Calibration system for spectrographic analyzing instruments
First Claim
1. A method of analyzing an unknown material to measure at least one measurable characteristic of said material comprising storing a library of a multiplicity of spectra obtained from the reflectance or transmittance of a multiplicity of sample materials in each of which the value of said measurable characteristic is known, measuring a target spectrum obtained from the transmittance or reflectance of said unknown material, selecting a subset of spectra from said multiplicity which most closely match said target spectrum, determining coefficients of at least one equation which relates said measurable characteristic to values in the target spectrum, said coefficients being determined from said subset of spectra and the known values of said measurable characteristic in said sample materials corresponding respectively to said spectra of said subset, and calculating said measurable characteristic of said unknown material from said coefficients and said target spectrum in accordance with said equation.
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Abstract
In a system for analyzing materials by near infrared analysis, a library of absorbance spectra from sample materials is stored in computer storage. The absorbance spectra of an unknown material is measured and is correlated with the library spectra to select those library spectra which most closely match the spectrum of the unknown material. The selected library spectra are used to determine, by least squares convergence, or by multiple regression, coefficients in equations relating measurable properties of the unknown material to absorbance measurements made on the unknown material.
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Citations
11 Claims
- 1. A method of analyzing an unknown material to measure at least one measurable characteristic of said material comprising storing a library of a multiplicity of spectra obtained from the reflectance or transmittance of a multiplicity of sample materials in each of which the value of said measurable characteristic is known, measuring a target spectrum obtained from the transmittance or reflectance of said unknown material, selecting a subset of spectra from said multiplicity which most closely match said target spectrum, determining coefficients of at least one equation which relates said measurable characteristic to values in the target spectrum, said coefficients being determined from said subset of spectra and the known values of said measurable characteristic in said sample materials corresponding respectively to said spectra of said subset, and calculating said measurable characteristic of said unknown material from said coefficients and said target spectrum in accordance with said equation.
Specification