MULTIFUNCTIONAL MULTILAYER OPTICAL COATINGS

Multilayer optical coatings which heated and defogged the substrate, p rovided permeation barriers to water and air, and controlled emittance have been developed. All coatings were deposited by reactive de and r f magnetron sputtering, and the polymer multilayer process being devel oped at Pacific Northwest National Laboratory. The three coatings disc ussed in this article were applied to flexible and rigid substrates wi th diameters up to 28 cm. Fourteen-layers SiO2/Si3N4/TiO2/Ag coatings were applied to surveillance camera lenses to reject at least two lase r wavelengths, defog the lens, and provide a high transmission notch a t the operating wavelengths. The coatings were able to heat the substr ates at a rate of 16 degrees C/min at relatively modest power inputs o f 2 W/cm(2). The second coating had eight Cr/Si3N4 layers, and absorbe d strongly at the 1.06 mu m laser wavelength and emitted strongly in t he 3-5 mu m wavelength band. This coating was used in infrared display s. The last coating was a 15-layer polymer Al2O3 permeation barrier to water and air on a flexible polyethylene substrate. The coating was t ransparent. The permeation rates for oxygen were less than 2.55E-6 cm( 3)/cm/day, and were less than 1.55E-6 g/cm(2)/day for water. The perme ation test results provided further evidence for a synergistic relatio nship between polymer and oxide layers to prevent surface and solution diffusion of gases and water. (C) 1997 American Vacuum Society.