單軸各向異性晶體之橢圓偏光參數量測

Abstract

在此我們利用橢圓偏光儀研究了各向同性和各向異性的介質。兩種介質的薄片均有多重反射的現象。我們雖利用折射率匹配的方法依然無法完全消除多重反射現象，以至於較難分析，故本文就僅俱單次反射的塊材為主要研究對象。 由實驗中我們發現，只會呈現單次反射的塊狀結構，其實驗結果較準確。因此，我們針對塊狀單軸晶體（石英）做了一系列的量測，量得光軸及折射率的分佈。我們提出一種線上校正入射角的方法，此法可修正橢圓偏光儀中，轉動偏光片對入射角造成的影響。

Both thin and thick plates made of isotropic and anisotropic medium were studied. Although the multiple reflection phenomena in thin plate can be reduced by index matching technique, but the intensity fluctuation is still too large. A bulk quartz crystal was used as the sample for this PSA ellipsometer. Only one of the ellipsometric paramter φ were measured in this experiment. The difference between the ordinary and extraordinary refractive index of quartz crystal obtained from this measurement is well matched with the expected value, but there are some discrepancies between its intrinsic value. After examining the incident angle effect, we found that the rotating polarizer can cause significant error on incident angle. Using a numerical fitting technique, we calibrated the effective incident angle and produced a well fitted result. This provides us an on-line alignment technique for incident angle.