Oxford Applied Research

Analysers WA/VM

The range of VSW CLASS analysers provide unparalleled versatility and performance for spectroscopy and research applications in surface science.

The range is modular allowing flexibility and range of entry level. Each analyser can be upgraded with the latest developments in lens or detector technologies. The analysers are based on precision engineered double focusing and fully mumetal screened hemispheres of 100 mm or 150 mm mean radius.

There are two basic series of CLASS analysers, the CLASS VM for small area analysis/high angular resolution and the CLASS WA range for applications requiring high angular acceptance and maximum throughput.



Class WA

For applications requiring the highest sensitivity CLASS WA combines all the advanced features of the CLASS range with the addition of the high transmission wide angle of acceptance lens. This new lens system ensures maximum sensitivity by having both a large angle of acceptance, and a large field of view, giving high collection efficiency for both small excited area applications (Synchrotron, Auger, UPS, Mono XPS) and standard XPS.


Class VM

Small area analysis is a powerful facility in XPS adding spatial resolution information to this important analysis technique.

The CLASS VM range provides variable area analysis by the use of state-of-the-art electrostatic lens design, allowing small spot XPS analysis to be done with either flood or focused X-ray excitation sources. In conventional hemispherical analysers the area of analysis is defined by the entrance aperture of the analyser. In the VM variable magnification lens system the analysed area is selected by purely electrostatic means with no additional lens aperturing. This ensures maximum transmission through the lens even down to the smallest analysis areas.

The change in magnification is performed electronically from the analyser control electronics, eliminating mechanical alignment problems associated with mechanical lens apertures.

All CLASS VM modules include the small spot lens mechanics as standard, allowing the upgrade to variable area analysis by a simple upgrade of the control unit and software. Ratemeter or computer acquisition and control with single or multichannel detection options make the CLASS VM range the most versatile hemispherical analyser packages available.


  • True focusing 180 degree geometry.
  • ALL UHV compatible construction.
  • Automatic fringe field correction using molybdenum electrodes.
  • Guaranteed non magnetic construction using aluminium and OFHC copper.
  • GRAPHITE coated hemispheres for even work function throughout.
  • Magnetic shielding by interlocking mu-metal screens on analyser and lens.
  • Slot in outer hemisphere for accurate through the lens alignment and beam dump for high energy electrons.