Surface Displacement Measurements of Artworks: New Data Processing for Speckle Pattern Interferometry

Curators have developed preventive conservation strategies and usually try to control the temperature (T) relative humidity (RH) variations in museum rooms stabilise artworks. The systems chosen by museums depend on size age of building, financial means that can be adapted. However, there is a lack methods monitor mechanical changes or chemical reactions objects real-time regularly. It would therefore ideally preferable each them alert preserve them. For this purpose, non-destructive, non-contact, full-field technique, Digital Holographic Speckle Pattern Interferometry (DHSPI), has already been allows direct tracking surface This technique based phase-shifting speckle interferometry gives deformation below level micro-meter analysed object. In order continuously, large number images are acquired DHSPI processed. existing process consists removing noise from interferogram, unwrapping image, deriving displaying 2D 3D map. improve time accuracy processing imaging data, simpler faster method developed. Using Matlab®, denoising methodology for interference pattern generated during data acquisition created, stationary wavelet transform. unwrapped image calculated using CPULSI (Calibrated Phase Unwrapping Least-Squares Iterations) algorithm as it fastest results among tested methods. phase then transformed into displacement. performs these steps interferogram automatically. access maps.