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Fiber, MOPA, galvo and UV lasers, explained
If you already run a CO2 or diode machine and keep hitting jobs it cannot do — metal marking, serial numbers, colour on stainless, marking clear plastic — this is the family of machines you are looking at next. The names get used interchangeably online, which is why the buying decision is so confusing. They are not four competing products; they are two different questions.
Price a job in your browser →The two questions hiding behind four words
“Fiber”, “MOPA” and “UV” describe what kind of light the machine makes. “Galvo” describes how that light is moved around. You are picking one from each list, not one from four.
| Term | What it actually refers to |
|---|---|
| Fiber | Source: 1,064 nm infrared. The metal-marking standard. |
| MOPA | A type of fiber source with an adjustable pulse width. |
| UV | Source: 355 nm ultraviolet. “Cold” marking. |
| Galvo | Delivery: two mirrors steer the beam instead of moving a head on rails. Fast, small field. |
So a “60 W MOPA fiber galvo” is one machine: a MOPA-type fiber source delivered through a galvo head. A “CO2 galvo” is a CO2 source delivered the same fast way — useful for high-speed engraving on organics, not for metal.
Galvo vs gantry — the delivery question
Your CO2 or diode machine is almost certainly a gantry: a head physically travels on rails over the work. A galvo keeps the optics still and steers the beam with two fast mirrors.
- Galvo is dramatically faster for marking — no mass to accelerate. Seconds instead of minutes.
- Galvo has a small field, typically 100×100 mm to 200×200 mm. Bigger fields need a longer lens, which costs resolution.
- Gantry wins on area. If you need to cut a 600 mm sheet, a galvo is the wrong tool.
This is why galvo machines are described as markers rather than cutters. They are superb at putting a logo, code or serial on a part, and poor at cutting shapes out of a large sheet.
Standard fiber (Q-switched) — the workhorse
A 1,064 nm fiber laser is absorbed well by metal and badly by most organics — the exact opposite of CO2. It is the default choice for:
- Deep or permanent marking on steel, stainless, aluminium, brass and titanium
- Serial numbers, data matrix codes, and tool or part identification
- Annealed (black, non-etched) marks on stainless for medical and food-contact parts
- Removing anodising or paint to expose bright metal underneath
- Cutting thin metal sheet, at higher powers
What it does not do well: wood, paper, most clear plastics, glass and fabric. If organics are your main business, a fiber machine is an addition to a CO2, not a replacement for one.
MOPA — the same thing with a tuning knob
MOPA stands for Master Oscillator Power Amplifier. Practically, the difference that matters is that you can adjust the pulse width (typically ~2–500 ns) rather than being fixed at whatever the source gives you. That control buys three things a standard fiber struggles with:
- Colour marking on stainless steel. Short pulses build controlled oxide layers that read as blues, golds, purples and greys. This is the headline MOPA feature, and it is also the most temperamental — colour is highly sensitive to settings, angle and the exact steel.
- Clean marking on anodised aluminium without blowing through to bright metal.
- Marking thin or heat-sensitive parts with less distortion, because you can put in less heat per pulse.
A MOPA is generally a modest step up in price over an equivalent standard fiber. If colour on stainless or quality work on anodised aluminium is in your plans, it is usually worth it; if you are marking mild steel parts all day, a standard fiber does that job just as well.
UV (355 nm) — the cold marker
UV works by a different mechanism: the photons have enough energy to break bonds directly, so it marks with very little heat. That makes it the answer for materials that char, melt or crack under fiber or CO2:
- Clear and light-coloured plastics, including many that fiber cannot touch
- Glass and some ceramics, with far less microcracking
- Delicate electronics, thin films, medical plastics
- Very fine detail — the short wavelength focuses to a smaller spot
UV machines are the most expensive of the three and their source has a shorter service life. It is a specialist purchase you make because a specific material demands it, not a general upgrade.
Quick decision table
| If you need to… | Machine |
|---|---|
| Mark steel, aluminium, brass; serial numbers; tool marking | Standard fiber galvo |
| Colour marks on stainless; quality work on anodised aluminium | MOPA fiber galvo |
| Mark clear plastics, glass, delicate electronics | UV galvo |
| Cut wood, acrylic, leather, card; engrave organics | CO2 (gantry) — what you probably already have |
| Engrave organics much faster, small area | CO2 galvo |
| Cut large sheets of anything | Gantry, not galvo |
What about Epilog and Trotec?
These are brands, not a fourth technology — and both sell CO2, fiber and combination machines. The real trade-off when they come up against a cheaper import is not beam quality so much as support, software, fume extraction and resale value. A budget galvo from a direct importer and a Trotec can both mark a steel tag; they differ in what happens when something breaks, and in whether an industrial customer will accept your quality documentation.
If the work is hobby or small-batch, the import is usually the rational buy. If you are marking parts under a customer's quality process, the branded machine is often what the customer is actually paying for.
Before you buy anything
Run the numbers on whether the machine pays for itself. Our laser ROI calculator works out payback period, break-even hours and monthly profit from your hourly rate and realistic billable hours — the honest version, where two billable hours a month means the machine takes years. For what to charge once it arrives, see how to price laser engraving.
FAQ
What is the difference between a fiber laser and a MOPA laser?
A MOPA is a type of fiber laser. Both emit at 1,064 nm, but a MOPA lets you adjust the pulse width, typically around 2-500 ns, instead of running at a fixed value. That control is what enables colour marking on stainless steel, cleaner marking on anodised aluminium, and lower heat input on thin or delicate parts. For plain marking on mild steel, a standard fiber performs the same job.
What does galvo mean on a laser?
Galvo describes how the beam is moved, not what kind of beam it is. Two fast mirrors steer the beam while the optics stay still, instead of a head travelling on rails as on a gantry machine. Galvo is far faster for marking but has a small working field, typically 100x100 mm to 200x200 mm, so it is a marker rather than a sheet cutter.
Can a fiber laser cut wood or acrylic?
Not well. Fiber light at 1,064 nm is absorbed strongly by metal and poorly by most organics, which is the opposite of CO2 at 10,600 nm. A fiber machine is an addition to a CO2 for metal work, not a replacement for it. If wood, acrylic, leather and card are your main materials, keep the CO2.
What is a UV laser used for?
UV at 355 nm marks by breaking molecular bonds rather than by heating, so it produces very little heat damage. That makes it the answer for clear and light-coloured plastics, glass and ceramics that would crack, delicate electronics and thin films, and very fine detail. It is the most expensive option and the source has a shorter service life, so it is a specialist purchase driven by a specific material.
Is a Trotec or Epilog worth it over a cheaper import?
It depends on the customer, not the beam. Both a budget galvo and a branded machine can mark a steel tag. The difference is support, software, extraction, resale value and whether an industrial customer will accept your quality documentation. For hobby and small-batch work the import is usually the rational buy; for parts marked under a customer's quality process, the branded machine is often what is actually being paid for.
Can I price fiber marking with the GetLaserQuote calculator?
Not directly. The calculator models CO2 and diode gantry machines, where cost follows cut length and machine time. Galvo marking is priced per part and per cycle rather than per metre, so time a single part on the machine and quote from that. The ROI calculator does apply to a fiber purchase, since payback depends on your hourly rate and billable hours regardless of machine type.