A passion for research and technology: here are the stories of some of the internationally acclaimed scientists who’ve worked at our company over the last century.
Werner Bolton

Werner Bolton (1868–1912)

Werner Bolton completed an internship at Siemens & Halske while still at university. In 1896, after obtaining a doctorate in chemistry, he started work in the laboratory of the Glühlampenwerk, the company’s incandescent lamp factory. His first task, assigned to him by Wilhelm von Siemens, was to improve lamp technology.


In 1903, Werner Bolton became the first person to successfully replace carbon filaments, which had been standard in incandescent lamps until that time, with stable metal filaments made of tantalum. Siemens began marketing tantalum lamps in 1905, scoring a technological breakthrough in the area of electrical illumination. 


In July of 1905, Werner Bolton was appointed head of the first Siemens laboratory independent of the company’s day-to-day business activities. This facility, the Versuchslaboratorium Bolton, the Bolton experimental laboratory, was initially located in the Moabit district of Berlin. In 1906, the laboratory was renamed the Physikalisch-Chemisches Laboratorium and moved to a new building on the grounds of what would later become Siemensstadt, the company’s main Berlin campus.

Bodo von Borries

Bodo von Borries (1905–1956)

Bodo von Borries, a university-trained mechanical and electrical engineer, came to Siemens in Berlin from the German utility company Rheinisch-Westfälische Elektrizitätswerke in 1934. Appointed to head a laboratory at Siemens-Schuckertwerke’s switchgear factory, his scientific research initially focused on the development of overvoltage protection devices. 


In 1937, Borries was appointed to set up and manage Siemens & Halske’s electron optics laboratory. In 1939, he and the physicist Ernst Ruska completed development of the first commercially viable electron microscope for series production, the Siemens Super Microscope. The two scientists had already conducted basic research in electron microscopy at the Technical University of Berlin at the beginning of the 1930s.


In 1948, Bodo von Borries left the company to set up an institute for hyper microscopy in Düsseldorf, Germany. Until his death in 1956, he played a key role in the foundation of a number of scientific societies in the area of electron microscopy.

Dennis Gábor

Dennis Gábor (1900–1979)

A native of Hungary, Dennis Gábor came to Berlin in 1921 to study electrical engineering at the city’s Technical University. In 1927, after obtaining his doctorate, he began work in the physics laboratory of Wernerwerk Meßtechnik und Medizinische Technik, Siemens & Halske’s metrology and medical engineering facility.


For the next six years, Gábor worked, among other things, on the further development of cathode ray oscilloscopes. These measuring devices enabled their users to visibly represent oscillating electric voltages. Ernst Ruska and Max Knoll used Gábor’s discoveries in their own research in microscopy. Dennis Gábor also made major contributions in the areas of gas discharge and plasma physics.


In 1933, he returned temporarily to Hungary before emigrating to England in 1934. From 1934 to 1948, he conducted research for the Thomson-Houston Company Ltd. in Rugby. It was there that, while attempting to improve the electron microscope, he somewhat accidentally developed holography in 1948. For the invention and further development of this process, Dennis Gábor was awarded the Nobel Prize for Physics in 1971.

Gustav Hertz

Gustav Hertz (1887–1975)

Gustav Hertz was awarded the Nobel Prize for Physics jointly with James Franck in 1925. The two scientists were honored for discovering the laws governing the collision of an electron with an atom (Franck-Hertz experiment). In 1927, Hertz was made a full professor of physics and appointed director of the Physics Institute at Berlin Technical University. In 1934, he resigned his position as institute director. Due to his Jewish origins, he was forced to resign his professorship in 1935.


In July 1935, Hertz was appointed head of the Siemens Research Laboratory II, which had been established especially for him. Under his leadership, research at this laboratory – which worked for both Siemens & Halske and Siemens-Schuckertwerke – was conducted in the areas of gas discharge, electron physics and, above all, nuclear physics. For one year, starting in April 1944, Hertz was responsible for all central research activities at Siemens.


In July 1945, he and some of his former students and colleagues were transported to the Soviet Union in order to set up a physics institute on the Black Sea. In 1954, Gustav Hertz returned to Germany, where he was appointed head of the Department of Experimental Physics at the University of Leipzig.

Ernst Ruska

Ernst Ruska (1906–1988)

While still studying electrical engineering at Berlin Technical University, Ernst Ruska – together with his supervisor Max Knoll – discovered that objects penetrated by electron beams could be magnified one or more times by means of "magnetized lenses." In 1931, the two physicists developed the prototype of a microscope that used electrons rather than light. However, the first electron microscope was less powerful than its optical counterparts. 


In 1937, Ernst Ruska moved to Siemens & Halske’s Laboratorium für Elektronenoptik, which was headed by Bodo von Borries. By 1939, he and Borries had developed the first commercially viable electron microscope – the Siemens Super Microscope – for series production. The device opened up a wide range of application fields – above all, in the areas of medical and biological research.


After Borries left Siemens & Halske in 1948, Ruska was appointed head of the Siemens research laboratory, whose development activities resulted in the construction of the first high-resolution electron microscope, the ELMISKOP. In 1954, the first such device to be manufactured in series production was presented to the general public in London.


In 1955, Ernst Ruska moved to the Max Planck Institute. Jointly with Gerd Binnig and Heinrich Rohrer, the inventors of the scanning tunnel microscope, he was awarded the Nobel Prize for Physics in 1986.

