Real-time alkali monitoring system

Claim 2

A real-time alkali monitoring system for detecting selected alkali emissions from a light source in the presence of interfering background radiation, comprising: a bifurcated fiber optic cable having first and second branches attached to a common trunk and adapted at the common end to optically couple light from a light source to said cable; a first bandpass optical filter having a passband centered about a selected emission line and a bandwidth at least as wide as the selected emission line and being disposed to intercept light passing from the end of said first branch of said cable; a second bandpass optical filter having a passband centered about a wavelength identical to that of said first bandpass filter and a bandwidth substantially wider than the bandwidth of said first bandpass filter and being disposed to intercept light passing from the end of said second branch of said cable; a first light detector means for generating a first signal having an amplitude proportional to the intensity of light transmitted through said first bandpass filter, a second light detector means for generating a second signal having an amplitude proportional to the intensity of light transmitted through said second bandpass filter; a means for scaling one of the output signals from said detectors; and, a means for calculating the difference between said scaled output signal and said other output signal to generate a third output signal having an amplitude proportional to the intensity of said emission line being monitored.

Claim 3

A system in accordance with claim 1 wherein said means for scaling comprises: a first variable gain amplifier connected to the output of said first light detector means and a second variable gain amplifier connected to the output of said second light detector means.

Claim 4

A system in accordance with claim 2 wherein said means for calculating comprises: a differential amplifier having a positive input connected to the output of said first variable gain amplifier and a negative input connected to the output of said second variable gain amplifier.

Claim 5

A system in accordance with claim 2 wherein the light source is a combustion flame.

Claim 6

A system in accordance with claim 2 further comprising: a lens means located between the light source and said common end of said cable for increasing the light gathering efficiency of the system.

Claim 7

A system in accordance with claim 5 further comprising: a diffuser means located between said lens means and said common end of said cable to improve the uniformity of illumination at said common end of said cable.

Claim 8

A system in accordance with claim 1 wherein said bandpass filters are dichroic filters having a passband centered about a wavelength selected from about 589 nm and about 766 nm.

Claim 9

A real-time alkali monitoring system for detecting two selected alkali emissions simultaneously from a light source in the presence of interfering background radiation, comprising: a bifurcated fiber optic cable having first and second branches attached to a common trunk and adapted at the common end to optically couple light from a light source to said cable; a first beam splitter disposed to intercept light passing from the end of said first branch of said cable and split the light into a first beam and a second beam; a second beam splitter disposed to intercept light passing from the end of said second branch of said cable and split the light into a third beam and a fourth beam; a first bandpass optical filter having a passband centered about a first selected emission line and having a bandwidth at least as wide as the first selected emission line and being disposed to intercept said first beam passing from said first beam splitter; a second bandpass optical filter having a passband centered about a wavelength identical to that of said first bandpass filter and a bandwidth substantially wider than the bandwidth of said first bandpass filter and being disposed to intercept said second beam passing from said first beam splitter; a third bandpass optical filter having a passband centered about a second selected emission line and a bandwidth at least as wide as the second selected emission line and being disposed to intercept said third beam passing from said second beam splitter; a fourth bandpass optical filter having a passband centered about a wavelength identical to that of said third bandpass filter and a bandwidth substantially wider than the bandwidth of said third bandpass filter and being disposed to intercept said fourth beam passing from said second beam splitter; a first light detector means for generating a first signal having an amplitude proportional to the intensity of light transmitted through said first bandpass filter; a second light detector means for generating a second signal having an amplitude proportional to the intensity of light transmitted through said second bandpass filter; a third light detector means for generating a third signal having an amplitude proportional to the intensity of light transmitted through said third bandpass filter; a fourth light detector means for generating a fourth signal having an amplitude proportional to the intensity of light transmitted through said fourth bandpass filter; a means for scaling one of the output signals from said first and second detectors and one of the output signals from said third and fourth detectors, and a means for calculating the difference between said scaled output signal from said first and second detectors and the difference between said scaled output signal from said third and fourth detectors and said other output signal from said third and fourth detectors to generate fifth and sixth output signals each having an amplitude proportional to the intensity of one of said emission lines being monitored.

