Short answer
Choose a laser marker by material, because absorption depends on wavelength. Fiber (1064 nm) is the default for metals, MOPA fiber adds colour on stainless steel and black on anodized aluminium, UV (355 nm) gives fine low-heat marks on plastics, glass and PCBs, and CO2 (10.6 µm) marks wood, leather, textiles, paper and glass but not bare metal.
Key takeaways
- Steel absorbs about 33% of 1.06 µm laser light but only about 11% at 10.6 µm, which is why metals are marked with fiber lasers and bare steel cannot be marked with a CO2 laser.
- Wood, paper, cloth, plastics, glass and stone absorb the 9–11 µm CO2 wavelength strongly, so CO2 is the default marker for organic and non-metal materials.
- UV (355 nm) lasers mark a wider range of plastics than 1064 nm sources, including flame-retardant grades, and are the usual choice for fine codes on PCBs and glass.
- MOPA fiber lasers let you change pulse duration, which makes colour marking on stainless steel and controlled dark marks on anodized aluminium practical.
- A longer f-theta lens gives a larger marking field and a larger spot: in one 1064 nm lens series, 160 mm gives 110 × 110 mm and 420 mm gives 300 × 300 mm.
Pick a laser marker by the material you need to mark, because each material absorbs some wavelengths far better than others. Fiber lasers (1064 nm) are the default for metals and many coloured plastics. MOPA fiber adds pulse control for colour on stainless steel and dark marks on anodized aluminium. UV lasers (355 nm) make fine, low-heat marks on plastics, glass and PCBs, and CO2 lasers (10.6 µm) mark wood, leather, textiles, paper, acrylic and glass but not bare metal.
Why wavelength decides what you can mark
A laser only marks with the energy the surface absorbs. The rest is reflected or passes through. How much is absorbed depends on wavelength.
- Metals absorb shorter wavelengths better. In figures published by Coherent scientists, steel absorbs about 33% at 1.06 µm and about 11% at 10.6 µm. Aluminium absorbs about 5% and about 2%. This is why metal marking uses fiber lasers.
- Organic and non-metal materials absorb 10.6 µm strongly. The same paper lists paper, wood, cloth, ceramics, oxides, plastics, glass and stone as strong absorbers in the 9–11 µm band.
- Plastics vary by grade and colour. TRUMPF reports that frequency-tripled 355 nm lasers mark a wider range of plastics and often do better than 1064 nm sources. Some industrial plastics need laser-sensitive additives for a legible mark.
- Clear glass transmits near-infrared light, so a 1064 nm beam mostly passes through it. UV and CO2 lasers mark glass instead.
- Precious metals such as gold and silver absorb 355 nm and 532 nm better than 1064 nm, according to a TRUMPF marking specialist writing in Laser Focus World.
A shorter wavelength also focuses to a smaller spot, which is one reason UV marks look finer.
The four marking lasers at a glance
| Laser | Wavelength | Common power range | Best on | Main limits |
|---|---|---|---|---|
| Fiber (Q-switched) | 1064 nm | 20–100 W; up to 200 W for deep engraving | Steel, stainless, aluminium, titanium, brass, many coloured plastics | Weak on clear glass, wood and paper. Copper is reflective and needs more power. |
| MOPA fiber | 1064 nm | 20–100 W | Everything fiber marks, plus colour on stainless, dark marks on anodized aluminium, cleaner plastic marks | Costs more than Q-switched fiber. Same blind spots on glass and organics. |
| UV | 355 nm | 3–15 W | Plastics including white and flame-retardant grades, glass, PCBs, precious metals, fine codes | Low power, so deep metal engraving is slow. Highest cost per watt. |
| CO2 | 10.6 µm | 30–150 W | Wood, leather, denim and textiles, paper and cardboard, acrylic, glass, rubber, painted metal | Cannot mark bare metal. Larger spot than fiber or UV. |
The power ranges are the ones most marking machines are sold in, and the ranges Maxwave builds. Coherent’s DIAMOND C/Cx CO2 sources for marking and cutting wood, cloth, leather, paper and glass are all below 150 W.
Material × laser-type matrix
Key: ●● first choice · ● works well · ○ possible, test first · – not suitable
| Material | Fiber | MOPA | UV | CO2 |
|---|---|---|---|---|
| Carbon and stainless steel (black, grey, engraved) | ●● | ●● | ○ | – |
| Stainless steel, colour marks | – | ●● | – | – |
| Bare aluminium | ● | ●● | ○ | – |
| Anodized aluminium | ● | ●● | ● | ○ |
| Brass, copper | ● | ● | ● | – |
| Gold, silver | ● | ● | ●● | – |
| Titanium (medical, tools) | ●● | ●● | ○ | – |
| Engineering plastics (ABS, PC, PA, PBT) | ● | ●● | ●● | ○ |
| White and flame-retardant plastics | ○ | ● | ●● | – |
| Acrylic (PMMA) | – | – | ○ | ●● |
| Glass | – | – | ●● | ● |
| Wood, bamboo, MDF | ○ | ○ | – | ●● |
| Leather | ○ | ○ | ○ | ●● |
| Denim and textiles | – | – | – | ●● |
| Paper and cardboard | – | – | ○ | ●● |
| PCB solder mask and components | ● | ● | ●● | – |
| Painted or coated metal | ● | ● | ● | ● |
Treat the matrix as a starting point. Pigments, additives, coatings and the contrast you need all change the result, so test real parts.
