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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In EMs, the resolution limit due to chromatic aberration can be estimated by, where, We can see that Equation 4241 is related to a beam broadening factor due to chromatic aberration (Cc) of the objective lens because of the finite width of the energy-selecting slit. Example of estimated resolution limits are shown in Figure 4241. At high accelerating voltages (e.g. 200 kV) the spherical aberration is dominant, while at low accelerating voltages (e.g. 1 kV) the chromatic aberration is dominant. Generally speaking, spherical aberration is the dominant resolution-limiting aberration at accelerating voltages larger than about 100 kV.
Figure 4241. The estimated resolution limits at 1 kV and 200 kV as function of Cs and Ccassuming only one of them is present in each case. The energy width of the beam was assumed to be 0.7 eV.
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