以雷射為光源之立體顯示技術

Abstract

本論文主要的研究目標在於探究以雷射作為光源之裸視立體顯示技術。 為了突破傳統的立體影像分光技術，本研究率先採用繞射光學中的閃耀式光柵和全像分光元件，以實現出不同於以往的裸視立體顯示技術。針對閃耀式光柵的製作上，本論文採用微機械加工技術與感應耦合電漿反應式離子蝕刻技術製作出四階閃耀光柵結構，並選用高透光性材料–聚二甲基矽氧烷以翻膜出對稱式四階閃耀式光柵膜片。除此之外，透過上述兩製程技術結合掃描浸潤式微影製程，可成功將結構直接轉印於石英並蝕刻之，突破於透明基板上蝕刻繞射元件的技術，值得一提的是該表面粗糙度可達到30奈米。除此之外，閃耀式光柵應用於雷射顯示器時，可同時作為分色分光之薄膜，創新的概念將為顯示器省去彩色濾光片。然而，全像分光元件，係以高穩定性的高分子分散液晶作為全像材料，並利用單色光建立符合三原色的振幅式光柵，完成立體影像分光之動作。此非浮雕之全像元件，也創下應用於雷射背光立體顯示器之另一項契機。 接著，本論文亦提出另一種應用於雷射背光源的立體顯示技術，電腦產生全像。使用修正型Gerchberg-Saxton演算法記錄視差立體圖像的相位函數，當完成解密之後可獲得左右視角內容的立體影像對。為了更加突顯此技術的價值，將之應用於視覺訓練，此結果表現相較於傳統以平面二維的左右圖卡，電腦全像所重建之影像內容，其高對比性、高清晰度及任意變化的差異性內容，可提高訓練的效果，甚至左右獨立的影像，可完全避免串音干擾的問題。另一方面，積分影像技術一直以來是屬於裸視立體顯示的一環，本論文也率先嘗試利用電腦產生全像取代積分攝影，省略了傳統積分影像的繁複地拍攝步驟，也突破現有積分影像之技術困難點。 最後，於本論文的終章，本研究重新探究了雷射作為背光源的本質，瞭解雷射光斑依然是雷射顯示器的一大阻礙，因此，本研究除了探討如何有效地降低光斑雜訊的機制，也分別提出了旋轉擴散片與振動光導管的方式，並且成功地驗證之。

This dissertation aims to explore the application of autostereoscopy based on laser backlight. In order to break through traditional spectroscopy for 3D images, blazed grating and holographic optical element in diffraction optics are first utilized in this dissertation for autostereoscopy technology. Aiming at the production of blazed grating, Lithographie GalVanoformung Abformung and inductively coupled plasma-reactive-ion etching are applied to produce four-order blazed grating structure, and highly transparent material, polydimethylsiloxane, is selected to mold the symmetric four-order blazed grating films. Besides, the above processing techniques are combined with scanning immersion lithography to successfully print the structure onto quartz for etching. It breaks through the technique of etching diffraction optical elements on a transparent substrate. Worthy mentioning, the surface roughness could be less than 30 nm. What is more, applying blazed grating to laser displays could also be used as the film for color division. Such an innovative idea would remove color filtering for LCD. Nonetheless, holographic optical elements use high-stability polymer-dispersed-liquid-crystals as the holographic materials and utilize monochorma for establishing the amplitude grating conforming to the primary colors in order to complete the holographic optical element of 3D images. Such a non-relief holographic optical element also creates a different opportunity for the application to autostereoscopic displays with laser backlight. Another application to autostereoscopic displays with laser backlight, computer-generated holography, is further proposed in this dissertation. With modified Gerchberg-Saxton algorithm (MGSA) to record the phase only function of parallax 3D images, the 3D image pair with left and right angles of view could be acquired after decoding. To further highlight the value of such a technique, it is applied to vision training. In comparison with traditional 2D training cards, computer-generated holographic images with high contrast, high definition, and changeable disparity could enhance the training effects and even affect the independent left and right images to completely avoid crosstalk. On the other hand, integral images have been a part of autostereoscopy. My research also attempts to replace integral photography with CGH, removing the complicated shooting steps for traditional integral images and breaking through the technological difficulty in current integral images. Finally, the essence of using laser as the backlight is re-explored to understand that speckles are still a major obstruction for laser displays. For this reason, both rotation diffusers and vibrated light pipes are proposed, in addition to the mechanism for effectively reducing speckle noise, and successfully verified in this dissertation.