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系統識別號 U0026-2808201319412300
論文名稱(中文) 以光聚合穩定法改善液晶透鏡之光電性能並實現偏振無關特性
論文名稱(英文) Using photo-polymerization to improve electro-optical performance and realize polarization-independence in liquid crystal lenses
校院名稱 成功大學
系所名稱(中) 光電科學與工程學系
系所名稱(英) Department of Photonics
學年度 101
學期 2
出版年 102
研究生(中文) 許哲儒
研究生(英文) Che-Ju Hsu
學號 L78981092
學位類別 博士
語文別 英文
論文頁數 76頁
口試委員 召集委員-傅永貴
召集委員-郭宗枋
指導教授-許家榮
口試委員-黃啟炎
口試委員-黃素真
中文關鍵字 液晶透鏡  鋸齒線  不連續線  光聚合  聚合網絡  共軸雙焦  偏振無關 
英文關鍵字 LC lenses  disclination line  zigzag line  polymer stabilization  photo-polymerization  coaxially bifocal  polarization independent 
學科別分類
中文摘要 圓孔型液晶透鏡擁有製作簡單及大的可調焦距性能,然而,由於非均勻對稱性電場的存在,對於水平排列的液晶容易產生轉向不一致的問題而導致不連續線產生。不連續線會對液晶透鏡產生反應時間提高與降低透鏡品質。由實驗發現,在操作電壓下,液晶透鏡樣品邊緣會有鋸齒線形成,此鋸齒線隨著時間會逐漸遷移至透鏡有效區域並與不連續線連結,而永久無法消除不連續線,經由實驗,我們找到了正確的方式組裝液晶透鏡樣品以避免鋸齒線和不連續線連結。然而,為了更方便有效的操作圓孔型液晶透鏡,我們使用聚合物穩定液晶分子排列的方式來有效的消除不連續線,即使任意的操作電壓下,都沒有不連續線形成,此外,我們也比較有光聚合穩定和沒有光聚合穩定的液晶透鏡樣品之光學特性差異,由於聚合物添加濃度低,所以並不影響原始透鏡的性能,包含可調焦距的能力及操作電壓大小。
在使用聚合穩定之方式去避免不連續線的產生後,我們更進一步為了產生聚合網絡去固定液晶分子的轉向而提升聚合物單體的濃度,此方法稱之為光聚合,藉由光聚合的方式,我們建立了一個擁有共軸雙焦距的液晶透鏡,隨著外加電壓的增加,此雙焦距特性仍非常明顯,直到一個較高的電壓時,雙焦距特性逐漸消失進而變成單一焦距,同時,我們也經由不同的曝光時間建立兩種共軸雙焦之液晶透鏡,並且量測其光學特性。
此外,為了增加光的使用率,我們使用簡單的滴流配向使液晶以軸對稱放射狀方式排列,然後組裝成圓孔型液晶透鏡,於電壓操作下,液晶以軸對稱的方式重排,因此透鏡聚焦性能和線性偏振無關。此線性偏振無關之液晶透鏡的可調焦距範圍可以從無限遠到27.5公分,電壓範圍從0伏特至80伏特。
英文摘要 The hole-patterned LC lens possesses the advantages of simple fabrication and strong tunable-focus capability. However, because of non-uniform symmetrical electrical fields produced from a circular-hole electrode, the LC molecules in the hole-region easily orient along two opposite directions for homogeneous LC cells, leading to the formation of a disclination line. The disclination line will slow down the response time and lower the image quality. Based on our initial study on the large apertures of LC lenses, disclination lines and zigzag lines typically occur in cells. Unfortunately, zigzag lines and disclination lines will possibly link to each other and permanently stay in the cells to degrade the performance of LC lenses. Therefore, we experimentally study and conclude that suitable rubbing conditions in cells will effectively prevent the problem of linked lines. For convenient operation of the hole-patterned LC lens, we use the method of polymer stabilization to successfully prevent disclination lines in LC lenses.
After successfully using the polymer stabilization method to prevent the occurrence of disclination lines, we further increase the concentration of monomers to fabricate coaxially bifocal (CB) LC lenses, and this method is called photo-polymerization. The characteristics of a tunable CB are clearly exhibited when the voltage applied is continuously increased, eventually disappearing until only one focus is left when significantly higher voltages are applied. We simultaneously demonstrate two types of tunable CB LC lenses fabricated via different photocurable processes, and then determine their optical functions.
The study in the dissertation is based on LC lenses with a hole-patterned electrode. To effectively exploit the incident light, a dropping-flow alignment method is used to achieve radially symmetric LC distributions in the cell, through which tunable LC lenses can be made as linearly polarization independent. A 7 mm-diameter LC lens is fabricated with a circular hole-patterned electrode; its focal lengths are tunable from infinite to 27.5 cm when voltages from 0 Vrms to 80 Vrms are applied.
論文目次 Contents
中文摘要 I
Abstract III
Acknowledgement V
Contents VI
List of figures IX
Chapter 1 Introduction 1
1.1 Preface 1
1.2 Reference 9
Chapter 2 Experimental Principle 12
2.1 Nematic Liquid Crystals [1] 12
2.2 Optics of Liquid Crystals [2] 13
2.3 Electrical Properties of Liquid Crystals 15
2.4 Category of Lens 16
2.5 Occurrence of Disclination Line in Hole-Patterned LC Lenses 19
2.6 Reference 20
Chapter 3 Preventing Occurrence of Disclination Line and Migrating Zigzag Lines in LC Lenses with a Hole-Patterned Electrode 22
3.1 Introduction 22
3.2 Experimental Analysis to Avoid Migrating Zigzag Lines Occurring in LC Lenses with a Hole-Patterned Electrode 23
3.2.1 Fabrication and Characteristics of LC Lens 23
3.2.2 Experiment and Discussion 25
3.3 Preventing Disclination Line Occurred in the Hole-Patterned LC Lenses Based on Polymer Stabilization 30
3.3.1 Process of Polymer Stabilization 30
3.3.2 Measurement and Optical Performance of PSLC Lenses 33
3.4 Conclusion 44
3.5 Reference 45
Chapter 4 Using Photo-Polymerization to Achieve Tunable Liquid Crystal Lenses with Coaxial Bifocals 47
4.1 Introduction 47
4.2 Experiment 48
4.2.1 Previous LC Lens Structure 48
4.2.2 Fabrication Process of Tunable CB LC Lenses with Photo- Polymerization 49
4.2.3 Optical Characteristics of CB LC Lenses with Experimental Measurements 50
4.3 Conclusion 59
4.4 Reference 60
Chapter 5 Quasi-Linearly Polarization-Independent Tunable Liquid Crystal Lenses Fabricated by Dropping-Flow Alignments 61
5.1 Introduction 61
5.2 Experiment 62
5.2.1 Fabrication Processes of the Quasi-Linearly Polarization- Independent LC Lenses 62
5.2.2 Optical Measurement of the Fabricated LC Lenses 64
5.2.3 Characteristics of Linear Polarization-Independence 66
5.2.4 Imaging Performance of the LC Lenses 68
5.3 Conclusion 70
5.4 Reference 70
Chapter 6 Summary and Future work 71
6.1 Summary 71
6.2 Future Work 74
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Chapter 3
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Chapter 5
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