Every year, metallurgical plants emit hundreds of thousands of tons of harmful substances into the atmosphere. The remote sensing of flue gases from the chimneys of metallurgical plants is an urgent task for both industrial enterprises themselves and the enviromental control systems of nearby settlements. In this study, based on the results of the remote optical monitoring of emissions from chimneys of metallurgical plants of the PJSC “MMC ‘Norilsk Nickel’s’,” Polar Division, the concentration of sulfur dioxide in flue gases is estimated. The measurements are carried out using infrared (IR) Fourier transform spectrometers operating in the 7–13 µm range with a spectral resolution of 4 cm–1. A new technology for remote optical sensing in the passive mode of flue gases from metallurgical plants is proposed, including measurements both on cross sections of chimneys and plumes.

The problem of global climate change has become one of the most important challenges to humanity in the 21 st century. The main reason is the appearance in the atmosphere of an excessive concentration of greenhouse gases, which absorb the thermal radiation of the Earth and partially return it to the Earth’s surface. The accumulation of greenhouse gases in the atmosphere leads to a rapid increase in the global average air temperature and, as a result, climate change. It is well known that greenhouse gases have a high transparency in the visible spectral range and high absorption in the infrared range. In this paper, we propose a new technique for recording the CO 2 and CH 4 spectra. An experimental setup based on dynamic Fourier spectrometer is developed. It allows to record IR absorption spectra in the wavelength range of 1.0 to 1.7 μm with a 10 cm –1 spectral resolution. Long-term recording of the atmospheric transmittance in the conditions of urban development is carried out. Based on the obtained data, the CO 2 and CH 4 integral and volumetric concentrations are monitored. It is shown that the carbon dioxide and methane volumetric concentrations time dependences accurately reflects the traffic congestion degree on that day. Reduction of volume concentrations in the evening hours is explained by the increase of the optical path and the additional capture of air masses outside the heavy traffic area.

Появление в атмосфере избыточной концентрации парниковых газов, которые, накапливаясь в ней, поглощают тепловое излучение Земли и частично возвращают его на земную поверхность, приводит к стремительному росту глобальной средней температуры воздуха и, как следствие, изменению климата. К парниковым относятся газы с высокой прозрачностью в видимом диапазоне и активным поглощением в тепловом инфракрасном диапазоне. В настоящей работе предложена новая методика регистрации спектров парниковых газов CO 2 и CH 4 . Представлен макет, разработанный на базе динамического фурье-спектрометра, который регистрировал спектры ИК-поглощения в диапазоне длин волн 1.0–1.7 мкм со спектральным разрешением 10 см –1 . Проведена долговременная запись коэффициента пропускания атмосферы в условиях городской застройки. По полученным данным осуществлялся контроль интегральной и объемной концентраций CO 2 и CH 4 . Показано, что поведение временны́х зависимостей объемных концентраций углекислого газа и метана хорошо отражает степень загруженности дорог. Уменьшение объемной концентрации в вечернее время объясняется увеличением оптической трассы и дополнительным захватом массы воздуха, находящегося за пределами области интенсивного движения.

The gravitational waves predicted by the general theory of relativity and detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) have typical frequencies in the range of 30 ... 300 Hz. Current theories of gravity predict the existence of high-frequency gravitational waves with frequencies of 10 ... 100 MHz, including those of cosmological origin, induced by quantum fluctuations of the scalar field at the stage of cosmological inflation in the early Universe.Multi-beam optical resonators, in particular the Fabry-Perot interferometers, can be used to detect high-frequency gravitational waves. When using multi-beam optical resonators, it is possible to use the phenomenon of low-frequency optical resonance, which allows us to have a selective response to the gravitational wave effect. The gravitational-optical resonance in a multi-beam interferometer occurs if the condition is fulfilled that an integer number of half-waves of gravitational radiation is along the length of the resonator.The use of a multi-beam interferometer to detect high-frequency gravitational waves does not require the creation of a complex system for decoupling mirrors used for gravitational antennas operating in the low-frequency part of the spectrum. This is due to the fact that the frequency of mechanical vibrations of the interferometer mirrors is significantly less than the frequency of the gravitational wave.The paper considers possible optical schemes of a high-frequency gravitational antenna: based on the traditional Michelson interferometer, in the arms of which two Fabry-Perot interferometers are available, and on the basis of the Mach-Zehnder optical scheme, where Fabry-Perot interferometers can be made in the form of two perpendicular arms, with reflecting mirrors at the bend of the beam. The advantage of the second scheme is that three photo-detectors, one being main and two others being auxiliary, can be used, and there is a possibility to detect radiation transmitted by Fabry-Perot interferometers.To prove that detection of high-frequency gravitational waves is possible, a potential sensitivity of the high-frequency gravitational antenna has been estimated in the paper.

