Non-Toxic Coatings for CO2-Laser Optical Systems

The standard antireflection coating of transmitting ZnSe optics for high power CO2 laser radiation (10.6µm) consists of a ThF4/ZnSe double layer. The best available coatings exhibit an absorption coefficient of approximately 10 cm−1, corresponding to a total absorption of less than 0.2%, and a damage threshold of more than 10 J/cm2. Since This a radioactive α-emitter, it would be advantageous to replace it by a less hazardous compound of similar optical and mechanical properties. Thus, the utilization of other metal fluorides as substitute low index materials has been the focus of many material studies [PELLICORI].