Document Detail


Efficient phase contrast imaging in STEM using a pixelated detector. Part II: Optimisation of imaging conditions.
MedLine Citation:
PMID:  25481091     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
In Part I of this series of two papers, we demonstrated the formation of a high efficiency phase-contrast image at atomic resolution using a pixelated detector in the scanning transmission electron microscope (STEM) with ptychography. In this paper we explore the technique more quantitatively using theory and simulations. Compared to other STEM phase contrast modes including annular bright field (ABF) and differential phase contrast (DPC), we show that the ptychographic phase reconstruction method using pixelated detectors offers the highest contrast transfer efficiency and superior low dose performance. Applying the ptychographic reconstruction method to DPC segmented detectors also improves the detector contrast transfer and results in less noisy images than DPC images formed using difference signals. We also find that using a minimum array of 16×16 pixels is sufficient to provide the highest signal-to-noise ratio (SNR) for imaging beam sensitive weak phase objects. Finally, the convergence angle can be adjusted to enhance the contrast transfer based on the spatial frequencies of the specimen under study.
Authors:
Hao Yang; Timothy J Pennycook; Peter D Nellist
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-11-5
Journal Detail:
Title:  Ultramicroscopy     Volume:  -     ISSN:  1879-2723     ISO Abbreviation:  Ultramicroscopy     Publication Date:  2014 Nov 
Date Detail:
Created Date:  2014-12-7     Completed Date:  -     Revised Date:  2014-12-8    
Medline Journal Info:
Nlm Unique ID:  7513702     Medline TA:  Ultramicroscopy     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2014 Elsevier B.V. All rights reserved.
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