Thermo Scientific Apreo User's Operation Manual page 91

Source Tilt & Shift
This procedure takes from 2 to 3 hours and should be executed when necessary. It centers the electron beam in the
column using three variables:
• DPA (Differential Pumping Aperture – separates the high vacuum column part from the chamber vacuum) –
centers the electron beam to pass through the column without any cutoff.
• Tilt – centers the beam on the optical axis.
• Shift – centers the beam on the center of the final lens.
C O N F I D E N T I A L – limited rights
Revision A Feb 2018
Alignments: E-Column: Supervisor Alignments
User Manual 4-11