There are some really complicated (and very beautiful) devices built to make lighthouses work as well as possible. They are big, heavy assemblies of glass lenses, prisms and metal frames to hold it all together. This is generally called an optic. If you have a system that only uses reflection (usually the older parabolic metal reflector type), it is called catoptric. If a system uses refraction only it is called dioptric. The most common modern system (because it is generally the best) is called catadioptric.