FEI Quanta FEG 250, Руководство пользователя

Страница: 11 / 228

2-1
2
SYSTEM OVERVIEW
The Quanta FEG Scanning Electron Microscope (SEM) produces
enlarged images of a variety of specimens, achieving magnifications
of over 100 000× providing high resolution imaging in a digital format.
This important and widely used analytical tool provides exceptional
field of view, minimal specimen preparation, and the ability to combine
the technique with X-ray microanalysis.
How Quanta FEG SEM Works
There are four main components of the microscope:
• Electron source
The electron beam is emitted within a small spatial volume with a
small angular spread and selectable energy.
• Lens system
The beam enters the lens system consisting of several
electromagnetic lenses and exits to hit the specimen surface.
• Scan unit
The scan generator signal, fed to the deflection systems, moves
the beam in a raster pattern over the specimen area. The electrical
voltage changes as it scans, which provides serial information of
the specimen surface. This signal, modulated by the detection
system signal, produces the onscreen image.
• Detection unit
Electrons striking the specimen react with its surface producing
three basic types of signal: back scatter electrons, secondary
electrons and X-rays. The detection system picks up these signals,
converts them into an amplified electrical signal which is sent to
the control PC and displayed on the monitor.