MATTER Undergraduate web site

 
  MATTERTEM | Site Map | Help | Contact us | Glossary | About  
 
     

Previous ] Continue ]

LENSES

 
Beam convergence
    G: 7 of 14
 

The state of focus makes a big difference to the beam convergence at any point on the specimen.

The convergence is defined as the angular range from which the electrons incident on a point appear to come. This is shaded blue in the diagram.

List in order of increasing convergence angle: focused, underfocused, overfocused.

What would be the maximum convergence angle for a system with a condenser aperture of 50 µm diameter and a C2-specimen distance of 20 mm? Express your answer in milliradians.

 
Previous ] Continue ]
  Electron-atom interactions | Electron gun | Lenses
 

2000 MATTER, The University of Liverpool. All rights reserved.
    contact us   Last updated: July 25, 2000 commercial information