Thermoelasticity component analysis in glasses during radiation cooling

摘要

Radiation cooling causes a non-uniform temperature field in the glass sample. In this case, heat flow arises in the sample and generates mechanical stresses and, as a consequence, optical anisotropy and birefringence. Modulation polarimetry technique for birefringence measuring was used. Phase differences between orthogonal components of linearly polarized light are linearly dependent on a stress magnitude. Detectability of the modulation polarimetry technique was high and ensured the registration of the mechanical stresses during radiative cooling by a fraction of a degree. The kinetics of the stress a(t) in the various coordinates of the sample demonstrates a complicated and variable dependence over the measurement time. Components related to radiation, conductive and convective heat transfer mechanisms are obtained from the a(t) dependence. Relaxation parameters of these components are determined.