This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.

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Figure 4260a shows the change of Ronchigram taken at overfocus of 50 nm during correction of C_s(spherical aberration). The characteristic feature of the aberration marked by white broken lines disappeared after the aberration correction. Note that the C_s-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 C_s(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 C_s-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 C_s-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 .