TEM Gun Alignments

1) Iteratively use

• beam shift
• beam tilt
• condensor astigmatism

To get a evenly distribute spot.

2) Use the 'holey cross' principle

• Block the beam by inserting the 'Beam stop' into the projection chamber
  
• Use gun shift to centre the cross
• Use intensity to keep the beam on the beam stop.
  
• Use condensor astigmatism