OPTICAL AND DIGITAL HOLOGRAPHIC INTERFEROMETRY APPLIED IN ART CONSERVATION STRUCTURAL DIAGNOSIS

Holography and holography-related interferometry have emerged as new tools for conservation researchers and practitioners, and are used to visualize structural faults and mechanical discontinuities in the bulk of an artwork. These may be an important factor of deterioration and can be a consequence of various degradation processes, caused by environmental parameters, transportation, handling, and various conservation and restoration actions. Holographic analysis is based on studies of interference patterns created by controlled surface reflection of diffused laser beams. Since no sample removal or surface preparation is necessary to visualise faults and defects the techniques are regarded as non-destructive and non-contact. This brief review provides a comprehensive introduction to the basic physical principles of operation with a description of some case studies.