Abstract: Embodiments of the present system and methods measure a concentration of a substance, such as glucose, in a body. The present embodiments measure a first amount of infrared (IR) radiation absorbed or emitted from the body in a first wavelength band, and a second amount of IR radiation absorbed or emitted from the body in a second wavelength band. The present embodiments also measure a temperature at a surface of the body and an ambient temperature. A normalized ratio parameter is calculated from the four measurements, and the concentration of the substance in the body is calculated by correlating the normalized ratio parameter with the body surface temperature and the ambient temperature using an empirically derived lookup table. Also disclosed are methods for creating the empirically derived lookup table.

Abstract: An apparatus and method for measuring a concentration of a substance in an eye using a retro-reflected measurement light beam having a first wavelength at which the substance has a non-zero first absorption coefficient and a retro-reflected reference light beam having a second wavelength at which the substance has a second absorption coefficient which is substantially equal to zero. The apparatus further includes a detector positionable to receive the retro-reflected measurement light beam and the retro-reflected reference light beam. The detector is responsive to light having the first wavelength by generating a measurement signal and responsive to light having the second wavelength by generating a reference signal. The apparatus further includes an electrical circuit coupled to the detector. The electrical circuit is responsive to the measurement signal and the reference signal to measure the concentration of the substance in the eye.

Abstract: An apparatus and method for measuring a concentration of a substance in an eye using a retro-reflected measurement light beam having a first wavelength at which the substance has a non-zero first absorption coefficient and a retro-reflected reference light beam having a second wavelength at which the substance has a second absorption coefficient which is substantially equal to zero. The apparatus further includes a detector positionable to receive the retro-reflected measurement light beam and the retro-reflected reference light beam. The detector is responsive to light having the first wavelength by generating a measurement signal and responsive to light having the second wavelength by generating a reference signal. The apparatus further includes an electrical circuit coupled to the detector. The electrical circuit is responsive to the measurement signal and the reference signal to measure the concentration of the substance in the eye.

Abstract: An apparatus for measuring a concentration of a substance in an eye (13) includes a measurement light source (4) producing a measurement light beam having a first wavelength at which the substance has a non-zero first absorption coefficient. The apparatus further includes a reference light source (6) producing a reference light beam having a second wavelength at which the substance has a second absorption coefficient which is substantially equal to zero. At least a portion of the measurement light beam retro-reflects from the retina (17) and at least a portion of the reference light beam retro-reflects from the retina (17). The apparatus further includes a detector (9) responsive to light having the first wavelength by generating a measurement signal and responsive to light having the second wavelength by generating a reference signal.