|
Abstract |
Application of Modified Matrix Method
for Solving of Direct Optoacoustic Problem in One-Dimensional Spatially
Inhomogeneous Media
V.Kozhushko, A.A.Karabutov
(International Laser Center, Moscow State Univerisity, Moscow, Russia);
I.M.Pelivanov, N.B.Podymova (Faculty of Physics, Moscow State University,
Moscow, Russia); G.S.Mityurich (Gomel State University, Gomel, Belarus)
e-mail:
vkozhushko@mail.ru
The
measurements of mechanical, thermal and optical properties of inhomogeneous
media under investigation are of great scientific and practical interest in
many fields of physics and technique. Photoacoustics proposes wide range of
diagnostics methods. The reconstruction of spatial distribution or localization
of inhomogeneities in a medium from detected photoacoustic (PA) signals is the
inverse problem, which however requires the solution of direct PA problem. The
numerous works deal with the solution of direct PA problem in model
one-dimensional inhomogeneous media [F. Saadallah, 1999, Optic. Mater., 12,
163]. A medium under study was excited by amplitude-modulated radiation and
signals were detected by gas-microphone methods. The main goal of our work is to develop the
general approach for solution of direct PA problem in inhomogeneous media
excited by laser pulse. The assumption that cross size of laser beam more than
light penetration depth makes it possible not take into account share waves and
effects connected with diffraction and consider purely the one-dimensional
model. The transfer function method, is utilized for the numerical
investigation of direct PA problem. This allows separating the contributions of
properties of investigated medium and parameters of incident laser radiation to
the resulting PA signal. Actually the transfer function determines frequency
dependent efficiency of PA signal generation. The transfer function is obtained
by sequential designing with modified matrix method [A. Karabutov, V.
Kozhushko, G. Mityurich, I. Pelivanov, 2001 Acoust. Phys., 47, 721] of the
following problems: calculation of distribution of heat-sources, temperature
field and scalar potential of particles velocities.
Section
: 9