Focusing a 1µm Galvo Fiber Laser Marking Machine

Accurate focusing of any laser marking machine is fundamental to achieving a successful laser mark.

When the laser marker is precisely focused, the resulting optimally sized focal point will deliver maximum resolution, higher energy density, higher productivity and a consistent mark with a desirable aesthetic.

A laser marker that is incorrectly focused will not only produce an undesirable result but it will potentially work at a far slower rate too, having a significant adverse impact on productivity.

For this reason, with every laser engraving machine that we manufacture we incorporate an electronic Z axis to which the beam deflection unit (scan head) is mounted, which is controlled by our software so that the user can precisely focus the laser.

Systems that incorporate a manual method of focusing (not controlled by software) are much more prone to operator error.

Even worse, with poorly designed machines where the worktable is moved to focus the laser rather than the scan head, significant errors are almost guaranteed. This is especially common where machines use a ‘lab jack’ type table that is often never perfectly level and/or can move during the laser marking process, especially when heavier items are loaded to the machine.

The problem of inaccurate focusing of the laser is compounded where the laser source is lower in power because any loss of energy density will be a significantly larger portion of the overall laser power. Therefore, it’s somewhat true that lasers of a higher power are more forgiving if they are used out of focus compared to the same machine fitted with a lower power laser source.

For some applications it can be desirable to deliberately defocus the laser. For example, when laser marking stainless steel with a near to black annealed effect, defocusing a machine by several millimetres can actually enhance the effect.

Marking with an intentionally defocused laser can also prevent unwanted material ablation that would otherwise occur with a perfectly focused laser. For example, when laser marking food packaging (coding), such as the foils used to wrap ice-creams, a perfectly focused laser can pierce the foil and deliver a very narrow mark that is harder to read where a defocused laser is less likely to pierce the foil and the larger focal point will provide for a wider character that is easier to read.

Also, when some products require marking at exceptionally high speed and high resolution is not a priority, using a defocused laser with a larger focal point size can allow for a lower hatch density, providing for a much faster mark. This technique can be used, for example, for marking of cattle tags.

In summary, precise control of focusing the laser is often critical to achieving the best overall result.

At Lotus Laser Systems we manufacture a wide range laser marking and engraving solutions ideally configured for laser cutting, laser marking and laser engraving all types of materials. Our experts would be happy to recommend which configuration best suits your application.