Leginon

h1. Beam Size Calibration

Beam size of FEI microscope can be approximate with a linear function.  This calibration determines the coefficient of this linear equation with two points, one where the beam is at cross-over and one at a known size on the main viewing screen (or FluCam on Krios).

h2. Procedure

# Select the preset beam size is to be calibrated in "Presets Manager" node and send it to the scope.  Most likely this is "en" preset used in the final exposure.

# Left click on  !http://emg.nysbc.org/software/leginon/images/icons/play.png! in the toolbar to start calibration.

# If C2 aperture size is not specified at the start of the session, the dialog will ask for the value at this point.

# Put the main screen of the scope down and expand the beam to a known size.  The 4 cm diameter circle on FEI scope is a good reference.

# Enter the size of the beam at this known size in the settings and then click on "Save" in the settings dialog

# Contract the beam to the cross-over and click on "Save Focused Beam" in the settings dialog.

# Click "OK" to exit the dialog and save the calibration

!beam_size_cal_settings.png!