Pál Selényi was born 135 years ago, on 17th November 1884. As a university teacher and member of the Tungsram Research Laboratory, he contributed to the development of optics, photometrics, vacuum technology, and various other fields of physics. Selényi is probably best known as the father of xerography.
“…Science has its inner drive to eventually turn into a technology; that is, an invention; and basically, the industrial researcher does not do anything else than accelerate this process.”
Pál Selényi started on a splendid academic career when, in 1910, at 26 years of age, he completed his doctoral studies in physics and mathematics. Between 1907 and 1918, he worked as assistant in the Institute of Physics II at the University of Budapest (today Eötvös Loránd University, ELTE). His most famous experiment from 1911 proved – contrary to Einstein’s theory – the wave-like nature of light and that these waves are capable of interference in every direction. These discoveries became important for quantum theory. Selényi received state scholarship to continue research in physics in Berlin and Göttingen. He was called home to perform military service during WWI. Due to his continuing to teach as the successor of Loránd Eötvös during the Hungarian Soviet Republic, he had to leave the University and was banned from state service. In 1921, Professor Pfeifer invited him to be the first to join the Tungsram Research Laboratory.
The citation above expresses Selényi’s conviction about the fundamentally similar nature of basic and applied scientific research, their mutually fruitful relationship, and their equal importance for humanity. Indeed, at Tungsram, the methods of measuring and analysis that Selényi developed, especially that of measuring light intensity, significantly contributed to the development of photocells, and the improvement of incandescent lamp and electron tube production technology. The instrument for measuring the intensity of illumination in cameras, calibrated for the time of exposition, was a by-product of his research on measuring light. Selényi’s pioneering work in electrostatic picture transmission and recording made him the father of xerography, though the business potential of his innovation was not recognized at Tungsram. He was the first to record pictures on selenium as well. In 1939, due to the second Jewish law, he was forced to retire.
Between 1940 and 1949, Selényi worked for a small electrotechnical company where he started the production of selenium rectifiers based on his own patent. During WWII, he had to perform labor service. As a late recognition, in 1948 he was elected corresponding member of the Hungarian Academy of Science; in 1952, he received the Kossuth Prize. From 1950 to 1954, Selényi taught at the Chair for Experimental Physics at ELTE, prepared the jubilee publication of Loránd Eötvös’ works, and organized the prestigious competition of the Loránd Eötvös Physical Society for secondary schools. He died in March 1954. Tungsram remembers him as one of its leading, inspiring researchers.
Picture: Pál Selényi with his electrostatic picture recording device from the 1930s. Koroknay, Ákos (ed.) A Tungsram Rt. története 1896-1996. Aschner Lipót alapítvány, Budapest, 2004, p. 49