Feasibility of imaging the internal structure of opaque objects by holographic interferometry of spatially inhomogeneous thermal waves

The use of holographic interferometry methods to evaluate the internal structure of opaque objects is described. The action of warming radiation pulses on the object produces thermal waves in the object and the surrounding medium, and the amplitude and phase characteristics of the waves provide data on the internal structure of the object. Heat-conduction equations for the object and medium are solved to determine the characteristics of the temperature oscillations. For evaluation of the procedure of 300-W halogen lamp is utilized to obtain temperature oscillations for an Al plate and water medium. The amplitude of the oscillation of the medium is an order of 1 C above the metallic parts of the plate and an order of 10 C above the thermal insulation material. The thermal waves of the sample and medium are recorded by a stroboscopic technique or a time-averaging procedure.