Research on optical properties of solid/liquid compounds

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The complex refractive indices of magnetic fluids were evaluated in the wavelength range of 0.6-1.6 mum by measuring the transmission and reflection spectra. The extinction coefficient varies between 0.003 and 0.03 depending upon wavelength. The refractive index varies between 1.6 and 1.7 depending slightly on wavelength. The experimental values agreed well with the theoretical values that were calculated by the effective medium theory. Preliminary experiment of optical switching was demonstrated by utilizing the mobility of the magnetic fluid.Nematic liquid crystals were put into the micropores of anodic alumina films. Molecules of a liquid crystal tend to orient along the axis of columnar pores, since the pore diameter is smaller than 0.2 mum. Accordingly, the refractive index of the liquid crystal varies with the polarization of the light that propagates in the alumina film ; i.e., the ordinary and extraordinary indices correspond to polarizations that are vertical and horizontal to the pores, respectively. The anisotropy in refractive index causes a prominent polarization function due to the index mismatch between a liquid crystal and alumina.In Raman-Nath diffraction by water, the intensities of even-order light beams are selectively enhanced by suspension of microparticles. The diffracted beams remain for several seconds even after the ultrasonic oscillation stops. These phenomena are elucidated by assuming the laminar arrangement of microparticles due to the ultrasonic wave.