Diffractive optical sensing of the surface quality of coated paper

Paper samples coated with one of five different pigment size distributions were investigated with the aid of a spectrophotometer and also with a senso r based on a diffractive optical element (DOE). With both methods of measur ement, differences in optical responses were observed between coated surfac es. The optical signal and the pigment size distribution were correlated on ly when the DOE sensor was used. In addition, anisotropy of the texture of the coating surface could be detected with the DOE sensor.