The value of a Cryo SEM system, attached to a conventional SEM, has already been demonstrated in the biological, pharmaceutical, oil, paint, plastics and food industry. Specimens are first rapidly frozen to below -160°C, transferred under vacuum to a cryo preparation chamber, fractured and examined at low KV (uncoated ) in the SEM. The sample is then usually etched, sputter coated and finally examined at 5-15KV. On conventional microscopes, successful cryo images can be obtained at 30,000 - 50,000X magnification at high KV.

With the invention of field emission gun technology, much higher resolution is now achievable at a lower KV. This allows higher resolution information to be visualised from the surface of the sample. To allow this successful resolution, with the low atomic number samples mentioned above, we have to put down a fine grain, artefact free coating of high atomic number material to prevent charging and help reduce beam penetration.