|Thin Film Design & Applications|
3 Layer AR Coatings
One of the most typical and straightforward 3 layer deisigns is referred to as the QHQ or Quarter-Half-Quarter. It is one of the first AR multilayer designs that is typically taught for use on glass. It is an extremely broadband AR for use in the visible and it can get the substrate surface reflectivity down quite low.The QHQ is as follows:
glass / M 2H L
The solid line just above 4% is the reflectance of bare glass. The dashed line is the performance of the QHQ where the L layer is SiO2. The blue solid line is the performance of the QHQ where the L layer is MgF2.