Patent ID: 8364218

Claim:
A method of determining the concentration of a substance in a subject's blood, the method comprising: measuring an interaction of at least one light beam with a portion of the subject's body, the measuring of the interaction of the at least one light beam including measuring reflections of a reference light beam and of a measurement light beam from the portion of the subject's body; calculating a value of an optically-measured parameter indicative of the interaction of the at least one light beam with the substance in the portion of the subject's body, the optically measured parameter including a reference ratio of a reflected power of the reference light beam to an incident power of the reference light beam and a measurement ratio of a reflected power of the measurement light beam to an incident power of the measurement light beam; measuring values of one or more temperature-indicative parameters corresponding to a temperature of the portion of the subject's body, the one or more temperature-indicative parameters including both a body temperature of the subject and an ambient temperature of the subject; accessing an empirical correlation of the optically-measured parameter and the one or more temperature-indicative parameters to concentrations of the substance in blood; and obtaining a concentration of the substance in the subject's blood using the empirical correlation, wherein the concentration corresponds to the value of the optically-measured parameter and the values of the one or more temperature-indicative parameters.