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Title: Optical emission line monitor with background observation and cancellation

Abstract

A fiber optics based optical emission line monitoring system is provided in which selected spectral emission lines, such as the sodium D-line emission in coal combustion, may be detected in the presence of interferring background or blackbody radiation with emissions much greater in intensity than that of the emission line being detected. A bifurcated fiber optic light guide is adapted at the end of one branch to view the combustion light which is guided to a first bandpass filter, adapted to the common trunk end of the fiber. A portion of the light is reflected back through the common trunk portion of the fiber to a second bandpass filter adapted to the end of the other branch of the fiber. The first filter bandpass is centered at a wavelength corresponding to the emission line to be detected with a bandwidth of about three nanometers (nm). The second filter is centered at the same wavelength but having a width of about 10 nm. First and second light detectors are located to view the light passing through the first and second filters respectively. Thus, the second detector is blind to the light corresponding to the emission line of interest detected by themore » first detector and the difference between the two detector outputs is uniquely indicative of the intensity of only the combustion flame emission of interest. This instrument can reduce the effects of interferring blackbody radiation by greater than 20 dB.« less

Inventors:
 [1];  [2]
  1. (Star City, WV)
  2. (Morgantown, WV)
Publication Date:
Research Org.:
National Energy Technology Laboratory, Pittsburgh, PA, and Morgantown, WV
OSTI Identifier:
866008
Patent Number(s):
US 4616137
Assignee:
United States of America as represented by United States (Washington, DC) NETL
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
optical; emission; line; monitor; background; observation; cancellation; fiber; optics; based; monitoring; provided; selected; spectral; lines; sodium; d-line; coal; combustion; detected; presence; interferring; blackbody; radiation; emissions; intensity; bifurcated; optic; light; guide; adapted; branch; view; guided; bandpass; filter; common; trunk; portion; reflected; centered; wavelength; corresponding; bandwidth; nanometers; nm; width; 10; detectors; located; passing; filters; respectively; detector; blind; difference; outputs; uniquely; indicative; flame; instrument; reduce; effects; 20; db; selected spectral; light detectors; detector output; bandpass filter; coal combustion; fiber optics; fiber optic; light guide; emission line; optic light; blackbody radiation; light detector; pass filter; light passing; spectral emission; optical emission; flame emission; emission lines; line emission; optics based; detector outputs; based optical; line monitoring; /250/340/356/431/

Citation Formats

Goff, David R., and Notestein, John E.. Optical emission line monitor with background observation and cancellation. United States: N. p., 1986. Web.
Goff, David R., & Notestein, John E.. Optical emission line monitor with background observation and cancellation. United States.
Goff, David R., and Notestein, John E.. Wed . "Optical emission line monitor with background observation and cancellation". United States. doi:. https://www.osti.gov/servlets/purl/866008.
@article{osti_866008,
title = {Optical emission line monitor with background observation and cancellation},
author = {Goff, David R. and Notestein, John E.},
abstractNote = {A fiber optics based optical emission line monitoring system is provided in which selected spectral emission lines, such as the sodium D-line emission in coal combustion, may be detected in the presence of interferring background or blackbody radiation with emissions much greater in intensity than that of the emission line being detected. A bifurcated fiber optic light guide is adapted at the end of one branch to view the combustion light which is guided to a first bandpass filter, adapted to the common trunk end of the fiber. A portion of the light is reflected back through the common trunk portion of the fiber to a second bandpass filter adapted to the end of the other branch of the fiber. The first filter bandpass is centered at a wavelength corresponding to the emission line to be detected with a bandwidth of about three nanometers (nm). The second filter is centered at the same wavelength but having a width of about 10 nm. First and second light detectors are located to view the light passing through the first and second filters respectively. Thus, the second detector is blind to the light corresponding to the emission line of interest detected by the first detector and the difference between the two detector outputs is uniquely indicative of the intensity of only the combustion flame emission of interest. This instrument can reduce the effects of interferring blackbody radiation by greater than 20 dB.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1986},
month = {Wed Jan 01 00:00:00 EST 1986}
}

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