Site: General Physics Institute
Russian Academy of Sciences
1, Letnaya St.
Moscow 109387
Russia

Date Visited: May 21, 1993

Report Author: D. Walsh

ATTENDEES

WTEC:

B. Mooney
D. Walsh

HOSTS:

Professor Fiodor Bunkin

Corresponding Member, Russian Academy of Sciences;
Head, Wave Phenomena Department;
Vice Chairman, Hydrophysics Council of the Russian Academy of Sciences

Professor Konstantin I. Voliak

Head, Hydrophysics Laboratory, Department of Wave Phenomena;
Member, Hydrophysics Council of Russian Academy of Sciences;
Head, International Programs Commission of the Institute

Dr. Valery Petnikov; Head, Acoustic Ocean Sounding Laboratory, Department of Wave Phenomena

Professor Alexei Bunkin; Senior Research Associate

Dr. Alexei Maliarovsky; Senior Research Associate

BACKGROUND

The Institute of General Physics was founded in 1982. Its director is Academician A.M. Prokhorov, who shared, together with the American Charles Townes, the 1964 Nobel Prize in Physics for their work in developing the laser.

The institute has nine departments, two independent laboratories, an instrumentation design bureau, and a patent division. The team's visit was primarily concerned with the institute's work in devices for oceanographic research. While several of the departments contribute to marine-related research, the majority of the work is done by the Department of Wave Phenomena. This department is divided into seven laboratories:

The team spent about two and a half hours at the institute. The entire visit was conducted in Professor Bunkin's office, where the team was briefed on the oceanographic-related work of the institute. The majority of this work involves the use of lasers and low frequency acoustics to measure ocean processes.

RESEARCH AND DEVELOPMENT ACTIVITIES

Ocean Remote Sensing by Airborne Laser Systems

Since beginning work in 1983, the institute has developed and tested a multipurpose airborne laser system that can detect the thermocline in the ocean down to depths of 65 m. The laser platform (helicopter or aircraft) is at an altitude of 500 m. Successful tests have been conducted in the Kara and Barents seas in the Arctic as well as off the Kamchatka Peninsula in the Pacific Ocean. The original purpose of the system was submarine location. This is accomplished by detecting the interference patterns in the surface and subsurface (on the thermocline) wave fields due to passage of a submarine.

The airborne laser for this application is a pulsed Nd:YAG unit with 700 millijoules power output. For thermocline detection the power level is 100 to 150 millijoules (from the third and fourth harmonics of the primary power level) and a wavelength of 532 nm. A 30 cm diameter mirror is used to reflect the laser output signal through a transmitting telescope to the ocean and to receive the return signals.

Over 1,000 hours of airborne testing have been done with this system. Currently it is fitted into a Kamov KA-32 helicopter.

Ocean Surface Materials and Processes by Laser

Through using different parts of its frequency band, this same airborne laser system is capable of several different types of remote ocean-environmental measurements:

Several of these measurements are made by laser energy fluorescing the substances at or near the sea surface. Determination of the type of substance is by spectrographic analysis of the returned signal using a polychromator and a spectro-temporal analyzer.

The complete system consists of several devices that can provide multipath signal outputs to the user:

The team was told that just a few days before its visit the institute was able to do plasma excitation of the sea surface with its airborne laser system. This would permit material analysis down to the molecular level.

Laser Bathymetry

This system also permits making bathymetric measurements where, depending on clarity, water depth can be as great as 25 m.

Low Frequency Acoustics for Ocean Measurements

The institute's Acoustic Ocean Sounding Laboratory has been using a towed fish, equipped with two transducers, in the Barents Sea to do sound path research at 100 Hz and 300 Hz frequencies. The output powers are 100 W and 300 W, respectively.

The institute's scientists can stream this array from a ship or install it on the seafloor (where it is battery powered). The seafloor receiving system consists of 12 hydrophones with a reception band of 10 to 1,000 Hz. The vertically oriented array is 70 m in length and can work as deep as 500 m. The array has sensors to measure depth and tilt angle to compensate for these variables in signal processing. Through use of buoys, the acoustic data can be transmitted by radio to a remote station up to 10 miles away.

The institute's scientists and engineers have sent acoustic signals over a 500 km path to determine losses for both vertical and horizontal paths. These data are useful for development of acoustic tomography. The institute's technical personnel are cooperating with Dr. Lynch of the Woods Hole Oceanographic Institute (WHOI) in this work. Mr. Craig Dorman, Director of WHOI, and representatives of Science Applications International Inc. (SAIC) have visited this laboratory.

The institute hopes to do work in the Arctic Basin for long range acoustic tomography (perhaps in cooperation with Mr. Walter Munk's program). The Russian equipment will be set up at North Island in Franz Joseph Land. In addition, the institute plans to do shallow water propagation variation studies in the Barents Sea.

Atmosphere Ocean Communications

Academician Alexei Bunkin described some very new work the institute is doing with an optical-acoustic communication system between submarines and aircraft. The aerial platform would use a very high power, modulated laser directed at a very small area of the sea surface. The power output of the laser would be high enough to create mechanical surface roughness that could be sensed by the submerged platform. Through signal analysis of the aperiodic surface roughness, the intelligence would be pulled out of the surface noise.

The submerged platform would use an upward directed very high frequency (100s of MHz) sound source to create a similar roughness on the sea surface. This would be detected by a high frequency, cross-polarized radar. The aperiodic roughness pattern would then be converted into a communications signal.

To date, this concept has been tested from an aircraft at very low altitudes.

SUMMARY

While it is clear that most of the work presented to the team was originally supported by major Soviet Navy efforts to successfully do nonacoustic antisubmarine warfare (ASW), the end of the Cold War has provided an opportunity to channel a lot of this enormous investment into civil applications. If these laser systems can be put into service for a reasonable price, then they could find wide use for commercial fisheries development and marine pollution detection and monitoring.

The low frequency acoustics work, which contributes to the current international effort in acoustic tomography, will be vital in helping to understand the global climate system in terms of ocean warming and cooling.

As with some of the team's other site visits, the information given to the team was very interesting and often surprising. As scientists and engineers, team members could certainly appreciate the emergence of so many things that had not been revealed previously. Unfortunately, much of this information was not relevant to the WTEC charter for assessing deep submergence technologies in the former Soviet Union. This was not the fault of the institute's representatives, but was due to the team's uncertainty about which organizations do what in present-day Russia.

REFERENCES

USSR Academy of Sciences Institute of General Physics

. 1990. A descriptive book. The Wave Phenomena Department is described on pages 25 to 29.

"Uses of Lidars for ocean remote sensing." Briefing paper.


Published: June 1994; WTEC Hyper-Librarian