Abstract

Releases of benzene and other gases have been detected and quantified using a novel optical, open-path instrument based on a deuterium light source and a static Fourier-transform spectrometer. The spectrometer uses Wollaston prisms to form an interferogram in the spatial domain that is recorded by use of a detector array. The instrument is designed to operate in the ultraviolet region of the spectrum between 200 and 270 nm, which coincides with strong absorption features in the spectra of many gases of environmental and health interest. Using the instrument with a 5-s measurement period provides a path-integrated concentration sensitivity to benzene of 2 parts in 106 times meter, which corresponds to a 20-parts in 109 detection limit over a typical path length of 100 m.

© 1998 Optical Society of America

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References

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  1. Motor Fuels (Compositions and Content) Regulations, which incorporates the levels specified in European Directive No. 85/210/EEC (Her Majesty’s Stationery Office, London, 1994).
  2. R. J. Bell, Introductory Fourier-Transform Spectroscopy (Academic, New York, 1972).
  3. Constructed by Siemens Environmental Systems, Ltd, Sopers Lane, Poole, Dorset BH17 7ER, England.
  4. J. Courtial, B. A. Patterson, W. Hirst, A. R. Harvey, A. J. Duncan, W. Sibbett, M. J. Padgett, “Static Fourier-transform ultraviolet spectrometer for gas detection,” Appl. Opt. 36, 2813–2817 (1997).
    [CrossRef] [PubMed]
  5. M. J. Padgett, A. R. Harvey, A. J. Duncan, W. Sibbett, “Single-pulse Fourier-transform spectrometer having no moving parts,” Appl. Opt. 33, 6035–6040 (1994).
    [CrossRef] [PubMed]
  6. M. J. Padgett, A. R. Harvey, “A static Fourier-transform spectrometer based on Wollaston prisms,” Rev. Sci. Instrum. 66, 2807–2811 (1995).
    [CrossRef]
  7. Deuterium Lamp Y02, Cathodeon, Ltd, Nuffield Road, Cambridge CB4 1TW, England.
  8. Opticon, 76 Treble Cove Road, Billerica, Mass. 01862.
  9. UV filter 260-B-1D, Acton Research Corp., Acton, Mass. 10720.
  10. D. V. Lindley, Introduction to Probability and Statistics from a Bayesian Viewpoint (Cambridge U. Press, Cambridge, 1965).
    [CrossRef]
  11. W. H. Press, S. A. Teukolsky, W. T. Vetterling, B. P. Flannery, Numerical Recipies in C, 2nd ed. (Cambridge U. Press, Cambridge, England, 1992).
  12. Spectrum obtained from AEA Technology, plc, 551 Harwell, Didcot OX11 0RA, England.
  13. Expert Panel on Air-Quality Standards, Benzene;Department of the Environment, ISBN 0-11-7528-59-5 (Her Majesty’s Stationery Office, London, 1994).

1997

1995

M. J. Padgett, A. R. Harvey, “A static Fourier-transform spectrometer based on Wollaston prisms,” Rev. Sci. Instrum. 66, 2807–2811 (1995).
[CrossRef]

1994

Bell, R. J.

R. J. Bell, Introductory Fourier-Transform Spectroscopy (Academic, New York, 1972).

Courtial, J.

Duncan, A. J.

Flannery, B. P.

W. H. Press, S. A. Teukolsky, W. T. Vetterling, B. P. Flannery, Numerical Recipies in C, 2nd ed. (Cambridge U. Press, Cambridge, England, 1992).

Harvey, A. R.

Hirst, W.

Lindley, D. V.

D. V. Lindley, Introduction to Probability and Statistics from a Bayesian Viewpoint (Cambridge U. Press, Cambridge, 1965).
[CrossRef]

Padgett, M. J.

Patterson, B. A.

Press, W. H.

W. H. Press, S. A. Teukolsky, W. T. Vetterling, B. P. Flannery, Numerical Recipies in C, 2nd ed. (Cambridge U. Press, Cambridge, England, 1992).

Sibbett, W.

Teukolsky, S. A.

W. H. Press, S. A. Teukolsky, W. T. Vetterling, B. P. Flannery, Numerical Recipies in C, 2nd ed. (Cambridge U. Press, Cambridge, England, 1992).

Vetterling, W. T.

W. H. Press, S. A. Teukolsky, W. T. Vetterling, B. P. Flannery, Numerical Recipies in C, 2nd ed. (Cambridge U. Press, Cambridge, England, 1992).

Appl. Opt.

Rev. Sci. Instrum.

M. J. Padgett, A. R. Harvey, “A static Fourier-transform spectrometer based on Wollaston prisms,” Rev. Sci. Instrum. 66, 2807–2811 (1995).
[CrossRef]

Other

Deuterium Lamp Y02, Cathodeon, Ltd, Nuffield Road, Cambridge CB4 1TW, England.

Opticon, 76 Treble Cove Road, Billerica, Mass. 01862.

UV filter 260-B-1D, Acton Research Corp., Acton, Mass. 10720.

D. V. Lindley, Introduction to Probability and Statistics from a Bayesian Viewpoint (Cambridge U. Press, Cambridge, 1965).
[CrossRef]

W. H. Press, S. A. Teukolsky, W. T. Vetterling, B. P. Flannery, Numerical Recipies in C, 2nd ed. (Cambridge U. Press, Cambridge, England, 1992).

Spectrum obtained from AEA Technology, plc, 551 Harwell, Didcot OX11 0RA, England.

Expert Panel on Air-Quality Standards, Benzene;Department of the Environment, ISBN 0-11-7528-59-5 (Her Majesty’s Stationery Office, London, 1994).

Motor Fuels (Compositions and Content) Regulations, which incorporates the levels specified in European Directive No. 85/210/EEC (Her Majesty’s Stationery Office, London, 1994).

R. J. Bell, Introductory Fourier-Transform Spectroscopy (Academic, New York, 1972).

Constructed by Siemens Environmental Systems, Ltd, Sopers Lane, Poole, Dorset BH17 7ER, England.

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Figures (6)

Fig. 1
Fig. 1

Photograph of the static FTUV spectrometer and telescope (left) and the retroreflector array (right).

Fig. 2
Fig. 2

Schematic diagram of the static FTUV spectrometer optics. The plate polarizers are oriented at 70° to the optical axis and at 45° to the plane of the page. The filter prevents the detector from being saturated with light outside the wavelength range of interest. The cylindrical lens focuses the light to a strip on the linear detector array. The detector array records a full interferogram when the input filter is illuminated by an extended beam.

Fig. 3
Fig. 3

Schematic diagram of the telescope optics for the static FTUV spectrometer.

Fig. 4
Fig. 4

Comparison of UV transmittance spectra of benzene vapor measured by the static FTUV spectrometer with data from a spectral atlas.12 The experimental data were taken with benzene vapor confined to a 50-cm-long test cell at a pressure that produced a concentration of 50 ppm-m. The interferogram signal was collected over a 50-s integration time.

Fig. 5
Fig. 5

Benzene vapor transmittance spectra recorded by the static FTUV spectrometer with 5-s integration times. The concentrations estimated by least-squares fitting were 50.7 ± 0.9, 25.8 ± 1.3, 10.7 ± 1.3, and 4.2 ± 1.4 ppm-m.

Fig. 6
Fig. 6

Absorption spectra recorded with the open-path gas detection system based on a static FTUV spectrometer.

Tables (1)

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Table 1 Minimum Gas Concentration Detectable with the Prototype Instrument Operating at a Range of 100 m

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