Durable broadband ultralow index fluoropolymer antireflection coatings for plastic optics

Durable broadband antireflection (AR) coatings remain an ongoing challenge for plastic optics used in a wide range of applications. Here, we show that glancing angle deposition of a commercial fluoropolymer can be used to fabricate extremely durable ultralow index AR coatings that reduce the solar spectrum-averaged (400 < lambda < 1600 nm) reflectance of acrylic and polycarbonate plastic to < 1% over a wide range of incidence angles up to similar to 40 degrees. The coatings feature strong adhesion and exhibit outstanding resistance to heat, humidity, dirt, ultraviolet light, outdoor exposure, solvents, acids, bases, abrasion, and repeated bend/compression cycling. They are successfully applied to f/1 curved lens surfaces as well as acrylic Fresnel lenses, where coating both sides increases the solar spectrum-averaged transmittance from 92% to 98%. These results represent a significant development for plastic optics commonly used in solar concentrators as well as more generally for broadband AR applications that demand extreme environmental, chemical, and mechanical durability. (C) 2017 Optical Society of America