鎖相式光彈調變穆勒矩陣偏光儀

Abstract

本系統結合了偏振態分析器與偏振態產生器，進行樣品穆勒矩陣的單點量測。利用波形分析法鎖定光彈調變器調制下的特定時間相位，本系統以特殊偏振態分析量測，相較於傳統的穆勒矩陣偏光儀，不僅減少元件的旋轉次數，同時也降低旋轉元件造成的光束偏移現象，並提升系統的量測速度。透過穆勒矩陣的分析，使我們可以得到樣品詳細的偏光特性，並使得本系統得以量測各種非等向性材料，並証明本系統具有拓展至二維量測的潛力。在本文中，我們透過空氣、偏光片以及相位延遲片的穆勒矩陣的量測，以驗證本系統的量測能力。由量測過程中光強度、量測系統以及各項待測參數的線性關係，我們改變量測系統的入射以及出射偏振態以減少系統誤差並提升信噪比，進行系統的最佳化。最後，藉由分析系統中的偏光元件於空間以及時間相位的偏差量，進行量測結果的誤差估計。

A phase-lock photoelastic modulated (PEM) polarimetry is used to measure the complete Mueller matrix of a sample. In the traditional rotating polarimetry, one has to utilize at least 15 mechanical rotations to complete the measurement, while in this PEM polarimetry we only require 7 rotations to achieve the same results. This technique not only reduces the measurement time, the beam deviation caused by rotation can also be diminished. In this work, we quantitatively estimate the errors of this PEM polarimetry by analyzing its measurement matrix. We find the optimal polarization state generator (PSG) and match the optimal polarization states analyzer (PSA) in this polarimetric system. In comparing the figure of merit of PSG and PSA with that of other configurations of polarimetry in the world, we proved that this PEM Mueller matrix polarimetry is a very competitive polarimetric technique. By acquiring the whole polarization proprieties of the sample, this polarimetry provides the potential for two-dimensional distribution of the optical anisotropic media by stroboscopic illumination technique.