Abstract: The invention provides an optical method and apparatus for non-invasively determining blood hematocrit. The method includes the step of first irradiating blood with optical radiation. Radiation reflected or transmitted from the blood is then collected to determine an optical spectrum. Hematocrit is then determined by comparing this spectrum to a mathmatical model relating optical properties to blood Hematocrit.

Abstract: The invention provides an optical method and apparatus for non-invasively determining blood hematocrit. The method includes the step of first irradiating blood with optical radiation. Radiation reflected or transmitted from the blood is then collected to determine an optical spectrum. Hematocrit is then determined by comparing this spectrum to a mathematical model relating optical properties to blood Hematocrit.

Abstract: Method and system for measuring the relative concentrations of first and second isotopic forms of a chemical species within a sample. The present invention need not use a laser or high resolution spectrometer. The system typically includes a waveguide cell with good transmission of particular wavelengths of IR radiation, such as a hollow glass fiber waveguide cell. A source emits electromagnetic radiation, which is modulated at first and second wavelength bands that correspond to absorption bands of the first and second isotopic forms of the chemical species, respectively. In certain embodiments, the source is a filtered broad band source, such as a plurality of LEDs. In some embodiments, an FTIR spectrometer may serve as a filtered source and signal detector.