Apparatus and method for measuring a paper surface roughness

Subjective paper characteristics such as visual appearance and print quality are often objectively related to certain scales of surface roughness. Three dimensional topographic surface data is obtained from a paper sample secured by vacuum to a flat, porous plate for translational movement in a grid pattern beneath a vertically compliant stylus that is resiliently suspended beneath a rigid, overhead support beam. Such surface data is mathematically filtered by a linear convolution technique or the distinctly alternative circular convolution technique to segregate the raw data characteristics of component surfaces that contain only certain frequencies of roughness. The root-mean-square variations of such component surfaces is then used to objectively characterize respective surface characteristics.