| 摘要 |
<p>Nondestructive acoustic method for the detection of detachments in fresco paintings and generally in mural paintings, which uses as detachment physical indicator, the acoustic absorption coefficient. In the present method, the acoustic source (1) and the detector (2) are placed at a certain distance from the painting. The use of the 'Cepstrum' technique allows to carry out the measurements also in presence of background noise, and without knowledge of the value of the direct signal pd(t), which should be subtracted from the detection signal p(t) in order to obtain the reflected signal pr(t). A microprocessor contained in the device used for the measurements, performs the necessary calculations to automatically determine the acoustic energy absorption on predetermined points of the painting surface. By means of an image processing of the so obtained values, bidimensional and tridimensional acoustic images are formed for representing the detachments or separation zones of the painting.</p> |
