Laser Cutter Theory

Theory: How it Works

Inside the laser cutter there is a very powerful CO₂ infrared laser that is bounced off of a few mirrors onto a moving head and is finally directed towards the material being cut or etched by a moving mirror and lens that focuses the coherent beam. These mirrors and lenses are gold coated to provide the best possible transmission of infrared energy.

The infrared (IR) light that the laser cutter produces would blind you instantly if you were to look directly at it - and it's so bright that even you were only looking at the light reflected off the material that's being cut, it could still blind you. The IR light is also totally invisible. Fortunately, IR light doesn't pass easily through the window of the cutter that is made of a Polycarbonate plastic (which strongly absorbs light in those wavelengths). For this reason, if the lid (and the front panel) of the laser are not properly shut, then the IR laser will turn off automatically. The intense white light that you sometimes see when the cutter is operating is actually visible light that's being emitted by the material that the laser is burning off (it's literally 'white hot'!).

For carbon-based (organic) materials (like wood, paper, cloth and leather), you see the material being burned away and there may be black residue left behind. For plastics like Acrylic, the material is chemically decomposed by the laser and you don't see that white hot trail as it cuts. However, when the laser hits the metal grid beneath the material, there will still be bright flashes of light from that.