The optical constants of birefringent and/or opaque liquids, e.g., liquid crystals and magnetic fluids, are difficult to measure at wavelengths at which a strong light source such as a laser or an are lamp is not accessible. The refractive index n and the extinction coefficient kappa of these Liquids can be simultaneously evaluated from the reflectance curves that are measured in the large incident angle range. A semicylindrical sample cell allows the spectral reflectance measurement with a weak light source even at large incident angles. By using this method, we evaluated the ordinary and the extraordinary indices of a nematic liquid crystal in the continuous wavelength range of 0.55-1.60 mu m. The complex refractive indices of magnetic fluids were also evaluated, and the affect of the magnetic field was demonstrated. (C) 1998 Optical Society of America. [References: 24]
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