Stereo Scan 440 - DCU

FIgUre 1.10 Image of First Peak Setting
of)
The filament current may be varied by using the associated scroll bar within the
Gun Alignment panel. either by SLOWL Y dragging the slider in the appropriate
direction. or by clicking over the arrow at the appropriate end of the scroll bar.
This should be done carefully and slowly, otherwise a blown filament may
result.
Alignment
For the best performance of the microscope the electron beam should pass down
the column along the electron optical axis, and any aperture in use should also be
centred about this axis. As no column can be perfect, various adjustments are
provided to compensate for this.
Final Aperture Alignment
The centring of the final aperture can easily be checked by having a recognisable
feature at the centre of screen and then taking the focus through focus and back
again. When aligned. the image will only rotate and not shift laterally. If the
aperture is mis-aligned the image will move backwards and forwards across the
screen in a slight arc. If the aperture is mis-aligned it will be necessary to move
the position of the aperture using the X and Y micrometers on the side of the
column until the image ceases to shift laterally.
Stereoscan 440 Operator Manual