Development of the technology of contacting ZnSe infrared optical windows using polyethylene films

We present a novel technology intended for contacting ZnSe IR optical windows. Thin polyethylene films located between plates made of ZnSe are irradiated by strong IR radiation produced by a CO₂ laser. The IR radiation caused changes in the structure of the polymer, which result in the high adhesion of polymer to the surfaces of ZnSe elements to be contacted. The technology enables contacting that maintains transparency in the broad IR band (1 to 25 µm) except for a few narrow absorption bands. Low wave-front distortion is established by a thorough interferometry study of contacted elements. The contacted ZnSe elements allow 100 W of CO₂ laser radiation to pass for 1 h with no drop in transparency. Special tests prove the high thermal stability of the bonded elements. The technology is intended for a wide range of IR optics applications.