Observation of internal structures using active thermography, optical coherence tomography and THz time-domain imaging in the field of cultural heritage

Nondestructive evaluation techniques using infrared and terahertz waves were employed to examine an aged violin and an inlaid dish. The results suggest that active thermography can rapidly reveal the general features of deterioration, while optical coherence tomography and THz imaging visualise cross-sectional images by scanning. These techniques are complementary and provide useful information for conservation planning.