Engineered polymeric IR-transparent protective coatings

This paper describes a novel infrared (IR)-transparent polymer engineered at Texas Instruments to protect IR windows. The polymer has greater than 80% transmission in the 8- to 12-micrometer range and can be combined with antireflection coatings to yield highly transparent IR window systems. The novel molecular structure of the polymer imparts a high, in-plane elastic modulus/strength to the coating, yet produces a lower-modulus material perpendicular to the plane. This very inexpensive coating can protect any IR window from both supersonic normal-incidence waterdrop erosion and damage by 200-mph blowing sand.