Determination of Optical Constants of Ktp Crystal using Ellipsometry Technique
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Date
2005-06
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Addis Ababa University
Abstract
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
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Determination of Optical Constants of Ktp Crystal