Apparatus and method for determining the concentration of species in a substance
First Claim
1. An instrument for determining the concentration of at least one species in a substance, said instrument comprising:
- an instrument housing having a chamber for receiving at least a portion of the substance;
a broad band light source associated with said housing and positioned in illuminating contact with said chamber for illuminating the substance in said chamber;
means for separating the optical signals transmitted through said substance into signals of different wavelengths that are preselected for absorbance by at least one species in the substance and for attenuating light outside the wavelengths transmitted, thereby providing a continuous increase in absorbance as the concentration of the species in the substance increases for any single transmitted wavelength independent of the wavelength for peak absorbance by the species;
means for generating electrical signals from the optical signals that are proportional to the absorbance of the optical signals by the at least one species in the substance; and
means electrically connected to said means for generating electrical signals for determining from the electrical signals the concentration of at least one species in the substance in dependence upon the absorbance of the optical signals by the species as light is transmitted through the substance, said means comparing the electrical signals with electrical signals corresponding to the substance in the substantial absence of the species.
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Accused Products
Abstract
An instrument and a method are provided for determining the concentration of at least one species in a substance. The instrument and method can be used to identify and distinguish among various degrees of contamination of motor oil, diesel fuel, and hydraulic fluid by water, ethylene glycol, wear particles, and loss of anti-oxidants. The instrument includes a broad band light source, such as a tungsten filament incandescent lamp, which is very inexpensive and reliable. A fiber optic link is provided to a detector that receives and discriminates among optical spectral transmissions through the fiber optic. Discrimination circuitry is provided for evaluating the transmission and providing a readout that indicates the quality of the fluid. The instrument is suitable for in situ determination of oil quality.
77 Citations
26 Claims
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1. An instrument for determining the concentration of at least one species in a substance, said instrument comprising:
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an instrument housing having a chamber for receiving at least a portion of the substance; a broad band light source associated with said housing and positioned in illuminating contact with said chamber for illuminating the substance in said chamber; means for separating the optical signals transmitted through said substance into signals of different wavelengths that are preselected for absorbance by at least one species in the substance and for attenuating light outside the wavelengths transmitted, thereby providing a continuous increase in absorbance as the concentration of the species in the substance increases for any single transmitted wavelength independent of the wavelength for peak absorbance by the species; means for generating electrical signals from the optical signals that are proportional to the absorbance of the optical signals by the at least one species in the substance; and means electrically connected to said means for generating electrical signals for determining from the electrical signals the concentration of at least one species in the substance in dependence upon the absorbance of the optical signals by the species as light is transmitted through the substance, said means comparing the electrical signals with electrical signals corresponding to the substance in the substantial absence of the species. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An instrument for determining the concentration of at least one species in a substance, said instrument comprising:
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an instrument housing having a chamber for receiving at least a portion of the substance; a broad band light source associated with said housing and positioned in illuminating contact with said chamber for illuminating the substance in said chamber; a plurality of optical fibers associated with said housing and positioned in relation to said chamber for receiving light that has been transmitted through the substance, said optical fibers transmitting different wavelengths of light that are preselected for absorbance by at least one species in the substance and for attenuating light outside the wavelengths transmitted, thereby providing a continuous increase in absorbance as the concentration of the species in the substance increases for any single transmitted wavelength independent of the wavelength for peak absorbance by the species; means for discriminating among the optical signals transmitted by said optical fibers based upon the wavelengths of the optical signals, wherein said means is operatively connected to said optical fibers; means for generating electrical signals from the discriminated optical signals that are proportional to the absorbance of the optical signals by the at least one species in the substance; and a comparator electrically connected to said means for generating electrical signals and including means for receiving electrical signals and means for determining from the electrical signals the concentration of at least one species in the substance in dependence upon the absorbance of the optical signals as light is transmitted through the substance by comparing the electrical signals to electrical signals corresponding to the substance in the substantial absence of the species. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. An instrument suitable for determining in situ the concentration of at least one species in a motor oil, said instrument comprising:
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an instrument housing having a chamber extending therethrough providing for flow of the oil through said chamber; a broad band white light source associated with said housing and positioned in illuminating contact with said chamber for illuminating the oil in said chamber; a plurality of optical fibers associated with said housing and positioned in relation to said chamber for receiving light that has been transmitted through the oil, said optical fibers transmitting wavelengths of light in the range of from about 380 nm to 2500 nm that are preselected for absorbance by at least one species in the oil and attenuating light outside the preselected wavelengths, thereby providing a continuous increase in absorbance as the concentration of the species in the oil increases for any single transmitted wavelength independent of the wavelength for peak absorbance by the species; a detector operatively connected to said optical fibers and including means for discriminating among the optical signals transmitted by said optical fibers and means for generating electrical signals proportional to the absorbance of the optical signals by the species in the oil; a comparator electrically connected to said detector and including means for receiving electrical signals from said detector and means for determining the concentration of the species in the oil in dependence upon the absorbance of the optical signal by the oil by comparing the generated electrical signals to electrical signals corresponding to the oil in the substantial absence of the species; and a display device operatively connected to said comparator for displaying to a user an indication of the concentration of at least one species in the oil.
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17. A method for determining the concentration of at least one species in a substance, said method comprising the steps of:
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a) illuminating the substance with broad band white light; b) segregating the transmitted light into optical signals having distinct bandwidths within which a species absorbs light and attenuating light outside the distinct bandwidths, thereby providing a continuous increase in absorbance as the concentration of the species in the substance increases for any single transmitted wavelength independent of the wavelength for peak absorbance by the species; c) converting the optical signals into electrical signals proportional to the absorbance of the optical signals at each of the distinct bandwidths as light is transmitted through the substance; d) comparing the generated electrical signals to electrical signals corresponding to the substance in the substantial absence of the species; and e) determining the concentration of at least one species in the substance based on the electrical signals. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A method for determining the concentration of at least one species in a fluid, said method comprising the steps of:
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a) illuminating the fluid with a broad band white light; b) segregating the transmitted light into optical signals having distinct bandwidths comprising receiving the optical signals by and transmitting the optical signals through optical fibers preselected for transmitting light of wavelengths absorbed by the species and attenuating light outside the wavelengths transmitted, thereby providing a continuous increase in absorbance as the concentration of the species in the fluid increases for any single transmitted wavelength independent of the wavelength for peak absorbance by the species; c) converting the optical signals into electrical signals proportional to the absorbance of the optical signals as light is transmitted through the fluid; d) preparing a plot of absorbance versus wavelength and integrating the area under the resulting curve from one wavelength to the next; e) comparing the integral obtained from step d) with that for a fluid in the substantial absence of the species; f) determining an indication of the concentration of at least one species in the fluid based on the comparison from step e); and g) displaying to a user an indication of the concentration of at least one species in the fluid.
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25. A method for determining the quality of motor oil, said method comprising the steps of:
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a) illuminating the motor oil with a broad band white light source; b) filtering the light transmitted through the motor oil into optical signals of distinct bandwidth that are preselected for absorbance by contaminants in the motor oil and attenuating light outside the distinct bandwidth, thereby providing a continuous increase in absorbance as the contaminants in the motor oil increase for any single transmitted wavelength independent of the wavelength for peak absorbance by the contaminants; c) converting the optical signals into electrical signals that are proportional to the absorbance of the light by the contaminants; d) comparing the electrical signal to one for reference motor oil to determine the quality of the oil based upon the electrical signal; and e) displaying to a user an indication of the quality of the motor oil. - View Dependent Claims (26)
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Specification