偏光片-樣品-析光片之影像式橢圓偏光術

Abstract

本論文將介紹一簡式影像式橢圓偏光術，此技術僅由偏光片、樣品及析光片所組成。 此法只需要量測三個析光相位角之亮度就可以量測樣品的橢圓參數以及偏光片方位角偏差，進而推算其折射率分佈。因為只需要量測三個亮度，不管是在量測速度還是資料處理上都可節省時間且具有一定的精準度，故而可作二維量測。由於在優化過程中須旋轉偏光片並造成光束偏差，我們選擇一楔型玻璃上非對稱油跡的重心作匹配及修正光束偏差。在文中將證明 a 為樣品表面法線的方向，故偏光片方位角偏差不但可以判斷所量得橢圓參數的準確性及樣品表面的平整性，並可以用來量測樣品表面法線變化的方向。 本文將此簡式影像式橢圓偏光術應用在非均勻平面 (GRIN lens) 材料光學參數之量測，及平凸透鏡之量測；我們不但量出了漸變式光纖折射率的徑向分佈並証明其表面的平整度，另外也量出平凸透鏡的曲率半徑及折射率。此法可將橢圓偏光術延伸到曲面薄膜量測。

This work presents a simple three-intensity measurement technique to determine the ellipsometric parameters and the azimuth deviation of the polarizer in a polarizer-sample-analyzer (PSA) imaging ellipsometer. Since we have to improve the ellipsometric measurements by using polarizer’s azimuth at 45o and –45o, the parasitic error of the beam deviation in rotating element ellipsometry is solved by a nonuniform dirt spot on the wedge glass. We will prove that the azimuth deviation of the polarizer can be used to measure the normal direction of surface, so we can use it to measure the surface topography. In addition to measure the refractive index profile of a GRIN lens, we also measure the refractive profile and radius curvature of a Plano-convex lens by means of this imaging ellipsometric technique.