Modulation polarimetry of thermoelasticity induced by thermal radiation in a glass

Abstract

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 tech nique. 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 gradi ent 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 mea sured. 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.

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

“…We would like to emphasize that, when studying the radiation thermoelasticity of a glass specimen irradiated with thermal radiation emitted by a black body, we have registered the radiation cooling [9]. This phenomenon, which accompanies the cyclic heatingcooling process, manifests itself as the relaxation of the specimen to an equilibrium state, when the radiation heating had been terminated.…”

“…1), whose main component is photovoltaic polarization modulator 5. By appropriately arranging the functional elements (the modulator and linear polarizer 6 were arranged behind the specimen), the installation was configured to register the linear birefringence, which was described in detail in work [9]. Therefore, here, we only describe the differences.…”

“…It includes some elements of differential spectroscopy [8] and, therefore, is characterized by the inherited analytical and high detection capabilities. In work [9], we showed that MP can be used to register thermal stresses, even if all mechanical and optical coefficients that are involved in the stress generation are almost temperature-independent. Therefore, the aim of this work is to continue and further develop researches started in work [9] and dealing with the peculiarities of radiation thermoelasticity in the case where the stresses are induced by external thermal radiation.…”

Determination of the thermal diffusivity coefficient of transparent solids by a modulation polarimetry technique

“…Для експериментального дослiдження коефiцiєнта температуропровiдностi використано технiку модуляцiйної поляриметрiї (МП) [21,22], яка здатна достовiрно реєструвати всi особливостi процесу встановлення еластокiнетики. Як показано в [23], з її допомогою можна реєструвати термонапруження в умовах незалежностi вiд температури механiчних, оптичних та теплофiзичних коефiцiєнтiв, що беруть участь у ґенерацiї напружень.…”

“…Методика вимiрювання термонапружень за допомогою технiки МП та оптична схема були неодноразово описанi в публiкацiях [21][22][23], тож зупинимося тiльки на основних принципових моментах експерименту. Оптико-поляризацiйна схема, що складається з двох схрещених лiнiйних поляризаторiв, доповнена модулятором поляризацiї електромагнiтного випромiнювання.…”