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What is a laser and how does it work?
What is a LASER?
The laser is a bunch of energy waves (streams of photons called radiation) with the same amplitude
and faze that are flowing in the same direction, meaning they are coherent - they stick together and
form a laser beam.
The width of a single wave is measured in nano-meters and defines the colour and visibility of the
laser beam. The visible spectrum of the human eye is roughly between 400nm and 700nm, going
from violet to a dark red colour. A human eye is most sensitive to a green light of around 555nm,
meaning that a 1W of green laser will always appear more visible than 1W of any other colour laser.
1W of quality laser light is very powerful and although it doesn’t sound like much it can burn eye
retinas, skin and clothes or even start a fire!
What makes the laser visible?
Mainly it is the particles of dust in the air that the laser beam hits on its path. That’s why we
“laserists” use haze or smoke machines to make lasers more visible. Too much of the haze or
smoke will kill it, but the right amount will make all the difference between no show and a great
show.
When outdoors, lasers mainly reflect off dust and mist in the air but due to unpredictable wind
conditions we can never make sure the hazers or smoke machines will be effective enough. And
that’s why we use high power lasers for outdoor shows - to substitute for the lack of dust, haze and
smoke.
How far does it go?
Depending on the power output of the system and weather conditions, the laser can be visible for
miles - that is why we need to be cautious about aircrafts when performing outdoor shows. And if
you get a system that is powerful enough then YES, it can reach the Moon.
Colours
Standard full colour analogue lasers use three primary colours: Red, Green and Blue. By mixing
those together you can pretty much get any secondary colour:
Red + Blue = Magenta Red + Green = Yellow Green + Blue = Cyan Red + Green + Blue = White
Of course the number and precision of the colours is determined by the modulation, stability and
linearity of the system. If the system is not stable enough, it will produce different colours every time
it is used, making it virtually impossible to match the colours of two systems at any one time. This is
very often the case with systems that use cheap DPSS technology.
Scanning System
A scanning system is essentially two tiny mirrors, each moving on X or Y axis. By working together
they can “scan” the laser beam in all directions. Once a shape is scanned more than 20 times per
second, it appears static to the human eye. So any shape drawn by a laser is actually produced by
one single laser beam running around like crazy. Every scanning system has a mechanical limit of
how fast it can move its mirrors and therefore how many points it can display at any one second
and that is usually represented in Points Per Second at a certain scanning angle, i.e. 8 degrees.
