In 1954, Charles Townes and Arthur Schawlow invented the maser (microwave amplification by stimulated emission of radiation), using ammonia gas and microwave radiation - the maser was invented before the (optical) laser. The technology is very close but does not use a visible light. On March 24, 1959, Charles Townes and Arthur Schawlow were granted a patent for the maser. Patent Number(s) 2,879,439; 2,929,922Theory of the Laser:
In 1958, Charles Townes and Arthur Schawlow theorized (but did not build) about a visible laser, an invention that would use infrared and/or visible spectrum light.
Charles Townes - Biography:
Charles Townes was born in Greenville, South Carolina on July 28 1915. During World War II, Townes was employed at Bell Telephone Laboratories Inc., where he worked on radar bombing systems. Beginning in 1948, he began work on the maser at Columbia University. Charles Townes was the director of research at the Institute for Defense Analysis in Washington, D.C. from 1959 to 1961. After that, he became the professor of physics at Massachusetts Institute of Technology. In 1964, Townes was awarded the Nobel Prize for Physics for his research in quantum electronics.
Arthur Schawlow was born in Mount Vernon, New York, on May 5 1921. In 1941, he received a bachelor's degree in physics and mathematics from the University of Toronto. He later his master's degree and Ph.D. in physics from the same university. Arthur Schawlow met Charles Townes at Columbia University, where he was doing research. In 1981, Schawlow was awarded the Nobel Prize for Physics for his research in laser spectroscopy