Patent ID: 8682407

Claim:
A pulse oximetry sensor comprising: a plurality of emitters configured to transmit light into a fleshy medium, wherein a first subset of said plurality of emitters are matched to transmit light at a first wavelength and a second subset of said plurality of emitters are matched to transmit light at a second wavelength, and wherein said plurality of emitters are configured such that an emitted DC intensity ratio is matched to a first predetermined constant, wherein said emitted DC intensity ratio is a ratio of an intensity of the light emitted at the first wavelength to an intensity of the light emitted at the second wavelength for given DC drive currents; and a detector responsive to said light after absorption by constituents of pulsatile blood flowing within said medium so as to generate a plurality of intensity signals, said detector configured such that a DC response ratio is matched to a second predetermined constant; wherein said matching of said emitters to said first and second wavelengths, said matching of said emitted DC intensity ratio to said first predetermined constant, and said matching of said DC response ratio to said second predetermined constant reduces variations in a mean pathlength ratio of said light traveling through said fleshy medium between said plurality of emitters and said detector.