軸方向光強度............................................90
3.2.1 動態圖形量測...............................................91
3.2.2偏光顯微鏡(POM)觀測......................................94
3.2.3 扭轉角量測.................................................102
3.2.4 傾角量測...................................................103
3.2.5 分析結果與討論...........................................110
4 不同強度的圓偏振光...............................................112
4.1偏光顯微鏡(POM)觀測.........................................112
4.2 扭轉角量測.....................................................116
4.3 傾角量測.......................................................117
4.4 分析結果與討論................................................121
5 左旋橢圓偏振光....................................................122
5.1動態圖形量測...................................................123
5.2 偏光顯微鏡(POM)觀測.........................................124
5.3 扭轉角量測.....................................................126
5.4 傾角量測........................................................127
5.5 分析結果與討論................................................128
6掃描式電子顯微鏡(SEM)觀測染料吸附表面結構...................129
6.1 ITO面吸附結果.................................................129
6.2 PVA面吸附結果.................................................130
6.3分析結果與討論.................................................130
第五章 結論與未來展望........................................132
1結論..................................................................132
2未來展望.............................................................133
2.1各種不同橢圓率偏振綠光及線或橢圓偏振紅光之雙光子效應研究...............................................................133
2.2弱強度長時間之圓偏振綠光激發MR染料分子吸附結構之研究...............................................................134

參考文獻.............................................................136
                                    

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校內：2012-07-28公開
校外：2013-07-28公開

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