Patent ID: 7482590

Claim:
A method for determining a quantity of a coating applied to a material web, said method comprising the steps of: directing radiation onto the material web coated with the coating; interacting said radiation at least with the coating; detecting at least a fraction of said radiation that has interacted with the coating, in order to determine, based on at least one measurement signal produced by detected said radiation, the quantity of the coating at least one of on and in the material web, said step of detecting further comprising detecting, after interacting with the coating, said radiation in a plurality of frequency bands in order to produce a plurality of respective specific measurement signals, said plurality of frequency bands including at least one common frequency which is common to all of said plurality of frequency bands; said plurality of frequency bands being selected such that, given a same quantity of the applied coating, at least one of said plurality of specific measurement signals varies more with a structure of the applied coating than another of said plurality of specific measurement signals so as to thereby account for, at least in part, any diffusion of said radiation caused by said structure when determining the quantity of the coating; said plurality of specific measurement signals of said plurality of frequency bands being mathematically linked with each other to determine the quantity of the coating.