影像系統中光斑現象與其抑制之研究

Abstract

同調光源在影像系統中的應用逐漸受到重視，例如：雷射投影顯示系統，且因為許多元件的表面對於光波長而言是相當的粗糙，因此會在影像上產生許多不規則的暗點及亮點而降低影像的品質，而這種不規則的暗亮點分布就是所謂的光斑。 我們建立一個模擬模型來分析在成像系統中不規則結構所造成的光斑。我們分析的方法除了從理論上的數學推導外，也利用模擬的方式來分析更複雜的情況。本論文分成兩大部分，第一部分是研究光斑的基本特性以及形成的條件，而利用此我們可以進一步討論在顯示器面板上的微結構對於影像的影響；而第二部分我們研究抑制光斑的方法，包含角度分集(angular diversity)及波長分集(wavelength diversity)。 從模擬結果來討論，我們了解如何在顯示器面板上安排不規則微結構，而使光斑現象受到抑制；而且也了解到在許多種顯示器都會產生光斑，不僅止於雷射顯示器。對於在影像系統中設計被動元件用來抑制光斑，本論文提供了定性與定量的理論基礎。

Application of coherent light in displays is gradually respected (e.g. laser projection system). In coherent imaging system, when image an object with a random surface fluctuation, a random intensity distribution would appear, as would degrade the image quality. We call the random intensity distribution a speckle pattern. In this thesis, we set up a simulation model to analyze speckle phenomena due to a random structure in imaging system. Our analysis includes not only mathematic derivation in theory, but also further discussion about more complicated situation by simulation. This thesis can be divided into two parts. One is investigation of basic character and cause of speckle, and further, we discuss the effect of micro-structure on display panel upon image. Another is investigation of methods of suppressing speckle, as contains angular diversity and wavelength diversity. From the simulation results and discussions, we understand how to arrange irregular micro-structure on display panel to avoid speckle. Besides, we also understand that speckle appears in many displays, not only laser displays; This thesis also set up a steppingstone for designing static elements to suppress speckle in image in the future.