Optical properties and infrared optics applications of composite films based on polyethylene and low-melting-point chalcogenide glass

A novel composite material based on medium-density polyethylene and thermoplastic chalcogenide glass has been produced. Both materials are highly transparent in the middle and far IR, but their refractive indices differ dramatically. The polymer and the glass have nearly equal viscosities at the temperature of polyethylene processing. This fact allowed the use of extrusion for homogenization. Single- and twin-screw extrusion processes yielded compositions that contain up to 40% of chalcogenide glass particles, which were dispersed in the polymer matrix. Highly homogeneous compositions that contain perfectly spherical glass particles 1 to 2 Am in diameter dispersed in the polymer matrix were obtained. Highly oriented structures involving chalcogenide glass fibers immersed in the polymer matrix were prepared at high stretch speeds. It was established that it is possible to produce a composite that is opaque in the visible and near IR, and highly transparent in the 2 to 25-mum wavelength band. The use of oriented films as IR laser light-shaping diffusers is possible. The composite films obtained were tried successfully as immersion adhesive layers for the contacting of IR fibers. (C) 2002 Society of Photo-Optical Instrumentation Engineers.