利用偏光儀量測補波片之方位角及其相位延遲

Abstract

在偏極光理論日益成熟的發展之下, 橢圓偏極儀利用偏極光與物質作用後 所造成之偏振態的變化, 以此來測量物質的一些光學特性, 一直是偏極光 理論的重要應用之一.為了建立精確的橢圓偏極儀量測系統, 先測量各種 偏光元件的精確度乃是重要的基本工作. 在本實驗中, 我們發展了一套偏 光儀量測技術:利用 PA (Polarizer-Analyzer) 系統中之析光角為 0,60,120 度所測得的三組亮度可校正偏光角 P , 再利用 PCA (Polarizer-Compensator -Analyzer) 系統中之析光角為 0,60,120 度所 測得的三組亮度可同時計算出補波片之方位角 C 及其相位延遲 Delta. 我們先以 632.8nm 氦氖雷射為光源, 發現此補波片材料具有旋光性, 並 進而掌握此補波片之真正光軸; 再用鹵素燈泡為光源, 其後以三種不同波 長的濾光片來產生 632.8nm, 543.5nm, 及 488nm 的單色光源, 來探究此 一原本為 632.8nm所設計的四分之一波長補波片在不同波長下之表現. For establishing an accurate ellipsometer system in the laboratory, it is essential to calibrate each element of the system. A simple polarimetric technique is developed in this experiment to measure the optical axis and the phase retardation of a quarter-wave plate. By three intensities measured in PA (Polarizer-Analyzer) system with Analyzer at 0, 60, and 120 degree, and another three intensities measured in PCA (Polarizer Compensator-Analyzer) system with Analyzer at 0, 60, and 120 degree, we can calculate the azimuth angle and the phase retardation of the compensator. We find the compensator's optical activity and its optical axis precisely when using the He-Ne Laser source first. Then we use a Tungsten-Halogen source which produces 632.8nm, 543.5nm, and 488nm light by three different filters to investigate the performances of this 632.8nm quarter-wave plate (compensator) under different wavelength of light.