Hitachi S-4800 manual Column Alignment Operation

3.4.3Column Alignment Operation

For the best performance of the instrument, alignment of the electron optical column axis is necessary. Generally, an electromagnetic alignment is sufficient, while a mechanical alignment may be needed for more critical applications.

Perform the following alignment when you change the accelerating voltage, Probe Current mode, or setting of Cond Lens1. If you notice the image moving while focusing or correcting astigmatism, only perform an Aperture Alignment or Stigma Alignment, respectively.

The S-4800 allows alignment conditions to be saved for each combination of accelerating voltage and Probe Current mode.

If an alignment operation has been made at a particular combination of settings, only a slight adjustment (usually Aperture Alignment) is necessary when you return to that condition.

For all electromagnetic alignments, either drag the mouse in the grid area of the Alignment dialog window or adjust the STIGMA/ALIGNMENT X and Y knobs on the control panel.

NOTICE: 1. For normal microscopy, use electro-magnetic column alignment. Do not manipulate the objective aperture. Mechanical alignment of the electron optical system including the objective aperture and beam monitor aperture is done at an accelerating voltage of 1 kV (See the alignment procedures 3.12.). If you do mechanical alignment at other voltages, you may end up with inability of performing complete electro-magnetic alignment at some other accelerating voltages.

2.Before performing mechanical alignment, wait for more than two hours after starting the heating of the objective lens aperture. If mechanical alignment is made immediately after the start of heating the objective lens aperture, the alignment condition will be affected by thermal expansion of the objective lens aperture.

3.To save operating conditions effectively, it is recommended to perform a Degauss operation after focusing and before column alignment.

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