You might remember Dr. Evil’s pool of sharks with “frickin’ laser beams attached to their heads,” but do you know how a laser beam actually works? We don’t have Dr. Evil here to help us explain it, but we’ll do our best.
Laser (“Light Amplification by Stimulated Emission of Radiation”) was first termed in 1959. Since then, lasers have been integrated in many devices and have many uses. There are a lot of household uses for lasers as well as in the industries of science, technology, and the environment.
Lasers need electricity in order to produce a source of light. The beam a laser produces comes from energy being pumped through a type of material.
A laser resonator uses mirrors to produce the laser beam. The type of mirror used will determine the quality and output of the laser beam. The type of mirror used in laser resonators is a dielectric mirror. A dielectric mirror is one that is coated with transparent, optical materials. Usually two types of materials are used. Glass is coated using transparent material or thin-film material.
The use of dielectric mirrors assures a very high reflectivity, usually above 99%. The unique properties of dielectric mirrors make them very different from household mirrors, which are silver-coated. A dielectric mirror has a very low reflective property in the visible light spectrum, so that they appear to the human eye as color rather than a reflection of an object.
The number of layers used in the coating of a laser mirror determines the way in which the mirror is used in the construction of the laser. A laser mirror can be either a plane (flat surface) mirror or a concave (curved) mirror.
The type and intensity of the laser beam depends on the materials used to produce the light, and the speed at which the photons (single light atoms) are moving through the laser resonator. The type of laser mirror also affects the light intensity.
The first working laser came on the scene in 1960. This was a ruby laser. Ruby is an aluminum oxide crystal material. In order to produce the red beam, some of the aluminum oxide is replaced with chromium oxide. Since chromium atoms have the elemental property of absorbing green and blue light, they reflect or give off only red light.
Laser mirrors are used in the laser resonator to provide the reflective power. The mirrors cause the light photons to bounce back and forth between the mirrors at a high rate of speed. The faster the light travels between the mirrors, the more energy, or radiated light is produced. One mirror is only partially reflective, allowing the beam of red light to escape through the opening. This is how we are able to see the red laser beam.
There are many other types of lasers in use today, but the general principle is the same. The ruby laser, emits short pulses of light, and is a solid state laser.
This article was provided by Precision Photonics, an optics company based in Boulder, CO which specializes in areas of photonics such as ion beam sputtering, micro optics and mirror coating.