Earlier this year we reworked some mirrors for a new customer, one of which was a 75mm diameter, 25mm thick Copper mirror used on a CO2 laser welding system. When looking at it again recently, I thought it was a good case study for our reworking service.
In order to assess the damage on the used mirror before repairing it, we used phase shifting interferometry to produce an interferogram. The dents and bulges in the surface are too large for the computer fringe analysis software to analyse. This damage would have been caused by handling, mounting and unmounting the mirror during its lifetime.
The ‘after’ interferogram is seen on the second page & shows that once the repair was complete, the flatness was 150 nm, and all the dents and bulges that were on the mirror had been removed, to give a smooth flat surface.
The customer was delighted, and has recently contacted us to repair a further 15 of their used co2 laser copper mirrors.