Ruska was born in Heidelberg, Germany, on December 25, 1906. He wasthe fifth child of Julius Ferdinand Ruska, an Asian studies professor, and Elisabeth (Merx) Ruska. After receiving his undergraduate educationin the physical sciences from the Technical University of Munich and theTechnical University of Berlin, he was certified as an electricalengineer in 1931. He then went on to study under Max Knoll at Berlin, and received his doctorate in electrical engineering in 1933. During thisperiod he and Knoll created an early version of the electron microscope,and Ruska concurrently was employed by the Fernseh Corporation in Berlin,where he worked to develop television tube technology. He left Fernseh tojoin Siemens as an electrical engineer, and at the same time accepted aposition as a lecturer at the Technical University of Berlin.
His ability to work in both academic and corporate milieus continued through his time at Siemens, and expanded when in 1954 he became a member of the Max Planck Society. In 1957 he was appointed director of the Society's Institute of Electron Microscopy, and in 1959, he accepted the TechnicalUniversity of Berlin's invitation to become professor of electron optics and electron microscopy. He remained an active contributor to his field until his retirement in 1972.
Prior to Ruska's invention of the electron microscope in 1931, the field of microscopy was limitedby the inability of existing microscopes to see features smaller than the wavelength of visible light. The conception that it was possible to construct a microscope that used electrons instead of light was realized in thelate 1920s when Ruska was able to build a short-focus magnetic lens using a magnetic coil. A prototype of the electron microscope was then developed in 1931 by Ruska and Max Knoll at the Technical University inBerlin. Although it was less powerful than contemporary optical microscopes, the prototype laid the groundwork for a more powerful version, which Ruska developed in 1933. That version was ten times stronger than existing light microscopes. Ruska subsequently worked with the Siemens Company to produce for the commercial market an electronmicroscope with a resolution to onehundred angstroms (by contrast, modern electron microscopes have are solution to one angstrom, or one ten-billionth of a meter).
Ruska's microscope--called a transmission microscope--captures on a fluorescent screen an image made by a focused beam of electrons passing through a thin slice of metalized material. The image can be photographed. In 1981 Gerd Binnig and Heinrich Rohrer took Ruska's concept further by using a beam of electrons to scan the surface of a specimen (rather than to penetrate it). A recording of the current generated by the intermingling of electrons emitted from both the beam and specimen is used to build a contour map of the surface. The function of this "scanning electron microscope" complements, rather than competes against, the transmission microscope, and its inventors shared the 1986 Nobel Prize in physics with Ruska.
In addition to the Nobel Prize, Ruska's work washonored with the Senckenberg Prize of the University of Frankfurt am Main in 1939, the Lasker Award in 1960, and the Duddell Medal and Prize of the Institute of Physics in London in 1975, among other awards. He also held honorary doctorates from the University of Kiev, the University of Modena, the Free University of Berlin, and the University of Toronto. Ruska died in West Berlin on May 30, 1988.
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