Claim 10

A real-time alkali monitoring system for detecting two selected alkali emissions simultaneously from a light source in the presence of interfering background radiation, comprising: a bifurcated fiber optic cable having first and second branches attached to a common trunk and adapted at the common end to optically couple light from a light source to said cable; a first beam splitter disposed to intercept light passing from the end of said first branch of said cable and split the light into a first beam and a second beam; a second beam splitter disposed to intercept light passing from the end of said second branch of said cable and split the light into a third beam and a fourth beam; a first bandpass optical filter having a passband centered about a first selected emission line and having a bandwidth at least as wide as the first selected emission line and being disposed to intercept said first beam passing from said first beam splitter; a second bandpass optical filter having a passband centered about a wavelength identical to that of said first bandpass filter and a bandwidth substantially wider than the bandwidth of said first bandpass filter and being disposed to intercept said second beam passing from said first beam splitter; a third bandpass optical filter having a passband centered about a second selected emission line and a bandwidth at least as wide as the second selected emission line and being disposed to intercept said third beam passing from said second beam splitter; a fourth bandpass optical filter having a passband centered about a wavelength identical to that of said third bandpass filter and a bandwidth substantially wider than the bandwidth of said third bandpass filter and being disposed to intercept said fourth beam passing from said second beam splitter; a first light detector means for generating a first signal having an amplitude proportional to the intensity of light transmitted through said first bandpass filter; a second light detector means for generating a second signal having an amplitude proportional to the intensity of light transmitted through said second bandpass filter; a third light detector means for generating a third signal having an amplitude proportional to the intensity of light transmitted through said third bandpass filter; a fourth light detector means for generating a fourth signal having an amplitude proportional to the intensity of light transmitted through said fourth bandpass filter; a means for scaling one of the output signals from said first and second detectors and one of the output signals from said third and fourth detectors, and a means for calculating the difference between said scaled output signal from said first and second detectors and the difference between said scaled output signal from said third and fourth detectors and said other output signal from said third and fourth detectors to generate fifth and sixth output signals each having an amplitude proportional to the intensity of one of said emission lines being monitored.

Claim 11

A system in accordance with claim 8 wherein said means for scaling comprises: a first variable gain amplifier connected to the output of said first light detector means; a second variable gain amplifier connected to the output of said second light detector means; a third variable gain amplifier connected to the output of said third light detector means; and a fourth variable gain amplifier connected to the output of said fourth light detector means.

Claim 12

A system in accordance with claim 9 wherein said means for calculating comprises: a first differential amplifier having a positive input connected to the output of said first variable gain amplifier and a negative input connected to the output of said second variable gain amplifier, and a second differential amplifier having a positive input connected to the output of said third variable gain amplifier and a negative input connected to the output of said fourth variable gain amplifier.

Claim 13

A system in accordance with claim 10 further comprising: a first colored glass filter located between the end of said first branch of said cable and said first beam splitter to reduce the amount of stray light that reaches the said first and second detectors, and a second colored glass filter located between the end of said second branch of said cable and said second beam splitter to reduce the amount of stray light that reaches the said third and fourth detectors.

Claim 14

A system in accordance with claim 9 further comprising: a lens means located between the light source and said common end of said cable for increasing the light gathering efficiency of the system.

Claim 15

A system in accordance with claim 12 further comprising: a shutter means located between said lens means and said common end of said cable to allow illumination at said common end of said cable to be cut off.

Claim 16

A system in accordance with claim 9 wherein said bandpass filters are dichroic filters, and said first and second bandpass filters having a passband centered about a wavelength of about 589 nm, and said third and fourth bandpass filters having a passband centered about a wavelength of about 766 nm.

