Справочник Пользователя для Hitachi Microscope & Magnifier S-4800

 

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3.10  Image Quality 
 
The followings are references for getting better image quality. 
 
3.10.1    Accelerating Voltage and Image Quality 
 
There is a multitude of accelerating voltages to choose from. Resolution, image quality, charging 
and other effects are greatly determined by the selected accelerating voltage. Below is a 
guideline for selecting an accelerating voltage in which to image various specimens. 
 
(1) Resolution 

Higher spatial resolution can be obtained at higher accelerating voltages. 
 

(2) Charging   

For uncoated insulator specimens, accelerating voltages lower than 1kV are recommended for 
minimizing charging.  In some cases, high accelerating voltages (20kV or higher) may 
produce a better image. 
 

(3) Contamination 

Influence of contamination appears more at low accelerating voltages. 
 

(4) Magnetic field disturbance 

Disturbance by leakage magnetic field (wobbling or distortion of the image) is greater at low 
accelerating voltages. 
 

(5) Contrast 

Generally a soft-tone image is obtained at low accelerating voltages, because more secondary 
electrons are detected than backscattered electrons at low accelerating voltages. 
 

(6) X-ray analysis 

X-ray analysis generally requires accelerating voltages higher than 10kV.  The required 
accelerating voltage depends on the exciting energy of elements for x-ray detection.