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I. Bodurov, I. Vlaeva, A. Viraneva, T. Yovcheva, S. Sainov
Abstract: For all kinds of optical applications it is important to know the refractive indices of materials for the corresponding wavelength. An accurately measured refractive index value can be used for structural analysis in many branches of the science and the industry. That is why investigators sometimes have to design new or to modify standard refractometers to perform adequate and precise measurements. This paper describes how a conventional laser refractometer can be modified with a CCD camera and a motorized rotary stage for precise determination of the refractive index. This system can determine the refractive indices of nanoscale solid films and liquids in micro quantities in wide spectral range with accuracy better than 1×10-4. The presented refractometer is based on the method of the disappearing diffraction pattern at the critical angle. Three laser pointers generating at 405 nm, 532 nm, 635 nm with up to 20 mW power are used as light sources. Measurements carried out on water, organic liquids, polymer films and nanoparticles dispersed in water are reported. Dispersion dependences for all investigated samples are built.
Keywords: dispersion dependences; refractive index; Sellmeier model; total internal reflection