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Fourier Transform UV-Vis-NIR spectrometer

Summary

New FT spectrometer is capable to measure in wide spectral range

Technology Benefits

Wideband FT spectrometer replaces several analogues by covering its spectral ranges

Technology Application

Material science, QA, transmission and reflection spectra measurements

Detailed Technology Description

Fourier transform spectrophotometer is based on a Michelson interferometer. Collimated beam of light falls onto the interferometer entrance. Then the beam is split by a beam splitter plate into two beams having approximately equal intensity. After being reflected from mirrors these beams interfere at the interferometer output. At least one mirror in FTS is movable. Special mirror movement control systems provide its periodic movement, moving speed being maintained constant for maximal possible part of the mirror’s path. The resulting interferogram that is registered with the photodetector includes all information about irradiation spectrum. Spectral resolution in this case is controlled by movable mirror path length, whereas spectral range is limited only with working range of the light source, the beam splitter, the mirrors and the photo detector.
It is worth noting that in order to provide spectral resolution of 10 cm-1 (being moderate for IR range, this value corresponds to more than dignified resolution of 0.1 nm in UV range) mirror’s movement is required as small as 1 mm. This movement can be done very quickly. Thus, high spectra acquiring rate is an obvious advantage of Fourier transform spectrophotometer. FTS design does not imply any slits, which might considerably blind the light beam; accordingly, these instruments are considered as light efficient. Scattered light does not participate in interference, therefore non it affects both the interferogram and the resulted spectrum. Also Fourier transform spectrophotometer does not have the problem, which is typical for grating instruments and related to the necessity of higher order suppression. An interferogram accumulation, on the contrary to a spectrum accumulation, does allow to expand dynamic range considerably.

Application Date

21/04/2014
27/06/2014

Application No.

RU2014115869;
RU2014125977

Patent Information

PCT/RU2015/000255; PCT/RU2015/000405

Others

The invention relates to optical instrument engineering and can be used in Fourier transform spectroscopy with extended spectral range. The summary of the solutions is to increase the number of oscillating the mirrors in the Michelson interferometer, which in particular can be used in a Fourier transform spectrometer, and each having the same frequency of mirror oscillation. Moreover, the oscillations phases can be offset to provide a maximum change in the path difference;
The invention relates to spectroscopy, and in particular to Fourier transform spectrometers interferometers.
The summary of the solutions consists in using electrodynamic head, in which the resonance frequency fr, causing parasitic vibrations, is effectively suppressed by using an active feedback system, due to a sufficient gap between the resonance frequency fr and the mirror oscillation frequency f.
The proposed interferometer with oscillating mirror which creates a parasitic vibration, solved the problem of increasing the accuracy of the measurement range.
The inventive interferometer and implemented on the basis of its Fourier transform spectrometer provide improved spectral resolution.

ID No.

RU2572412

Country/Region

Russia