An industrial laser cutter in operation The first working laser was built by American physicist Theodore Maiman in 1960. A laser is a device that creates an intense beam of light called a laser beam. A laser beam is monochromatic: it is made up of light of just one colour of the spectrum. This means that all the light waves in it have the same wavelength. Just as importantly, all the waves are “in phase”, which means that as they leave the laser, their crests and troughs all line up with each other.
How a laser works
How a laser worksThe word “laser” is short for Light Amplification by Stimulated Emission of Radiation. Inside the laser is lasing material, which can be a solid, a liquid or a gas. The atoms of the material are excited or “stimulated” by giving them energy, either in the form of light or electricity. This makes them emit light (a type of radiation), which in turn makes other atoms emit light of the same wavelength. This process creates an intense laser beam.
The wavelength, and so the colour, of a laser beam depends on the lasing material. Some lasers produce ultraviolet or infrared radiation rather than visible light. The lasing material is contained in a tube with a mirror at one end and half-silvered mirror at the other. Light bounces up and down, gaining strength until it is powerful enough to break out.
Low-power lasers can now be used in acupuncture, the technique used in traditional Chinese medical healing practice, instead of the usual insertion of needles into the skin at certain points on the body.
Find the answer