CO2 vs diode lasers for acrylic
Two kinds of laser sit on makers’ benches, and on acrylic they do not behave alike. The difference is not power — it is wavelength, and it decides which colours you can buy.
The short version
A CO2 laser cuts every acrylic we sell, clear included. A diode laser cannot cut clear or transparent acrylic at all — order opaque colours instead. No amount of power, speed or passes changes that.
Why clear acrylic defeats a diode
A diode laser emits blue light at roughly 450 nanometres. Clear acrylic is transparent at that wavelength — which is the entire point of clear acrylic — so the beam travels straight through and deposits almost no energy. Nothing melts, nothing vaporises, and you get a faint line at best.
A CO2 laser emits at 10.6 microns, far into the infrared. Acrylic absorbs that strongly, right at the surface, which is why a CO2 machine cuts it so cleanly and leaves a flame-polished edge. Same material, same power, opposite result — because one wavelength is absorbed and the other is not.
Opaque acrylic changes the picture: pigment absorbs blue light, so black, white and the solid colours cut fine on a diode. Black is the most forgiving place to start.
Side by side
| On acrylic | CO2 | Diode |
|---|---|---|
| Clear / transparent | Cuts and engraves | Will not cut |
| Black & opaque colours | Cuts and engraves | Cuts and engraves |
| Edge quality | Flame-polished, clear | Rougher, more scorch |
| 1/4″ stock | Routine | Slow, multiple passes |
| Fluorescent / edge-glow | Yes | Transparent ones, no |
The workaround, and its limits
Diode owners do get marks on clear acrylic by giving the beam something to absorb: leaving the protective masking on, painting the back, or using a marking spray. That works for surface engraving and it is worth trying. It does not let a diode cut through clear acrylic in any practical way — the coating absorbs at the surface, and there is nothing to carry the cut down through the thickness. If you need clear parts cut out, you need a CO2 machine.
What about images engraved inside a clear block?
Those photo-like images floating inside a crystal or acrylic block are sub-surface laser engraving, and they come from neither of the machines above. They are made with a pulsed green laser at 532nm, focused to a point inside the material rather than on its surface. At the focal point the energy density is high enough to create a microscopic fracture; thousands of those, placed on a 3D grid, make the image. The surface is left untouched.
It is reasonable to assume a green laser is a diode laser, because there is a diode inside it. It is a diode-pumped solid-statelaser: an 808nm diode pumps a neodymium crystal, that crystal lases at 1064nm, and a second crystal halves the wavelength to 532nm. The diode is the power supply, not the thing doing the work — which is the whole difference. A maker’s diode cutter emits its 450nm blue light directly from the diode itself.
The second difference matters just as much: a sub-surface engraver is pulsed, firing extremely short bursts whose peak power is enormous but whose average power is modest, which is what lets it fracture a point deep inside the material while leaving everything the beam passed through untouched. A cutting diode runs continuously and works at the surface. Different wavelength, different delivery, different job — and sub-surface engraving does not cut at all: it will never get you a part, only an image inside a solid block.
Add-on laser modules
Plenty of machines take a laser as an accessory rather than being a laser — swappable heads on an xTool, module kits for CNC routers and 3D printers, multi-tool machines. Almost all of those modules are diodes, and usually lower-powered ones than a dedicated cutter, so the rule on this page applies with room to spare: opaque colours only, thin stock, expect more passes.
The other common swap is an infrared (1064nm) module, sold for marking metals. That does not rescue clear acrylic either — acrylic is largely transparent at 1064nm too. Only a CO2 source at 10.6 microns is absorbed by the acrylic itself. If you are choosing a module and want to cut clear, the wavelength is the specification that matters, not the wattage.
Which is your machine?
CO2 — every colour available
Diode — opaque colours only
Neither type should cut these
PVC, vinyl and Sintra release chlorine gas — toxic to you, corrosive to the machine. Polycarbonate (Lexan) scorches brown, cuts badly and can catch fire. That applies to CO2 and diode alike.