LASER - Light Amplification by Stimulated Emission of Radiation - is known in technology as coherent light : producing / emitting light of in-step waves of identical frequency and phase.
The Third Law of Thermodynamics establishes that the orderliness of a system compounds upon itself as increasing levels of order are introduced. Laser light serves as an excellent and extraordinary example of such increased coherence.
Einstein - in his paper "On The Quantum Theory Of Radiation" ( "Zur Quantentheorie der Stralung" / 1917) - extrapolated upon Max Planck's Law of Radiation / Planck's Constant, Planck - Einstein Equation, describing the proportionality constant of a photon and the frequency of its associated electromagnetic wave.
Advances in technology verified the theory and its associated constants and equations. By the late 1950's - 1957 and on - scientists at Bell Labs, Columbia University and Hughes Research were rapidly approaching the breakthrough from theory to a practical laser.
Hughes Research Labs - in Malibu, California - constructed the first functioning laser (1960). A synthetic ruby crystal produced red laser light. Further research led to the development of the first gas laser - using Helium and Neon, a laser diode - made of gallium arsenide - and other variants of diode lasers.
Over the years, the range of laser types has blossomed : Gas - Chemical - Excimer - Solid State - Fibre-hosted - Photonic Crystal - Semiconductor - Dye and Free Electron lasers have been adapted for many different elements of use, including :
Medicine - / Bloodless surgery, eye treatment and dentistry -
Industry - / Cutting, welding and marking -
Defence - / Monitors, countermeasures and alternatives to radar -
Outer Space - / Measurements of different cosmic bodies -
Research - / Spectroscopy, scattering and interferometry -
Cosmetics - / Treatments for skin and hair conditions -
Business - / Scanners and readers -
Entertainment - / DVD players, CD players and light shows -
The future of laser technology carries the promise of greater knowledge, higher quality sound and visual entertainment and increasing improvements in our standard of living.