What Is a Galvo Laser? How Galvanometer Marking Works

LaserEngraveHQ earns a commission from purchases made through these links, at no extra cost to you. Read our affiliate disclosure.

Step 1: Understand how galvanometer mirror scanning works

A galvanometer converts electrical signals into precise angular motion. In laser processing, a scan head contains galvanometer actuators with polished mirrors mounted on orthogonal X and Y axes above the workpiece.

The laser generator remains stationary. The beam strikes the X-axis mirror, reflecting to the Y-axis mirror, which directs it downward. The wonsung optical scanner listing specifies a galvanometer based optical scanning system with X Y sets, noting a ±20° optical scan angle in its bullets and 30 degrees in its spec table.

Because mirrors rotate tiny angles and have minimal mass, mechanical inertia is negligible. Unlike gantry systems that drag a carriage across rails, a galvo moves only reflected light, enabling swift direction changes.

Step 2: Contrast galvo speed with traditional gantry systems

Flatbed lasers move a carriage along rails with belts and stepper motors. The aliencell X1 Lite listing specifies a gantry speed of 600mm/s with 20,000 mm/s² acceleration across a 26″ × 21″ bed for its 40W laser cutter. Carriage mass limits how quickly rails can reverse direction without vibration.

Galvo systems steer the beam by pivoting lightweight mirrors. The wonsung optical scanner listing illustrates high-speed mirror deflection with a scanning speed rating greater than 20Kpps (using a 30K ILDA pattern) for stage animation laser lights. In workshop engraving, this enables swift marking of barcodes and logos without raster passes.

The trade-off is work area. A gantry spans broad sheet dimensions, while a galvo beam deflects through an optical lens with a compact field. For shops marking small parts, fiber laser engravers using galvo heads maximize throughput.

Step 3: Learn how F-Theta field lenses focus the beam

A laser beam exiting angular galvo mirrors naturally focuses onto a curved surface, losing focus at the edges of a flat bed. Galvo systems correct this distortion using an F-Theta flat-field lens mounted beneath the mirrors so image height remains proportional to scan angle.

The OMTech F-Theta lens listing specifies a 1064nm field lens for fiber laser marking machines supporting 20W, 30W, 50W, and 60W power ratings. The OMTech listing shows an internal contradiction: its title and bullets describe a 175×175 mm scanning field (6.9×6.9 in. or 17.5×17.5 cm) delivering an exact 20 micron spot size and 99% throughput, but its spec table lists a 110×110 mm scan field alongside a 158 mm scan length, ±28° scan angle, 160 mm effective focal length, and standard M85x1 mounting threading.

As the Ovsuqu listing notes, a smaller lens field achieves deeper engraving because it concentrates power into a narrower spot diameter, while a larger lens field expands marking area at the expense of lower energy density. A 110×110 mm lens maximizes power density for deep engraving, whereas 175×175 mm or 300x300mm lenses cover broader parts with reduced depth per pass.

Step 4: Identify the laser source paired with the galvo head

A galvo head steers the beam but does not generate the laser light. Common sources paired with galvo scanners include:

• Fiber laser sources: Operating in the near-infrared spectrum, fiber units mark metals and plastics. The Ovsuqu listing specifies a JPT MOPA M7 100W fiber laser machine with a 300x300mm (11.8×11.8″) working lens, 1-4000kHZ pulse frequency, 2-500ns pulse duration, and 1.5mJ pulse energy. Compare models in our best fiber laser engraver guide, or read what is a fiber laser engraver.
• CO2 laser sources: Emitting in the far-infrared spectrum, CO2 tubes mark non-metallic organics. The SFX listing specifies a 30W CO2 DAVI galvo marking machine with a 140×140mm marking area and 0.01mm~2mm engraving depth. See our guide on what is a CO2 laser engraver.
• Diode laser sources: Diode galvos offer compact desktop marking. The Genmitsu Kintix listing specifies 5W (5000mW) and 10W (10000mW) models with a 200x100mm work area, 0.01mm precision, and motorized focus. The 10W uses dual X-Y galvos, while the 5W pairs an X-axis stepper with a Y-axis galvo.

Step 5: Match materials to the correct laser source

Material compatibility depends on source wavelength:

Fiber galvo lasers mark bare metals like stainless steel, aluminum, brass, copper, silver, and gold. See our guide to the best metal for laser engraving. Fiber lasers with MOPA pulse control can also produce oxide colors on stainless steel; see how to color engrave stainless steel with a MOPA laser.

CO2 galvo lasers mark organics that do not absorb near-infrared wavelengths. The SFX listing specifies wood, glass, acrylic, paper, and rubber. Diode galvos mark wood, leather, and slate, but require topical marking sprays for bare stainless steel, as noted on the Genmitsu Kintix listing.

