Optics in the preservation of cultural heritage. Micro topographic and rugometric evaluation of wood artifacts

Optics and optical techniques and instruments are long time being successfully employed in the preservation of cultural heritage: both in cleaning and reconstruction but especially in inspection and noninvasive diagnosis. Humankind cultural heritage includes a vast number and variety of wood objects and artefacts. The inspection and characterization of the surface of wood artefacts and structures is very important for registering its status and in evaluating how it evolves when subjected to a certain kind of environmental constraint, or in the defining the suitability of a certain kind of material for a specific application. Both 2D and microtopographic inspection should be performed extensively and in a oninvasive way. For several years we have developed a series of active optical triangulation based microtopographers, the MICROTOP' family, improved and adapted according to particular inspection needs. Currently five system are available: the main system the MICROTOP.03.MFC intended for general use on the inspection of rough surfaces (both 2D and 3D) ; the PL system is a simplified version used on the inspection of polymer pieces and materials; a version to be used on the automotive industry for real time detection of fracture conditions in structural pieces; a simple hand held version; and the version .06 adapted by incorporation of an angle resolved scattering structure with height resolution measuring capabilities down to the nanometer range is the latest and more versatile version. The inspection of wood surfaces is successfully performed using the MICROTOP systems even when painted wood or 'talha dourada' gold engraved wood is involved. The three-dimensional evaluation is complemented by 2D image acquisition and processing, and by rugometric characterization making available all available ISO parameters and a reduced set of statistical parameters and function more meaningful on this kind of application. Also this set is adjusted to the particular characteristics of the surface involved and functional application. In this communication we will describe the microtopographer and present a set of representative applications to the inspection of wood samples. (Author)