Optical device for thermal diffusivity determination in liquids by reflection of a thermal wave

In this work, we present a device for determination of the thermal diffusivity using the oblique reflection of a thermal wave within a solid slab that is in contact with the medium to be characterized. By using the reflection near a critical angle under the assumption that thermal waves obey Snell’s...

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Bibliographic Details
Published in:Review of scientific instruments 2017-08, Vol.88 (8), p.084901-084901
Main Authors: Sánchez-Pérez, C., De León-Hernández, A., García-Cadena, C.
Format: Article
Language:English
Subjects:
Angle of reflection
Critical angle
Diffusivity
Laser beams
Photothermal deflection spectroscopy
Scientific apparatus & instruments
Thermal diffusivity
Wave reflection
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Summary:In this work, we present a device for determination of the thermal diffusivity using the oblique reflection of a thermal wave within a solid slab that is in contact with the medium to be characterized. By using the reflection near a critical angle under the assumption that thermal waves obey Snell’s law of refraction with the square root of the thermal diffusivities, the unknown thermal diffusivity is obtained by simple formulae. Experimentally, the sensor response is measured using the photothermal beam deflection technique within a slab that results in a compact device with no contact of the laser probing beam with the sample. We describe the theoretical basis and provide experimental results to validate the proposed method. We determine the thermal diffusivity of tridistilled water and glycerin solutions with an error of less than 0.5%.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.4998983