A new interferometer concept has been successfully applied to the measurement of dynamic response associated with thermally induced stress waves. The technique involves the use of two Michelson interferometers to simultaneously measure front and back surface displacements of a specimen exposed to an intense electron pulse. Application of the method to porous copper (86 and 70% of the theoretical density) has resulted in dynamic data over an energy range spanning elastic and plastic behavior of the porous material. These data were compared to the predictions based on a hydrodynamic model for stress wave generation and propagation in a porous medium. The results indicated semiquantitative agreement, complete agreement not being possible using a single set of porous material model parameters. The study demonstrated that some important differences exist in porous material response to constant volume heating and planar plate impact loading. Finally, the results indicated that the double interferometer technique is uniquely suited to simultaneously studying thermally generated stress and attenuation in complex materials.