Revised 03/25/2020
13
c.)
Press the LC “
Stigmator
” button or click on “
Objective
” in the “Stigmator”
window.
d.) Use the
MF knobs
to adjust the objective stigmator. The goal is for the
rings
in the FFT to
appear circular
, not elliptical or hyperbolic. The rings will grow
larger and astigmatism will be more apparent when closer to focus. Adjust the
focus so that the rings are large enough to be clearly visible but are not
hyperbolic. As astigmatism is corrected, move closer to focus (larger rings) to
fine tune the stigmator settings.
e.)
Click “
None
” in the “Stigmator” window or press the LC “
Stigmator
” button.
Note: Objective astigmatism should be checked periodically throughout a
session. It can be changed by changes in magnification mode, spot size, Z-
height of the sample, or objective aperture size or position.
Note: Each stigmator has three registers
available. Clicking on a register selects among
them. These can be used to store stigmator
settings for different conditions, such as
different objective apertures. They can also be
used to store a backup before adjusting the
astigmatism. One register can be copied to
another by right clicking.
Astigmatism
present
Astigmatism
corrected
Stigmator
register
