Patent ID: 8175666

Claim:
A method of generating a beam of electromagnetic radiation for the non-invasive measurement of a concentration of a target analyte in a fluid within a sample matrix, the method comprising: directing a combined beam of electromagnetic radiation at the sample, the combined beam including at least two repetitive periods of radiation including a principal beam and a reference beam, the principal and reference beams having different wavelengths, the target analyte having different absorption coefficients for the different wavelengths, and the reference beam including a mixture of at least two radiations of different wavelengths, having an effective wavelength equal to an intensity-weighted mean of the two component wavelengths, wherein intensities of the periods of radiation are adjusted when the sample is at a first sample fluid state, and at least one effective wavelength of the at least two repetitive periods of radiation is selected to minimize detectable transmission or reflection difference when the sample is at a state different from the first state.