Laser Interferometric Determination of the Dynamic Response of Solids

Measurements of the dynamic response of a solid induced by charged particle interaction are presented. The measurements were made using a laser interferometric technique to determine the free surface motion of silicon and germanium exposed to a pulsed electron beam. The results show that the free surface displacement and velocity can be determined in detail. The measured displacement and velocity histories are directly related to the energy spectrum of the incident electron beam and proportional to the electron fluence. The measurements are compared with the motion predicted by a thermoelastic calculation using known material properties. The difference between the predicted and measured response is discussed with respect to the coupling between the absorbed energy and the acoustic phonons.