Never laser PVC, vinyl, PVC-based faux leather, polycarbonate, or ABS. Although the Ovsuqu and SFX listings mention PVC or ABS, lasering these polymers releases corrosive hydrogen chloride gas and toxins that damage optics and health.

Step 6: Review workshop safety and beam enclosure ratings

Galvo mirrors deflect beams across wide angles, creating optical hazards that require workshop precautions:

Enclosed units achieve Class 1 safety via interlocked covers that pause the beam when opened, as listed on the Genmitsu Kintix. Open-frame galvos present severe hazards. While the Ovsuqu 100W listing quotes Laser Class 2 with 0.874mW output power (the red alignment guide beam under FDA Accession Number 2420799-000), and the SFX 30W quotes Class 1 with 0.39mW, their primary 100W fiber and 30W CO2 beams are high-power emissions requiring workshop shielding.

Protective eyewear is mandatory with open systems. Eyewear protects only if certified for the matching wavelength and optical density (OD), such as 1064nm for OMTech fiber lasers. See our laser safety glasses guide.

Fume extraction is essential for vaporized particulates. Use dedicated exhaust or a filter; see our best fume extractor for laser engraver guide.

Step 7: Plan for marking area limits and part alignment

Because galvo working fields are restricted by the F-Theta lens, batch efficiency depends on repeatable fixturing:

For repeat runs of small blanks, operators use mechanical alignment fixtures. The 328 Collective Generic 8-Piece galvo fence kit fits 25mm pattern tables with M6 bolts, including 1 cross piece, 2 angle pieces (90°), 2 single-length pieces, 2 double-length pieces, 1 triple-length piece, and 8 M6×10mm bolts to lock part coordinates without realignment.

For cylindrical items, galvo systems pair with rotary attachments, such as the SFX D80 rotary axis or Ovsuqu 80D rotary chuck, synchronizing mirror deflection with part rotation for tumblers and rings.

Common mistakes to avoid

• Expecting a galvo laser to cut thick boards like a large flatbed gantry.
• Assuming all galvo lasers mark bare metal without checking for a fiber or UV source.
• Swapping to a larger field lens without realizing power density drops and spot size widens.
• Operating an open galvo laser without wavelength-certified eye protection.
• Lasering prohibited polymers like PVC, vinyl, or ABS based on factory listing mentions.

What is a galvo laser: the short version

1. A galvo laser steers a stationary beam using motorized mirrors on perpendicular axes.
2. Negligible mirror inertia allows rapid marking speeds compared to heavy gantry carriages.
3. An F-Theta field lens flattens the focal plane across the work area.
4. Galvo heads pair with fiber, CO2, or diode sources to process different materials.
5. Work areas are optically limited by the lens, requiring alignment fences or rotary chucks.
6. Safety requires certified protective eyewear, beam shielding, and fume extraction.

Using a galvo laser comes down to matching the source to your materials, choosing an F-Theta lens that balances field size with focal power, and locking down part coordinates for repeat batch production.

FAQ: lasers and CNC

What does galvo stand for in laser engraving?

Galvo is short for galvanometer, an actuator converting electrical signals into angular motion. Motors swivel mirrors on orthogonal axes to steer the beam across X and Y dimensions.

Can a galvo laser cut materials or only mark them?

Galvo lasers are built primarily for marking. While high-power fiber units can cut thin metal foil with multiple passes, galvo systems do not replace gantry cutters for thick wood or acrylic.

What is the difference between a galvo laser and a gantry laser?

A gantry laser moves an optical carriage along mechanical rails. A galvo laser keeps the generator fixed and deflects the beam with high-speed mirrors, trading broad bed area for rapid marking speed.

Can a galvo laser mark bare metal?

A galvo laser marks bare metal directly when fitted with a fiber source (like 1064nm) or UV source. Diode lasers require a marking spray for stainless steel and cannot mark brass or copper, while CO2 beams reflect off metal.

Why are galvo laser work areas smaller than gantry beds?

Work areas are limited by the F-Theta lens. A larger field requires a longer focal length, which widens beam spot size and lowers power density, reducing engraving efficiency.

Do I need special safety glasses for a galvo laser?

Yes. You must wear safety glasses with certified optical density (OD) for your laser wavelength, such as 1064nm for fiber machines. Unrated tinted shields provide no protection.

Related: the laser engraver hub, our guide to types of laser engraving, our list of fiber laser engraving ideas, and our guide on how to choose a laser engraver. Also see can a fiber laser cut metal.