Diode vs CO2 vs Fiber Laser: Which Type Do You Need?

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The laser type has to follow from the material, not from the wattage on the box. A blue diode source (roughly 450–455 nm) is the cheapest way into wood, leather, paper and coated or painted surfaces, but its light passes straight through clear acrylic and it cannot mark bare metal. A CO2 tube (10.6 µm) is what you buy if clear acrylic, glass or thicker stock is on the list. A fiber source (about 1,064 nm) is a metal marker that happens to sit on a desk: it is poor on wood, leather and clear acrylic, and it works inside a small galvo field.

Three things settle the question before watts enter the conversation. Whether "clear acrylic" or "bare metal" appears on your material list. How much optical output the machine actually delivers, as opposed to the number in its name. And whether you can get fumes out of the room you intend to work in.

Safety class comes right behind those. An enclosed Class 1 product and an open-frame beam you can reach are different objects to live with, even at identical power.

The two rows of the material list that decide everything

Diode, CO2 and fiber differ first by wavelength, and wavelength decides which materials absorb the beam at all. That is why the same sheet of acrylic is trivial on one machine and impossible on another.

The clear-acrylic row is where most first purchases go wrong. Blue diode light is not absorbed by transparent acrylic; it travels through the sheet and leaves nothing behind, no matter how many passes you run. CO2 light at 10.6 µm is absorbed by it.

The bare-metal row is the second trap. Bright metal reflects both diode and CO2 light, so those machines only mark it through a spray or a coating that the beam can darken. A 1,064 nm fiber source couples into the metal itself, which is why it marks stainless and aluminium with nothing applied.

What the watts in the machine name actually measure

Two different numbers hide behind the same word. Optical output is the laser light leaving the head. Electrical draw is what the machine pulls from the wall — and it is always the larger figure, often by a wide margin. Hobby machines quote one or the other, and the name badge does not tell you which.

Creality is the clearest of the mainstream brands: the Falcon2 Pro 22W is listed with an optical power of 22 W, the 40 W model as "40 W + 1.6 W", and the Falcon A1 as 10 W optical. Sculpfun phrases several models as light energy rather than electrical — the S9 at "up to 5.5 W", the S30 Pro Max at 20 W — and states plainly that the S30 Ultra's 11/22/33 W figures come from a single enhanced 6 W diode in a combined design, so the name is not one diode's output.

xTool and OMTech publish a laser-power number without an optical column on the product page. Treat the 40W on an xTool S1 as "the 40 W in the name" until a spec sheet says optical. The consequence is practical: an engraver badged 40 W and one badged 20 W can sit much closer together than the labels suggest, and what actually cuts is power density — watts divided over the spot. The xTool F1 Ultra shows the gap inside one machine: a diode spot of 0.08 x 0.10 mm against a fiber spot of 0.03 x 0.03 mm, same head, very different concentration.

An infrared module is not a fiber laser, either. The 2 W 1064 nm module sold for the xTool S1 marks metal to roughly 0.05–0.1 mm per pass and cannot cut it; deep engraving into brass or copper is 20 W-plus fiber work.

Diode: the cheap way in, with two hard limits

A diode engraver is an air-cooled blue module on a gantry, running from a standard outlet and driven by GRBL-based software — LightBurn, LaserGRBL, or the brand's own app such as xTool Creative Space and its successor xTool Studio. Open-frame units from Sculpfun, Atomstack, Ortur and Longer expose the beam completely; enclosed units from xTool and Creality put it behind a lid with an interlock. That enclosure is not cosmetic, and it is worth more than an extra 10 W of nominal power.

On thin stock it is genuinely capable. Per xTool, the S1 40 W is published at 18 mm cherry and 15 mm dark opaque acrylic in a single pass, and the 20 W version at 10 mm and 8 mm. Thick hardwood, long production runs and anything transparent are CO2 territory.

The xTool S1 is the reference enclosed diode: 498 x 319 mm of bed, lid-open stop, e-stop, key lock and flame detection. Two things its marketing glosses over — it is Class 1 only with the baseplate installed or with the riser base and its doors closed, and safety goggles are not in the box.

Check the xTool S1 40W on Amazon

The Creality Falcon2 Pro 22 W is the same idea with a camera and a real optical figure: 400 x 415 mm, Class 1 per FDA, LightBurn supported. The 2 W IR module sold alongside it marks coated metal; it does not turn the machine into a metal cutter.

Check the Creality Falcon2 Pro 22W on Amazon

Below that, open-frame machines like the Sculpfun S30 Pro Max or the SF-A9 ship goggles in the box and no interlock at all. They work, and they leave you responsible for the enclosure, the extraction and the eyewear.

CO2: what a CO2 laser is, and what the tube costs you

A CO2 laser is a sealed glass tube filled with a CO2 gas mixture, excited by a high-voltage supply; the beam comes out at 10.6 µm, far infrared and invisible. That wavelength is absorbed by acrylic, glass, wood, leather and fabric, including clear acrylic that a diode cannot touch. What it will not do is mark bare metal without a spray or a coating.

What that costs is the part buyers underestimate. The tube is a consumable and its life is quoted in hours of operation — vendor figures that vary widely, in the thousands of hours, with overdriving the tube current shortening it. Glass-tube units need water cooling or a chiller and, on open-optics frames, mirror alignment. Exhaust demand is heavier than on a diode, the footprint is bigger, and the current draw is higher.

