| abstract |
An apparatus for non-invasively measuring the concentratiuon of a predetermined substance in blood. Light of first and second wavelengths is emitted through a pulsating living tissue, either alternately of simultaneously. The amounts of light of the first and second wavelengths transmitted through the pulsating living tissue are measured for first and second different thicknesses of the pulsating tissue. A calculation is then carried out to determine the concentration of the predetermined substance based on the detected amounts of light of the first and second wavelengths when the pulsating living tissue has the first thickness, the amounts of light of the first and second wavelengths detected when the pulsating living tissue has the second thickness, and absorption coefficients of the substance and absorption coefficients of water at the first and second wavelengths. |