01.04.2007 - 1907 - 2007 | Manfred von Ardenne | Episode 4: Scanning Electron Microscope

Euphoria about the fantastic possibilities of the transmission electron microscope developed by Ruska had hardly calmed down when it became more and more clear that its theoretical resolution capacity in practice could never be reached.

This was due to classic abberation. Furthermore, the thermal load on the samples to be examined required intricate preparation methods for medical and biological applications.  
"But then on 16 February 1937 -  inspired by the principal of picture segmentation of the electronic television - suddenly the idea of a totally different reproduction principle came into my mind", von Ardenne later remembered: It was not the primary electron beam modulated by intensity which was needed for picture composition but the emission electrons produced as a sideeffect by the electron beam on the sample. Within a few hours I set out these thoughts in writing and started immediately afterwards with their practical implementation. It was only then that the material advantages of this new reproduction principle became visible: the unbelievable depth of sharpness and comparably low thermal load of the preparations to be examined."  
It can be stated today without exaggeration that hardly any other technical device has more revolutionalized material research, biomedical sciences and medicine than the Scanning Electron Microscope.  

From: G. Barkleit: "Manfred von Ardenne - Selbstverwirklichung im Jahrhundert der Diktaturen" (Manfred von Ardenne - Self-fulfilment in the Century of the Dictatorships), Publisher: Duncker & Humblot, Berlin (2006)