利用扭轉型聚合物網絡液晶製作 偏振選擇性光散射之研究;Polarization-Selective Light Scattering by Polymer Network Twisted Nematic Liquid Crystals

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71537

Title:	利用扭轉型聚合物網絡液晶製作偏振選擇性光散射之研究;Polarization-Selective Light Scattering by Polymer Network Twisted Nematic Liquid Crystals
Authors:	陳維軒;Chen,Wei-Hsuan
Contributors:	光電科學與工程學系
Keywords:	聚合物網絡液晶;光散射
Date:	2016-07-22
Issue Date:	2016-10-13 13:15:11 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文的研究主題主要是利用向列型液晶(E7)與聚合物液晶(RM257)依一定比例均勻混合成之液晶材料，並搭配經摩擦配向的ITO (indium tin oxide)玻璃基板成為90°扭轉向列液晶(90° twisted nematics)，再經過紫外光固化製程後成功製作出聚合物網絡液晶(polymer network liquid crystals)，該元件外加電壓後呈現光散射態，且具有偏振選擇性散射的特性，同時此特性可藉由關閉外加電壓使其回到扭轉向列型液晶結構之透射態。經由本論文實驗結果得知，由於液晶盒本身因90°扭轉配向而產生的結構型態以及選用之向列型液晶與聚合物液晶折射率的巧妙搭配，故產生偏振選擇性散射的特性，因此在外加電壓於此液晶元件使其處於散射態時，特定方向之線偏振光入射該元件後將發生強烈散射而無法穿透液晶盒；反之，另一正交方向之線偏振入射光卻幾乎毫無阻礙地穿透液晶盒，本研究成功開發出將偏振度(degree of polarization)為0之無偏振入射光經過此液晶元件後轉變為偏振度為0.97之線偏振光的能力，且此能力會在關閉外加電壓後完全消失，亦即該類似於偏振片的液晶元件為一可電控切換之液晶元件。此外，利用上述特性可將其應用於電控光學元件與顯示器技術等，如電控散射型液晶偏振片及半反半穿式液晶顯示器等，且從實驗結果得知，使用不同偏振態之紫外光進行固化聚合物液晶之製程亦會對此種液晶元件的數據表現有所影響，讓此種液晶元件的變化性與延伸應用更加提升。 ;In this study, we have successfully demonstrated a polarization selective scattering liquid crystal (LC) device based on polymer network twisted nematic LCs. Briefly, the combination of the adopted LC cell, generated by two indium-tin-oxide-coated glass substrates having orthogonally homogeneous alignment layers, and the homogeneously mixed materials of LC polymer (RM257) and nematic LC (E7), is the key point to achieve the LC devices. Such a LC device shows polarization-selective light scattering state when an external voltage is applied, and can be switched back to normally white mode twisted nematic LCs when the applied voltage is switched off. The obtained results indicate that this LC device possesses the polarization-selective light scattering ability because of the refractive index collocation between nematic LC and LC polymer, as well as the 90o twisted alignment of LC cell. When this LC device is set as a scattering mode, the incident light with the particular direction of linearly polarization will not be able to pass through the LC cell due to strong scattering; on the contrary, the orthogonal direction of the incident linearly polarized light can easily penetrate through the LC device. Moreover, the achieved LC device can be used as an electrically controllable LC linear polarizer, which can filter an unpolarized light into a linearly polarized light when a suitable voltage is applied, and can be turned off when the applied voltage is switched off. The degree of polarization of the output linearly polarized light is 0.97. Besides, such a reported characteristic of polarization-selective scattering can be applied to generate electrically controllable optical devices and display modes, such as electrically controllable LC polarizers and transflective LCDs. According to the obtained results, we also realize that the various polarization states of the illuminated UV light to polymerize LC polymers cause different performances for the LC devices.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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