Last updated 10/29/2020
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f.
Focus beam using “Focus” knob on right knob-set and camera/FFT. Reset defocus to 0
(press R3 on right knobset)
6.
Beam tilt pivot point X and Y (“Tune” → “Direct Alignments” → “Beam tilt pivot point”)
a.
At eucentric height and eucentric focus.
b.
Flu screen down. Focus beam to the size of inner diameter circle on flu screen.
c.
Click “Beam tilt pivot point x”
d.
Use MF X and Y to minimize beam shift
e.
Repeat for pivot point Y
7.
Coma free pivot point X & Y (“Coma free pivot point X”)
a.
Repeat similarly to step 6
8.
Objective Aperture Centering (~25 – 50K)
a.
Focus and center beam to a point
b.
Click “Diffraction” on right knob-set
i.
D = 460 mm
c.
Insert objective aperture (silver tab pointed left) and center aperture
9.
Objective Astigmatism (~25 – 50k)
a.
At slightly underfocus (2-3 thon rings) use live FFT and get rings to be a circle (elliptical
= objective astigmatism).
b.
Use MF X and Y to correct the astigmatism.
10.
Coma Free Alignment X and Y
a.
Done via Beam_Tilt_Image node
b.
Click on “Simulate target”
c.
Use click tool to ensure that
11.
Preset alignments
a.
Find feature that is visible at medium mag
b.
Center feature on the flu screen using FA preset
c.
Under navigation node, acquire image; make sure the feature is centered
d.
Send scope to “HL” preset and take a picture; using “image shift”, center the feature
using the click tool
e.
Go to “preset manager” and apply the image shift to the HL preset “from scope”
f.
Under “navigation” node, send scope to “SQ” preset and take a picture; using “image
shift”, center the feature using the click tool
g.
Go to “preset manager” and apply the image shift to the SQ preset “from scope”
h.
Under “navigation” node, send scope to “GR” preset and take a picture; using “image
shift”, center the feature using the click tool (you may need to take out the objective
aperture) (from SQ to GR, there is a flip/translation in the image)
i.
Go to “preset manager” and apply the image shift to the GR preset “from scope”
j.
You are done! Make sure to reset back to “stage position” for movements
12.
Gain references. For gains, it does not matter if objective aperture is in or out. Must be done over
vacuum.
Summary of Contents for TF20
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