Zoltán Lajos Bay (July 24, 1900 in Gyulavári – October 4, 1992 in Washington, D.C.)[1] was a Hungarian physicist, professor, and engineer who developed microwave technology, including tungsten lamps. He was the second person to observe radar echoes from the Moon. From 1930, he worked at the University of Szeged as a professor of theoretical physics.
In 1923 at Tungsram Ltd., a research laboratory was established for improving light sources, mainly electric bulbs.

In 1955, Zoltán Bay became head of the Department of Nuclear Physics in the National Bureau of Standards (NBS, called today NIST), where he measured the velocity and frequency of light by a previously unknown measurement method. As a result of Zoltán's research, the 1983 conference of the International Weights and Measures Bureau accepted, as a standard, the definition of a meter (metre) as recommended by Zoltán Bay.