Hello, I would like to ask why, when a surface is not polished, it reflects less. I understand that when the surface is not polished, microscopically it presents a lot of irregularities so that when the light strikes the surface it gets reflected in all directions and instead of getting specular reflection, one gets diffuse reflection. The problem is that then the surface is not reflecting less, it's just you that are collecting less light. I'm working with an integrating sphere (http://en.wikipedia.org/wiki/Integrating_sphere), so theoretically, it doesn't matter that the light get scattered and diffuse in all direction because anyway it cannot get out of the sphere. In practice, when I measure not polished metallic surfaces, I get values of reflectivity which are up to 70% less than polished ones. Obviously the light gets absorbed (I can't see any other option) but I can't justify why so much. Especially I don't understand why this phenomena would depend so much on wavelenght (the same sample (copper, not polished), reflectivity reduced by 65% around 400 nm, reduced by 5% around 900 nm).