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Talbot Bands : Determination Of Material Dispersion

A new method for the wavelength dependence of the index of refraction has been recently proposed. It is based upon an accurate determination of the positions of dark bands which appear in the source spectrum observed in the focal plane of a spectroscope while a phase plate is partly inserted in its field. After the method has been reminded, experimental results obtained with known glasses and liquid crystals are reported proving the efficiency and the reliability of the method. In addition of those experimental data, a discussion is devoted to the versality of this new method also the accuracy of the results is considered.