Patent ID: 7952692

Claim:
A method for use in measurements of the concentration of an analyte in a medium having a certain extinction coefficient spectrum, said method comprising: providing a selected light source unit capable of generating at least first and second radiation components, each having a selected mean wavelength and a selected spectral bandwidth such that the mean wavelength and spectral bandwidth of said first radiation component correspond to a first spectral region of the extinction coefficient spectrum of said analyte where variation of an extinction coefficient, Δβ 1 , per volume fraction of the analyte across the spectral bandwidth of the first radiation component is higher than in other spectral regions of the extinction coefficient spectrum, and the mean wavelength and second spectral bandwidth of said second radiation component correspond to a second spectral region of the extinction coefficient spectrum where variation of an extinction coefficient, Δβ 2 per volume fraction of the analyte across the spectral bandwidth of the second radiation component is smaller than in other spectral regions of the extinction coefficient spectrum, and at least one of said at least two radiation components contains a plurality of wavelengths with radiation intensities that are in a fixed relation to each other during periods of said measurements; irradiating the medium with said at least first and second radiation components during a certain measurement time to thereby produce detectable radiation responses of the medium thereto, analyzing data indicative of detected radiation responses of the medium to said at least first and second radiation components to determine the concentration of said analyte.