Laser Fundamentals - Fraunhofer ILT

This section explains the physical and technical principles of laser technology. It provides a concise overview of the properties of laser light, key parameters such as wavelength, power and beam quality, as well as fundamental principles such as coherence, beam shaping and stimulated emission. In this way, it lays the groundwork for understanding laser-based processes and applications.

Laser	Light source generating monochromatic, coherent light via stimulated emission.
Laser beam source	Device that generates and emits laser radiation.
Diode laser	Semiconductor-based laser with high efficiency and compact design.
Fiber laser	Laser using a doped glass fiber as active medium; high beam quality.
Solid-state laser	Laser with a solid active medium (e.g. crystal or glass).
Ultrashort pulse laser (USP)	Laser generating femto- or picosecond pulses; high-precise processing without thermal damage.
Wavelength	Distance between two successive wave crests of light, expressed in nanometers (nm) or micrometers (µm); determines how a material absorbs, reflects or transmits laser radiation.
Beam quality (M²)	Measure of a laser beam's focusability.
Beam shaping	Targeted modification of the beam profile for optimized results
Frequency conversion	Nonlinear optical process for changing the laser wavelength.
Coherence	Property of laser light with constant phase and wavelength.
CW laser (continuous wave)	Laser source emitting a continuous, uninterrupted beam – as opposed to pulsed lasers; typical applications include welding, cutting and surface treatment at consistently high average power.
Stimulated emission	Core principle of the laser: a photon stimulates an excited atom to emit an identical photon.
Optical resonator	Mirror arrangement that reflects laser light back and forth through the active medium, enabling amplification.
Reflection / Transmission	Reflection: portion of light reflected at a surface. Transmission: portion passing through. Both determine material suitability for laser processes.
CO₂ laser	Gas laser with a wavelength of 10.6 µm; widely used for cutting, welding and structuring metals, plastics and glass
Nd:YAG laser	Solid-state laser with neodymium-doped YAG crystal; wavelength 1064 nm; used in industry and medicine.
Thin-disk laser	Solid-state laser with a thin-disk active medium; very high efficiency and beam quality at high power levels.
Green laser	Laser with a wavelength of approx. 515–532 nm; especially suited for processing copper, gold and transparent materials.
Heat-affected zone (HAZ)	Zone adjacent to the laser processing area that is thermally affected but not melted; relevant for material quality and dimensional accuracy.
Laser power	Radiant energy emitted by a laser per unit time, given in watts (W) or kilowatts (kW); critical for process speed and penetration depth.
Laser safety classes (Class 1–4)	International safety classification of lasers by their hazard to eyes and skin; from Class 1 (safe) to Class 4 (high hazard potential).
Laser protection levels	Protection measures and requirements for laser safety eyewear and workplace safety according to applicable standards (e.g. DIN EN 207).
Laser scanning	Non-contact acquisition of surfaces and geometries using a deflected laser beam; used in metrology, quality assurance and reverse engineering.