Nukon Blog: Fibre Lasers and back reflections - Nukon Lasers UK fibre laser

November 23, 2023

Nukon Blog: Fibre Lasers and back reflections

Blog by Steve Haddrell.

If you work with a fibre laser cutting machine you may have heard the term “back reflection”, but what exactly does this mean?

fibre laser cutting machines

Well, the laser light that does the cutting is generated in a “resonator”. In the case of a fibre laser this is literally a piece of fibre optic cable that the light is trapped within until it reaches the right energy level to be released out of the laser to do its work. It’s a bit like using a megaphone to make your voice louder.

However, when you are cutting reflective materials the energy from the laser can reflect back up into the cutting head, along the beam path, and cause the whole system to be a resonator.

This causes a massive overload on the components in the laser and the beam delivery system, damaging some or all of them irreparably.

It’s important to understand that reflective materials aren’t necessarily shiny to the human eye. The reflectivity is at an atomic level and is to do with material structure. Commonly used materials that fall in to the category of reflective to fibre laser light are, aluminium, copper, and brass.

It is also possible to get a reflection on polished stainless steel as well.

There are a couple of common ways laser manufactures combat this issue:

  1. Electronic/software systems that shut the power off being popular as they aren’t expensive to implement.
  2. Hardware isolation systems converts the back-reflected power to heat which dissipates before it can damage the laser.

The issues with the electronic/software systems are that they are relatively slow to respond.

When you are dealing with things that move as fast as light the sweep time on electronics is an age, and not quick enough to protect the laser source from being damaged.

The hardware system is not dependant on reaction time and is therefore superior to the electronic system.

Nukon mount nLight lasers on their UK machines, and these nLight devices use the hardware isolation method.

It’s therefore very unlikely that the laser will be damaged by a back reflection. Making Nukon machines an excellent choice for processing reflective materials!

Find out more about Nukon’s fibre laser cutting machines – here.

Contact our team by emailing us –

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