本研究利用偏光旋轉調變器研發三種新的強度比率法架構來量測扭轉向列型液晶的液晶盒厚度，其中前兩種架構為液晶盒厚度的單點光學量測系統，第三種架構為液晶盒厚度的全場光學量測系統。偏光旋轉調變器是由兩片四分之波片以及電光調變器組成，而電光調變器是利用由訊號產生器提供的鋸齒波訊號作為驅動訊號。
偏光旋轉調變器可替代旋轉的偏振片，用來調變偏振光的旋轉角度，因此我們可以達到更精確的量測結果以及縮短量測時間。在我們的全場光學量測系統中，利用電荷耦合元件(CCD)可以擷取到扭轉向列型液晶盒厚度的全場影像。與原來的強度比率法比較，這三種方法的可以提供更快的偏光旋轉調變速度，更可靠的量測架構以及全場的光學檢測。

This study presents three modified total intensity ratio methods (TIRM) using the polarization rotation modulator for measuring the cell gap of Twisted Nematic Liquid Crystal (TNLC) cell. The first two modified methods are single point measuring systems and the third modified method is the full-field measuring system. The polarization rotation modulator is composed of two quarter waveplates and an electro-optic modulator driven by a saw-tooth waveform signal supplied by a function generator.
We use the polarization rotation modulator to replacing the conventional rotating polarizer. As a result, the accuracy and measuring time could be much improved in modified TIRMs. In our full-field measuring system, the CCD is used as photodetector, and we can measure the full-field image of the cell gap of of Twisted Nematic Liquid Crystal cell.
As compared to the conventional TIRM, the modified TIRMs has a faster polarization rotating velocity, more stable setup and full-field measuring ability.

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