Variable pressure SEM and SEM with X-ray micro-analysis

Backscattered electron image of a meteorite

Backscattered electron image of a thick section of the Vigarano meteorite. This carbonaceous chondrite section was imaged using Oxford Instruments INCA automated montaging software. 

Key facts

Techniques: variable pressure SEM, SEM with X-ray micro-analysis

Magnifications: 20x-60,000x

Image output: 8-bit TIFF, up to 3072x2304 pixels

Large chamber accommodates samples up to: 15x15x15 centimetres

The LEO 1455VP is a highly versatile scanning electron microscope (SEM) that can be used for both imaging and analysis of specimens. It can operate in two modes - variable pressure and high vacuum.

Low-vacuum mode (variable pressure)

  • for imaging and qualitative X-ray analysis of uncoated and delicate material including type specimens
  • pressure may be increased to as much as 200 pascals, although best image resolution will be obtained at approximately 10-60 pascals

High-vacuum mode

  • for imaging and quantitative analysis
  • at short working distances images may be obtained at magnifications in excess of 10,000x, giving submicron resolution 

Other features

The LEO 1455VP SEM can accommodate long working distances for imaging at low magnifications (x20).

A Peltier cooling stage can be attached for freezing samples down to -30ºC, useful for imaging specimens that may otherwise dehydrate with the SEM.

The instrument can also operate in scanning transmission electron microscope (STEM) mode using a dedicated detector, and can be used for energy dispersive X-ray spectroscopy (EDX) analysis.

About EDX analysis

Energy dispersive X-ray spectroscopy (EDX) is a kind of scanning electron microscopy that involves X-ray micro-analysis. The key features of this technique are:

  • Non-destructive qualitative analysis can be carried out for elements with an atomic number greater than five.
  • Detection limits are of the order of 0.2 weight per cent, dependent on the type of specimen, elements of interest, etc.
  • Analyses can be undertaken in spot mode or the beam can be scanned to acquire X-ray element maps of areas of the sample surface.
  • Automated image and elemental analysis can be carried out over large specimen areas using Oxford Instruments INCA software's feature mode.
  • Backscattered electron and X-ray element map montages can be acquired and automatically stitched using Oxford Instruments INCA software's montage mode.

Museum lead

Dr Alex Ball, Head of Imaging and Analysis


  • secondary electron detector
  • four-quadrant solid state backscattered detector
  • variable pressure secondary electron detector
  • energy dispersive X-ray (EDX) detector (Oxford Instruments X-Max detector)