Abstract: Spectrographic instruments at remote site locations measure near infrared absorbance spectra for unknown materials and transmit the absorbance spectra to a central web site where, the measurements are standardized to be the same as if they were measured by a master instrument. The standardized absorbance spectra are then compared with a library of spectra stored at the central web site to select a subset of absorbance spectra from the library which most closely correlate with the absorbance spectrum received from the remote sites. The library spectra are obtained from measurements on materials, the measurable characteristics of which are known. From the selected subset, equations are developed relating the measurable characteristics of the unknown material to the absorbance spectra and from these equations, the measurable characteristics of the unknown materials are determined. The results of this analysis are then transmitted back to the remote site locations electronically.

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.

Abstract: In a calibration system for optical instruments of the type which make measurements at incrementally spaced wavelengths throughout a spectrum, a plurality of standard samples are measured by a master instrument and a field instrument. The measurement data obtained from each instrument are then statistically correlated to determine a calibration file which is stored with the field instrument. The calibration file includes identification on the field instrument of index locations at which the field instrument will respond to the same wavelength as corresponding index points on the master and includes correction coefficients for each of the index locations. The calibration file is stored in a computer connected to the field instrument and the computer is provided with a program to correct the measurements made by the field instrument in accordance with the stored calibration file.