What is laser and its uses

Laser - light that cuts steel

How does a laser work?

Albert Einstein provided the basis for the development of the laser. As early as 1916 he published his idea of ​​"stimulated emission". According to this theory, material that is irradiated with energy creates particles of light. Einstein never checked this thesis himself.

Only years later was his suspicion confirmed and thus the foundation stone for the development of the first laser was laid.

Laser is the abbreviation for "Light Amplification by Stimulated Emission of Radiation".

Behind the complicated name there is a special method with which light is generated and bundled. The laser technology is based on the physical effect of the stimulated emission.

If you bombard various materials such as chromium or nitrogen with electrical energy or certain light, atoms are excited and release light particles (photons).

If you add even more energy, the photons collide with other atoms in the material, which themselves then emit light particles again.

In order to focus the light obtained and make it even more intense, there are two mirrors inside a laser device. The photons are shot back and forth between them, ensuring that more and more light particles are created.

One of the mirrors in the laser is minimally transparent and around one percent of the light generated can escape to the outside. This tiny fraction is the typical ray of light we see with a laser.

The laser light

A laser can be of many different colors. This depends on the material from which the light particles are extracted. Different materials (called media) release slower or faster vibrating particles. The length of the vibrations is responsible for the color of the light.

Since all the light particles in a laser always vibrate in the same rhythm, they always have the same color. For this reason, lasers are referred to as monochromatic (single-colored) light.

However, the same oscillations of the photons are not only responsible for the color of the laser. They also have the effect that the light is concentrated in one point and not radiated sideways. It is through this bundling that the laser light achieves its enormous energy.

Laser light therefore differs from that of an incandescent lamp, for example, whose light emits different wavelengths in different directions.

Not only solid substances such as crystals, but also liquids and various gases are suitable as a laser medium. Depending on the medium, laser light can be generated from a wide range of the optical light spectrum - from infrared to visible light to ultraviolet light.

Excitingly versatile: the laser light

The laser is a relatively new phenomenon in the history of physics. Einstein's theory of stimulated emission was first demonstrated in an experiment in 1928 by the German-born American Rudolf Ladenburg.

In 1954, the American physicist Charles H. Townes built the predecessor of the laser, the Maser (Microwave Amplification by Stimulated Emission of Radiation). This amplified microwaves in the same way as later the laser amplified light.

It was not until 1960 that the Canadian scientist Theodore Mainman built the first functional laser. He used a ruby ​​as a medium to release photons. The extensive application possibilities of the new technology inspired countless scientists to further research the laser phenomenon.

Today we encounter lasers in many areas of everyday life: In the supermarket, a laser transfers the barcodes of the products to the cash register, the lasers in CD and DVD players read image information, holograms on EC and credit cards are made with laser light, laser shows in discos create a mystical atmosphere.

In addition, laser beams are also suitable for non-contact measurement of distances and surfaces or for cutting and welding objects. Even metal can be cut through with the bundled light.

Modern laser medicine

One of the most important areas of application of the laser is medicine. Shortly after the invention of the laser, medical professionals investigated the effect of laser beams on living tissue.

In 1962, the American dermatologist Dr. Goldmann for the first time skin diseases with laser light. After its success, numerous groups of experts were formed to research how the laser could be used, particularly in neurosurgery and urology.

Since a laser can be controlled very precisely, it is mainly used today for operations that require very precise work. The best-known laser operation is probably the "laser removal" of a visual impairment.

First, a tiny incision is made on the cornea with the laser. Then this is folded over and the laser removes wafer-thin layers of the cornea. After the operation, the light hits the lens of the eye again at the right angle and the poor eyesight is eliminated.

But lasers are not only used for cutting in medicine. Another extensive field of application is cosmetics. The wavelengths of some lasers trigger various chemical reactions in the body's cells.

The dyes in the skin cells are very sensitive to red laser light, for example. If you irradiate dark pigment spots or tattoos with the laser, the color pigments are dissolved and broken down by the body. After a few treatments, unpleasant tattoos, age spots or dark pigmentation disorders disappear.