Investigation of polarization magnetooptic responses of a low-concentration ferrofluid

Weak polarization-optical responses of diluted magnetic nanofluid probed by laser radiation with polarization modulation

“…A simplified diagram of the experimental setup adapted for the study of magnetic nanofluids is shown in Fig. 1 (see also [16][17][18]). Probing laser radiation (λ = 0.63µ) passes through a polarization modulator, a cuvette with a magnetic nanofluid, and enters a polarization analyzer, where polarization-sensitive optical detection and preliminary processing of the photosignal performed, and then the signal enters the registration system and the computer.…”

“…light arising as a result of passing through the object under study. Thus, the measured quantity is birefringence (linear optical anisotropy) of the magnetic fluid induced by an external magnetic field [16][17][18]. Further, we assume that the scale of the output signals is calibrated in units of the measured anisotropy (in our case, in angular minutes).…”

“…Further, we assume that the scale of the output signals is calibrated in units of the measured anisotropy (in our case, in angular minutes). A detailed description of the measurement and calibration procedures is given in [16][17][18].…”

“…In a number of practical cases it is important to investigate samples with small optical anisotropy [16][17][18][19]. Our proposed natural criterion for the smallness of anisotropy is based on the inequality ∆ 1 rad [14].…”

“…Earlier, by the methodology developed on this basis, we investigated the polarization characteristics of various objects, including optical elements with a high degree of optical and structural homogeneity [16], magnetically ordered materials [17], and perfect optical crystals, including those with a modified crystal structure [15]. A preliminary polarization-optical diagnostics of magnetic fluids was also performed [18]. This paper presents the results of a study of weak polarization responses obtained for a wide range of concentrations in experiments with magnetic nanofluid probing by laser radiation with polarization modulation.…”