Index
Two-Fold Astigmatism

Two fold astigmatism can in principle always be corrected in a TEM. Its effect on HREM images can be simulated by introducing its amplitude and direction in the HREM images calculated using the Bloch-wave or the multislice methods. 2-fold astigmatism depends strongly on its orientation (Figures 1a, 1b, 1c, 1d).

Figure1a

Figure1b

Figure 1a HRTEM (Titan 300kV), no 2-fold astigmatism.

Figure 1a 2-fold astigmatism: 3 nm, 0 deg.

Figure1c

Figure1d

Figure 1c 2-fold astigmatism: 3 nm, 30 deg.

Figure 1d 2-fold astigmatism: 3 nm, 90 deg.