Optical emission line monitor with background observation and cancellation

Patent · Wed Jan 01 00:00:00 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 (NETL), Pittsburgh, PA, Morgantown, WV (United States)
• 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

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/