Optical quantitative analysis using curvilinear interpolation
First Claim
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1. An apparatus for optically obtaining a quantitative value of a constituent having a wavelength variable optical absorptivity in a sample, comprising:
- means for measuring optical absorptivity of a sample at a plurality of predetermined different wavelengths to obtain a corresponding plurality of measured optical absorptivity values,means for computing a plurality of computed optical absorptivity values by a curvilinear interpolation technique from the measured optical absorptivity values, andmeans for computing the constituent quantitative value from optical absorptivity values including one or more of the computed optical absorptivity values.
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Abstract
In the quantitative analysis of a sample by computing constituents from optical absorptivity data at different wavelengths, optical absorptivity data values for selected nominal wavelengths are obtained by curvilinear interpolation from measured optical absorptivity data values obtained by use of narrow band width filters. The computed optical data values are utilized to compute percentage constituents by means of algorithms which may include one or more first or second derivatives.
38 Citations
18 Claims
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1. An apparatus for optically obtaining a quantitative value of a constituent having a wavelength variable optical absorptivity in a sample, comprising:
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means for measuring optical absorptivity of a sample at a plurality of predetermined different wavelengths to obtain a corresponding plurality of measured optical absorptivity values, means for computing a plurality of computed optical absorptivity values by a curvilinear interpolation technique from the measured optical absorptivity values, and means for computing the constituent quantitative value from optical absorptivity values including one or more of the computed optical absorptivity values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of optically obtaining a quantitative value of a constituent having a wavelength variable optical absorptivity in a sample, comprising the steps of:
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measuring optical absorptivity of the sample at a plurality of predetermined different wavelengths to obtain a corresponding plurality of measured optical absorptivity values, computing a plurality of computed optical absorptivity values by a curvilinear interpolation technique from the measured optical absorptivity values, and computing the constituent quantitative value from optical absorptivity values including one or more of the computed optical absorptivity values. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method of calibrating an apparatus for optically obtaining a quantitative value of a constituent having a wavelength variable optical absorptivity in a sample, wherein the apparatus includes an assembly of (a) radiant energy source means for impinging upon the sample, (b) means for detecting radiant energy transmitted or reflected from the sample, (c) a plurality of narrow bandpass filters for being interposed in one or more optical paths between the radiant energy source means and the detecting means, and (d) computer means including a memory for analyzing a plurality of output values of the detecting means corresponding to the respective filters wherein the number and nominal center response wavelengths of the filters have been selected so that curvilinear interpolation of absorptivity data reading corresponding to the filters generates absorptivity data spectrum traces with less than a predetermined deviation from measured absorptivity data spectrum traces;
- the method comprising the steps of;
obtaining absorptivity data readings corresponding to the filters from the assembled (a), (b) and (c) for a plurality of samples; generating a plurality of wavelength spectrum traces of absorptivity data values corresponding to the plurality of samples by curvilinear interpolation from the obtained data readings; selecting wavelengths at which the optical data values, when utilized in an algorithm, produce the least deviation in computed constituent percentages of the samples from actual measured constituent percentages; and incorporating indications of the selected wavelengths into the computer memory to thereby enable the computer to utilize the algorithm to accurately compute constituent percentages. - View Dependent Claims (18)
- the method comprising the steps of;
Specification