Laser – what is it?

The word “laser” is an artificial word in English and means:

Light Amplification by Stimulated Emission of Radiation

The history of the laser goes back to Albert Einstein, who discovered in 1917 the physical principle of absorption and emission of radiation through atoms or molecules. However it was possible to build the first “light amplifier” in the form of ruby lasers only in 1960. Today, we cannot imagine life without the laser with its many applications in varying areas.

The effect of the stimulation emission of radiation is used with the laser. A photon with the energy h(ny)=E2-E1 stimulates an atom (in our case neodymium) in a stimulated condition of energy supply to make the transfer from E2 to E1 and produce a second photon. This second photon is identical in direction, frequency, phase and polarization (coherent) of the produced photon. As an active medium for the laser stimulus, in the industrial application very often artificially made Nd:YAG (Neodym doped Yttrium Aluminum Granite) crystals are used.

If you bring such an active medium in a resonator which is made of two mirrors, there is a landslide-like effect because each photon which was produced through stimulated emission produces further photons which continuously reflect back and forth between the two mirrors. The laser beam which thus results leaves the resonator through the partially permeable mirror.

The stimulus of the Nd:YAG crystal follows according to the model either through arc discharge lamps or diodes whereas the diodes feature a higher efficiency, the lamps however provide a higher output power.

For applications in the area of laser marking, today almost exclusively diode-pumped laser beams are used. These systems are compact, maintenance free and need no additional water cooling but are completely cooled by air. Through the arrangement of the pump diodes in the control part, the laser unit which is sensitive to dust can itself remain in the system in case of an exchange of parts. This minimizes the downtime and reduces costs.

In the area of deep engravings by laser, still mainly lamp-pumped laser beams are used. These offer sufficient laser power and corresponding energy and guarantee excellent processing results.

Laser processing system

A laser processing system consists of the following main components:

- Laser beam source
- Control / Network part
- Beam deflection
- Focus optic (F-Theta objective)
- Laser protective housing if necessary with additional mechanical axis

The deflection of the laser beam follows through two motor driven mirrors in X and Y direction. Then the laser beam is focused through a lens, a so-called F Theta Optic, on the part. The production of the respective marking or engraving layout follows using the PC controlled laser software AC-LASER. Using this full graphic software package, serial numbers, logos, barcodes, data matrix codes can be labeled and two to three dimensional engravings can be produced and processed.