Quantitative topography measurements of rolled aluminium surfaces by atomic force microscopy and optical methods

We have compared the results of quantitative topography measurements on typ ical industrial, rolled or etched aluminium surfaces, using three different methods that can measure surface features in the 10-mu m to sub-micrometre range. The methods used, atomic force microscopy (AFM), white-light interf erometry, and confocal laser scanning microscopy (LSM), utilize very differ ent mechanisms of image formation. We find good agreement between data meas ured by AFM and by white-light interferometry. The two techniques complemen t each other. AFM is not limited to reflecting samples, it has a better res olution than interferometry, and it can measure steeper slopes. White-light interferometry is faster and allows larger areas to be analysed, and data from neighbouring areas can be spliced more easily. When used on strongly r eflecting, rolled or etched aluminium surfaces, LSM yields results that dev iate strongly from those of the other two methods and from the true sample surface topography. (C) 1999 Elsevier Science S.A. All rights reserved.