Measurement of the thermo-optical coefficient of a nanofluid without the use of Abel inversion

In this work, a method is proposed to measure the thermo-optical coefficient of a nanofluid sample. Thermal lensing is the most important phenomenon among the phenomena happening when a laser beam interacts with a nanofluid. A graphene oxide (GO) nanofluid sample is studied and Non-scanning Moiré deflectometry method is used to study thermal lensing effect and measuring the resultant deflection in the Moiré pattern. In the proposed method two lasers are used: a low power, wide beam as probe and a high power with specific wavelength as pump. This method is fast, easy and insensitive to environmental noise. Having the position of maximum value of the deflection and the slop of Moiré pattern, the thermo-optical coefficient is obtained without needing the inverse Abel integral to be solved. This transform is almost always calculated numerically and introduces error to the result. Although this method is inexpensive and accurate, it is applicable for liquid, solid and gas samples.

Moiré deflectometry; inverse Abel integral; thermo-optical coefficient; thermal lensing effect; nanofluid.