本文提出一套以Twyman-Green干涉儀為架構的偏極相移干涉儀，用以量測薄膜的光學導納值，並且由公式推導可直接求得單層膜的折射率(Refractive Index)與厚度(Thickness)，而在多層膜的情況下，則需要利用數值方法擬合（fitting）出各層薄膜的折射率以及厚度。 量測系統採用的低同調的光源為涵蓋可見光範圍多波長的白光鹵素燈，外加上窄帶濾光片構成高斯光譜密度的光源，而消色差相移法的使用，使本實驗的架構可以對不同波長進行量測。 本研究使用具四個偏極態的偏極陣列在CCD鏡頭前，在偏極相移干涉儀中可同時取出四步相移的值，帶入電腦運算即時求解得到相位，速度快且減少環境擾動造成的誤差。最後將量測得到的折射率與厚度結果與SOPRA橢偏儀進行比較，量測結果相當精確。In this thesis, we proposed a polarize phase shifting interferometer based on Twyman-Green interferometer structure which is used to measure the thin film optical admittance, and the refractive index and thickness of single layer thin film can be derived directly; moreover, the refractive index and thickness of multilayer thin film can be solved by numerical fitting method. In our arrangement, the low coherence light source is composed of a halogen lamp, which is a polychromatic light source and covering the visible spectral range, and a choosable narrow band pass filter, which is used to create a Gaussian power spectral density source, and achromatic phase shifter are need to this multi-wavelength measurement. As a polarization interferometer, a novel pixelated mask with a micro-polarizer phase shifting array are placed just prior to the CCD, so that we can use single interferogram to extract phase information and that’s effective in reducing environmental vibration. The measurement results were compared with the results obtained by ellipsometer. The results meet reasonable values in both refractive index and thickness.