Ptychographical同調繞射顯微術應用於大面積週期結構之研究

Abstract

Ptychographic同調繞射顯微術(Ptychographic coherent diffraction microscopy, PCDM)是一種新穎且無透鏡的顯微技術，以實現高空間解析度。綜合許多優點與潛力，PCDM已被應用於許多光源，像可見光源、X射線和電子束影像。 PCDM具有Ptychographic interative Engine (PIE)演算法和擴展extend PIE（EPIE）兩種演算法。本論文中，我們首先建立壹套綠光PCDM系統，並使用此系統觀測大面積非週期和週期樣品。對於非週期性樣品，PIE和EPIE模式都可成功地重建相位影像；而且EPIE法的重建影像品質比PIE還好。但是對於週期性結構，EPIE法無法順利工作；不過，我們證實若利用EPIE法重建非週期樣品的影像獲得較準確的入射光場函數，我們還是可以利用準確的入射光場函數並透過PIE法得到週期樣品影像。且從重建影像的訊雜比可知，重建相位品質比震幅影像還佳。

Ptychographic coherent diffraction microscopy (PCDM) is a new powerful technique developed in recent years to achieve high spatial resolution using diffraction-based imaging without lens. Due to many potentials and advantages, it has been demonstrated experimentally for many light sources like visible, X-ray and electron beam. PCDM have ptychographic iterative engine (PIE) and extend PIE (EPIE) algorithm. Therefore, in this thesis, we will build our own PCDM system with green laser pointer and use this system for retrieving phase images of both extended non-periodic and extended periodic structures. In non-periodic structures, we have successfully used both PIE and EPIE methods to recover the images. In addition, the images retrieved using EPIE have better image quality than that obtained from the traditional PIE. However, for the periodic structures such as a microlens array, EPIE method does not work well, but we confirm that if we have an accurate enough illumination function obtained from non-periodic structures by EPIE, we are able to well reconstruct the image of an extended periodic structure by PIE. Finally, we also confirm that the better S/N ratio for phase images than for the amplitude in PCDM.