A novel method has been developed for nondestructively determining the thermal inertia (kpCp) of solids near room temperature. The method involves heating, with radiant energy, for a short time a small area on the surface of a solid whose dimensions are such that it appears semi-infinite during this period. Simultaneously, the characteristically shaped temperature rise of the central region of this area is observed using an ir radiometer as the sensor. A comparison of this history with that for a reference standard yields the local thermal inertia value. The localized thermal conductivity and diffusivity can then be determined if the density and specific heat are known. Present technique precision for good conductors is slightly less than that for destructive measuring techniques.
Arnold W. Schultz, "An Infrared Transient Method for Determining the Thermal Inertia, Conductivity, and Diffusivity of Solids," Appl. Opt. 7, 1845-1851 (1968)