Specific features of the miniature ionisation BSE multi-detector unit for 3D imaging in environmental conditions.

The author has been striving to develop SEM equipment that could extend the capabilities of standard instruments to allow advanced environmental techniques, including 3D imaging. Now its improved version is presented in a form of the miniature ionisation multi-detector unit that can be accommodated inside a bore of the objective lens and does not limit the minimal Working Distance (WD). The miniature detector unit seems well suited to VP/ESEM of any type to be used instead a standard Pressure Limiting Aperture and even to the classic SEM when combined with the vacuum-detector head and an intermediate vacuum system. An acceptable pressure of the environmental gas (preferably water vapour of ca 10 hPa) and the capability of 3D imaging make this solution particularly suitable in applications for highly hydrated samples of smooth surfaces. The unit can also deliver an abundance of signals which may be a source of better contrasts and additional information when digitally processed. Its present investigations are focused on the surface shape fidelity obtainable with the system working in gaseous environment of air or water and tested on metal and glass wires or hydrated organic samples. The detector unit may be reckoned an underpass electron energy filter which facilitates imaging details under sample surface, the feature demanded strongly in biomedical applications.