A suitable design of a three-layer antireflection coating based on ZnS
e and PbF2 layers on KCl windows for CO2 laser radiation is chosen to
match the requirements for a low loss and moisture-protection coating.
It is deposited on KCl plates by conventional and low-energy ion-assi
sted thermal evaporation. The local absorptance at different places bo
th at the interfaces and in the volume of the layers is measured by th
e photothermal deflection technique at 10.6 mu m. A considerable decre
ase of the local absorptance is observed in the coating deposited by t
hermal evaporation with Ar-ion bombardment of energy 40 eV. Conclusion
s regarding the absorptance value distribution in the depth of the coa
ting are drawn.