繞射區域調光LCoS投影系統應用於擴增實境之研究

Abstract

本實驗提出一個結合繞射與區域調光的投影系統，使本實驗室目前所發展的擴增實境膜片更有效的利用入射光。膜片表面上的結構依特定比例分配散射區及透射區，以兼具透明度及成像品質。而本論文的主要概念為將投射影像限制在膜片散射區，而不通過透射區，來減少能量損耗。我們的做法是設計一繞射元件，成像在LCoS的面板上，作為投影機的光源。其繞射圖形尺寸同LCoS的面板，並由周期性排列的光點組成，每一光點的位置配合面板上的特定像素，使LCoS調變結果為像素化影像。而調變過的影像放大後投射在膜片上時，影像上的每一像素都將投射在對應到的散射區上，此時便可以減少因通過透射區而損耗的光能。 本實驗考慮LCoS面板上的像素分布及物理限制，藉由SIFTA計算出合適的相位型繞射元件，並以熔融石英製成樣品測試。實驗結果可以成功建立一LCoS投影系統，且繞射圖形的分布及光點大小符合計算上的理論值，唯現階段可用的雷射頻寬過大，而導致圖形產生色散現象。

This thesis presents a projective system combined with diffraction and local dimming technique to make the diffusion film we have invented to make an augmented reality system which have less light consumption. We designed a diffractive optical element (DOE) whose diffraction pattern can project the pixelated image to the liquid crystal on Silicon (LCoS) and some of the modulating pixels of it would contribute to imaging on diffusion structure. According to the distribution of modulating pixels and the physical limitations, we use Symmetrical Iterative Fourier Transform Algorithm (SIFTA) to calculate a suitable DOE and make the sample with fused quartz. The experimental result shows that we can construct a successful LCoS projective system and the distribution and the size of diffraction pattern could match our calculation. However, the bandwidth of laser we used was so wide that there was a dispersion in the diffraction pattern.