設計與製作相位式繞射光柵以消除液晶投影系統的顆粒狀結構影像

Abstract

以液晶顯示板（Liquid Crystal Display Panel）為顯像元件的液晶投影系統（Liquid Crystal projection System）中，由於液晶顯示板上的薄膜電晶體與電子導線結構所形成的週期性書素結構，經投影系統投影後，在投影螢幕上的影像會產生由顆粒狀畫素所組成的影像。這種獨特的顆粒狀結構組成的投影影像，造成了人們在觀賞液晶投影系統的不適應與不舒服的感覺。 為解決此一問題，本論文提出一新方式一以相位式繞射光柵元件複製周期性的畫素結構，並將複製的畫素影像橫向偏轉3/2個畫素大小後與原影像疊合以消除液晶顯示板的不透光區所造成的陰影，減低視覺上不舒服的顆粒狀結構影像。論文中詳細探討了相位式繞射光柵的設計步驟、製程製作、作品量測及實際應用在液晶投影系統中對消除影像顆粒結構的效果評估。由本論文的實驗量測可得知以相位式繞射光柵元件插入投影系統中可達到消除投影影像顆粒狀結構的目的，且不必造成現有光學系統其他元件的改變。

Liquid Crystal panels are the key components for high performance projection systems and head mounted displays (HMDs) for various multimedia applications. However, the discrete"grain-like" pixel structure on the screen by an LCD projection system reduce picture quality of the imagery .the dead spaces. due to the projection of the black matrix, which is used to block the un-modulated light to transmit through LC pixels, create an uncomfortable appearance of pixel structure. In this thesis, we propose a new optical device, phase grationgs. The diffractive gratings can transform light emitting from each pixel of an LC panel into mainly 0-th and 1-st diffraction order light beams of equal energy .By deflecting the 1-st order beams to 3/2 amount of sub-color pixels to fill the dead space between each pixel, thus doubling the number of pixels within the image, the image quality of the LCD projection can be improved. The design rules of phase gratings, devices fabrication, measurements of the gratings and analyses of the results are described in this thesis, LCD projection is improved by the diffractive gratings without the change of the current system design.