TY - JOUR
T1 - Dynamic scan control in STEM
T2 - spiral scans
AU - Sang, Xiahan
AU - Lupini, Andrew R.
AU - Unocic, Raymond R.
AU - Chi, Miaofang
AU - Borisevich, Albina Y.
AU - Kalinin, Sergei V.
AU - Endeve, Eirik
AU - Archibald, Richard K.
AU - Jesse, Stephen
N1 - Publisher Copyright:
© 2016, The Author(s).
PY - 2016/1/1
Y1 - 2016/1/1
N2 - Scanning transmission electron microscopy (STEM) has emerged as one of the foremost techniques to analyze materials at atomic resolution. However, two practical difficulties inherent to STEM imaging are: radiation damage imparted by the electron beam, which can potentially damage or otherwise modify the specimen and slow-scan image acquisition, which limits the ability to capture dynamic changes at high temporal resolution. Furthermore, due in part to scan flyback corrections, typical raster scan methods result in an uneven distribution of dose across the scanned area. A method to allow extremely fast scanning with a uniform residence time would enable imaging at low electron doses, ameliorating radiation damage and at the same time permitting image acquisition at higher frame-rates while maintaining atomic resolution. The practical complication is that rastering the STEM probe at higher speeds causes significant image distortions. Non-square scan patterns provide a solution to this dilemma and can be tailored for low dose imaging conditions. Here, we develop a method for imaging with alternative scan patterns and investigate their performance at very high scan speeds. A general analysis for spiral scanning is presented here for the following spiral scan functions: Archimedean, Fermat, and constant linear velocity spirals, which were tested for STEM imaging. The quality of spiral scan STEM images is generally comparable with STEM images from conventional raster scans, and the dose uniformity can be improved.
AB - Scanning transmission electron microscopy (STEM) has emerged as one of the foremost techniques to analyze materials at atomic resolution. However, two practical difficulties inherent to STEM imaging are: radiation damage imparted by the electron beam, which can potentially damage or otherwise modify the specimen and slow-scan image acquisition, which limits the ability to capture dynamic changes at high temporal resolution. Furthermore, due in part to scan flyback corrections, typical raster scan methods result in an uneven distribution of dose across the scanned area. A method to allow extremely fast scanning with a uniform residence time would enable imaging at low electron doses, ameliorating radiation damage and at the same time permitting image acquisition at higher frame-rates while maintaining atomic resolution. The practical complication is that rastering the STEM probe at higher speeds causes significant image distortions. Non-square scan patterns provide a solution to this dilemma and can be tailored for low dose imaging conditions. Here, we develop a method for imaging with alternative scan patterns and investigate their performance at very high scan speeds. A general analysis for spiral scanning is presented here for the following spiral scan functions: Archimedean, Fermat, and constant linear velocity spirals, which were tested for STEM imaging. The quality of spiral scan STEM images is generally comparable with STEM images from conventional raster scans, and the dose uniformity can be improved.
KW - Aberration-corrected STEM
KW - Distortion
KW - Scan control
KW - Spiral scan
UR - http://www.scopus.com/inward/record.url?scp=85013473812&partnerID=8YFLogxK
U2 - 10.1186/s40679-016-0020-3
DO - 10.1186/s40679-016-0020-3
M3 - Article
AN - SCOPUS:85013473812
SN - 2198-0926
VL - 2
JO - Advanced Structural and Chemical Imaging
JF - Advanced Structural and Chemical Imaging
IS - 1
M1 - 6
ER -