OPTICAL DIFFUSE-REFLECTANCE ACCESSORY FOR MEASUREMENTS OF SKIN TISSUEBY NEAR-INFRARED SPECTROSCOPY

An optimized accessary for measuring the diffuse reflectance spectra o f human skin tissue in the near-infrared spectral range is presented. The device includes an on-axis ellipsoidal collecting mirror with effi cient illumination optics for small sampling areas of bulky body speci mens. The optical design is supported by the results of a Monte Carlo simulation study of the reflectance characteristics of skin tissue. Be cause the results evolved from efforts to measure blood glucose noninv asively, the main emphasis is placed on the long-wavelength near-infra red range where sufficient penetration depth for radiation into tissue is still available. The accessory is applied for in vivo diffuse refl ectance measurements.