diffraction research under Professor Paul Langevin. His studies were interrupted in 1914 by the outbreak of World War I. He returned to Russia and served as an officer in the Russian Army Signal Corps, mostly in radio communications. The Bolshevik Revolution forced him to flee his native country. He made two trips around the world before settling in the United States in 1919. After some odd jobs, such as bookkeeping in the Russian Embassy, he finally joined the staff of Westinghouse Company in Pittsburgh in 1920. He became a U.S. citizen in 1924, the earliest date at which this was possible.

At Westinghouse he worked first on photocells, which at that time were not very sensitive and could not be made uniformly. He greatly improved the method of sensitization using alkali metals. In 1926 he obtained a Ph.D. from the University of Pittsburgh for his work in this field; he also coauthored a book on the subject. But his main interest was television. For years television systems had operated by scanning successive picture elements by means of rotating discs or drums that exposed one element at a time to a photosensitive cell. These systems were very cumbersome, but worse, they worked only for extremely bright scenes, as only the light from the element being scanned was used, while the enormously greater light from all other elements was wasted.

This last question intrigued Zworykin for some years and he finally invented a way to capture all the light from all elements of the frame, rather than just that from the element being scanned, and thereby provided for the first time a means for a viable television system. His idea was to have a vast number of tiny photocells, a “mosaic” of photo-emitting spots, on an insulating sheet such as mica. Actually the spots were tiny islands of silver sensitized by the method he had developed for macroscopic photocells. When



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