The xTool P2S is the tidy version: 55 W in the name, 600 x 305 mm, per xTool up to 18 mm basswood and 20 mm acrylic in one pass, with a closed coolant loop. Its product page states Class 4. LightBurn runs it, but not the camera or the autofocus.

Check the xTool P2S 55W CO2 on Amazon

The xTool P3 goes the other way on safety: 80 W in the name, 915 x 458 mm, certified Class 1 as sold. It is Class 1 with a Class 4 laser sealed inside, and it becomes Class 4 once the conveyor feeder is fitted.

A K40-class machine is the budget door into CO2 and the most common false economy: 45 W rated, 200 x 300 mm, water cooling and alignment to handle yourself, LightBurn compatible but not included. Budget for cooling, ducting, alignment tools and CO2-rated eyewear before you compare it to anything. OMTech's page states no laser class or interlock, so treat it as an open Class 4 source.

See the OMTech K40+ 45W CO2 on Amazon

Glowforge sits in the same wavelength category with a different trade: the Pro is a 45 W CO2, Class 4, driven entirely from a browser and dependent on an internet connection. Note the naming trap in the family — the Glowforge Aura is a 6 W, ~450 nm diode, not a CO2 machine, even though the brand is known for CO2 cutters.

Fiber and UV: two narrow infrared tools

A fiber laser runs at about 1,064 nm from a ytterbium-doped source, delivered through a galvo head that steers the beam over a small field rather than moving a gantry. It couples into bare steel, aluminium, brass and anodised or coated metal directly, and at 20 W and above it can emboss and deep-engrave brass and copper. Fiber sources are generally rated far longer than glass CO2 tubes, though vendor figures vary.

The limits are the mirror image of the diode's. The field is small — 110 x 110 mm on the Gweike G2, 150 x 150 mm on the G2 Pro, 220 x 220 mm on the xTool F1 Ultra. It marks rather than cuts at consumer power, and it is weak on wood, leather and clear acrylic. Software is the other hurdle: EZCad2 or EZCad3 on industrial heads, with LightBurn Pro as the alternative for supported galvo controllers.

The Gweike G2 Pro puts 30 W in the name behind a fully enclosed shell, LightBurn-compatible, with safety goggles sold separately rather than included. Gweike states no laser class on the page, so treat the beam as Class 4 and buy 1,064 nm goggles first.

Check the GWEIKE G2 Pro 30W fiber on Amazon

The ComMarker B4 is the open-galvo approach: 20 W, dual 110 mm and 200 mm lenses, EZCAD2 bundled, LightBurn on a separate licence, Windows only. Nothing shields the beam, so a 1,064 nm-rated pair of glasses is part of the purchase, not an accessory.

Check the ComMarker B4 20W fiber on Amazon

Dual-head machines compress both jobs into one chassis. The xTool F1 Ultra pairs a 20 W fiber with a 20 W diode over 220 x 220 mm at up to 10,000 mm/s — metal marking plus wood and leather engraving, stated Class 4, and still not an acrylic cutter. The LaserPecker LP5 does the same trick with a 20 W diode and a fiber source, and adds door sensors on the enclosure and cone that stop the laser when opened.

Check the xTool F1 Ultra on Amazon

UV is the niche of the family: 355 nm, cold marking on glass and plastics with very little heat, 5 W on the xTool F2 Ultra UV and a 70 x 70 mm inner area. It solves a specific problem and costs like a specialist tool.

Safety is a buying criterion, not a footnote

Laser class tells you what the product is like to own. An enclosure with an interlock can make a whole machine Class 1 even with a Class 4 source inside it, because the beam is not reachable. Open-frame gantries and bare galvo heads leave the beam in the room.

Read the class on the product page, not on the badge. The xTool P2S, F1 Ultra, F2 Ultra and F2 Ultra UV are stated Class 4; the P3 and the M2 are Class 1; the Creality Falcon2 Pro and Falcon A1 are Class 1 per FDA; the Glowforge Aura is a Class 1 product containing an embedded Class 4 laser. The xTool S1 sits in between: Class 1 with the baseplate installed or the riser base closed, and not Class 1 with the riser plus conveyor feeder, which needs a Class 4 procedure.

Eyewear is wavelength-specific and there is no universal pair. Blue-diode glasses do nothing against 1,064 nm fiber light, and neither pair does anything against a CO2 beam at 10.6 µm. xTool's own tables list OD6+ for the S1 and the F1 Ultra, and OD5+ for the F1. Goggles are absent from the box on the xTool S1 and the Gweike G2; they ship with the Sculpfun S30 Pro Max, the SF-A9 and the LaserPecker LP4.

Every one of these machines produces fumes. An open window is not extraction: duct to outside or run filtration, and expect CO2 to demand the most of it. An enclosure helps twice over — it keeps the beam in and gives the smoke one direction to leave.

PVC, vinyl and any PVC-containing faux leather are never acceptable, on any laser type. The chlorine in them becomes hydrogen chloride gas, turns to hydrochloric acid on moisture, and attacks optics, rails and electronics; it also voids warranties. Polycarbonate is the other material to leave alone.

Fire is a risk on every laser type, enclosed or not: wood and acrylic can ignite, and flame detection is a backstop, not a substitute for watching. Never leave a running machine unattended, keep the bed clean, and keep a CO2 extinguisher within reach.