隨著頭戴式近眼顯示器對於混和實境的發展與國際IT大廠對全像公司的併購，體積全像光學元件在資訊光學的尖端系統上的不可取代特性越來越清楚，也越來越重要。體積全像光學元件對光波的調制具有相當多的優勢，其在材料上的不足也漸漸被克服，剩下的就是如何駕馭這個頂尖的光學元件，在材料上、在設計上、在製程上達到實用的標準。目前體積全像的模型包括耦合模態法、波恩近似法與相位疊加法都無法處理複雜體積全像的繞射效率與實際的布拉格選擇性問題。本計畫是整合型計畫的子計畫一，是為期三年的研究計畫，計畫中就是將提出一個新的模擬方式，來做為體積全像光學元件實用化的計算模型。我們將以計畫主持人所提出的相位疊加法為基礎，第一就是研究相位轉換因子，該相位轉換因子就是在穿透式全像中，被繞射的光波無法在傳輸的過程中再繞射至回原來的光波的重要因子。第二就是要將耦合強度放入相位疊加法，並以耦合模態法計算平面波的繞射效率來比較，再以相位疊加法來掌握繞射效率與布拉格選擇性，最後能掌握繞射效率與布拉格選擇性的計算，體積全像光學元件的元件特性才算是能夠被清楚的模擬與精確地設計。此稱為VOHIL-SD方法若能成功，必然是國際創新的計算模型，不但是學術上的一大突破，同時對於產業上在IT產業將是明日之星的體積全像光學元件的發展更是重要。 ;A current story happening for that near-eye head mounted display has been regarded as the most important system to mixed reality, and some of the world-largest IT companies have started mergers and acquisitions for holography company. Volume holographic optical element (VHOE) has clearly performed its unique property and characteristic in IT industry. VHOE has been shown its advantage to generate desired optical wavefront, and the shortage in recording medium has been conquered. One of the remaining important problems for practical application is how to optimize a VHOE regarding to medium, design and manufacturing processes. So far, there are three popular calculation models available for volume holography, including couple mode theory, Born’s approximation, and VOHIL model. All the three models cannot effectively calculate diffraction efficiency and Bragg selectivity in case of complex wavefront. This project is a three-year project, and is one of the four sub-projects of an integrated project. The objective of this project is to propose a new simulation model to solve the essential simulation problem and accordingly VHOEs will be more practical. In the project, first we will follow the original model VOHIL, which was proposed by the project leader CC SUN, and study the phase transfer factor upon diffraction in a VHOE. The phase transfer factor is the key factor to prevent double diffraction to the reading light from the diffraction light. Then we have to study how to insert the coupling strength factor into the simulation model. We need to refer the calculation result by the couple mode theory with two planar waves. The results will be compared with the results by the modified VOHIL, which is called VOHIL-SD. VOHIL-SD will be used to precisely simulate strong diffraction efficiency and Bragg selectivity of a VHOE so that effective optimization and practical design of a VHOE becomes possible. The success of the project will be a big impact to the academics. Also the VOHIL-SD will be very useful in designing new VHOE, which will be important in international IT industry.
