在一般的液晶顯示器裡，液晶盒的厚度對顯示器的亮度、對比度及反應時間有極大的影響，尤其反射式液晶盒的厚度在設計上通常比穿透式的更小，些許的誤差就會導致光學特性的偏差，而在液晶盒製程裡，實際上的液晶盒厚度往往不會和我們所設計的一樣，為了能夠讓顯示器的光學設計更完美，所以我們必需正確的量測液晶盒厚度。

　　本論文便是在研究一般常用液晶盒厚度的量測，分別對穿透式扭轉型向列相液晶盒、反射式扭轉型及非扭轉型液晶盒等作精確的量測，另外對於現在最新的半反半透式顯示器，設計多為水平配向，我們也量測液晶厚度較小的反射式部份；而我們介紹的量測方法裡，都是在液晶盒前後各放一片偏振片，以旋轉偏振片方法得到的穿透率或反射率，和理論做比對來得到正確的厚度。

　　In a LCD (liquid crystal display), the cell gap plays an important role in determining its performances, such as brightness, contrast ratio, and response time. In particular, a reflective LCD cell gap is usually smaller than a transmissive LCD one, so a little deviation of the cell gap from the desired one leads to poor performances. During the device fabrication, the LC cell gap may deviate from its designed value. For optimizing the performances of LCDs in the manufacturing process, simple, precise, and fast methods to measure the cell gap is required.

　　This thesis researches the measurement methods of cell gaps of LCDs employed commonly. We establish simple and precise cell-gap measurements of a transmissive twisted nematic LC cell and reflective twisted nematic and non-twisted LC cells. The experimental method we use is to place the LC cell between two polarizers and then rotating the polarizers to get transmittance and reflectance. Accurate cell gap can be obtained by fitting the experiment value with the calculation using Jones Matrix.

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