Modern metal laser cutting machines use a fiber optic laser source as the emitter. The generation process takes place in the pump diodes by means of a resonator, and then the laser beam is fed through an optical fiber to the laser head of the metal laser cutting machine, where a collimator and a focusing lens are located.
The focused laser beam has a high power density due to its monochromaticity and coherence.
Monochromaticity means that the spectrum of wavelengths emitted is so narrow that the photons of laser radiation can be said to have the same or close to the same wavelength.
Coherence refers to the coherence of the wave motions of a laser. Temporal coherence ensures the consistency of oscillations at the same point in space at different times, while spatial coherence ensures that the laser radiation is unidirectional and that the diffraction limit, i.e. the minimum value of the laser beam spot emitted by a metal laser cutting machine, is reached.
It is thanks to this that a metal laser cutter is able to focus to a point 0.01mm in diameter with a power density of 10¹³W or more, which allows the laser radiation to heat metal to a melting point at an area 8 times smaller than a human hair in a fraction of a second.
In pulsed mode, the duration of each individual pulse can be as long as 10‾¹⁵ seconds.
Metal laser cutting is divided into two basic methods: fusion cutting and sublimation cutting.