Claim 17

A real-time alkali monitoring system for detecting two different selected alkali emissions simultaneously from a light source in the presence of interfering background radiation comprising: a quadfurcated fiber optic cable having first, second, third and fourth branches attached to a common trunk and adapted at the common end to optically couple light from a light source to said cable; a first bandpass optical filter having a passband centered about a first selected emission line and having a bandwidth at least as wide as the first selected emission line and being diposed to intercept light passing from the end of said first branch of said cable; a second bandpass optical filter having a passband centered about a wavelength identical to that of said first bandpass filter and a bandwidth substantially wider than the bandwidth of said first bandpass filter and being disposed to intercept light passing from the end of said second branch of said cable; a third bandpass optical filter having a passband centered about a second selected emission line and having a bandwidth at least as wide as the second selected emission line and being disposed to intercept light passing from the end of said third branch of said cable; a fourth bandpass optical filter having a passband centered about a wavelength identical to that of said third bandpass filter and a bandwidth substantially wider than the bandwidth of said third bandpass filter and being disposed to intercept light passing from the end of said fourth branch of said cable; a first light detector means for generating a first signal having an amplitude proportional to the intensity of light transmitted through said first bandpass filter; a second light detector means for generating a second signal having an amplitude proportional to the intensity of light transmitted through said second bandpass filter; a third light detector means for generating a third signal having an amplitude proportional to the intensity of light transmitted through said third bandpass filter; a fourth light detector means for generating a fourth signal having an amplitude proportional to the intensity of light transmitted through said fourth bandpass filter; a means for scaling one of the output signals from said first and second detectors and one of the output signals from said third and fourth detectors, and a means for calculating the difference between said scaled output signal from said first and second detectors and said other output signal from said first and second detectors and the difference between said scaled other output signal from said third and fourth detectors and said output signal from said third and fourth detectors to generate fifth and sixth output signals each having an amplitude proportional to the intensity of respective of said first and second emission lines being monitored.

Claim 18

A real-time alkali monitoring system for detecting two different selected alkali emissions simultaneously from a light source in the presence of interfering background radiation comprising: a quadfurcated fiber optic cable having first, second, third and fourth branches attached to a common trunk and adapted at the common end to optically couple light from a light source to said cable; a first bandpass optical filter having a passband centered about a first selected emission line and having a bandwidth at least as wide as the first selected emission line and being diposed to intercept light passing from the end of said first branch of said cable; a second bandpass optical filter having a passband centered about a wavelength identical to that of said first bandpass filter and a bandwidth substantially wider than the bandwidth of said first bandpass filter and being disposed to intercept light passing from the end of said second branch of said cable; a third bandpass optical filter having a passband centered about a second selected emission line and having a bandwidth at least as wide as the second selected emission line and being disposed to intercept light passing from the end of said third branch of said cable; a fourth bandpass optical filter having a passband centered about a wavelength identical to that of said third bandpass filter and a bandwidth substantially wider than the bandwidth of said third bandpass filter and being disposed to intercept light passing from the end of said fourth branch of said cable; a first light detector means for generating a first signal having an amplitude proportional to the intensity of light transmitted through said first bandpass filter; a second light detector means for generating a second signal having an amplitude proportional to the intensity of light transmitted through said second bandpass filter; a third light detector means for generating a third signal having an amplitude proportional to the intensity of light transmitted through said third bandpass filter; a fourth light detector means for generating a fourth signal having an amplitude proportional to the intensity of light transmitted through said fourth bandpass filter; a means for scaling one of the output signals from said first and second detectors and one of the output signals from said third and fourth detectors, and a means for calculating the difference between said scaled output signal from said first and second detectors and said other output signal from said first and second detectors and the difference between said scaled other output signal from said third and fourth detectors and said output signal from said third and fourth detectors to generate fifth and sixth output signals each having an amplitude proportional to the intensity of respective of said first and second emission lines being monitored.

Claim 19

A system in accordance with claim 15 wherein said means for scaling comprises: a first variable gain amplifier connected to the output of said first light detector means, a second variable gain amplifier connected to the output of said second light detector means, a third variable gain amplifier connected to the output of said third light detector means, and a fourth variable gain amplifier connected to the output of said fourth light detector means.

Claim 20

A system in accordance with claim 16 wherein said means for calculating comprises: a first differential amplifier having a positive input connected to the output of said first variable gain amplifier and a negative input connected to the output of said second variable gain amplifier, and a second differential amplifier having a positive input connected to the output of said third variable gain amplifier and a negative input connected to the output of said fourth variable gain amplifier.

Claim 21

A system in accordance with claim 16 further comprising: a lens means located between the light source and said common end of said cable for increasing the light-gathering efficiency of the system.

Claim 22

A system in accordance with claim 18 further comprising: a diffuser means located between said lens means and said common end of said cable to improve the uniformity of illumination at said common end of said cable.

Claim 23

A system in accordance with claim 15 wherein said bandpass filters are dichroic filters and said first and second bandpass filters have a passband centered about a wavelength of about 589 nm and said third and fourth bandpass filters have a passband centered about a wavelength of about 766 nm.