INVESTIGATION OF ELECTRICAL AND OPTICAL SUBTRACTIONS USING TWO INPUT-PORT AND TWO OUTPUT-PORT FT-IR SPECTROMETERS

Authors
  1. Laroche, G.
  2. Giroux, J.
  3. Bordeleau, A.
  4. Garneau, J-M.
Corporate Authors
Defence Research Establishment Valcartier, Valcartier QUE (CAN);Bomem Inc, Sainte-Foy QUE (CAN)
Abstract
Two FT-IR spectometers, each using two input ports and two output ports, have been used to minimize the effect of background noise and source fluctuation noise in infrared emission spectra of various sources. Blackbody sources, propane/air flames, and infrared flares have been studied, and spectra were recorded in the spectral region ranging from l.7 to 5 mu m. With the use of the two input-port and one output-port configurations, it was found that real-time optical subtraction could generate 80% background-noise-free spectra. When the spectrometers were operated in the one input-port and two output-port configurations, spectra that were free of source fluctuation noise were obtained with the use of real-time electrical subtraction of signals measured at both detectors. New signal processing techniques have thus been developed. An increase in the signal-to-fluctuation-noise ratio by a factor of seven has been observed in the interferograms, which in turn leads to a 2X increase of the signal-to-noise ratio in the corresponding spectra. During this signal processing sequence requiring the use of two analog-to-digital converters (ADC) (one for each detector channel), intensity information was then lost, so that no calibrated spectra could be measured. TRUNCATED
Date of publication
20 Oct 1993
Number of Pages
7
Reprinted from
Applied Spectroscopy, vol 48, no 3, 1994, p 356-362
DSTKIM No
94-03449
CANDIS No
143229
Format(s):
Hardcopy;Originator's fiche received by DSIS

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