The Invention of the Electron Microscope

The invention

The development of the electron microscope (EM) was based on the discovery that a magnet coil may function as an optical lens. After having shown in his thesis of 1929 that sharp and magnified images of electron-irradiated hole apertures could be obtained with the short coil, Ernst Ruska was now interested in finding out if such images could be further magnified by arranging a second imaging stage behind the first stage. Such an apparatus with two short coils was easily put together. In April 1931 Ruska obtained the definite proof that it was possible. This apparatus is justifiably regarded today as the first electron microscope even though its total magnification of 3.6 x 4.8 = 14.4 was extremely modest.

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 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.

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. 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.

 Ernst Ruska once said that “… occasionally it can be more a matter of luck than of superior intellectual vigour to find a better – or perhaps the only acceptable way”. It maybe that one or the other research performed in Your lab contains inventive steps? Support with respect to pharmaceutical patent inventions one will find at www.pharmoveo.de.

Biography

Ernst Ruska was born 1906 in Heidelberg, Germany. He is the son of a professor. 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. 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. Prof. Dr. Ing. Dr. h.c. mult. Ernst Ruska died in Berlin 1988.

There is a website on his person with more detailled information e.g. the text of his nobel lecture. There is also a book published on his memoires. More information on the inventions he made can also be found on the website of the German Patent and Trademark Office.