VPSE - Variable Pressure SE Detector

Scanning Electron Microscopes

enlarged version The SUPRA™ series VP detection system configuration offers four imaging detectors available at any time: 1 In-lens detector for SE1 electron detection in HV mode 2 Enhanced VPSE detector for true SE imaging in VP mode 3 Everhart-Thornley detector for SE imaging in HV mode 4 BSE detector (optional) for imaging in HV and VP mode		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. 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. In optional BSE (Backscattered Electron) detector can be used to obtain additional image information.

enlarged version Secondary electrons are accelerated away from the sample surface and collide with the gas molecules in a collision zone to create further electron which are also accelerated in the electrical field. The avalanche of secondary electrons provides amplification of the SE signal. In addition to ions, secondary electron collisions also produce photons. These photons are collected by the VPSE detector to produce a true secondary electron image. Although BSE also cause collisions their contribution is less than 1% of the low energy SE, ensuring that the VPSE is genuinely secondary electron imaging.		Secondary electrons are accelerated away from the sample surface and collide with the gas molecules in a collision zone to create further electrons which are also accelerated in the electrical field. The avalanche of secondary electron provides amplification of the SE signal. In addition to ions, secondary electron collisions also produce photons. These photons are collected by the VPSE detector to produce a true secondary electron image. Although BSE also cause collisions their contribution is less than 1% of the low energy SE, ensuring that the VPSE is genuinely secondary electron imaging.