無透鏡繞射影像術

Lensless Coherent Diffractive Imaging

Roman Dronyak ； 唐欣瑜(Hsin-Yu Tang) ； 陳福榮(Fu-Rong Chen) ； 梁耕三(Keng-San Liang)

《科儀新知》 177期 (2010/08) Pp. 13-20

https://doi.org/10.29662/IT.201008.0002

摘要

近年來高解析電子顯微鏡學發展逢勃，目前在實空間的二維影像已可達到次埃級(sub-Å)的解析力。儘管如此，電子顯微鏡仍有許多本質上的問題尚待解決，其中又以磁透鏡像差及相位遺失，使得影像無法直接定量解釋，故希望藉由無透鏡繞射影像術將上述的問題解決。無透鏡繞射影像術並非真的不使用電子顯微鏡中常使用的電磁透鏡成像，而是使用干涉性佳的電子束在倒空間記錄一系列繞小強度，並利用並合模擬迭代法，回復帶有樣品訊息的電子波函數相位。這樣的方法可成功地恢復遺失之相位及修正透鏡像差對影像造成的影響，使得影像可以直接解釋並定量樣品，故稱之為無透鏡繞射影像術。此外，儘管電子繞射影像術還在發展階段，仍可利用此項技術還原出高解析度的氧化鎂奈米顆粒三維影像及其出射波重構。

並列摘要

Recent advances in high-resolution transmission electron microscopy were of most popular in the field of phase problem, correction of electromagnetic lens aberrations, and three-dimensional atomic tomography. The phase restoration and elimination of lens aberrations could be achieved simultaneously by applying coherent diffractive imaging (CDI) technique in electron microscopy. High resolution image (sub-Å) could be obtained by Fourier transform of high frequency signal from reciprocal space. The aberration-free 3-dimentional structure can be reconstructed from a series of diffraction patterns. The phase of exit wave can be retrieved from diffraction pattern by applying HIO algorithm. Although the method of coherent electron diffractive imaging remains under development, we have successfully performed a detailed investigation of the electron CDI restoring the 3-dimentional structure of MgO nanocrystals and the electron exit wave.