A group of scientists of SB RAS V.E. Zuev Institute of Atmospheric Optics develops laser device that will allow detecting explosives vapours on a dozens meters distance.
All explosives contain many nitrogen atoms. One can detect them by irradiating a suspicious object with a beam of neutrons. But, for example, it is not easy to detect an object on which the explosive vapor detection equipment should point in a large flow of people. Other technologies are required to send a laser beam into the arbitrary space volume and by studying its radiation scattered in the opposite direction to detect the steam components of explosives at a particular location - for example, directly above the luggage or above the person. And, to show not only the presence of these clouds, but their quantitative content, and thus immediately appreciate the scale of the threat. In Russia, a technology is being developed by a team of scientists of SB RAS V.E. Zuev Institute of Atmospheric Optics. The researchers are concluding the creation of the prototype of the device for detecting the most common explosives - TNT from 50 meters.
"It's quite a long distance, which provides security for a person who serves the detection device, and for the tool itself also. Advantage of the technology is that it can help to probe the presence of hazardous substances remotely", - Gennady Matviyenko, Director of the Institute, project leader, says.
The device itself is a lidar, or laser radar, of rather voluminous size - about 1.5 cubic meters. Laser source that sends impulses to the area of the space being tested and receiver system, collects and processes the reflected signal from the trace gases are combined in it. The coordinates of impurities which are in the atmosphere are calculated with the amplitude of signals in specific areas of the optical spectrum, coming from different ranges of lidar.
"The recording of signals has the most of nuances, - Gennady Matviyenko said. - We use radiation not only in the visible but also in the infrared and ultraviolet ranges, where there is a very strong background illumination from the Sun. It is necessary to somehow eliminate the background light to successfully detect the signals throughout the large areas. We use different filters for it. And when they do not suffice, we develop monochromators by ourselves - a kind of compound of gratings, providing isolation of really narrow spectrum and therefore a significant reduction in solar radiation".
Now scientists collect individual parts into a single layout that should be reincarnated as a model for industrial production in about a year - with full engineering study and industrial design completed.
Note that quite well-known theory lies at the heart of the development describing the possibility of creating of laser technology, fixing the explosives vapours at a distance. But, as domestic developers assure, they have not been implemented in specific devices yet neither in the world, nor in Russia.
"We have selected the wavelength, which is in resonance with the spectrum of nitrogen oxide, very carefully and thereby have got the best results for the detection range. There are articles, which describe the distance of half a meter and a meter and a half, but no one has reached 50 meters yet", - Gennady Matviyenko says.
A number of instruments, recording harmful emissions at enterprises, as well as manifestations of extreme weather events should be made under the same project, and based on close technologies.
"There is specificity in these tasks, - the project manager says. - For example, chlorine leakage can not be detected by means aimed at registration of explosive vapors. You need a special lidar to do this. Aerosol impurities generated by volcanoes, forest fires, dust storms, and even fires in the workplaces have more general nature. For their registration you can create a universal lidar with different wavelengths, recording the suspended solids in concentration of half a microgramm per cubic meter. For example, it can detect a campfire in the forest from a distance of 10 km, and the fire from 30 km, volcanic ash - at altitudes up to 30 km. Devices for recording the atmospheric conditions have already been made, they work in the atmosphere. But remained are some scientific problems. In particular, the identification of that very substance, which is currently in the atmosphere; or detecting the particle size distribution taking into account the mass concentration. We also continue to work on cheaper devices, because solid-state lasers used in lidar, have stayed expensive still".
The project "Creation of technologies of laser remote sensing of atmospheric manifestations of emergency situations of natural (volcanoes, forest fires, sandstorms, etc.) and anthropogenic (explosives, accidental releases of industrial enterprises, etc.) character" is supported by the Federal Target Program "Research and Development in priority areas of scientific and technological complex of Russia for 2014-2020".