臺灣博碩士論文加值系統

許多光電元件中應用的光學薄膜會在製程或使用時因溫度與濕度的環境，產生應力使光學薄膜收縮或擴張，如有薄膜受到一定的組裝限制則會形成邊界條件而產生殘留應力，例如液晶顯示器發生漏光的現象於本研究中即推測與光學薄膜的殘留應力相關，若想要由殘留應力進行光學設計欲改善光學成像品質，則需要研究應力大小與光學薄膜的光延遲特性之關係。而穿透式光彈法是能夠得到透明光學元件內部二維應力分佈狀態的實驗方法，用於材料在全域的應力分佈檢測。光彈法用於材料受到應力作用或含有殘留應力的量測，主要是利用雙折射性材料具有的光學雙折射特性進行應力分析，雙折射性材料受外力作用後，光以不同速度通過材料造成相位差而形成干涉。藉由分析光波干涉所形成之光彈條紋即可得知應力分佈情形，再透過應力─光學定律即可反算獲得光彈材料條紋常數，也才能進一步探討光學薄膜的殘留應力對光通量的影響。
本研究旨在探討量測光學薄膜之材料條紋常數，對光學薄膜施加負載使其產生光彈條紋，但對應力─光學定律不敏感材料其光彈材料條紋常數欲量測獲得相當不容易，如本論文採用之應用於液晶顯示器之擴散片與偏光片皆為對應力─光學定律不敏感之材料；另一方面，光彈條紋影像可視為灰階分佈的條紋，若加上外界環境雜訊的干擾都也會影響實驗結果，故本研究所得到的影像會不易辨識。本研究使用不易產生光彈條紋的光學薄膜利用圓孔造成應力集中增加負載，並開發影像處理程式除了將實驗影像的雜訊濾波，使得影像可清楚的辨別光彈條紋外，光彈影像的亮暗場也進行影像相減取絕對值使條紋增加，並作細線化處理藉以明確得到條紋位置，再配合理論計算與有限元素數值分析，即可得到一致的應力分佈型態，並可反算獲得光學薄膜之材料條紋常數。由已知的光彈敏感材料進行本研究的方法反算其材料條紋常數具一定的準確性，故推測未知材料條紋常數的光學薄膜也具備可信的反算結果。

Residual stress of optical film might be caused by shrinkage and deformation, because of under the environments of variable temperature and humidity. It would result in light leakage in liquid crystal display. If relationship would like to be between stress and light leakage, the photoelastic method is used to inversely calculate the stress-optic coefficient. The photoelastic method is an experimental technique which it obtained the state of stress on full-field distribution. The birefringence is used to analyze the stress of the birefringent material. When birefringent material was subjected to external force, the phase difference of light causes the interference. According to the material fringe value by the stress-optic law, the interference fringe could be corresponding to the difference of principal stresses. In this study, the photoelastic method is applied to determine the stress distribution of the optical film material.
In order to study the residual stress of optical film, material fringe value of the component is also needed. However, the purpose of this study is to investigate the insensitive material fringe value of the optical films, including the polarizer and diffuser used in the liquid crystal display. Some image processing methods were applied to enhance the quality of photoelastic experimentally results. The Fourier transform was used to filter noise from environment. To increasing and sharpening fringe patterns, the absolute value of subtraction from images of the dark field and bright field was processing. After thinning patterns clarified the fringe position, the experimental identical positions on the stress distribution can be compared with theoretical analysis and finite element calculation. The material fringe values of optical films can be inversely calculated by subjected load on disk, ring, and plane with hole.

中文摘要
Abstract
誌謝
目錄
圖目錄
表目錄
第一章 緒論
1.1研究目的與背景
1.2研究動機
1.3文獻回顧
1.4內容簡介
第二章 光學薄膜簡介
2.1液晶顯示器簡介
2.2擴散片簡介
2.3偏光片簡介
第三章 相關理論與研究方法
3.1光彈理論
3.1.1光的波動理論
3.1.2雙折射性材料(Birefringent Material)
3.1.3光學元件介紹
3.1.4應力─光學定律(Stress-Optic Law)
3.1.5平面偏光系統(Plane Polariscope)
3.1.6圓偏光系統(Circular Polariscope)
3.2厚度h的圓盤受徑向壓力之理論解
3.3圓環受徑向壓力之理論解
3.4受單軸向拉伸負荷含圓孔無限平板之理論解
3.5有限元素法
3.6影像處理
3.6.1 傅立葉轉換濾波
3.6.2光彈條紋倍增
3.6.3條紋細線化
第四章 實驗設備
4.1實驗設備
4.2實驗試片
4.3實驗步驟
第五章 光彈圓盤與圓環之實驗分析與討論
5.1圓盤受徑向壓力之材料條紋常數計算
5.2圓環受徑向壓力之材料條紋常數計算
5.3施力靈敏度與應力集中範圍影響之討論
第六章 光學薄膜之實驗分析與討論
6.1受單軸向拉伸負荷含圓孔無限平板之材料條紋常數計算
6.2擴散片進行材料條紋常數計算
6.3偏光片進行材料條紋常數計算
第七章 結論與未來工作
7.1結論
7.2未來工作
參考文獻

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