The citric acid (CA) coated Fe<sub>3</sub>O<sub>4</sub> ferrofluids are prepared by a co-precipitation method and the magneto-optical retardance property is measured by a Stokes polarimeter. Optimization and multiple regression of retardance in ferrofluids are executed by combining Taguchi method and Excel. From the nine tests for four parameters, including pH of suspension, molar ratio of CA to Fe<sub>3</sub>O<sub>4</sub>, volume of CA, and coating temperature, influence sequence and excellent program are found. Multiple regression analysis and <i>F</i>-test on the significance of regression equation are performed. It is found that the model F value is much larger than <i>F</i><i>critical</i> and significance level P <0.0001. So it can be concluded that the regression model has statistically significant predictive ability. Substituting excellent program into equation, retardance is obtained as 32.703°, higher than the highest value in tests by 11.4%.
In the present study, magnetite (Fe<sub>3</sub>O<sub>4</sub>) magnetic nanoparticles (MNPs) were prepared by an improved chemical co-precipitation method. The effects of the pH value of the solution after titration, the reaction temperature in surface coating, and the molar concentration of Fe<sup>3+</sup>/Fe<sup>2+</sup> salts in dispersibility and size of MNPs are studied. Characterization of the dispersibility and size in MNPs involved using transmission electronic microscope and X-ray diffractometry. Above all, the measurement of magneto-optical effect including the linear birefringence and dichroism of magnetic fluid are executed by a Stokes polarimeter.
This paper presents a new technique using both linearly and circularly polarized lights with measured Stokes parameters
for measuring the optical rotation of optical sample with depolarization effects under a linearly birefringent medium
placed before the optical sample. For a half-wave plate sample in series with a quarter-wave plate, the average
normalized error in the measured rotation angle of the half-wave plate is determined to be 0.01 % by a circularly
polarized probe light, and the average surviving linear and circular polarization fractions of the half-wave plate are
determined to be 1.0051 and 0.9994, respectively, with a standard deviation of 0.0022 and 0.0012, respectively. From the
inspection of a half-wave plate followed by glucose solutions with concentrations ranging from 0~1.2 g/dl, the average
normalized error in the measured rotation angles of the glucose solutions is determined to be 3.11 % by a linearly
polarized probe light. The average surviving linear and circular polarization fractions of the glucose solutions are
determined to be 1.0252 and 0.9945, respectively, with a standard deviation of 0.0028 and 0.00005, respectively.
Overall, the proposed technique for measuring the optical properties of the optical rotation and depolarization is proved
to be feasible, and the preservation of circular polarization is successfully measured with good precision.
Measurements of the principal axis and phase retardation using a new circular polariscope and the Senarmont setup with electro-optic modulation is presented. In the first step of measurements, we use the electro-optic modulated circular heterodyne interferometer and the phase-lock technique to precisely measure the principal axis angle. After removing the first quarter-wave plate in the first setup, a Senarmont setup is designed to determine the phase retardation also using the phase-lock technique. The simple phase extraction algorithm for the principal axis angle and the phase retardation measurement is presented. The average absolute errors of the principal axis angle and the phase retardation of the λ/8-wave plate are determined to be only 0.468<sup>0</sup> and 0.23%.