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Ocean Measuring Devices

#0488


Elaboration of New Class of Oceanographic Optical-electronic Devices for the precise Measurements of Fine Structure of the Hydrophysical and Hydrochemical Ocean Fields.

Tech Area / Field

  • ENV-WPC/Water Pollution and Control/Environment

Status
8 Project completed

Registration date
16.11.1995

Completion date
09.03.2004

Senior Project Manager
Lapidus O V

Leading Institute
Institute of Oceanology, Russia, Moscow

Supporting institutes

  • NIIIT (Pulse Techniques), Russia, Moscow\nVNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • ORCA Instrumentation, France, Brest\nME Meerestechnik-Elektronik GmbH, Germany, Trappenkamp\nIFREMER, France, Issy les Moulineaux\nIFREMER, France, Plouzane

Project summary

As a result of the realization of the project the set of precise oceanographic devices, which has no World analogs, will be elaborated:

1. Optical nSTD-probe "Lamina" (sea experimental sample).

2. Photo-luminescence (fibre-optical) sensors of the gases dissolved in sea water and PH-parameter (model for the sea conditions).

3. Laser interference sensor of the ocean surface level (zunami detector) (model for sea conditions).

The new principles and expected high techno-metrological characteristics of the devices were tested and confirmed on their laboratory models. The sea model of the optical nSTD-probe was tested in sea conditions in 1990 during the 14 cruise of the R/V "Professor Sergei Dorofeev". Its inter calibration was carried out in 1993 in USA on the calibration facility of Woods-Hole Oceanographic Institution (WHOI, USA). The results of this work were described in the corresponding scientific reports of organizations-participants, WHOI Preliminary Report (inter calibration) and in the publications of specialists.

Thanks to the new scientific (optical) principles and modern optical-electronic (integral) technology, used in the developed devices, it is easily to achieve in them the technical-metrological characteristics at the level of World standards or even higher. It should be noted that analogies traditional oceanographic devices are at the upper 1imit of their technical and metronomical possibilities.

So, for example, in the optical nSTD-probe "Lamina" (in comparison with the known CTD-probe MARK-III (V) Neil Brown, USA), there are no CTD-sensors (where C - conductivity, T - temperature, D- depth) and the determination of hydrophysical parameters - salinity S, temperature T and pressure P (depth D) is carrying out through the thermodynamical parameter - the refraction index (n) of sea water. This is achieved on the base of the new principle of optical self-balancing of the refraction index by any two from the defining three parameters and by its following measurement by high sensitive precise method of the laser photoheterodyne interferometry.

The high sensitivity and accuracy of this method are stipulated by the comparison of the measured value (optical length of way n*l, where 1 - geometrical length of the measuring base) with a small reference standard - wavelength of the light l, which is known with high metronomical accuracy.

As a result the device's sensitivity, accuracy and time response, corresponding to the World level, are reached without use of expensive and complicated technologies of primary measuring transducers (CTD-sensors), and of secondary measuring convertors (18-20 bits digital bridges), which are at the limit of the instrument accuracy.

Besides that, the physical parameters and principles, which lay in the base of the optical nSTD-probe: united small reference standard-wavelength of the light and united thermodynamic parameter - the refraction index of sea water (not the different electrical-mechanical parameters of CTD-sensors};

Compensating optical (not calculating) principle of separation and definition of hydrophysical parameters, allow to exceed the World level of oceanographic instrument industry, achieved in CTD-probes of Neil Brown, and to get the following principally new technical characteristics of the device:

- pronounced potential technological reserve for increase of sensitivity and accuracy,

- practically unlimited (without subranges) dynamic range of measurements of hydrophysical parameters,

- a possibility of primary self-balancing of the device scales without use of reference standards,

- an absence of instabi1ity stipulated by pollution and aging of materials and surfaces of primary measuring convertors (CTD-sensors),

- an absence of hysteresis during pressure measurements,

- an absence of false calculating overshoots at fine structure of vertical stratification of salinity and density.

Laser interference sensor of small changes of the sea surface level , based on the analogy's principles, has a high sensitivity to the pressure changes of the order of 3 mm of water column independently of the depth of submergence (absolute hydrostatic pressure), absence of hysteresis, and temperature constructive autocompensation of the error due to temperature change of the medium. The possible remaining undercompensation may be fully excluded by use of rough temperature sensor by calculation method. Such combination of parameters is not achievable for the traditional vibrating (quartz and string) pressure sensors. Sensor, in comparison with traditional electro-chemical ones, do not lose the capacity for work in the sulphuretted hydrogen layer (for example, in the Black Sea). They have not instability connected with the contaminations and have, at least, one order higher time response and possibility of simple calibration by pressure at the air in the sea conditions.

Combination in the elaborated devices of new scientific principles, modern technology and high technical-metrological characteristics allows to ascribe these devices to the class of so called scienceca-pacious and high technologies, which have high competitiveness and profitability in the World market.


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