Accession Number : ADD013542

Title :   Optical Waveguide Sensor for Methane Gas.

Descriptive Note : Patent, Filed 7 Mar 85, patented 24 Nov 87,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Giuliani, John F

Report Date : 24 Nov 1987

Pagination or Media Count : 10

Abstract : A device for detecting small amounts of alkanes such as methane, ethane, propane, and butane gases, comprising an optical waveguide and a light source for propagating light therethrough; apparatus for obtaining samples of air to be tested; apparatus for adding water vapor to these air samples to yield gas mixtures with at least a 30% relative humidity; and means for flowing these mixtures over the surface of the optical waveguide at a rate sufficient to favor condensation of the mixture on the waveguide surface to thereby form a thin film thereon. The presence of alkanes is determined by detecting the intensity of the light after propagation through the optical waveguide and then comparing that detected intensity to a reference. In a preferred embodiment, the optical waveguide is an optical glass capillary in which the surface is closed in a lens-like configuration at the detector end.

Descriptors :   *ALKANES, *BUTANES, *ETHANES, *METHANE, *OPTICAL DETECTORS, *OPTICAL WAVEGUIDES, *THIN FILMS, *WATER VAPOR, *PATENTS, AIR, CONDENSATION, GASES, INTENSITY, LIGHT, LIGHT SOURCES, MIXTURES, OPTICAL GLASS, PROPAGATION, PROPANE, SAMPLING, SURFACES, WAVEGUIDES, YIELD

Subject Categories : Physical Chemistry
      Optics
      Organic Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE