A Combined Non-Invasive Approach to the Study of A Mosaic Model: First Laboratory Experimental Results

Area of Science:

• Materials Science
• Archaeometry
• Non-Destructive Testing

Background:

• Wall mosaics are susceptible to deterioration, requiring advanced non-destructive methods for analysis.
• Existing non-destructive techniques offer complementary but often localized or surface-level information.
• A combined approach using multiple electromagnetic methods can provide comprehensive subsurface defect detection.

Purpose of the Study:

• To present the first laboratory results of a combined non-invasive electromagnetic approach for analyzing wall mosaic models.
• To evaluate the efficacy of digital holographic speckle pattern interferometry (DHSPI), stimulated infrared thermography (SIRT), and holographic subsurface radar (HSR) in identifying simulated defects.
• To contribute to the development of efficient in-situ subsurface analysis techniques for ancient wall mosaics.

Main Methods:

• Digital holographic speckle pattern interferometry (DHSPI): Optical imaging and interferometry to visualize surface micro-deformation under thermal stress.
• Stimulated infrared thermography (SIRT): Visualization of thermal energy diffusion on the surface after induced thermal stress.
• Holographic subsurface radar (HSR): Contact method providing localized dielectric permittivity contrast information.

Main Results:

• The combined DHSPI, SIRT, and HSR approach successfully identified known simulated defects (cracks, voids, detachments) in a custom-built wall mosaic model.
• DHSPI and SIRT provided complementary full-field contactless data on subsurface discontinuities.
• HSR offered localized information on dielectric anomalies, complementing the optical and thermal data.

Conclusions:

• The integrated use of DHSPI, SIRT, and HSR offers an efficient and effective non-invasive method for subsurface analysis of wall mosaics.
• This combined approach enhances the detection and characterization of defects in complex structures like wall mosaics.
• The study demonstrates a promising pathway for in-situ, non-destructive evaluation of cultural heritage artifacts.