DESIGN OF LOW EMISSIVITY SYSTEMS BASED ON A 3-LAYER COATING

The energy losses of window panes due to thermal radiation can be redu ced by low emissivity systems based on an Ag-film. In these low pass I R reflection filters the Ag-film is sandwiched by two dielectric layer s to achieve a small reflectance and large transmittance in the visibl e spectral range. The large IR reflection is achieved by a 12 nm Ag-fi lm. The optimal properties of the three layer coating including an Ag- film an calculated. In this algorithm the thickness and refractive ind ex of the two dielectric coatings are optimized using the admittance. The theoretical results are experimentally verified by a low emissivit y system prepared by dc-magnetron sputtering. (C) 1997 Elsevier Scienc e B.V.