It s hard nowadays to find a person who would never hear a word “laser”, however, very few have a clear idea of what it is.
For half a century since the invention, lasers of various types have found application in a wide range of areas, from medicine to digital technology. So what is a laser, what is its principle of operation, and what is it for?
What is a laser?
The possibility of the existence of lasers was predicted by Albert Einstein, who, back in 1917, published a paper talking about the possibility of electrons emitting light quanta of a certain length. This phenomenon was called stimulated emission, but for a long time it was considered unrealizable from a technical point of view.
However, with the development of technical and technological capabilities, the creation of a laser became a matter of time. In 1954, Soviet scientists N. Basov and A. Prokhorov received the Nobel Prize for the creation of a maser, the first microwave generator operating on ammonia. And in 1960, the American T. Meiman made the first quantum generator of optical rays, which he called a laser (Light Amplification by Stimulated Emission of Radiation). The device converts energy into narrow directional optical radiation, i.e. light beam, a flux of light quanta (photons) of high concentration.
How the laser works
The phenomenon on which the operation of a laser is based is called stimulated, or induced, radiation of the medium. Atoms of a certain substance can emit photons under the influence of other photons, while the energy of the acting photon must be equal to the difference between the energy levels of the atom before and after radiation.
The emitted photon is coherent with the one that caused the radiation, i.e. exactly like the first photon. As a result, a weak flux of light in the medium is amplified, and not chaotically, but in one given direction. A beam of stimulated radiation is formed, which is called a laser.
As research into the nature and properties of lasers, various types of these rays have been discovered. By the type of state of the initial substance, lasers can be:
- on free electrons.
Currently, several methods have been developed for obtaining a laser beam:
- using an electric glow or arc discharge in a gas environment – gas discharge;
- by expanding hot gas and creating population inversions – gas-dynamic;
- by passing current through a semiconductor with excitation of the medium – diode or injection;
- by optical pumping of the medium with a flash lamp, LED, other laser, etc .;
- by electron-beam pumping of the medium;
- nuclear pumping when radiation comes from a nuclear reactor;
- using special chemical reactions – chemical lasers.
All of them have their own characteristics and differences, thanks to which they are used in various fields of industry.
Practical use of lasers
Today, lasers of various types are used in dozens of industries, medicine, IT technologies and other fields of activity. With their help, the following are carried out:
- cutting and welding of metals, plastics and other materials;
- application of images, inscriptions and marking of the surface of products;
- drilling of ultra-thin holes, precision machining of semiconductor crystal parts;
- formation of product coatings by spraying, surfacing, surface alloying, etc .;
- transmission of information packets using fiberglass;
- performing surgical operations and other therapeutic effects;
- cosmetic procedures for skin rejuvenation, removal of defective formations, etc.;
- targeting various types of weapons, from small arms to rocket weapons;
- creation and use of holographic methods;
- application in various research projects;
- measurement of distances, coordinates, density of working media, flow rate and many other parameters;
- launching chemical reactions for various technological processes.
There are still many areas in which lasers are already being used or will find application in the very near future.