Zworykin , Vladimir Kosma

(1889–1982) Russian–American physicist

Born at Mouron in Russia, Zworykin studied electrical engineering at Petrograd (now St. Petersburg), graduating in 1912. During World War I he served as a radio officer in the Russian army. He moved to America in 1919 and joined the Westinghouse Electric Corporation in 1920. He did graduate research at Pittsburgh University, receiving a PhD in 1926. In 1929 he joined the Radio Corporation of America. Zworykin made a number of contributions to electron optics and was the inventor of the first electronic-scanning television camera – the iconoscope.

The first such device was constructed at Westinghouse in 1923. The principle was to focus an image on a screen made up of many small photoelectric cells, each insulated, which developed a charge that depended on the intensity of the light at that point. An electron beam directed onto the screen was scanned in parallel lines over the screen, discharging the photoelectric cells and producing an electrical signal.

Zworykin also used the cathode-ray tube invented in 1897 by Karl Ferdinand Braun to produce the image in a receiver. The tube (which he called a ‘kinescope’) had an electron beam focused by magnetic and electric fields to form a spot on a fluorescent screen. The beam was deflected by the fields in parallel lines across the screen, and the intensity of the beam varied according to the intensity of the signal. In this way it was possible to reconstruct the electrical signals into an image. In 1923 an early version of the system was made and Zworykin managed to transmit a simple picture (a cross). By 1929 he was able to demonstrate a better version suitable for practical use.

Zworykin also developed other electron devices, including an electron-image tube and electron multipliers. In 1940 he invited James Hillier to join his research group at RCA, and it was here that Hillier constructed his electron microscope.