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Prof. Dr.Ing. Dr.h.c.mult.

Ernst Ruska

Born: 25 December 1906, Heidelberg

Died: 27 May 1988, Berlin

"... occasionally it can be more a matter of luck than of superior intellectual vigour to find a better - or perhaps the only acceptable way".

Ruska developed the electron microscope and was many years later awarded the Nobel Prize for his findings.

Magnetic coils and pole shoe lenses

In 1925, Ruska took up studies in electrical engineering in Munich, which he pursued in Berlin two years later. From 1928, his studies at the Hochspannungsinstitut (institute of high voltage technology) focused on high voltage and vacuum technology. At that time, he discovered the basic principle of electron microscopy. He joined a project group headed by Dr. Max Knoll. This group built the first functioning electron microscope in 1931. For the first time, sharp images were obtained by means of electron beams. In 1933, pole shoe lenses developed in cooperation with Dr. Knoll allowed to obtain the first images magnified 12,000 times, surpassing the resolution capacity of the light microscope. In the same year he gained his doctorate.

Electron microscope

The development of the electron microscope (EM) was based on the discovery that a magnet coil may function as an optical lens. Instead of light, the EM uses focused electrons accelerated by high voltage within a vacuum for imaging extremely small objects. The magnified image can be viewed on a fluorescent screen.
The type of microscope designed by Ruska is called transmission electron microscope. The electron beam passes through the specimen being observed that must be sufficiently thin.
The resolution (i.e. the minimum distance between two points that are perceived as separate by the human eye) of EMs is considerably higher than the resolution of light microscopes since the wavelength of the used electron beams is 10,000 times lower than that of light. Conventional light microscopes have a resolution of about 4,000 Å (1 Å, Angström = 10-8 cm), whereas EM resolution averages 1 Å.

Nobel laureate

Ruska left the university to pursue his research in the field of electron optics in industry and joined Siemens & Halske, where he developed an electron microscope together with Dr. Bodo von Borries. This serially produced EM was put on the market in 1939.
From 1949 to 1971 he gave lectures at the Freie Universität and Technische Universität of Berlin. In 1955, he left Siemens & Halske AG to become Director at the Institut für Elektronenmikroskopie (institute for electron microscopy) of today's Fritz-Haber-Institut of Max-Planck-Gesellschaft.
Ruska considerably improved the research tool over the years.
In 1986 he was awarded the Nobel Prize in Physics together with Dr. Gerd Binning and Dr. Heinrich Rohrer.

Patent search

To find out more about Ernst Ruska's patents, go to DEPATISnet

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Foto Ruska
© T. Ruska

Patent document DE-680284

"Magnetische Sammellinse kurzer Feldlänge"

(PDF - 136 KB)

"Electron microscopy"

Dr. Kerschbaumer, E.

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