Method and apparatus for measuring coating

摘要

The invention relates to a method and an apparatus for measuring a coating from paper or board. The measurement is carried out by one detector at different times or by two detectors simultaneously. IR radiation directed at the coating and radiation emerging from the coating are chopped synchronously in blocks. A wavelength band sensitive and insensitive to the absorption are bandpass filtered and measured in both the MIR and NIR region. The absorption strength is measured in a digital signal processing block by comparing the radiation sensitive to absorption to the radiation insensitive to absorption, and the amount of each coating component is determined in the digital signal processing block on the basis of the absorption strength.