Hitachi Microscope & Magnifier S-4800 Manual De Usuario

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3.4.3  Column 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.