Применение эталона температуропроводности для контроля параметра теплопереноса в поглощающих материалах

Metrological support creation and use of heat transfer etalons are important stages in the development of modern materials science. This is especially concerned to the emergence of new materials in the world with previously unattainable thermophysical parameters. The purpose of this work was to develop and experimentally verify the idea of joint application of the transient gratings method which is well-known in nonlinear optics and the single thermal diffusivity etalon of conventional type for the heat transfer metrological control in materials of a wide values range. The method proposed is based on thermal diffusivity etalon application as a source of calibrated optical signals that are excited in it by short laser pulses. Their lifetime is formed by the etalon thermal diffusivity and on the transient grating spatial period. The etalon linear graph of gratings lifetimes as a function of the gratings periods squared and grating lifetime of the material under study are used for the thermal diffusivity calculation. Thermal diffusivity of thin sub-surface layers of the samples under study – duraluminium, monocrystalline silicon and thermoelectric lead telluride film was measured. The results obtained are in close agreement with the reference values.Создание, контроль и постоянное использование эталонов теплопереноса являются важнейшими факторами в развитии современного материаловедения. Это в особенности актуально в связи с появлением новых материалов с недостижимыми ранее теплофизическими параметрами. Целью работы являлась разработка и экспериментальное апробирование идеи совместного применения известного в нелинейной оптике метода динамических решёток и одного эталона температуропроводности стандартного типа для метрологического контроля параметров теплопереноса в материалах с широким диапазоном значений. Предложенный метод основан на использовании стандартного эталона температуропроводности как источника калиброванных оптических сигналов, возбуждаемых в нём короткими лазерными импульсами. Их длительность определяется коэффициентом температуропроводности эталона и периодом динамической решётки. Последний легко контролируется средствами современной оптики. Построенный с помощью эталона линейный график зависимости времени жизни множества динамических решёток от квадрата их периодов в сочетании с измеренным временем жизни решётки в исследуемом материале позволяют вычислить коэффициент температуропроводности. В приповерхностных слоях микронной толщины в трёх образцах – дюралюминий, монокристаллический кремний и термоэлектрик теллурид свинца – проведены измерения искомых параметров. Результаты тестирования близко соответствуют справочным значениям

Application of the Thermal Diffusivity Standard for the Heat Transfer Parameter Control in Absorbing Materials

Metrological support creation and use of heat transfer etalons are important stages in the development of modern materials science. This is especially concerned to the emergence of new materials in the world with previously unattainable thermophysical parameters. The purpose of this work was to develop and experimentally verify the idea of joint application of the transient gratings method which is well-known in nonlinear optics and the single thermal diffusivity etalon of conventional type for the heat transfer metrological control in materials of a wide values range. The method proposed is based on thermal diffusivity etalon application as a source of calibrated optical signals that are excited in it by short laser pulses. Their lifetime is formed by the etalon thermal diffusivity and on the transient grating spatial period. The etalon linear graph of gratings lifetimes as a function of the gratings periods squared and grating lifetime of the material under study are used for the thermal diffusivity calculation. Thermal diffusivity of thin sub-surface layers of the samples under study – duraluminium, monocrystalline silicon and thermoelectric lead telluride film was measured. The results obtained are in close agreement with the reference values

Association of polymorphism rs10841855 in the glycogen synthase 2 gene with hypercholesterolemia and type 2 diabetes mellitus

The aim of the study: To investigate the association of polymorphism rs10841855 (G>T) GYS2 with the risk of T2D in residents of Central Russiaassessmen

ОПТИЧЕСКИЙ МЕТОД И УСТРОЙСТВО ДЛЯ ИЗМЕРЕНИЯ ТЕМПЕРАТУРОПРОВОДНОСТИ ТВЕРДОТЕЛЬНЫХ МАТЕРИАЛОВ

Application of light-induced thermal transient gratings for measurement of thermal diffusivity of solid state materials including thin films is presented. Laser-optical set-up, which allows non-contact measurement of thermal diffusivity by transient gratings′ method is described. The set-up was designed in B.I. Stepanov Institute of Physics of NAS of Belarus.Приводится принцип измерения температуропроводности твердых тел, в том числе тонких пленок, с помощью наведенных светом тепловых динамических решеток. Дается описание созданного лазерно-оптического комплекса, позволяющего производить на основе метода динамических решеток бесконтактные измерения температуропроводности.

Optical phase conjugation for turbidity suppression in biological samples

Elastic optical scattering, the dominant light-interaction process in biological tissues, prevents tissues from being transparent. Although scattering may appear stochastic, it is in fact deterministic in nature. We show that, despite experimental imperfections, optical phase conjugation (λ = 532 nm) can force a transmitted light field to retrace its trajectory through a biological target and recover the original light field. For a 0.69-mm-thick chicken breast tissue section, we can enhance point-source light return by a factor of ~5 x 10^3 and achieve a light transmission enhancement factor of 3.8 within a collection angle of 29°. Additionally, we find that the reconstruction's quality, measured by the width of the reconstructed point source, is independent of tissue thickness (up to a thickness of 0.69 mm). This phenomenon may be used to enhance light transmission through tissue, enable measurement of small tissue movements, and form the basis of new tissue imaging techniques

OPTICAL METHOD AND SET-UP FOR THE THERMAL DIFFUSIVITY MEASURMENT OF SOLID STATE MATERIALS

Application of light-induced thermal transient gratings for measurement of thermal diffusivity of solid state materials including thin films is presented. Laser-optical set-up, which allows non-contact measurement of thermal diffusivity by transient gratings′ method is described. The set-up was designed in B.I. Stepanov Institute of Physics of NAS of Belarus