Physical Oceanography, Vol.
PRINCIPLE OF REMOTE CONTROL OVER THE PRESENCE OF DISSOLVED GASES
IN WATER MEDIA
S. M. Kukhtin,
S. M. Bashchenko,
and A. M. Negriiko
We propose a method that allows one to carry out a remote estimation of small concentrations of gases
dissolved in water at large depths. The method is based on modulation laser spectroscopy combined
with the application of a fiber-optical communication line. We demonstrate specific features and advan-
tages of the method of modulation laser spectroscopy for the spectral analysis in aqueous media with
large attenuation. We develop the structural scheme of a measuring system, whose main components
are a one-mode fiber-optical communication line, a laser diode with tuning frequency, and a gauge in the
form of a hollow ellipsoidal mirror reflector. The principle of self-focusing of radiation in the gauge is
considered. The expedience of the use of modulation laser spectroscopy and a measuring system in the
solution of problems of the analysis of aqueous media is evaluated.
One of the important components of the technical improvement of modern systems for registration and es-
timation of the concentration of dissolved gases in water is the development of new methods and facilities which
allowing one to carry out measurements with high accuracy under natural conditions. Among numerous avail-
able optical spectral methods for measurement of the concentration of gases, only few can be used under real
natural conditions because these methods have been laboratory one up to now and their application was possible
only under conditions of specially equipped laboratories. Undoubtedly, the methods of optical absorption spec-
troscopy ensure the required level of quality of measurements. However, their realization for the registration of
small concentrations of gases  is limited not only by the possibilities of the modern laser spectral technique,
but also by conditions of their use. For example, the use of spectroscopic methods for the measurement of the
concentration of dissolved gases in water media meets serious difficulties because dissolved gases are at high
pressure and decreased temperature, which can substantially affect the spectral lines of absorption.
The application of methods of laser absorption spectroscopy, as well as of all optical methods, for meas-
urements in water requires the solution of numerous fundamental and practical problems. First, the radiation in
the visible and, especially, near-infrared ranges has a large level of absorption and scattering in water media.
Therefore, it is necessary to provide the optimum conditions for the interaction of laser radiation with the me-
dium under study so that the effect of spectroscopic absorption at separate lines exceeds the total level of absorp-
tion of optical radiation. Second, the spectroscopic measurements in water media have sense in the case where
the wavelengths of the absorption lines of gases dissolved in water are exactly known. The values of frequen-
cies of absorption lines of gases that are given in numerous spectroscopic tables for normal values of tempera-
ture and pressure can deviate from the standard values under these conditions. Third, the problem of a practical
Institute of Physics, Ukrainian National Academy of Sciences, Kiev, Ukraine.
Corresponding author; e-mail: email@example.com.
Kharkov National University of Radioelectronics, Kharkov, Ukraine; e-mail: firstname.lastname@example.org (corresponding author).
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
74–83, July–August, 2010. Original article submitted January 20, 2009;
revision submitted December 17, 2009.
308 0928–5105/10/2004–0308 © 2010 Springer Science+Business Media, Inc.