Gaslaser

Gas laser is a type of laser in which the lasing medium is a gas or gas mixture. The gas is typically excited by an electrical discharge or radio-frequency field to create a population inversion, and photons produced by stimulated emission are amplified by an optical cavity formed by mirrors. Gas lasers are valued for high beam quality, good coherence, and a wide range of usable wavelengths, from the ultraviolet to the infrared.

Most gas lasers rely on energy transfer processes that populate specific electronic, vibrational, or rotational levels. An electrical discharge sustains the excited states, while a resonator of high-reflectivity mirrors provides feedback and selects the lasing mode. Gases are maintained at low to moderate pressures and cooled to preserve stability and component lifespan. The exact transitions determine the output wavelength and efficiency, which can vary widely among designs.

Common types include helium–neon lasers, which emit primarily at 632.8 nanometers and are widely used for alignment and metrology; carbon dioxide lasers, operating around 10.6 micrometers and favored for cutting and welding; argon ion lasers, producing visible lines such as 488 nm and 514.5 nm; nitrogen and related transitions that yield ultraviolet light; and mid-infrared systems such as hydrogen fluoride and deuterium fluoride lasers used in spectroscopy.

Applications span scientific research, optical alignment, holography, materials processing, spectroscopy, and medical instrumentation. Advantages include tunable wavelengths, good beam quality, and rapid pulsing in some designs; limitations involve gas handling, system size, efficiency, and the need for robust cooling and high-voltage power supplies. The development of gas lasers began in the 1960s and has evolved with decades of industrial and scientific use.