3D thermography for the surface and internal defects detection of lacquerware artifacts

This study presents a monocular 3D active thermography approach based on laser line scanning for high-precision inspection of lacquered wooden cultural artifacts. By integrating continuous line-laser excitation with an infrared camera, a unified mapping framework was established using spatial transformation and temporal calibration matrices. This configuration correlates transient thermal-response sequences with three-dimensional geometric coordinates, enabling the synchronized reconstruction of surface topography and internal defect signatures without external 3D scanning hardware. Experimental validation on an antique-style lacquer plate with nine prefabricated flat-bottom holes (diameter-to-depth ratios from 2.5 to 15) demonstrated that the method effectively identifies subsurface anomalies while maintaining a low temperature rise of ~1.61 °C, ensuring the thermal safety of organic heritage materials. The results indicate that this lightweight, non-contact method intuitively visualizes the spatial coupling between surface decoration and internal degradation, offering a robust technical solution for digital preventive conservation and restoration of complex lacquerware.