How flat is your detector? Non-uniform annular detector sensitivity in STEM quantification

Electron Microscopy and Analysis Group Conference 2013

Macarthur, K.E.^1 ; Jones, L.B.^1 ; Nellist, P.D.^1

Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom^1

关键词: Active regions;    Annular detectors;    Detection sensitivity;    HAADF-STEM;    Image quantification;    Image simulations;    Non-uniform;    Non-uniformities;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/522/1/012018/pdf
DOI  :  10.1088/1742-6596/522/1/012018

来源: IOP

【 摘 要 】

Recording HAADF STEM data on an absolute scale for image quantification is becoming increasingly common. A particular challenge with this method is that most image simulation programs model the detector as being circularly symmetric and exhibiting uniform detection sensitivity across its entire active region. For a real detector this is rarely the case; it then becomes vital to understand how far one's detector deviates from the ideal. Here we investigate a collection of detector maps recorded using hardware from each of the current major manufacturers. Using these maps we compare their different asymmetries and any non-uniformities in their sensitivity. To facilitate this we define the parameters; 'flatness', 'roundness', 'smoothness' and 'ellipticity', evaluate each hardware with respect to these and rank them.