Zinc sulfide optics for high power laser applications

As disc and fiber laser powers increase and beam qualities improve, the optical systems required for focusing these new beams are being challenged. Newly available, multi-spectral, zinc sulfide optical material has been investigated as a possible solution to this challenge. The high thermal conductivity and the ability of ZnS to be diamond turned to an acceptable optical finish for 1 micron wavelength operation make it possible to produce single-element focusing solutions for high power applications. In this work a multi-functional, ZnS lens was designed and tested at laser powers to 6 kW. The single element, Integrated Focusing and Imaging (IFI) lens was shown to produce a theoretically correct focal spot as well as an accurate image of the work plane. Thermally-induced focal point shift was shown to be similar to that reported for traditional, fused silica optics, while focal spot size was maintained at a perfectly constant diameter.