| | 
 enlarged version
enlarged version
| | Next technology EVO® series XVP® SEMs
Featuring - the enhanced VPSE (variable pressure secondary electron) detector... no compromises, just secondary electron surface imaging in all modes.
- Image and analyse insulators, moist specimens, out gassing specimens without intrusive specimen preparation
- Fast pumping and specimen throughput
- Secondary electron imaging - throughout the whole pressure range. See what's really there!
- Easy to use and powerful software control, change pressure regime by a simple mouse-click EVO® series
XVP® vacuum system
The specimen chamber and the EVO® column are divided into four pressure regions separated by pressure limiting apertures.
The vacuum in the gun area and the upper part of the EVO® column is maintained at high vacuum. The specimen chamber can be separated from the TMP vacuum by a chamber isolation valve. As soon as XVP® mode is selected the system automatically regulates the chamber pressure and additionally selects the variable pressure detector for you. An automatic feed back loop ensures that the new pressure is accurately set and regulated in the specimen chamber. With a single mouse click high vacuum can be selected if required.
Principles of XVP® operation
In XVP® mode, the gaseous pressure in the specimen chamber is raised whilst the EVO® column vacuum is maintained at a high level. With a higher gas pressure (1 - 750Pa) in the vicinity of the specimen, electrons leaving the specimen collide with gas molecules causing ionisation to occur. Ions created as a consequence of the gaseous collisions are responsible for neutralising any charge build up in insulating specimens. In general, the more insulating the specimen the greater the gas pressure required. Another advantage of the elevated pressure is the capability to investigate moist specimens. Together with a Peltier cooling stage water can be retained in moist samples to avoid artifacts caused by dehydration. XVP® mode enables imaging of specimens in their natural state without the need for time consuming and expensive preparation techniques.
VPSE - Variable Pressure SE detector
Since the standard lateral secondary electron detector (Everhart-Thornley type) and the high efficiency in-lens detector are both designed for use in high vacuum, secondary electrons cannot be detected by these detectors in XVP® mode. The solution has been to develop the unique enhanced VPSE (Variable Pressure Secondary Electron) detector to allow true secondary imaging under both normal and variable pressure conditions. An optional BSE (Backscattered Electron) detector can be used to obtain additional image information.
 XVP® mode demo |