Hysteresis Factor in TEMs
- Practical Electron Microscopy and Database -
- An Online Book -

http://www.globalsino.com/EM/  



 
This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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Hysteresis factor affects the TEM operations under changed lens conditions once magnetized lenses retain a certain amount of residual magnetism. This means that the level of current used does not always specify lens strength. This effect can particularly affect:
        i) The total magnification. That is, the total magnification redouts may be in error,
        iii) The standard focus,
        ii) The magnification calibration. On most microscopes, one gets the best calibration data by calibrating at the highest magnification, and then works down the range because of inherent hysteresis in the electromagnetic lenses.

i) and ii) can be corrected by pressing the STANDARD FOCUS bottom a number of times during the operation. In this way, the applied current is essentially returned to zero a number of times. This reduces lenses to the standard level of magnetization.

 

 

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