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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。
    ;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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