Patent ID: 6278889
Filing Date: 2001-08-21
Classification: A61B,G01N

Abstract:
A method of determining noninvasively an unknown value of a known characteristic, particularly the concentration of at least one analyte in tissue containing multiple spectral interferences, said method including the steps of:(a) providing at least one source of infrared energy having multiple wavelengths;(b) using at least one means for introducing said infrared energy into said tissue and at least one means for collecting said infrared energy to provide first and second optical paths of different lengths through said tissue;(c) measuring with at least one detector the intensities of at least some of said multiple wavelengths which have traversed said tissue through said first and second optical paths; and(d) calculating said unknown value by using said measured intensities from said first and said second optical paths, said calculating using said measured intensities from both optical paths to compensate for said spectral interferences in said tissue.