目前用於投影技術的光閥(Light Valve)元件主要可分為穿透式與反射式元件，穿透式液晶顯示面板(LCD)是目前最主要的穿透式光閥元件，相較於反射式光閥元件(LCOS、DMD、GLV)其光利用率太差，通常不到10%。相反地，從光路系統設計上來考量，穿透式光閥較反射式光閥更好設計，也就是光路設計上更為簡單。但穿透式液晶投影顯示器因為投影亮度的關係，現在多為三片式液晶投影顯示器，除了增加光路系統的複雜性外，也因此無法做出輕巧的光學系統。
所以本論文提出一種穿透式的光閥元件－液體透鏡光閥，預期擁有高穿透率與高對比度。由於是穿透式的光閥元件，光路設計較為直觀，所以更容易將整體光路系統做得更為輕巧與簡單。而本研究主要使用可調變焦距之液體透鏡來做為一個光路開關的元件，當光線經過透鏡能改變其透射光之強度分佈，再藉由遮光元件（針孔遮光與圓環遮光）來形成光路的亮態與暗態，產生對比。目前實驗結果顯示液體透鏡光閥的穿透率可達70%，對比度最大為40:1。也顯示出其液體透鏡光閥的高穿透率是值得被注意的，在光學系統上的發展更多元化。

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