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.

This paper presents a portable Fourier spectroradiometer with resolution 8 cm(-1), operating in the 7-14-mu m range, with an MG-32 uncooled single-element pyroelectric photodetector. This Fourier spectroradiometer with uncooled photodetector is intended for remote determination of pollutant vapors in the open atmosphere, as well as for methane leaks on gas pipelines. (c) 2006 optical Society of America.

An algorithm based on a model of constancy of temperatures on the path and in a cloud of contaminants is proposed for solving the problem of identifying and determining contaminant concentrations by means of a Fourier spectroradiometer. The main problems of the procedure for processing the initial interferograms and the experimental spectra are considered, including those with small radiance contrasts of the paths. The experimental results of field tests of a spectroradiometer based on the proposed algorithm are presented. (C) 2004 Optical Society of America.

This paper discusses how the intrinsic background radiation of a Fourier spectroradiometer affects the results of the processing of two-sided interferograms. The operation of a Michelson interferometer is considered theoretically, and it is shown that, when objects with radiance temperatures close to the intrinsic temperature of the spectrometer are observed, inverted spectral sections and bands may appear in the final spectrum. The paper proposes an algorithm for correcting the initial interferograins and an experimental technique that makes it possible to eliminate the inversion of the spectrum and to compensate the intrinsic background radiation of the interferometer. (C) 2003 Optical Society of America.

The effect of background (instrumental) self-radiation of a Fourier transform infrared (FTIR) spectrometer on the processing of double-sided interferograms is studied. From a theoretical analysis of the Michelson interferometer it was shown that when the brightness temperature of the object of study is close to the temperature of the instrument, the measured spectrum may contain inverted spectral ranges or isolated bands. The interferogram correction algorithms and experimental technique for elimination of the spectrum inversion and for compensation of the background self-radiation of the instrument are suggested.

A scanning system for the moving mirror of the Michelson interferometer is described. The system is based on a linear motor with a ring-shaped permanent magnet. The operating velocity of the mirror is about 4 cm/s; the shift from the equilibrium position, ±2.5 mm. A mathematical model of the control system is discussed. The electrical schematic circuit of the control unit and tests results of the control system are described.

Field tests involving the determination of the pollutant concentrations under the conditions prevailing in Moscow are performed using an experimental model of a Fourier spectroradiometer (its working range is 800- 1200 cm(-1), its resolution is 4 cm(-1), and the interferogram scanning time is less than 0.3 s) and an ethanol vapor cloud as a test simulant. The possibility of determining ethanol concentrations in the range from 10-15 to 5000-7500 ppm is demonstrated experimentally. (C) 2000 The Optical Society of America.

A scanning system for a medium-resolution (delta nu = 1-5 cm(-1)) IR Fourier spectrometer is described. The system suspends the mirror by a spring parallelogram mechanism and uses a linear motor with two electromagnets whose thrust vectors are collinear and opposite. When the movable minor experiences a linear displacement of +/-2.5 mm, its misalignment is no higher than +/-2 ". At a 0.7-A nominal current, the linear motor develops no less than a 5-N thrust, which is sufficient to operate the scanning system in an inclined position, with the mirror moving at an operating speed of up to 5 cm/s.