A laser beam is basically radiation, similar
to light that a light bulb emits. There are
3 big differences:
1. The light bulb emits several wavelengths,
but the laser has only one wavelength (meaning
it is monochromatic).
2. The light bulb radiates in all directions,
whereas the beam of the laser is directed.
3. Laser light is coherent, so the wave trains
are much longer than those from a light bulb.
But what does laser mean, anyway?
LASER is an acronym for: Light Amplification
by Stimulated Emission of Radiation
Sounds complicated at first – but actually
it is not.
A laser consists of a laser medium, for example
a gas, an energy source (“pump”) and two
mirrors, one of which is partially transmissive.
Here is a general overview of how it works.
1. The laser medium consists of particles
that are in their basic state.
2. The pump feeds energy into the particles,
and they rise to a higher energy level.
3. If any of these particles then falls back
into their basic state, energy is released
in the form of a photon, also called light
quantum.
4. If this photon then hits another excited
particle, then it's forced back into the basic
state, releasing another photon. This is referred
to as stimulated emission.
If these photons hit other excited particles,
then further photons are released, and so
on – a sort of "photon avalanche" is triggered.
5. Energy is repeatedly pumped into the laser
medium, stimulating the particles so that
they can release more photons.
6. The mirrors reflect the photons, thereby
increasing the number of photons further and
further → a directional beam is formed.
This beam can leave the laser through the
partially transmissive mirror and is directed
onto the material -- where it engraves, marks
or cuts the desired motif.
