Digital holographic interferometry for cultural heritage structural diagnostics: A coherent and a low-coherence optical set-up for the study of a marquetry sample

Cultural heritage conservation is an active field of research, where there is an ever-growing demand for nondestructive and noninvasive diagnostic techniques, for performing remote analysis and diagnosis of the condition of historical structures and pieces of art, often of very high cultural and historical value. In this context, holographic interferometry is a very well-established optical technique for research in cultural heritage, which brings together some very basic and critical properties such as contactless examination and nondestructivity, accuracy, repeatability, and a wide range of applicability. In this paper, the optical technique of digital holographic interferometry is tested on mock-up, art-related targets, with 2 different light sources, in an attempt to expand the technique towards a new approach that will profit from an easy-to-operate, inexpensive, and tunable source, offering a broad spectrum and wavelength selectivity, according to the needs of the experiments. Examples are presented, and the results demonstrate the effectiveness of the proposed modified experimental scheme for defect mapping, to be used in structural documentation reports, and for its exploitation in future hybrid optical diagnostic systems and data processing.