Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix
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Figure 4260a shows the change of Ronchigram taken at overfocus of 50 nm during correction of Cs(spherical aberration). The characteristic feature of the aberration marked by white broken lines disappeared after the aberration correction. Note that the Cs-correction process induced large twofold astigmatism (A1), which can be corrected later.
Figure 4260a. Change of Ronchigram taken at overfocus of 50 nm during correction of Cs(spherical aberration). Adapted from [1] Figure 4260b shows that an observed Ronchigram from an amorphous germanium TEM film showed a coherently converged angle > 40 mrad in half-angle when the Cs-corrector was turned on. This angle was much lager than that for the uncorrected beam.
Figure 4260b. Ronchigrams for the probe-forming lens system with a Cs-corrector (a) corrector off and (b) corrector on.
[1] H. Akima, Y. Hirayama and T. Yoshida, Automated Alignment Cs Correction System for STEM (II): Installation of Reinforcement Learning, www.microscopy.org, 2011 .
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