Laser Laboratory for Heritage Science

LLHS offers new analytical strategies specifically tailored for Heritage Science applications based in the use of laser methods. It includes techniques and systems for non-invasive analysis and advanced laser cleaning methodologies. Capabilities include expert knowledge based on almost two decades of research activity by the team, and in-house developed equipment for: a) The non-invasive determination of the elemental and molecular composition of materials of artworks and heritage substrates based in the combined application of laser spectroscopies, i.e. laser-induced breakdown spectroscopy, laser-induced fluorescence and Raman. These techniques are well established for compositional analysis of artworks and heritage materials, substrates and objects and to provide information of physicochemical transformations associated with ageing, degradation or restoration. b) The morphological, structural and chemical non-destructive characterization in all dimensions with micrometre accuracy, allowing identification of multilayers and determination of thickness and composition as a function of surface position and depth, using the non-linear optical microscopy (NLOM) imaging techniques of Multi-Photon Excited Fluorescence, and Second or Third Harmonic Generation. NLOM is based on the excitation of the non-linear optical response that any material can generate upon excitation with laser pulses of very short duration, in the range of femtoseconds. c) The laser removal of unwanted layers constituted by materials of diverse origin (organic and inorganic), assembled in mixtures (e.g., thick pollution, burial accumulations) or in layers (e.g., multiple protective, metallic, dirt and/or overpaint layers) on weathered, even fragile, original surfaces. The laser action is based on the process of ablation or vaporization and it offers unique possibilities in surface cleaning as it entails precise control, material selectivity and immediate feedback. These attributes are particularly important in Heritage conservation and within the last twenty years, lasers have evolved as exceptionally practical, and at the same time, delicate cleaning tools. This laboratory possesses a variety of pulsed laser sources emitting in the ultraviolet, visible and infrared spectral ranges with pulse duration in the nanosecond and femtosecond regimes.