Abstract: Methods and apparatus for non-invasively verifying human identities using near-infrared spectroscopy. Near-infrared tissue spectra can be obtained by projecting near-infrared radiation into skin on the underside of human forearms and capturing the light reflected back and out through the tissue. The tissue spectrum collected preferably includes primarily diffuse reflected light reflected from the inner dermis. Multiple tissue spectra and identities can be collected from individuals for whom identity verification may later be desired. The tissue spectra for each individual can be analyzed on a computer, and the spectra for each individual clustered or classified together using tools such as linear discriminant analysis. A target individual seeking identity verification can submit both a purported identity and a near-infrared tissue spectrum for analysis through near-infrared spectroscopy of the forearm.

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 method and apparatus for diffuse reflectance spectroscopy. A specular control device is provided that can discriminate between diffusely reflected light that is reflected from selected depths or layers within the tissue. The specular control device permits a spectroscopic analyzer to receive the diffusely reflected light that is reflected from, for example, a first layer or depth within the tissue, while preventing the remaining diffusely reflected light from reaching the spectroscopic analyzer. Furthermore, the specular control device may prevent the specularly reflected light (e.g. surface reflected light) from reaching the spectroscopic analyzer.

Abstract: Methods and apparatus for performing biometric identification or verification of identities using optical spectroscopy of tissue. Tissue optical spectra can be obtained by projecting optical radiation into skin and capturing the light transmitted or reflected back and out through the tissue. The tissue spectra collected preferably includes primarily light that has passed through skin tissue below the epidermis. Multiple tissue spectra and identities can be collected from one or more individuals. These tissue spectra can be analyzed on a computer, and the spectral features that are most important for classifying person-to-person differences can be established using principle component analysis, linear discriminant analysis, or a variety of other related techniques. One or more tissue spectra and identities can be collected from individuals for whom identification or verification may later be desired.

Abstract: Methods and apparatus for performing biometric identification or verification of identities using optical spectroscopy of tissue. Tissue optical spectra can be obtained by projecting optical radiation into skin and capturing the light transmitted or reflected back and out through the tissue. The tissue spectra collected preferably includes primarily light that has passed through skin tissue below the epidermis. Multiple tissue spectra and identities can be collected from one or more individuals. These tissue spectra can be analyzed on a computer, and the spectral features that are most important for classifying person-to-person differences can be established using principle component analysis, linear discriminant analysis, or a variety of other related techniques. One or more tissue spectra and identities can be collected from individuals for whom identification or verification may later be desired.

Abstract: An improved method and apparatus for diffuse reflectance spectroscopy. A specular control device is provided that can discriminate between diffusely reflected light that is reflected from selected depths or layers within the tissue. The specular control device permits a spectroscopic analyzer to receive the diffusely reflected light that is reflected from, for example, a first layer or depth within the tissue, while preventing the remaining diffusely reflected light from reaching the spectroscopic analyzer. Furthermore, the specular control device may prevent the specularly reflected light (e.g. surface reflected light) from reaching the spectroscopic analyzer.

Abstract: Methods and apparatus for non-invasive tissue urea concentrations during or subsequent to hemodialysis using near-infrared spectroscopy are discussed. Near-infrared tissue spectra can be obtained by projecting near-infrared radiation into skin on the underside of human forearms and capturing the light reflected back and out through the tissue. An index matching medium is used to couple the tissue to the analyzer. The tissue spectrum collected preferably includes primarily diffuse reflected light reflected from the inner dermis. Multiple tissue spectra of known urea concentration are used to build a model from which the urea concentration of an unknown sample can be devised. The model is based on a partial least squares algorithm applied to multiple tissue scans and concomitant blood sample urea measurements. This model is then applied to an unknown tissue spectra.

Abstract: An improved method and apparatus for diffuse reflectance spectroscopy. A specular control device is provided that can discriminate between diffusely reflected light that is reflected from selected depths or layers within the tissue. The specular control device permits a spectroscopic analyzer to receive the diffusely reflected light that is reflected from, for example, a first layer or depth within the tissue, while preventing the remaining diffusely reflected light from reaching the spectroscopic analyzer. Furthermore, the specular control device may prevent the specularly reflected light (e.g. surface reflected light) from reaching the spectroscopic analyzer.

Abstract: Methods and apparatus for non-invasive tissue urea concentrations during or subsequent to hemodialysis using near-infrared spectroscopy are discussed. Near-infrared tissue spectra can be obtained by projecting near-infrared radiation into skin on the underside of human forearms and capturing the light reflected back and out through the tissue. An index matching medium is used to couple the tissue to the analyzer. The tissue spectrum collected preferably includes primarily diffuse reflected light reflected from the inner dermis. Multiple tissue spectra of known urea concentration are used to build a model from which the urea concentration of an unknown sample can be devised. The model is based on a partial least squares algorithm applied to multiple tissue scans and concomitant blood sample urea measurements. This model is then applied to an unknown tissue spectra.

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 method and apparatus for diffuse reflectance spectroscopy. A specular control device is provided that can discriminate between diffusely reflected light that is reflected from selected depths or layers within the tissue. The specular control device permits a spectroscopic analyzer to receive the diffusely reflected light that is reflected from, for example, a first layer or depth within the tissue, while preventing the remaining diffusely reflected light from reaching the spectroscopic analyzer. Furthermore, the specular control device may prevent the specularly reflected light (e.g. surface reflected light) from reaching the spectroscopic analyzer.