SEMC J1230, User Manual

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Last updated on 9/20/19
7
Troubleshooting
● EN/FA/FC beam should be at least as large as flu screen, otherwise images will
sensitive to beam movements
● EN preset
○ Brightness 20-25 pA/cm2
○ 500 ms at 2048 x 2048, bin2
○ If quadrants show up in images, then the beam is too dim or too bright
○ Should be ~8000 counts
● FA/FC presets
○ Brightness 20-30 pA/cm2
○ 200 ms exposure at 1024x1024, bin4
○ If beam is too condensed, focus will fail because the image will move too much
● If focus is off
○ Pause in J1Exposure node
○ In J1Focus node, simulate target; verify that focus is good
○ If focus is still off, adjust using manual focus (MF) under J1Focus node
■ It is often easier to use the OBJ FOCUS knob on the microscope hand
panel to find true focus and reset using MF display in Leginon
○ Resume collection in J1Exposure node (play button)
● Exposure and Focus node should use “Image Beam Shift” to move to target
● Grid, Square and Subsquare node should use “Stage position” to move to target
● YOU MUST USE THE J1230 Raster app!
STAFF USE ONLY
Alignments
Frequently you will need to adjust gun tilt and possibly gun shift after a vacuum crash. You
should not have to do any other alignments regularly. If you have not done alignments before,
please consult EMG staff for supervision before attempting.
Gun tilt:
You will find this under the HT panel. Click <<Tilt>> and use right mouse click and drag
to maximize brightness.
Gun shift:
You will find this under the HT panel. Click <<Shift>> and go to spot size 1. Center
beam. Unclick <<Shift>>. Click BEAM SHIFT button on hand panel and go to spot size
3. Center beam. Iterate between gun shift (ss1) and beam shift (ss3) until stable.