Refractive index determination by micro interferometric reflection detection

摘要

A method and an apparatus for absolute refractive index measurements are disclosed, wherein a beam of spatially coherent laser light is directed perpendicularly on to a side of a capillary tube ( 12 ) and back reflected light is detected ( 16 ) over a range of angles ( 22 ) with respect to the incident light beam. The refractive index of a liquid contained in the capillary is determined from the angle at which a marked change in the intensity of the interference fringes of the interference pattern formed by said back reflected light is observed or from the amplitude of a low frequency component of the angular variation of the intensity of interference fringes.