Goniophotometry of optical media with different dielectric function
L.V. Poperenko1, B.V. Karlenko1, O.V. Makarenko1, T. Aoki2
1
Faculty of Physics of Taras Shevchenko National University of Kyiv,
Academician Glushkov Avenue 2, Building 1, Kyiv 03680, Ukraine
2 Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu
432-8011, Japan
Angular and azimuth polarization dependences of photometric variables of light
scattered by sample with concrete dielectric function may serve as an informative source on
optical properties and features of intrinsic structure of such sample.
In order to determine these variables the automated goniophotometric installation on a
base of a standard goniometer Г-5 is fulfilled. As a light source the semiconductor laser that
emits at a wavelength λ = 655 nm and possesses the power of 3 mW is used. The instrument
permits to carry out the polarization measurements and obtain the polar dependences of the
intensity of the scattered light as well as to determine dielectric function for optical media
with different type of conductivity.
The method for determination of such optical characteristics as absorption coefficient
and refractive index is developed. Optical characteristics of strongly scattered glasses and
some standard filters (color glass) produced in Izum Optical Instrumental Plant, Kharkiv
region, Ukraine, were measured.
To determine the optical constant of such glass samples the method involving
measurement of a transmittance of sample within angles of incidence from 0° to 55° and
using experimental results as preliminary ones for further approximation as well as a
selection of the optimality criterion with its minimalization due to the precision objective
function. Minimization of this function leads to obtaining the required characteristics. For
laser radiation at a wavelength of 655 nm the absorption coefficients of several glass
samples were determined. The accuracy of the numerical results of the absorption
coefficient is of 0.5-1%.
The second important characteristic of the above-mentioned material within the visible
is the refractive index. The method for obtaining this characteristic based on the Brewster’s
angle definition measurement is realized. Its mathematical algorithm may minimize the
difference between the experimental and the calculated data using at least five experimental
points due to different angles of light incidence. When the Brewster’s angle is determined
then it is possible to find the refraction index. The accuracy of its determination is of 1-3%.
In the installation the additional device using polarized light permits to provide the
measurement of the Stokes parameters for scattered radiation and obtain the Mueller matrix
of appropriate optical media at different angles of light incidence.