Patent ID: 6124134
Filing Date: 2000-09-26
Classification: A61B,G01N,Y10T

Abstract:
In apparatus for determining the response to electromagnetic energy received after passing through material in a measurement volume using a calibrated diode array spectrometer to modify electrical signals developed from said response, the improvement comprising means for calibrating the response of the diode-array spectrometer including:a) means for measuring the spectral response of each diode-array signal channel over a substantial part of wavelength range covered by said diode-array spectrometer by introducing to said diode-array spectrometer electromagnetic radiation1) for which the characteristics over said substantial part of wavelength range are known to higher spectral resolution than the spectral width of each diode-array element and2) for which higher energy amplitude accuracy is known than the desired energy amplitude accuracy of the diode-array spectrometer,and recording electrical data signal outputs for each diode-array channel as a function of the wavelength of said introduced electromagnetic energy over said substantial part of wavelength range covered by said diode-array spectrometer;b) means for calculating response factors of each of said diode-array signal channels as the ratio of said electrical data signal output, S, to the output electromagnetic energy for its associated wavelength band (R.sub.jj T.sub.jj) and for each of the other wavelength bands associated with the other diode-array signal channels (R.sub.ij C.sub.ij) where T.sub.jj represents the transmission efficiency for energy in wavelength band j to diode-array element j and C.sub.ij is the coupling of energy in wavelength band I to the diode-array element j, which response factors may be expressed as an n by n response matrix; andc) means for forming corrected data signals, S', in accordance with the matrix multiplication [S].times.[R].sup.-1 where [R].sup.-1 is the inverse of said measured and calculated matrix [R].