
9.5. Atmospheric Dispersion Correctors 235
TSA = 14.6, TTC = -6.0, TAS = 0.6; for the wedge effect we get TTC = -2.6
and TAS =
2.0.
The only difference for the spot patterns in Fig. 9.16 is that
TTC = 0 for the wedge effect.
From these numbers we see that coma due to thickness is more significant than
that due to the wedge effect. We can use the signs and relative sizes of the coma
numbers to account for the differences between positive and negative 9 seen in
Figs.
9.15 and 9.16. We also see that spherical aberration is a factor in this//4
beam, but that astigmatism is relatively unimportant.
The sizes of the computed aberrations suggest tha ...