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A large-scale survey (~700 m 2 ) of frescos and wall paintings was undertaken in the U.S. Capitol Building in Washington, D.C. to identify regions that may need structural repair due to detachment, delamination, or other defects. The survey encompassed eight pre-selected spaces including: Brumidi's first work at the Capitol building in the House Appropriations Committee room; the Parliamentarian's office; the House Speaker's office; the Senate Reception room; the President's Room; and three areas of the Brumidi Corridors. Roughly 60% of the area surveyed was domed or vaulted ceilings, the rest being walls. Approximately 250 scans were done ranging in size from 1 to 4 m 2 . The typical mesh density was 400 scan points per square meter. A common approach for post-processing time series called Proper Orthogonal Decomposition, or POD, was adapted to frequency-domain data in order to extract the essential features of the structure. We present a POD analysis for one of these panels, pinpointing regions that have experienced severe substructural degradation.

The aim of this research is to evaluate the effect of the interaction between the Laser Doppler Vibrometer and the sample in the microscale. In particular the attention will be focused in the numerical and experimental evaluation of the heating effect due to the laser beam power. The consequent temperature variation will be related to the measurement results in terms of resonance frequencies and vibrational modes determination.

In the present work the development of a customised vibrometer able to work on Microsystems is shown. The system is based on a commercial Laser Doppler vibrometer, in which the optical set-up, the mechanical arrangement and the processing software and hardware were modified and developed to measure vibrations of small object with a resolution in the micro scale. The main characteristics of this system is a very versatile platform, in which laser Doppler Vibrometry, two-axis stages micropositioner, digital signal processing and image acquisition and processing can work together in order to obtain the integration of vibration measurements with other experimental techniques. The system developed, which represents the first step in this project, has been applied to a typical test case in order to verify performances and limits. A discussion about main features and limits is presented.

In this work a system for static and dynamic calibration of in-fibre Bragg grating sensors (FBG), is described. Our idea starts from the calibration procedure of strain gauges that is done by applying a pure bending on the sample. The aim of this work is to develop a system that allows as to apply an analogous experimental technique. In this case we use as reference a Laser Vibrometer, and therefore to the sample a dynamic excitation by an electrodynamic actuator. The test bench is used to apply a sinusoidal force in a symmetrical way in order to obtain an alternate pure bending in the area where the sensor is glued on the structure. The greatest excitation frequency, limited by the characteristics of FBG interrogation system, is about 20 Hz.

During the last years the growing importance of the correct determination of the state of conservation of artworks has been stated by all personalities in care of Cultural Heritage. There exist many analytical methodologies and techniques to individuate the physical and chemical characteristics of artworks, but at present their structural diagnostics mainly rely on the expertise of the restorer and the typical diagnostic process is accomplished mainly through manual and visual inspection of the object surface. The basic idea behind the proposed technique is to substitute human senses with measurement instruments: surfaces are very slightly vibrated by mechanical actuators, while a laser Doppler vibrometer scans the objects measuring surface velocity and producing 2D or 3D maps. Where a defect occurs velocity is higher than neighboring areas so defects can be easily spotted. Laser vibrometers also identify structural resonance frequencies thus leading to a complete characterization of defects. This work will present the most recent results coming out of the application of Scanning Laser Doppler Vibrometers (SLDV) to different types of artworks: mosaics, ceramics, inlaid wood and easel painting. Real artworks and samples realized on purpose have been studied using the proposed technique and different measuring issues resulting from each artwork category will be described.