Methods and apparatuses for the determination of an attribute of the tissue of an individual use non-invasive
Raman spectroscopy. For example, the
alcohol concentration in the
blood or tissue of an individual can be determined non-invasively. A portion of the tissue is illuminated with light, the light propagates into the tissue where it is Raman scattered within the tissue. The Raman
scattered light is then detected and can be combined with a model relating Raman spectra to
alcohol concentration in order to determine the
alcohol concentration in the
blood or tissue of the individual. Correction techniques can be used to reduce determination errors due to detection of light other than that from
Raman scattering from the alcohol in the tissue. Other biologic information can be used in combination with the Raman
spectral properties to aid in the determination of alcohol concentration, for example age of the individual, height of the individual, weight of the individual,
medical history of the individual and his / her family, ethnicity,
skin melanin content, or a combination thereof. The method and apparatus can be highly optimized to provide reproducible and, preferably, uniform
radiance of the tissue, low
tissue sampling error, depth targeting of the tissue
layers or sample locations that contain the attribute of interest, efficient collection of Raman spectra from the tissue, high optical
throughput, high photometric accuracy,
large dynamic range, excellent
thermal stability, effective calibration maintenance, effective calibration transfer, built-in
quality control, and ease-of-use.