How a Laser Cutter Works

A laser cutter looks like a printer that grew up, and in a way it is one. Instead of ink it uses a concentrated beam of light, and instead of paper it works on wood, acrylic, leather, card and many other materials.

Light, concentrated

The machine produces a beam of light of a single wavelength. On its own the beam is a few millimetres wide and fairly harmless to a sheet of wood. The trick is the focus lens in the laser head: it squeezes the beam down to a spot a fraction of a millimetre across. All the energy lands on that tiny point, the material heats up almost instantly and simply vaporises or burns away.

Moving the beam

The laser head rides on a gantry driven by two motors, one for each direction (X and Y). Software sends the head along a path, switching the beam on and off and changing its power hundreds of times per second. That is how a drawing on a computer becomes a shape in a real material.

Air, smoke and safety

• Air assist blows a thin stream of air at the spot where the beam hits. It clears smoke, keeps flames from forming and gives cleaner edges.
• Extraction pulls fumes out of the machine and away from the workshop.
• Enclosure and eye protection matter: the beam, and even its reflection, can damage eyes, and a laser job should never be left running unattended.

Three settings that decide everything

Almost every result comes down to power, speed and focus. Slow and strong cuts through; fast and gentle only marks the surface. Finding the right combination for each material is most of the craft — and it is the subject of the next story: cutting, engraving and scoring.

Photo: Opt Lasers / Unsplash