The information-measuring complex designed to register high-frequency fluctuations of the space-time metric and its main elements are described in paper. The complex is based on a Fabry-Perot interferometer with highly reflective mirrors and a two-meter resonator. A solid-state Nd: YAG laser with a wavelength λ = 1064 nm is used for pumping. To read the signal, an InGaAs receiver DET10N2, with a working spectral range of 500-1700 nm and an active region of 0.8 mm2, is applied. Using the developed complex, experimental studies of signal registration at readout frequencies of 1 MHz and 20 MHz were carried out. The graphs of signal fluctuations in time and the spectra constructed from them are given.

A specific feature of scanning Fourier-transform IR spectroradiometers (FTIR SRs) is the use of a multiarea photodetector. The optical scheme of these SRs is calculated so as to provide the most efficient transfer of the IR radiation from each sector of the IR channel to the corresponding element of the multiarea photodetector. An indirect method is proposed, which makes it possible to estimate the alignment quality of the IR channel of a scanning FTIR SR based on the calculation of its characteristic instrumental functions, which should eventually provide the best sensitivity for the entire multiarea photodetector of scanning FTIR SR.

The construction and principle of operation of a imaging Fourier transform infrared spectroradiometer (FTIR spectrometer) equipped with a cooled 32-area photodetector designed for spectral analysis of open atmospheric paths are considered. The main technical characteristics of the Fourier spectrometer are reported. The technique of visualization of the detected vapor cloud is described. The results of field experiments using the imaging FTIR spectrometer are shown. Based on these results, the dynamics of motion of the cloud of material has been investigated, its angular and linear velocities have been estimated, and data on propagation of the cloud of material and change in its angular sizes in air have been obtained. A technique for analyzing data provided by two FTIR spectrometers is given, based on which one can estimate the size of the cloud and the distance to it from each device. It is shown that the results of detection of the cloud of material by the imaging FTIR spectrometer can be used to predict the propagation of material under study in space.

Рассмотрена конструкция и принцип действия панорамного инфракрасного фурье-спектрорадиометра. Приведены основные технические характеристики прибора.Описана методика визуализации обнаруженного облака паров вещества

The authors analyze opportunity of application of the Fabry Perot interferometers for detection of high-frequency gravitational wave perturbations occurred during the initial stage of the formation of the Universe. It is shown that at usage of the phenomenon of low-frequency optical resonance there is opportunity of tuning of laser interferometric gravitational wave antenna for detection of high-frequency perturbations. The calculation formulas for determination of the spectral sensitivity of the Fabry Perot interferometer are obtained and the level of the minimum detectable spectral density of fluctuations of the space-time metric is evaluated. We have the advantage of this version of laser interferometric gravitational wave antenna due to absence of necessity to host mirrors of the interferometer on free masses

The authors analyze opportunity of application of the Fabry – Perot interferometers for detection of high-frequency gravitational wave perturbations occurred during the initial stage of the formation of the Universe. It is shown that at usage of the phenomenon of low-frequency optical resonance there is opportunity of tuning of laser interferometric gravitational wave antenna for detection of high-frequency perturbations. The calculation formulas for determination of the spectral sensitivity of the Fabry – Perot interferometer are obtained and the level of the minimum detectable spectral density of fluctuations of the space-time metric is evaluated. We have the advantage of this version of laser interferometric gravitational wave antenna due to absence of necessity to host mirrors of the interferometer on free masses.