Dynamic Laser Speckle Technique Sensing Long-Term Changes Caused by Painting Treatments in Restauration of Paintings

Abstract

Dynamic laser speckle is applied as a reliable sensor of activity in all sort of material. 1Traditional applications are based on a time rate that is usually higher than 10 frames-per-second 2 (FPS). Even in drying processes, where there is a high activity in the first moments after the painting 3 and a slow activity after some minutes or hours, the process is based on the acquisition of images in 4 a time rate that is the same in both moments of high and low activity. In this work, we present an 5 alternative approach to follow the drying of paint and the other processes related to restauration of 6 paintings that takes long-term to reduce the activity. We illuminated, using three different 7 wavelength lasers, an accelerator (Cyclododecane) and a varnish used in restauration of paintings 8 and monitor them at long-term drying using an alternative fps, comparing the results to the 9 traditional method. The work also presents a way to do the monitoring using a portable equipment. 10The results present the feasibility to use the portable device and show the improvement in the 11 sensitivity of the dynamic laser speckle to sense long-term process regarding the drying of 12Cyclododecane and Varnish used in restauration. 13