High Reflector Coating HR

High-reflection (HR) coatings work the opposite way to antireflection coatings. The general concept is usually based on the periodic layer system composed from two materials, one a high index and the other a low index material. This periodic system significantly enhances the reflectivity of the surface in the certain wavelength range called band-stop, whose width is determined by the ratio of the two indices (for quarter-wave system), while the maximum reflectivity is increasing nearly up to 100% with a number of layers in the stack.