Laser

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A laser produces a highly focused beam of light that is very intense. The wavelength of the light can be adjusted with great accuracy. This makes lasers precision instruments.

Lasers

Ein rotes gewundenes Objekt bewegt sich durch ein zylindrisches Gerät mit blauen Rundungen an den Enden.

How it works

Pump

This injects energy into the transparent laser medium, which can be solid, liquid, or gaseous. This excites the atoms in the medium.

Resonator

Two mirrors reflect the photons, which thus pass through the medium several times, amplifying photon emission. One of the mirrors is partially transparent. Some of the photons escape through it, forming the laser beam.

Laser Medium

Some of the excited atoms release their energy as photons (particles of light). These stimulate further excited atoms to emit photons of the same wavelength and direction of travel.

Rotes dreieckiges Schild mit blauem Rand und strahlenförmigem Muster im Inneren. (Mistral: Mistral Medium 3.5, 2026-07-10)

Applications

Lasers read data in machines such as DVD players and scanners. They weld and cut, serving as scalpels in medicine, for example, and are also used to measure the Earth and accelerate particles.

Eine Person mit Umhang hält ein Gerät mit rotem Lichtstrahl. (Mistral: Mistral Medium 3.5, 2026-07-10)

Pure fantasy

Lightsabers, as seen in the sci-fi epic Star Wars, are purely fictional: a laser beam does not just stop, nor can blades of light bounce off one another.

What does Jülich do?

Researchers use lasers in materials and fusion research, as well for measuring substances in the atmosphere, for example. They also develop new lasers.

This text is published in the effzett issue 1-26. Illustrations: Diana Köhne

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Last Modified: 14.07.2026
effzett issue 1-26besserwissen