Determination of thermal diffusivity by nonstationary spot heating

A thermographic express method for determining the coefficient of thermal diffusivity (a) of platelike objects is presented. It may be regarded as a modification of, and the next step in, the evolution of the laser flash method. In contrast to laser flash analysis, the proposed method, which involves spot stage heating by a focused laser beam ($\sim$0.1 mm$^2$) with simultaneous high-speed recording of the nonstationary temperature field by a thermal camera, does not require cutting out samples of a specific shape and access to two sides of the tested object. The developed algorithm for deriving the value of a from raw data makes it unnecessary to determine the absolute temperatures and the absorbed incident energy.