Using Stokes Polarimeter for Linear Birefringence and Dichroism in Ferrofluid
In this paper, an optical scheme based on Stokes-Mueller Formalism and rotating-wave-plate Stokes polarimeter is presented for measuring the magnetic-field-induced linear birefringence and dichroism in thin ferrofluid film. For a quarter-wave plate sample, the measured principal angle and retardance are found to have average absolute and normalized errors of 0.086° and 0.76%, respectively, while the measured dichroism of a quarter-wave plate has an average value of 0.0203. The experimental technique is then verified. When analyzing ferrofluid film samples with concentrations ranging from 2% to 6%, it was found that for a given concentration of ferrofluid, the retardance increases with applied magnetic fields and tends to saturate at high levels. Additionally, under the condition of the same magnetic field, the experimental results show that the retardance is proportional to the concentration; the higher concentration will result in more retardance and absorption. Consequently, the technique for measuring the linear birefringence and dichroism in ferrofluid film is feasible and straightward.
KeywordsMagnetic Fluid Stokes Parameter Wave Plate Linear Dichroism Linear Birefringence
The financial support provided to this study by the National Science Council of Taiwan under Grant NSC-99-2221-E-269-004 is gratefully acknowledged.
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