Browsing by Author "Molla Asmamaw"

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    Determination of Optical Constants of Ktp Crystal using Ellipsometry Technique
    (Addis Ababa University, 2005-06) Molla Asmamaw; Asfaw Araya (PhD)
    The Thesis discusses the use of reflection ellipsometry as a precise, and non-destructive technique for the determination of the optical constants of a Potassium Titanyl Phosphate (KTP) crystal. The KTP is a biaxial orthorhombic flux grown crystal. It has three refractive indices: nx, ny and nz • Out of which only two linear refractive indices nx and ny for the two reflective faces correspond to x and y axis, respectively, could be measured while the third refractive index nz could not be measured due to poor surface quality. The refractive indices are measured at three wavelengths in its transmission range using He-Ne (>. = 632.Snm), and temperature tuned diode lasers (>. = S04.4.nm and>. = SOS.4nm). The obtained experimental data of the reflected intensity and analyzer angles are fitted to the theoretical model of curve fitting in the computer. The results of refractive indices are found in good agreement with the theoretical values. The relative errors are assessed up to 0.170/0 for the nx at >. = 632.Snm and 0.02S 0 /0 for ny at >. = SOS.4nm. We also demonstrate the normal behaviour of the experimental refractive indices nx and ny respectively