The gas laser
The gas laser (light amplification by stimulated emission of radiation) emits a thin, intense beam of light, coherent over time and space, whose wavelengths depend on the gas used.
Lasers have numerous applications: sophisticated tools are commercially available that use lasers, which have often revolutionized measurement techniques such as engineering non-destructive testing, vibration analysis, measures of speed, quality control and surface roughness, micron positioning, control of flatness and inclination, precision measurements at a distance of thicknesses, diameters and distances; lasers have also found applications in medicine, spectroscopy, information technology and graphics, printing techniques and display; with CD and DVD readers and writers, lasers have also entered the market for consumer products.
All these different applications are based on the specific characteristics of coherent beams of laser light; some use only the great brightness and collimation resulting from these properties, others use the more complex features of temporal and spatial coherence, e. g. in flow visualization. Laser sources have not only been successfully used in conventional optical methods but also have developed completely new methods such as holography and holographic interferometry.