Scanning Electron Microscopy


New possibilities for the application of high current density magnetic electron lenses in commercially produced electron microscopes are discussed. The optimum current density in the windings of a commercially produced instrument has been determined. An improved indirect water cooling arrangement with a closed, vibration-free, cooling circuit has been found to be a reliable and practical system. This has been made possible by a substantial improvement in the method of manufacturing wire coils, leading to a greatly increased heat transfer. The reduced dimensions of such. coils have made it possible to design a general purpose lens body, that is readily adapted to the various imaging modes required in practice. The optical properties of a new combined condenser-objective-diffraction lens, exploiting the best features of conventional and non-conventional lenses, allows one to achieve new imaging modes, e.g. low-angle selected area diffraction or combined convergent-beam electron diffraction and high resolution imaging. This compact but complex lens unit requires microprocessor control of the lenses to ensure rapid and convenient transfer between the various imaging modes that are available. Fortunately systems for implementing this are now currently available.

Included in

Life Sciences Commons