8-11 keV 穿透式X 光顯微鏡系統中Zone plate 傾斜之研究

Abstract

光學元件Zone plate 在近幾年來被應用為穿透式X 光顯微鏡(TXM)系統中的聚焦透鏡。當系統中的zone plate 被傾斜時,顯微鏡影像會受到像差的影響。以入射光的觀點來看,zone plate 的穿透函數形狀因傾斜改變了,因此傾斜的zone plate 不再能正常的聚焦入射光。 在本篇論文中,將呈現實驗與模擬的結果。在TXM 系統中有一個五軸座台可幫助完成此實驗,該座台可以三維的移動zone plate,以及傾斜zone plate(以垂直或水平方向為旋轉軸皆可) 。根據富立葉光學理論,只要知道光源的光場,每個元件之間的距離,樣品與zone plate 的穿透函數,即可計算整個顯微鏡系統中任何地方的光場。在此論文中,將運用matlab 平行處理的程式去完成複雜的計算。以模擬出來的影像和實驗結果做比對,找出顯微鏡影像可接受的zone plate 最大傾斜角度。

Zone plate has been used as a focal lens in transmission X-ray microscope (TXM) optical system in recent decades. When zone plate is tilted, the image quality will be affected by aberration. Since for incident beam the shape of zone plate’s transmission function will look different when zone plate is tilted, the tilted zone plate cannot focus light normally. The both experimental and simulation result will be shownin this thesis. A five axes stage is designed and manufactured for the zone plate holder for three dimensional movement, tip and tilt. According to Fourier theory, the wave distribution on image plane can be calculated, if we know the original wave function, the distances between each element, and the transparencies of the sample and zone plate. A parallel simulation process code in MATLAB is developed in workstation cluster with up to 128Gbytes memory. The effects of aberration generated by tilt effect are compared from the experimental data and simulation result. A maximum tilt angle within the acceptable image quality is calculated by simulation and will be verified by experiment.