Laser-Based Surface Tension Measurement

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Amini, Mansoureh | 2015

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 47150 (04)
University: Sharif University of Technology
Department: Physics
Advisor(s): Seyed Reihani, Morteza
Abstract:
Surface tension is the most important interfacial parameter of a liquid. This quantity plays a key role in many processes such as extraction, distillation, absorption and chemical reactions. Various methods are proposed for measuring this quantity among which, the laser based methods are the most accurate ones. Unlike most of the mechanical methods, laser based methods remotely measure the surface tension. The aim of the current thesis is to measure the surface tension using laser beam, more specifically using homodyne detection system. This method implemented in both reflected and transmitted modes. In each of the mentioned methods, first the laser beam was incident to the liquid-air interface. Depending on the method transmitted or reflected beam was leaded to the detection photodiode. The incident beam is scattered by the capillary waves present at the fluid’s interface. Measuring the beating rate at the signal recorded from the photodiode and comparison to the theoretical calculation can lead to the value of the surface tension. More specifically, the surface tension is calculated by Fourier analysis of the signal recorded from the photodiode
Keywords:
Light Scattering ; Fourier Analysis ; Surface Tension ; Copillary Waves