A method to measure surface structure

摘要

For measuring a surface structure, one takes two or more pictures with a progressive-scan CCD camera (15) and drag light from different directions for different pictures. A two-dimensional Fourier transform is then carried out for each picture and the two spectra are added to form a spectrum that is an approximation of the correct spectrum for the surface that is photographed. This spectrum illustrates the surface structure. The method can be carried out on-line in a paper machine and the result will be as good as the result of conventional laboratory tests.