Temperature effects on a fiber-optic evanescent wave absorption sensor

Journal Article · Tue Mar 01 04:00:00 EST 1994 · Applied Spectroscopy; (United States)

DOI:https://doi.org/10.1366/0003702944028344· OSTI ID:7004998

Klunder, G L ^[1]; Buerck, J; Ache, H ^[2]; Silva, R J ^[3]; Russo, R E ^[1]

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1. Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)
2. Kernforschungszentrum, Institute for Radiochemistry, 76021 Karlsruhe (Germany)
3. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

A coiled fiber-optic chemical sensor has proven to be effective for the remote detection of volatile organic compounds, such as trichloroethylene (TCE), 1,1-dichloroethylene (DCE), and gasoline, in aqueous solutions. The analyte diffuses into the hydrophobic cladding and evanescent wave absorption spectra are measured in the near-infrared (1600-1850 nm) without the presence of the water absorption bands. In order for fiber-optic chemical sensors to operate effectively in remote environments, the influence of temperature on the sensor response must be known. The C-H bonds of the polysiloxane cladding material also have absorption bands in the near-infrared (NIR). Changes in temperature will change the density (i.e., concentration of C-H bonds) and refractive index of the cladding. Due to these effects, a temperature change of only 3[degree]C from the reference has been shown to significantly alter the background absorbance. The temperature-dependent background absorption is found to be linear with the slope, and the values are proportional to the absorption coefficient of the cladding material. The intercept of the absorbance vs. temperature plot is found to follow the first derivative of the fiber sensor transmission spectrum. Evanescent wave absorption spectra of TCE solutions have been corrected for temperature.

• DOE Contract Number: W-7405-ENG-48; AC03-76SF00098
• OSTI ID: 7004998
• Journal Information: Applied Spectroscopy; (United States), Journal Name: Applied Spectroscopy; (United States) Vol. 48:3; ISSN 0003-7028; ISSN APSPA4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ABSORPTION SPECTRA
AQUEOUS SOLUTIONS
DISPERSIONS
FIBER OPTICS
MIXTURES
NOISE
SOLUTIONS
SPECTRA
TEMPERATURE DEPENDENCE