Werner Bolton, undated

Werner Bolton, the inventor of the tantalum lamp, began his career at Siemens & Halske as an intern while a student of chemistry in Berlin and Leipzig. In 1896 he joined the company as head of a laboratory in the company's incandescent lamp factory. In 1902 Bolton made the discovery that tantalum was the ideal material for making metal filaments, at a time when the only lamps on the market had carbon filaments. The first metal-filament incandescent lamps were available on the market in 1905 and by 1914 over 50 million had been produced worldwide using Bolton's method. In 1905 he also took over as head of the company's first central laboratory, which was renamed the Physics and Chemistry Laboratory shortly afterwards. Here the wolfram filament was produced as the next generation of metal filaments.

Bodo von Borries, 1939

Bodo von Borries was already conducting basic research in the field of electron microscopy together with Ernst Ruska at the Technical University of Berlin before he joined Siemens as head of the laboratory in the Schaltwerk of Siemens-Schuckertwerke in Berlin-Siemensstadt in 1934. Until 1937 he worked on overvoltage protection at the Siemens Schaltwerk. He was subsequently responsible for establishing and running Siemens & Halske's Laboratory for Electron Optics. It was here that Bodo von Borries and Ernst Ruska developed the electron microscope, and around 35 different apparatuses were mass-produced for research purposes up until 1945. Bodo von Borries was also a cofounder of the German Association for Electron Microscopy.

Dennis Gabor, undated

Dennis Gabor started work in the Physics Laboratory of the Wernerwerk M (measuring and medical equipment) in 1927. In the following six years Gabor, who had a doctorate in physics, conducted research in areas such as gas discharge and plasma physics. He also worked on the verifiability of mitogenetic radiation during cell division in organisms and was involved in the development of cathode ray oscillographs and cadmium high-pressure burners. In 1933 Gabor, who was Hungarian by birth, emigrated to England, where he worked as a research engineer for the British Thomson-Houston Company Ltd. Here, in 1948, he developed holography, more by chance as a result of an attempt to improve the resolution of the electron microscope. For the invention and further development of this procedure, Dennis Gabor was awarded the Nobel Prize in Physics in 1971. From 1949 to 1967 he was Associate Professor and subsequently Professor at the London Imperial College of Science and Technology. After his retirement, Gabor worked in the research laboratories of Columbia Broadcasting System (C.B.S.) in Stanford, Connecticut, U.S., and in London and Rome. He is also one of the founding members of the “Club of Rome”. Dennis Gabor died in 1979 in London.

Friedrich von Hefner-Alteneck, 1870

With the invention of the drum armature in 1872, the chief engineer at Siemens & Halske, Friedrich von Hefner-Alteneck, succeeded in developing a marketable form of the dynamo machine, which is still used in basically the same form in electrical machines today. In the lighting area he set new standards with a self-regulating differential arc lamp, with which streets could be lit very brightly as well as safely and economically. In 1884 he invented a laboratory light standard, the Hefner lamp, which provided light of a precise intensity (= 1 Hefner Kerze, named after the inventor). In 1886, together with Carl Hoffmann, Hefner-Alteneck developed a direct current revolving field machine, which influenced the development of power plant construction for over a decade. When Werner von Siemens withdrew from the company management in 1889, Friedrich von Hefner-Alteneck, one of his closest and longest-standing colleagues, also left the company. He was a member of the Berlin Academy of Sciences and in 1897 was awarded an honorary doctorate in Munich.

Gustav Hertz, 1913

Gustav Hertz, the nephew of Heinrich Hertz who discovered electromagnetic waves, also studied physics and in 1911 became an assistant at the Physics Institute of Berlin University. While still only a young man, together with James Franck he studied the effects on electron beams of collisions with gas molecules. For their discovery of the laws governing the impact of an electron on an atom, Franck and Hertz received the Nobel Prize for Physics in 1925. From 1935 to 1945 Gustav Hertz ran the Siemens Research Laboratory II, which was founded especially for him. The projects completed here during this period included the development of a cyclotron with an 80-ton magnet. At the end of the 1930s, Hertz also conducted basic research at Siemens in the area of electroacoustics. In 1945, together with former students and colleagues, he established an institute in the former Soviet Union and in 1954 he became head of a university institute in Leipzig.

Ernst Ruska, 1939

When he was still only a student, Ernst Ruska discovered the principle of electron microscopy when he established that electron beams can be focused like light in a lens. His electron lens was a magnet, and in its field the electrically charged elementary particles were deflected from their path. In 1931, together with Bodo von Borries and Max Knoll at the Technical University in Berlin, he built the first microscope that functioned according to this principle. In 1939 Ruska and von Borries developed a marketable electron microscope in the Siemens Laboratory for Electron Optics and Electron Microscopy. When Borries left the laboratory in 1948, Ruska succeeded him as its director, and continued to contribute substantially to the improvement of the microscope in subsequent years. Ernst Ruska, who had received many awards for his pioneering work, received the Nobel Prize for Physics in 1986.

Walter Schottky, lecturing at the Fritz-Haber-Institut, Berlin 1953

From 1912 on, the theoretical investigations of the physicist Walter Schottky had a major influence on the development of telecommunications. The invention of the screen grid tube and the tetrode, the theory of shot noise (Schottky effect) and the invention of the superheterodyne receiver are all Schottky's work, the outcome of his research from 1915 to 1919 as a scientist in the Weak Current Cable Laboratory of Siemens & Halske. After teaching at the universities of Würzburg and Rostock, Schottky worked again in the research laboratory of Siemens & Halske and the Siemens-Schuckertwerke in Berlin and Pretzfeld from 1927 to 1951. Among Schottky's major achievements was the development of a theory (1938) which explained the rectifying behavior of a metal-semiconductor contact as dependent on a barrier layer at the surface of contact between the two materials, and revolutionized semiconductor technology. The scientist, who died in 1976, received numerous awards during his lifetime.

Ferdinand Trendelenburg, ca. 1965

Ferdinand Trendelenburg began work in the Siemens Research Laboratory after obtaining his doctorate in 1922 and worked for the company virtually until he retired in 1962. He was primarily involved with basic research in the areas of acoustics and structural analysis. Trendelenburg's work paved the way for the introduction of objective sound recording. He was also involved in the development of special amplifiers for heart diagnosis. In 1951 Trendelenburg became head of the newly founded General Laboratory of Siemens-Schuckertwerke in Erlangen, which was renamed "Research Laboratory" in 1953. Here he was involved in research in the areas of semiconductor technology, plasma physics and radiochemistry. His publications, including "Klänge und Geräusche" (Sounds and noises) (1935) and "Einführung in die Akustik" (Introduction to Acoustics) (1939) were highly respected by experts worldwide.

Heinrich Welker, 1970

After numerous scientific activities, Heinrich Welker joined the General Laboratory of Siemens-Schuckertwerke in Erlangen in 1951 as head of the department of solid-state physics. In the same year he discovered the III-V connections (from the 3rd and 5th group in the classification of elements) and predicted their semiconductor properties. His findings led to the widespread exploitation of galvanomagnetic and opotelectrical effects and new switching circuits in microelectronics. Welker and the research group he built up paved the way for microwave semiconductor elements and luminescent and laser diodes. From 1961 to 1969 he was head of the Siemens-Schuckertwerke's research laboratory in Erlangen and from 1969 until he retired in 1977 was head of all the company's research laboratories.