本研究針對擴增實境（AR）波導顯示器中常用的反射式體積全像光學元件（VHOE），提出一套基於反射式光學繞射斷層掃描的三維折射率分布量測與分析方法，相較於穿透式體積光柵，反射式體積光柵的繞射訊號主要沿反向傳遞，且反射式量測更貼近 AR 元件的實際應用情境，但也面臨更嚴峻的系統相干雜訊與背景光干擾問題。 量測過程中，各掃描角度之反射與繞射訊號強度並不一致，弱訊號角度所取得之干涉影像品質亦相對降低。因此，重建時依各角度實際量測品質設定權重，以降低低品質資料對最終結果之影響，並於系統可完成之最大掃描範圍下進行反射式VHOE折射率分布重建。 此外，反射式 ODT 中容易受到鏡面反射、寄生干涉、光學元件表面散射、灰塵散射與固定背景光影響而產生的相干背景雜訊，並降低重建品質。為了解決此問題，本研究提出以樣品橫向位移為基礎的雜訊抑制方法。藉由電控位移平台以固定步距移動待測 VHOE，於五個離散橫向位置分別取得多角度複數場資料，使樣品訊號隨時間產生已知位移，而系統背景雜訊近似固定不動；再透過數位位移補償與複數場疊加，使樣品訊號相干疊加，並降低固定背景與非樣品相關雜訊對重建結果的影響，有助於改善相位對比度、背景純淨度與折射率重建穩定性。;This study presents a reflective ODT method for 3D refractive index analysis of AR-based reflection VHOEs. While back-propagated signals align better with practical applications， this configuration faces significant coherent noise and background interference. Because the reflected and diffracted signal intensities varied with scanning angle， angle-dependent weighting was applied during reconstruction to reduce the influence of low-quality data. The reflection-type VHOEs were then reconstructed using the maximum achievable scanning range. Furthermore， reflective ODT is susceptible to coherent background noise arising from specular reflections， parasitic interference， surface scattering from optical components， dust scattering， and static background light， which degrades reconstruction quality. To address this issue， this study proposes a noise suppression method based on lateral sample displacement. By translating the VHOE under test at five discrete lateral positions with a fixed displacement step， the sample signal undergoes a known displacement over time while the system background noise remains relatively stationary. Subsequently， through digital shift compensation and complex-field summation， the sample signal is coherently accumulated， reducing the impact of fixed background and non-sample-related noise on the reconstruction results. This approach helps improve phase contrast， background purity， and the stability of refractive index reconstruction.
