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Update Calibrations

skoupy_r
2024-03-15 17:26:28 +01:00
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Calibrations.md

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##### Probe semi-angle
##### Detector camera length
Pixelated STEM detector is located at a different position compared to level of nominal camera length (dedicated STEM detectors in our case). Real camera length to the pixelated detector has to be measured for each available nominal camera length. Otherwise wrong detector cover angle is used in reconstructions.
##### Scanning step correction ##### Scanning step correction
Scanning step size is given by magnification and number of scanning points giving together field of view. In reality, original calibration may not be perfectly accurate and own re-calibration may be needed. Scanning step calibration is based on known inter-atomic distance. In our case _SmB6_ in [110] orientation where _Sm_ to _Sm_ distance is 2.92 or 4.13 A respectively. Line of 23 _Sm_ atoms was imaged in 499 pixels, 1 pixel is 22 * 2.92 / 499 = 0.1287 A. Microscope field of view at 30e6 magnification is 7.154 nm here divided into 512 pixels (pixel 0.1397 A). Correction factor between real and nominal pixel size is then 0.1287/0.1397 = 0.9212 = 92.12 % Scanning step size is given by magnification and number of scanning points giving together field of view. In reality, original calibration may not be perfectly accurate and own re-calibration may be needed. Scanning step calibration is based on known inter-atomic distance. In our case _SmB6_ in [110] orientation where _Sm_ to _Sm_ distance is 2.92 or 4.13 A respectively. Line of 23 _Sm_ atoms was imaged in 499 pixels, 1 pixel is 22 * 2.92 / 499 = 0.1287 A. Microscope field of view at 30e6 magnification is 7.154 nm here divided into 512 pixels (pixel 0.1397 A). Correction factor between real and nominal pixel size is then 0.1287/0.1397 = 0.9212 = 92.12 %