相移影像式橢圓儀之建立; Phase Shifting Imaging Ellipsometer

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/48146

Title:	相移影像式橢圓儀之建立;Phase Shifting Imaging Ellipsometer
Authors:	洪青宏;Ching-hung Hung
Contributors:	光電科學研究所
Keywords:	液晶可調相位延遲器;橢圓偏極參數;影像式橢圓儀;imaging ellipsometer;liquid crystal variable retarder;ellipsometric parameter
Date:	2011-07-23
Issue Date:	2012-01-05 14:35:24 (UTC+8)
Abstract:	本論文提出並建立一個二維量測樣本橢圓偏極參數的相移影像式橢圓儀，在相移影像式橢圓儀的光學架設中，我們使用了液晶可調相位延遲器可以達到快速相位延遲調控。由於液晶可調相位延遲器的相位延遲取決於輸入電壓的調制訊號，所以校正液晶可調相位延遲器相位延遲在相移技術中是很重要的步驟，我們亦提出一個校準的程序，以準確地確定特定相位延遲所對應的輸入電壓值，因此橢圓偏極參數的空間分佈即可經由相移的轉換，並由CCD 照像機擷取光強度分佈影像推算出。相移影像式橢圓儀量測系統能夠量測均向性與非均向性材料的物理特性，為我們發展之系統的一大特色，本論文提出以下兩個實驗：(1)量測矽基材上之二氧化矽薄膜分佈 (2)量測扭轉向列型液晶盒的扭轉角和單元間隙，分別做為均向性和非均向性材料的實驗驗證。最後實驗結果皆接近參考值，可以證實我們理論的正確性和實驗的量測精確度。 In this thesis, a phase shifting imaging ellipsometer (PSIE) is developed and set up for two-dimensionally measuring ellipsometric parameters of a tested specimen. In the optical setup of the PSIE, a liquid crystal variable retarder (LCVR) is employed to change the phase retardation at high speed. The phase retardation adjustment of an LCVR, plays an important role in phase-shifting technique, where the phase retardation is dependent upon the applied voltage of modulation signal. We also propose a calibration process to accurately determine the applied voltages relative to the specific retardations. Therefore, the spatial distributions of the ellipsometric parameters can be calculated through the intensity images of phase shifting transformation, acquired by a CCD camera. PSIE has ability to to measure the physical properties of both isotropic and anisotropic materials. This is one of the features of our developed system. We give the experimental verifications for characterizing them, which are done by (1) measuring the thickness distribution of a SiO2 thin film on the Si substrate and (2) measuring the twisted angle and cell thickness of a twisted nematic liquid crystal cell, as the experimental demonstration for an isotropic and an anisotropic materials. The experimental results are all close to the given values, shown that the correctness of our theory and measurement accuracy.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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