Walter Schottky

Walter Schottky (1886–1976)

Walter Schottky studied physics and chemistry in Berlin. For his dissertation on the special theory of relativity, which was supervised by Max Planck, he was awarded a doctoral degree in 1912. He then accepted a position at the University of Jena, where he devoted himself to theoretical and experimental research on electron tubes. He succeeded in mathematically deriving the behavior exhibited by electrons when they pass through a vacuum tube.


At the beginning of 1915, Schottky accepted an offer to cooperate as a freelancer in tube development at Siemens & Halske in Berlin. He received a full employment contract somewhat later, advancing after only two years to become scientific head of the company’s low-voltage cable laboratory. While in this position, Schottky formulated a theory related to his previous discoveries regarding physical processes in vacuum tubes. On the basis of this theory, he succeeded in developing the screen grid amplifier tube at the beginning of 1916.


In 1919, Schottky left Siemens to teach theoretical physics – first at Würzburg University and then in Rostock, Germany. In 1927, he returned to Siemens & Halske as a "scientific advisor." Together with his assistant Eberhard Spenke, he conducted basic research in semiconductor physics and electronics. In 1938, Schottky began the three-step publication of his boundary layer theory (also known as the space-charge theory of the barrier layer), which was to prove a groundbreaking innovation in the field of semiconductor technology.


In 1944, Schottky moved from war-torn Berlin to Pretzfeld, a small town in the mountainous region of Bavaria known as Franconian Switzerland. After World War II, Siemens-Schuckertwerke established a semiconductor laboratory in Pretzfeld under the leadership of Eberhard Spenke. Schottky continued his research at this laboratory until his retirement in 1951.

Ferdinand Trendelenburg

Ferdinand Trendelenburg (1896–1973)

The physicist Ferdinand Trendelenburg began working at Siemens’ central research laboratory in Siemensstadt, the company’s main Berlin campus, in 1922. In 1929, he was appointed head of the company’s Engineering Physics Department. His pioneering achievements in electro-acoustics followed in quick succession. These included an acoustic recording process that made it possible to record frequency-modulated sound using a condenser microphone. He also used the properties of this microphone to examine heart and respiratory sounds.


While continuing to work for Siemens, Trendelenburg began teaching at the University of Berlin in 1929. After World War II, he worked for a short time at the German-French Laboratoire de Recherches Balistiques et Aérodynamiques in Weil am Rhein, Germany (1949-50).


In 1951, he was appointed to head Siemens-Schuckertwerke’s new Allgemeines Laboratorium, the company’s general laboratory, in Erlangen, Germany. Under his leadership, this facility – which was renamed the Forschungslaboratorium der Siemens-Schuckertwerke in 1953 – subsequently became a leading research and development center. Ferdinand Trendelenburg retired in the fall of 1962, having conducted research at Siemens for nearly 40 years.

Heinrich Welker

Heinrich Welker (1912–1981)

In 1951, the physicist Heinrich Welker was appointed head of the Solid State Physics Department at Siemens-Schuckertwerke’s general laboratory in Erlangen, Germany. In the same year, he discovered the III-V compounds of elements from the third and fifth groups of the periodic table. This discovery led to the widespread application of galvanomagnetic and optoelectronic effects as well as to completely new switching elements in microelectronics. These elements included gallium arsenide, which is still a key building block of high-frequency components and semiconductor lasers for optoeletronic systems.


In 1961, Welker was appointed general director of Siemens-Schuckertwerke’s research laboratory. He and the research team he created there paved the way for the development of microwave semiconductor elements, LEDs and laser diodes based on compound semiconductors.


In 1969, after the establishment of Siemens AG, the research laboratories of Siemens-Schuckertwerke in Erlangen were combined with those of Siemens & Halske in Munich and placed under the direction of Heinrich Welker, who headed the electrical engineering company’s central research and development activities from 1973 to 1977. 

Willi Kalender

Willi Kalender (*1949)

Willi Alfred Kalender joined Siemens AG in Erlangen in 1976 as a research assistant in the Medical Engineering Group. After earning his doctoral degree in 1979, he worked at a Siemens Medical Systems research laboratory and went on to head the Medical Physics department from 1988 to 1995.


During his time at Siemens, the research of this physicist and mathematician primarily focused on the area of diagnostic imaging. He is credited with inventing spiral computed tomography. By the mid-1980s, development of existing computed-tomography (CT) technology was thought to have run its course. Nevertheless, Kalender and his team in Erlangen managed to make a breakthrough. With the introduction of the SOMATOM Plus-S in 1990, after several years of research, Siemens presented one of the biggest innovations in diagnostic imaging technology: spiral CT. The approach was based on slip-ring technology and enabled continuous rotation of the tube and the detector combined with simultaneous continuous forward movement of the examination table. A special algorithm corrected the image data by removing blur due to artifacts caused by motion. This advance reduced examination time considerably and enabled full-body scans and a level of precision unheard-of up to that time.


Willi Kalender left Siemens in 1995 and became chair of diagnostic imaging at the newly founded Institute of Medical Physics at the Friedrich-Alexander-Universität Erlangen-Nürnberg, a position that he still occupies today. In 1992, while still working at Siemens, he became  a visiting professor at the University of Wisconsin. He has received numerous awards for his contributions to the field of medical imaging. Kalender currently holds 15 patents, has published just over 1,000 research papers and has advised more than 100 young doctoral candidates on their dissertations.


Highlights from more than 170 years of Siemens history

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