New Lock-In Infrared Thermography Method Enables Rapid Thermal Conductivity Measurements Across Wide Material Range
Researchers have developed a phase-based lock-in infrared thermography technique capable of measuring thermal conductivity in bulk materials and layered structures ranging from approximately 1 W/m/K to over 2000 W/m/K. The method uses a modulated laser to heat materials while an infrared camera tracks the spatial phase distribution, which is then fitted to a multilayered thermal model to extract conductivity values. The approach is non-contact, insensitive to surface roughness, and does not strictly require a transducer layer, potentially simplifying characterization of a wide variety of materials.
A team of researchers has reported a phase-based lock-in thermography technique that combines infrared imaging with a multilayered thermal model — commonly used in thermoreflectance analysis — to measure thermal conductivity across an exceptionally wide range of materials. The system locks an infrared camera to the frequency of a modulated laser heating source, capturing the spatial distribution of thermal phase across the sample surface. This phase map is then fit to a thermal model from which thermal conductivity and other properties are extracted as free parameters. Crucially, the technique is non-contact and performed entirely from the front side of the sample, making it insensitive to surface roughness — a common limitation of competing methods. While no transducer layer is strictly required, the authors demonstrate practical advantages of applying a removable adhesive layer as a near-surface absorber. The method was validated on materials spanning over three orders of magnitude in thermal conductivity, from roughly 1 W/m/K to greater than 2000 W/m/K, suggesting broad applicability from polymers and insulators to highly conductive materials such as diamond or metals.
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- arXiv physicsCenter
Lock-In Infrared Thermography: Phase Analysis for Rapid, Wide-Range Thermal Conductivity Measurements
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