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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/76958


    Title: 利用雙扭轉向列型液晶製作可電光調控之線性偏振光液晶光圈;Electro-opto controllable aperture for linearly polarized lights using double twisted nematic liquid crystal cells
    Authors: 李家豪;Li, Jia-Hau
    Contributors: 光電科學與工程學系
    Keywords: 液晶相關應用;液晶光圈;扭轉向列型液晶
    Date: 2018-08-06
    Issue Date: 2018-08-31 11:54:32 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本論文中利用高分子聚乙烯基咔唑(簡稱PVK)製作扭轉向列型液晶(Twisted Nematic Liquid Crystals, 簡稱TNLC)之水平配向膜,並且利用PVK之光導電特性以及TNLC之線性偏振旋轉的特性製作可電光調制之液晶光圈,並且成功利用電控(施加直流電壓)及光控(照射紫光)的方式分別調控於常亮態(NW mode)下暗光圈及常暗態(NB mode)下亮光圈的光圈孔徑大小,光圈可調最大範圍約為紫光光束直徑大小。
      本論文的研究中除利用單片90°-TNLC製作可電光調制之光圈外,亦將兩片相同45°-TNLC串聯形成之雙片串聯90°-TNLC應用於製作可電光調制之光圈,其可調控光圈孔徑之範圍大致相同。但由於雙片串聯45°-TNLC因其串聯方式可自我補償不必要的相位延遲,因此任意線性偏振方向及任意波長之線偏振光入射此雙片串聯45°-TNLC後,其出射光皆能保有良好的線偏振度(DoLP)及高度的穿透率,因此在應用上可更加廣泛且多元。
      在實驗中分別對單片90°-TNLC及雙片串聯45°-TNLC量測不同偏振方向之線偏振光入射後其出射光之線偏振度(DoLP)的關係,且使用鹵素光源分別入射此兩種TNLC液晶盒,觀察不同波長之線偏振光經過此兩種TNLC液晶盒出射後之光譜分布以及目視觀測之結果,經由上述實驗驗證雙片串聯45°-TNLC相較於單片90°-TNLC於實際應用上,其入射光並無波長範圍以及線偏振方向之限制。而在本論文中最後則使用了此液晶光圈,將其應用於液晶光圈快門,利用開關電壓而形成快門的效果,其中快門與光圈的控制在液晶光圈中即可完成。
    ;In this study, the poly(9-vinylcarbazole) (PVK) was adopted to be the planar alignment layer for a twisted nematic liquid crystal (TNLC) cell. Combing the photoconductive property of PVK and the polarization rotation property of TNLC, the fabricated TNLC cell can be applied as an electro-opto controllable LC aperture for linear polarized lights. The electrical control by an applied DC voltage and the optical control by a UV light illumination make the controllable aperture size of the ring-like aperture (normally white state) and the spot-like aperture (normally black state). The controllable range of aperture diameter is based on the spot size of UV light.
    In addition to the demonstration of LC aperture by a single layer 90˚-TNLC, this study also proposes that the combined two 45˚-TNLC cells, also known as a tandem 90˚-TNLC, can improve the performances of the electro-opto controllable LC aperture. The basic concept of the tandem 90˚-TNLC is the self-compensation of the undesirable phase retardation. Hence, the degree of linear polarization (DoLP) value of the output beam and the transmittance after passing through an analyzer can be significantly improved. In other word, a LC aperture based on such a tandem 90˚-TNLC cell is independent of wavelength and the direction of the polarization of the incident light so that the LC devices have high potential for practical applications.
    The relationships between the polarization directions of the incident linearly polarized light and the DoLP values of output beams through a single layer 90˚-TNLC and a tandem 90˚-TNLC have been examined experimentally. Moreover, the transmittance spectra in the visible range of the output beam through the analyzer for these two cases of TNLC devices have also been discussed. According to the experimental results, the tandem 90˚-TNLC is more widely applicable than the single 90˚-TNLC due to its properties of independences of wavelength and the direction of input polarization. Finally, the LC aperture can be applied to combine with the properties of light shutters according to the electrical switching. By controlling the conditions of UV illumination and the applied DC voltage, the dose of light can be controlled by such a LC shutter.
    Appears in Collections:[光電科學研究所] 博碩士論文

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