How to clean the focal lens of my laser cutting system?

Regular care and maintenance of your laser system is essential for ensuring optimum cutting results. In our video tutorial we will show you step-by-step how to clean the focal lens of your laser system

correctly (current model series – G3/S3). Ensure a high degree of value retention and optimum condition of your laser system quickly and simply.

Please observe all warnings 

Removal of the lens holder

Removal or replacement of the focal lens could be necessary for inspection and cleaning purposes. The eurolaser laser cutting system focal lens is installed in a lens holder that can be removed from the laser tool module without having to detach the module itself from the system.It is not necessary to switch off the system for removal/replacement. Instead use the system-integrated tool changeover function to ensure trouble-free procedure.

Removal procedure

  • Press function key F4 on the control panel or enter the code 1-5-1; the laser tool module (LM-Z) may be at any position on the work surface
  • Acknowledge the user query “Start module/tool changeover” in the display with START
  • The LM-Z moves to the changeover position in the machine zero point
  • Display shows: “Module/Tool mounting/removing…”
  • Dismount the cover and unscrew the lens holder
  • Screw in the new lens holder (replacement) or the same holder after inspecting/cleaning it. Make sure it is completely screwed into the LM-Z
  • Mount the cover
  • Acknowledge the displayed message (see point 4) with OK
  • Once the lens is replaced the message “Module 1: Tool Manager” is displayed with the lens recognised by the system in the highlighted line
  • The holder is not completely screwed into the LM-Z or the respective recognition sensing device in the LM-Z is defective if this information does not correspond to the actually mounted lens
  • Acknowledge the message with OK


  • Never replace the lens holder with the LM-Z dismounted
  • Never replace the lens holder by bypassing the tool replacement function

This constitutes an impermissible tool replacement that would lead to error messages and in the worst case would damage to the system.


Get the following material ready:

  • The lens holder must be dismounted before cleaning.
  • Take care that the lens is replaced correctly after cleaning. It must be mounted with the curved side facing upwards. In the most favourable case a lens that is inserted incorrectly can result in a reduction in the quality of the cutting results, but in most cases it causes damage to the laser cutting system!
  • Place the focal optics on a clean, dust-free underlay, so that the lens is then free to be removed.
  • Unscrew the brass thread on the top of the lens and then carefully turn the lens holder upside down in such a way that it can be lifted off carefully.


Great care must be taken when removing the lens from the holder so that the edges are not damaged or the lens broken.

  • For this reason never use tools or hard objects to remove or clean the lens.
  • Prepare a clean, dust-free workplace where you can clean the lens.

Slight soiling (dust, lint, dirt spots, finger prints)

  • Only ever take hold of the lens on its edge.
  • In the first cleaning step place the lens on a sheet of lens paper. Cover the lens with another sheet of lens paper, then sprinkle a few drops of acetone on the paper so that the entire surface of the lens is dampened.
  • Next move the paper slowly over the lens without exerting any pressure. Normally the fluid evaporates behind the paper without leaving any smears.
  • Turn the lens over and repeat the procedure using a new piece of lens paper.

If there is no longer any visible soiling, cleaning is completed.
If you can still see soiling on the lens, continue with the second cleaning step.

  • Only ever use wooden or cardboard swab holders for the second cleaning step. Do not use plastic swab holders as acetone can dissolve these!
  • Use a new cotton swab for every cleaning step to ensure that any dirt sticking to the used swab is not rubbed onto the lens again.
  • Remove any slight soiling with a cotton swab soaked in acetone without exerting any pressure. Move the cotton swab over the surface while twisting with just enough pressure so that the liquid evaporates and leaves no smears on the lens.
  • Repeat the procedure until the lens is clean without any streaks.
  • Next turn the lens over and clean the back of it

If the lens is still soiled after you have carried out the cleaning procedure explained above,
it can be cleaned in a third mild cleaning step.

Medium soiling (oil, water splashes)

  • To do this moisten a cotton swab with pure distilled vinegar and wipe it over the surface of the lens while twisting it and exerting slight pressure. Soak up any excess vinegar with a dry cotton swab.
  • Next soak a cotton swab with acetone and clean the vinegar residues off the lens. To do this move the cotton swab over the surface while twisting with just enough pressure so that the liquid evaporates and leaves no smears on the lens.
  • Repeat until the lens is clean and has no smears.

Severe soiling

Some kinds of soiling caused by material remnants, burns or scratches cannot be cleaned off.

  • Replace such lenses as a precautionary measure.
    Damaged ZnSe lenses must be handled in compliance with the “ZnSe info sheet” and disposed of by the user.


Once the lens has been completely cleaned, the focal optics can be re-assembled in the reverse order.

  • Place the spacer sleeve on a flat, clean surface.
  • Position the space ring (red) and place the cleaned lens on it.
  • The lens must be mounted with the curved side facing upwards.
  • Reattach the lens holder carefully so the brass ring can be screwed back on.


Please be aware of your national laws and regulations for the usage of hazardous substances and the instructions in your manual!

  • In order to guarantee consistent cutting quality, the meniscus lenses used in the optical head of the systems must be inspected daily and cleaned of any visible soiling.
  • Cleaning and inspection of lenses must only be carried out by appropriately trained personnel and is undertaken at the user’s own risk.

 The following precautionary measures must be observed when cleaning the ZnSe lenses:

  • Always observe the operating instructions for acetone, ZnSE and for the equipment used by the owner.
  • Handle the ZnSe lens and optical components with extreme care. This applies especially to burnt or broken lenses. The particles released in this case can cause serious damage to health.
  • Avoid the material coming to contact with the skin.
  • Never touch the optics or lens with your bare fingers. Greasy or dirty hands soil the surface and shorten the service life of the lens.
  • Always wear finger stalls or gloves made of synthetic material. Do not use cotton gloves, because these are not lint-free.
  • Always store lenses that have not been used or that have been dismantled in the lens paper provided in the scope of delivery.
  • A scratched or burnt lens must no longer be used!

 Excerpt from the data on the toxicology of Selenium and its compounds:

  • Toxic by inhalation and if swallowed.
  • Do not eat, drink or smoke while working
  • After contact with the skin wash immediately with plenty of water
  • If you feel unwell, seek medical advice...
  • Acetone is recommended for cleaning the optical components

Hazard warnings for acetone:

  • Highly flammable
  • Keep out of reach of children
  • Keep the container tightly closed, store in a well ventilated place
  • Keep away from sources of ignition - do not smoke
  • Avoid contact with the skin
  • do not empty into drains

Do you have any questions? We are pleased to advise you.

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