非共平面角度-偏振多工及同調篩選合成孔徑數位全像顯微術之研究

Abstract

本論文主要探討合成孔徑在數位全像顯微術中，以共光程技術來簡化光學實驗架構，提升系統穩定度與相位精準度；最後架構出一套非共平面合成孔徑數位全像系統。研究中以穿透式數位全像顯微術為基礎，利用合成孔徑技術提升系統空間解析度，透過改善系統掃描時的失焦問題，完成最佳化解析度之系統設計。在最佳化解析度的實驗架構下我們成功地以可見光波段雷射光源量測出線寬約200 nm的線對物體，並達到相位精準度約3.8 nm，並也用此系統來量測活體細胞。另外非共平面合成孔徑數位全像系統架構中，我們透過設計偏振與同調，並搭配使用空間光調制器，而得以在單次曝光條件下記錄合成孔徑數位全像片。接著由合成孔徑頻譜疊加的方法即可得出物體提升振幅影像橫向解析度的資訊，在此架構下於物體光與參考光端我們皆使用空間光調制器分出所需掃描的光束，避免了傳統機械掃描時的振動，如此即有效地增加系統穩定度且簡化了光學實驗拍攝次數。最終非共平面數位全像顯微術與合成孔徑技術結合後，以波長為405 nm雷射為實驗光源與單次拍攝的條件下，系統橫向解析度增加為原本的1.5倍。若以拍攝6張做空間平均抑制雜訊，系統橫向解析度增加至原本的1.72倍。This works mainly discusses how to optimize the system resolution in the digital holographic microscopy (DHM). We also try to enhance the system stability and simplify the experimental architecture by applying common-path setup. Finally, we set of non-coplanar angular-polarization multiplexing and coherence gating in synthetic aperture digital holographic microscopy system. This research bases on transmission type DHM. This work presents a common-path synthetic aperture digital holographic microscopy using spiral phase plate to improve phase stability and spatial resolution. The influence of lateral shift and defocus in spiral phase plane were analyzed at different illumination angles. In the experiments, the SA technique gives better image resolution up to about 200 nm with phase accuracy about 3.8 nm by using visible light source. In addition, we produce a non-coplanar angular-polarization multiplexing and coherence gating in synthetic aperture digital holographic microscopy system. We designed polarized and coherence gating, and with the use of spatial light modulator (SLM). We were able to record synthetic aperture digital images in single exposure conditions. In the experiments, the non-coplanar angular-polarization multiplexing and coherence gating in SA-DHM technique gives better image resolution up to about 1.5 times. If we record six hologram to do the space average. The system image resolution increased to 1.72 times.