Optical emission line monitor with background observation and cancellation

Patent · Wed Jan 01 04:00:00 EST 1986

OSTI ID:866008

Goff, David R ^[1]; Notestein, John E ^[2]

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1. Star City, WV
2. Morgantown, WV

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.

• Research Organization: National Energy Technology Laboratory, Pittsburgh, PA, and Morgantown, WV
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 4616137
• OSTI ID: 866008
• Country of Publication: United States
• Language: English

Related Subjects

/250/340/356/431/
10
20
adapted
background
bandpass
bandpass filter
bandwidth
based
based optical
bifurcated
blackbody
blackbody radiation
blind
branch
cancellation
centered
coal
coal combustion
combustion
common
corresponding
d-line
db
detected
detector
detector output
detector outputs
detectors
difference
effects
emission
emission line
emission lines
emissions
fiber
fiber optic
fiber optics
filter
filters
flame
flame emission
guide
guided
indicative
instrument
intensity
interferring
light
light detector
light detectors
light guide
light passing
line
line emission
line monitoring
lines
located
monitor
monitoring
nanometers
nm
observation
optic
optic light
optical
optical emission
optics
optics based
outputs
pass filter
passing
portion
presence
provided
radiation
reduce
reflected
respectively
selected
selected spectral
sodium
spectral
spectral emission
trunk
uniquely
view
wavelength
width