An experimental technique using real-time holographic interferometry c
ombined with digitized image processing has been developed to measure
the thermal diffusivity of polymers. This technique uses a cantilever
beam or an annular disk with one side subjected to a pulse of radiant
energy from a photographic flash. The resulting thermally induced defl
ection is measured by holographic interferometry. The observed deflect
ion is due to a resultant thermal moment induced by a temperature grad
ient through the thickness. As time goes on, the heat conducts from th
e exposed surface through the thickness, resulting in a decrease of th
e bending moment and transverse deflection. It is shown that the defle
ction is proportional to the thermal moment, and the thermal diffusivi
ty can be retrieved by moment analysis without deriving the analytical
solution to the thermomechanical problem.