Main site nadinmacht.deDeutsch

Glossary · Design

Laser

MOPA

A special type of fibre laser in which the length of the light pulses can be adjusted. Among other things, this makes coloured marks on stainless steel possible.

Explained in more detail

A MOPA fibre laser separates the generation of the pulses (seed laser) from their amplification. This allows pulse duration and pulse frequency to be set independently, with common sources offering about 2 to 500 ns and 1 to 4000 kHz. A classic Q-switched fibre laser, by contrast, works with a largely fixed pulse duration of around 100 to 200 ns. Short pulses generate less heat in the material, which allows clean marks on plastic, black marks on anodised aluminium and controlled annealing colours on stainless steel. As with a regular fibre laser, the wavelength is 1064 nm.

Where does the term come from?

MOPA stands for Master Oscillator Power Amplifier. The name describes the two-stage design of pulse generator and amplifier.

In practice

  • Coloured marks on stainless steel only work with very consistent distance, material and settings. Test every new sheet with a colour grid.
  • For black marking of anodised aluminium, short pulses and high frequency are typical, and a material test supplies the values.
  • If you only want to mark metal, a Q-switch laser is often enough. MOPA is worthwhile for colour, plastic and fine effects.
  • The colours come from oxide layers and can change through abrasion, heat or aggressive cleaners.

Not to be confused

MOPA is not a separate laser type alongside the fibre laser, but a design variant of it. Colour marking does not mean colour printing: it only produces temper colours from gold through violet to blue.

Frequently asked questions

What is the difference between MOPA and Q-switch?

With MOPA, pulse duration and frequency can be set separately, while with Q-switch the pulse duration is largely fixed. MOPA is more flexible for colours and plastics, while Q-switch is cheaper and sufficient for simple metal marking.

Can you engrave in colour with MOPA?

On stainless steel and titanium yes, through controlled oxide layers in annealing colours. True photo colours or white are not produced this way.