(Ernst August Friedrich Ruska, Heidelberg, 1906 – Berlin, 1988) German electronic engineer. He studied at the Technical University of Munich and in Berlin, where he received his doctorate in engineering in 1934. He worked at the Technical University of Berlin, for the company Siemens and the Fritz Haber Institute of the Max Planck Society (Berlin). In 1933 he invented the electron microscope, an instrument of great resolution, Claude A. first applied to biology. In 1986 he received the Nobel Prize in recognition of his merits, sharing it with the inventors of the scanning tunneling microscope, Gerd Karl Binnig physical and Heinrich Rohrer.
Modern electron microscopes, much more powerful than the first prototype Ernst Ruska and Max Knoll constructed in 1932, however maintaining the same principle: the use of a mobile electron beam instead of light to illuminate the subject. electromagnetic lenses produce magnetic fields which deflect the electron beam in the same way that glass lenses direct light rays. However, the object must be in a vacuum because air molecules can deflect electrons. Since electrons have a much smaller wavelength than light, they can show much smaller structures, which allows direct visualization of many molecules and some atoms.
The microscope Ernst Ruska was able to expand the image of an object four times, which meant a great advance over optical microscopes, but small compared to the levels that would reach electron microscopes that were subsequently developed from his idea . The transmission electron microscope produces images of objects in a fraction of a micron or less in thickness, which means that an image can increase a million times. In a transmission electron microscope, the bundle to the object so directed that a part of the electrons are absorbed by it or bounce on it, while the remaining traverse and form a magnified image when focusing to a fluorescent screen or to special photographic plates through the use of magnetic lenses.