Mark types and which laser makes them
- Engraving. The beam removes material and leaves a recess. Short pulses and high peak power work best on metal. Fiber lasers engrave metal, and CO2 lasers engrave wood and acrylic.
- Annealing. The beam heats the metal so an oxide film forms without removing material. The film sets the colour. It is used on stainless steel and titanium where a smooth surface matters, such as medical and food equipment.
- Colour marking on stainless steel. This is controlled annealing. In a 2017 Scientific Reports study, a 20 W, 1064 nm nanosecond fiber laser with pulse width tunable from 4 to 260 ns coloured AISI 304 by changing scan speed, repetition rate and pulse width. The oxide films were roughly 0.3–0.8 µm thick. MOPA sources give this pulse control. Colours depend on the alloy, surface finish and focus, so fix the settings per part.
- Ablation. The beam removes a thin top layer to show a contrasting layer below, such as anodizing, paint or multi-layer plastic. Ablation of anodized aluminium is one of the most forgiving marking processes.
- Colour change and bleaching. Pigments in the plastic change colour while the surface stays smooth. UV lasers do this with the least heat.
- Carbonization. Carbon-containing plastics darken at the surface. TRUMPF says this is typically used on light-coloured plastics. CO2 lasers mark wood, paper and leather in a similar way, by charring the surface.
- Foaming. The beam melts the plastic and gas bubbles are trapped as it cools. The result is a light, slightly raised mark, usually on dark plastics.
Field size, spot size and speed
A galvo marker steers the beam with two mirrors and focuses it through an f-theta lens. The lens focal length sets the marking field and the spot size. One optics maker’s 1064 nm series shows the trade-off:
| Focal length | Marking field | Spot size |
|---|---|---|
| 100 mm | 70 × 70 mm | 16 µm |
| 160 mm | 110 × 110 mm | 26 µm |
| 254 mm | 175 × 175 mm | 31 µm |
| 330 mm | 220 × 220 mm | 40 µm |
| 420 mm | 300 × 300 mm | 50 µm |
A larger field gives a larger spot and lower power density, so the same laser marks more slowly or less deeply. Pick the smallest field that covers the part. For larger parts, use a rotary axis, an XY table or several marking positions.
Speed depends on how much energy each mark needs. Surface marks such as text, logos and 2D codes are fast. Deep engraving needs many passes, and time grows with depth and area. Extra power buys speed and depth, while fine detail depends on spot size. For colour marking and fine UV work, pulse control and spot size matter more than watts. Ask for a timed test on your own part before you choose a power level.
Machine formats: desktop, cabinet, handheld and online
- Desktop (open) markers. A galvo head on a column with manual or motorized height adjustment. They are compact and the lowest-cost format, and suit workshops, jewelry and small batches. The beam area is open, so operators need eyewear rated for the wavelength and a controlled work area.
- Cabinet (enclosed) markers. An interlocked enclosure contains the beam and fumes. They suit factories where several people work near the machine. Add fume extraction for plastics and organics.
- Handheld and portable markers. The galvo head is on a cable or a light frame, so you bring the laser to large or fixed parts such as castings, frames and machinery. Full laser safety measures apply. See our laser safety guide.
- Flying (online) markers. Fixed above a conveyor, they mark moving products using a line-speed encoder and a trigger sensor. Low-power CO2 lasers have long been used to mark manufacturing and expiry dates and lot numbers on products. Fiber and UV online markers code metal and plastic parts. Plan the line speed, product spacing and PLC signals with the supplier.
How to decide
- List every material and finish you need to mark, with the contrast and depth required.
- Metals only: choose fiber. Add MOPA if you need colour on stainless steel, dark marks on anodized aluminium, or cleaner marks on plastics.
- Heat-sensitive or white plastics, flame-retardant plastics, glass, PCBs or very small codes: choose UV.
- Wood, leather, textiles, paper, acrylic or glass at larger sizes: choose CO2.
- Metal and organic materials in the same shop: plan for two machines.
- Choose the lens from your largest mark, and the power from depth and cycle time.
- Choose the format: desktop, cabinet, handheld or online.
- Test real parts before you buy.
Maxwave builds fiber, MOPA, UV and CO2 markers in desktop, handheld and online formats, listed under laser marking machines. To compare lasers on your own part, use sample testing and get back a test video and the settings used.
Sources
- DeMaria & Hennessey (Coherent), The CO2 Laser: The Workhorse of the Laser Material Processing Industry, SPIE Professional
- Laser Focus World: Laser marking, how to choose the best laser for your marking application
- TRUMPF: Laser marking plastic
- TRUMPF: Laser marking processes
- Lu et al., Nanosecond laser coloration on stainless steel surface, Scientific Reports 7, 7092 (2017)
- Coherent: DIAMOND C/Cx series CO2 lasers
- EKSMA Optics: F-theta lens for 1064 nm (focal length, scan field and spot size table)