Image shifts SA

Purpose: Aligning all SA images with each other.
Importance: CONVENIENCE so that the image remains centered when the magnification is changed.
Method: Center a recognizable image with the specimen stage. Lower the magnification one step, center the image with the Multifunction X,Y knobs. Repeat for all magnifications.

Procedure
The alignment procedure consists of two or four steps, dependent on the presence of absence of Parfocal Magnification Series (last two steps) :

• A preparation step in which an image feature is centered (with the specimen stage) in the highest SA magnification.
• A step in which all SA magnifications are aligned relative to the highest SA magnification.
• A preparation step in which the highest SA magnification is focused accurately.
• A step in which all other SA magnifications are focused accurately.
  

Parfocal magnification series
The parfocal magnification series applies an automatic correction to each SA magnification so as to make the focus difference between the SA magnification steps as small as possible. This correction factor is independent of focus settings and applies only to the SA magnifications. Similar correction factors for the M (Mi, and Mh) magnifications as well as diffraction (D) are already present as standard in the Tecnai software.

Notes:

• The magnification system (projector lenses) is normalized when the magnification is changed to make the image position better reproducible.
• The highest SA magnification is the reference image for the whole microscope, with regard to focus (eucentric focus preset) and image shift.

Page last modified on 11/13/00