Abstract: A method for non-invasively measuring the concentration of an analyte, particularly blood analyte in blood. The method utilizes spectrographic techniques in conjunction with an improved optical interface between a sensor probe and a skin surface or tissue surface of the body containing the blood to be analyzed. An index-matching medium is disclosed to improve the interface between the sensor probe and skin surface during spectrographic analysis. In a preferred embodiment, the blood analyte concentration in blood is quantified utilizing a partial squares analysis relative to a model incorporating analysis of plural known blood samples.

Abstract: An improved apparatus for diffuse reflectance spectroscopy having a specular control device. The specular control device has at least a first surface divided into an even-numbered plurality of reflecting sections and open or transmitting sections. The number of reflecting sections is equal to the number of open sections. Each reflecting section is situated between a pair of open sections and opposite to another reflecting section. Similarly, each open section is situated between a pair of reflecting sections and is opposite to another open section. In one preferred embodiment, the total surface area of the reflecting sections is equal to the total surface area of the open sections. In another embodiment, the total surface area of the reflecting sections is unequal to the total surface area of the open sections.