Generalized Virtual-Wave Theory Advances Photothermal Imaging for Composite Material Inspection
Researchers have developed a generalized virtual-wave photothermal tomography framework that extends imaging capabilities beyond traditional impulsive excitation to handle pulsed, harmonic, and chirped waveforms. The method converts diffuse thermal responses into wave-like fields with clearer boundaries, addressing fundamental limitations in subsurface inspection of composite materials. This advancement could improve non-destructive testing in industrial applications where accurate depth localization and defect detection are critical.
A new photothermal imaging framework addresses long-standing limitations in non-destructive composite material inspection by transforming diffusive heat transport into propagating wave fields. The researchers derived a Fredholm integral mapping that links measured thermal diffusion fields to virtual wave fields governed by wave equations, while explicitly enforcing causality and thermodynamic irreversibility. The approach handles arbitrary boundary excitations—including pulsed, harmonic, and chirped waveforms—rather than only idealized impulsive conditions. Experiments on carbon fiber reinforced polymer samples with embedded defects demonstrated enhanced contrast, sharper boundaries, and more reliable depth interpretation compared to conventional thermographic techniques. The ill-posed inverse problem is solved using ADMM or truncated SVD depending on excitation characteristics, establishing a unified, physically grounded framework for practical industrial applications.
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- arXiv physicsCenter
Generalized Virtual-Wave Theory for Photothermal Coherence Tomography under Arbitrary Excitation Toward Non-Contact Industrial Inspection of Composite Materials
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