JEOL 840A Scanning Electron Microscope

The JEOL 840A Scanning Electron Microscope (SEM) is used for low to medium magnification studies of a variety of specimens; from failure analysis to micro-compositional analysis. Samples of all shapes, sizes and types can be examined using the SEM and it the most heavily used microscope in the Facility.

Some facts about the SEM:

  • Variable accelerating voltage: 200 to 40,000V
  • Variable probe current: 1 x 10-8 to 1 x 10-12 Amps
  • Maximum sample size of 6 in any one dimension
  • Working distances: 8 to 48 mm
  • Sample rotation: 360°
  • Sample tilting: 90°
  • Variable magnification: 10x to 300,000x
  • Maximum resolution: 10 nm
  • Secondary and Backscattered Electron detectors
  • Equipped with EDS capable of detecting Carbon and forming X-ray maps of composition; composition to within 0.1 wt%
  • Integrated digital imaging system
  • Noise reduction through frame averaging
  • Image capture and export in electronic form (TIFF..1 MB), storage on floppy (one image per) or removable Syquest disk (270 MB)
  • Low cost (FREE), medium quality thermal printouts
  • High quality, medium cost Polaroid type 55 film containing both negative and positive











SEM sample results:


iron oxide Organically Deposited Iron Oxide - 10,000x (58 KB)

steal Brittle Fracture of Steel - 500x (64 KB)

EDS Spectra of Nd-Fe-B

Permanent Magnet (7.5 KB GIF)


Learn more about Scanning Electron Microscopes (SEM)