Modulation polarimetry of thermoelasticity induced by thermal radiation in a glass

The phenomenon of thermoelasticity induced by an external thermal radiation in a model glass sample was investigated experimentally. The thermoelasticity was detected by the optical polarization method used in studies of the photoelastic effect and modified by the probe radiation polarization modulation technique. This technique made it possible to increase the sensitivity of the measurement system to the strain state of a solid so that it became possible to detect thermoelasticity under conditions where the temperature gradient across the sample reaches a few fractions of a degree. The spatial and temporal changes of the mechanical stresses induced in the sample by a nonuniform radiation heating and, consequently, by a heat flux were measured. The coordinate functions of temperature as solutions of the inverse problem of thermoelasticity were obtained using the graphical integration of the experimental characteristics. The characteristic parameters of some of the heat transfer mechanisms were determined by analyzing the experimental characteristics of the kinetics and dynamics of mechanical stresses.