Fiber laser basics and marking (incl. MOPA)¶

Fiber markers are the metal specialists in many shops. Instead of a gantry dragging a head across a bed, most hobby/small-shop fibers use a galvo head and an F-theta lens that marks inside a fixed field. LightBurn talks to them differently than a Ruida CO₂ — but the shop goals are familiar: clean logos, serials, and durable marks.

Course: Galvo workflows make more sense after Master LightBurn foundations.

What “fiber” usually means in a maker shop¶

Wavelength around 1064 nm — strong for many metals; not a wood/acrylic cutter replacement for CO₂.
Pulsed source (Q-switched or MOPA) with adjustable frequency and (on MOPA) pulse width.
Marking field size trades off against spot size when you change lenses.

Q-switched vs MOPA (community consensus)¶

	Q-switched	MOPA
Pulse width	Largely fixed	Adjustable over a wide range
Frequency range	Narrower	Much wider
Everyday metal logos	Excellent	Excellent
Color / fine anneal control on stainless	Possible but limited	Preferable for wider, more repeatable color
Price	Usually lower	Usually higher

LightBurn forum consensus: non-MOPA machines can produce some color, but MOPA makes consistent color marking far more practical because you can tune pulse shape and frequency. Buy MOPA if color (or sensitive plastics) is a primary goal — not only because a brochure listed “color.”

Color itself is mostly controlled surface heating that forms an oxide / anneal layer. Results change with steel grade, thickness, lens, ambient temperature, and even fingerprints. There is no universal color chart that transfers machine-to-machine.

Want this to click faster? Master LightBurn walks the tools and workflows step by step — lifetime access, one clear path.

Lenses and focus (galvo reality)¶

Shorter F-theta lenses → smaller spot, higher energy density, smaller field, shallower depth of focus. Longer lenses → larger field, larger spot, more depth of focus. Community troubleshooting often finds “the machine won’t mark aluminum” is really wrong working distance or an oversized field lens spreading energy too thin.

Red-dot framing is a helper, not the beam. Calibrate offsets in LightBurn device settings so the preview matches the burn.

LightBurn habits that transfer¶

Even though the motion system is galvo, you still win by:

Naming layers by process (anneal, deep, cleanup)
Saving Material Library entries with lens focal length + metal grade in the name
Framing every production job until offsets are trusted
Disabling rotary mode when you return to flat work

If you are new to LightBurn generally, start with LightBurn basics before diving into pulse-width grids.

Practical marking modes (qualitative)¶

Surface etch / ablation — remove coating or material for contrast.
Annealed / black mark — heat without deep digging; often used on stainless.
Deep engrave — many passes; watch warping and discoloration from heat.
Color mark (esp. MOPA) — heat-controlled oxide colors; slow and fussy compared with mono logos.

Details and material notes: fiber metal marking.