為改善目前市面上的頭戴式顯示器，常面臨體積較大且攜帶不便問題（因其光學元件較大），本研究致力於研究其色散元件的微型化，並確保其具備良好能量利用率，以利頭戴式顯示器能縮減體積並更便利攜帶。 本研究開發一片利用體積全像片製作的色散元件，用於改善白光LED入射至光導系統（其由兩片體積全像片組成）所產生的能量損耗；同時，在光導系統輸入端前，利用色散元件將白光進行多次頻譜的分光，製造相對應的頻譜分布後再輸入至光導系統，以期充分利用白光的效率而不被濾除。此外，也調整改善色散元件之繞射頻寬，使其小於光導系統之頻寬，使其能完整被光導系統所繞射，並提高匹配程度。 本研究在前人林崇瑋的研究基礎下，改利用體積全像光學元件製作三個反射式光柵，來取代原本的單一反射式光柵，並透過多次的優化設計來提升整體效率。其中透過相位疊加法(VOHIL)模型來模擬傳導後的頻譜，再進行色散元件的模擬與設計，以獲得最佳能量效率，減少不必要的能量流失；並透過調整雷射頻譜，以獲得更窄的繞射頻寬，提高匹配程度。 本研究採用三組光柵來減少能量的浪費，以及將光源與色散元件進行一體化的整合，一方面確保能量有效利用，一方面也實現縮小元件體積之目標。本研究提供了樣品證明微型化色散元件的可行性，並比較了藍光與綠光雷射的製作色散元件差異性，透過藍光雷射可以用更小的角度拍攝出指定的頻譜。本研究之色散元件技術改良成果，有助於縮小頭戴式顯示器之色散元件體積，並保有良好的能量利用率與匹配程度，實現微型化、便利攜帶的商用目標，對於頭戴式顯示器之技術改良有所助益。;To improve current head-mounted displays (HMDs)， which often suffer from large volume and poor portability due to bulky optical components， this study focuses on the miniaturization of dispersive elements while ensuring high energy utilization efficiency. The goal is to reduce the overall size of HMDs and enhance their portability. This study develops a dispersive element fabricated using a volume holographic grating (VHG) to reduce the energy loss that occurs when white-light LEDs are coupled into a light-guiding system composed of two VHGs. Before the light enters the light-guiding system， the dispersive element separates the white light into multiple spectral components， generating corresponding spectral distributions that are then injected into the system. This approach allows more efficient use of white light without unnecessary filtering. Additionally， the diffraction bandwidth of the dispersive element is adjusted to be narrower than that of the light-guiding system to ensure complete diffraction within the system and improve spectral matching.
Building upon the previous study of Chung-Wei Lin， this study replaces a single reflective grating with three reflective gratings fabricated using volume holographic optical elements. Through multiple optimization designs， the overall efficiency is enhanced. The VOHIL (Volume Holographic Interference Layer) phase superposition model is employed to simulate the transmitted spectra， which are then used to design and optimize the dispersive element for maximum energy efficiency and minimal energy loss. Moreover， by adjusting the laser spectrum， a narrower diffraction bandwidth is achieved， further improving spectral matching. The proposed design utilizes three gratings to reduce energy waste and integrates the light source with the dispersive element into a single compact structure. This integration ensures efficient energy use while achieving the goal of size reduction. Experimental prototypes demonstrate the feasibility of miniaturized dispersive elements， and a comparison between blue and green laser-fabricated elements reveals that blue lasers can record the target spectrum at smaller incident angles. The advancements presented in this study contribute to reducing the volume of dispersive elements in head-mounted displays while maintaining high energy utilization and spectral matching， supporting the realization of compact and portable commercial HMDs and facilitating further technological improvements in the field.
