Spectral Transmittance and Reflectance of Excised Human Skin

Using the absolute method of goniometric spectrophotometry, the diffuse reflectance and transmittance of excised white and Negro skin have been measured in the spectral region 0.55–2.4 μ. Skin specimens were obtained fresh and maintained hydrated in cold moist chambers during experimentation. Skin thicknesses from 0.3 to 2.0 mm were studied for each skin specimen. Complete goniometric summations of the transmitted and reflected energy were made at wavelengths 0.55, 0.70, 0.95, 1.23, 1.68 and 2.20 μ. Computations of absorption coefficients for the skin were made for each of these wavelengths. Intermediate values were obtained by interpolation. In the spectral range of wavelengths 1–2.4 μ, white and Negro skin have essentially the same optical characteristics. Except for absorption due to water content and scattering, skin appears to be almost nonabsorbing in this region. In the spectral range 0.55–1 μ, skin pigments alter the optical characteristics of the skin by increasing the absorptance of radiation in the most superficial layers. Submitted on February 8, 1956