Dielectric thin films for maximized absorption with standard quality black surfaces

Optical coatings deposited on rough black surfaces permit one to reduce scattering and increase absorption with broadband properties. To optimize the optogeometrical parameters (thickness, refractive index) of the coating, to obtain the best performances, it is necessary to know the refractive index of the bare surface. For this purpose we use both theoretical and experimental approaches. It is shown that with our method the total amount of scattered light from a common standard black surface can be reduced by a factor of 10. An absorption of greater than 99.5% is obtained.