Ruby laser weaknesses in the lining. Ruby lasers were used extensively in tattoo and hair removal, but are being replaced by alexandrite and s in this application. The ruby laser was the first laser to be made functional. Built by Theodore Maiman in 1960, the device was created out of the concept of an "optical maser," a maser that could operate in the visual or infrared regions of the spectrum. In 1958, after the inventor of the maser, Charles Townes, and his colleague, Arthur Schawlow, published an article in the "Physical Review" regarding the idea of optical masers, the race to build
X-ray laser The line is mostly Doppler broadened, which depends on the ions' temperature. As the common visible-light laser transitions between electronic or vibrational states correspond to energies up to only about 10 eV, different active media are needed for X-ray lasers. Again, different active media — excited atomic nuclei — must be used if yet higher frequency, gamma ray lasers are to be constructed. Between 1978 and 1988 in Project Excalibur the U.S. military attempted to develop a nuclear explosion-pumped X-ray laser for ballistic missile defense as part of the "Star Wars" Strategic Defense Initiative (SDI). The most often used media