Automated serial sectioning applied to 3D paper structure analysis

A better understanding of paper properties requires a detailed knowledge about the spatial arrangement of its constituent materials in its structure. This paper presents a novel approach for the analysis of the three-dimensional paper structure at the fibre level. A technique combining a rotary microtome and an optical microscopy was developed allowing serial sectioning of hundreds of cuts. The microscope is fixed on a moveable stage and mounted in front of a microtome. Repeatedly, thin slices are cut off an embedded paper sample and the cut block surface is scanned in a fully automated process. The prototype built is able to digitize paper samples with a size of more than 1 cm(2) at a possible three-dimensional resolution below 1 μm. Advanced computer vision methods are applied to extract relevant information from the digitized samples. Currently, the most important applications are the analysis of pigment coating layers on the paper surfaces and the analysis of fibre transverse morphology. Besides the analysis of paper structures, this technique is also suited for the spatial analysis of other materials, if the structural features are accessible with light optical microscopy.