Component Analysis of Radiation-Induced Thermoe-lasticity Using Modulation Polarimetry

Abstract

A radiation field of an external or internal origin creates a non-uniform temperature gradient in a glass specimen. In this case, there appears a heat flux in the specimen, which generates mechanical stresses and induces an optical anisotropy in the form of birefringence. In this work, using the optical-polarization method, the birefringence magnitude is measured as the phase difference between the orthogonal components of the linearly polarized probing radiation. The capability of the method is enhanced by modulating the radiation polarization, which provided a reliable registration of stresses in the specimen at a temperature drop of about 0.1 K. The stress kinetics with a complicated behavior and ambiguous by sign is detected at the observation point within the temperature establishment time interval. Its modeling in terms of exponential functions made it possible to decompose the measurement results into components associated with the radiative, conductive, and convective heat transfer mechanisms, as well as determine their relaxation parameters. The measurement data can be of practical use while determining such technically important material characteristics as the thermal diffusion and heat transfer coefficients.