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FORWARD SCATTERING PROPERTIES OF HUMAN EPIDERMAL LAYERS
Author(s) -
Bruls Wiel A. G.,
Van Der Leun Jan C.
Publication year - 1984
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1984.tb04581.x
Subject(s) - stratum corneum , scattering , wavelength , radiation , collimated light , optics , epidermis (zoology) , materials science , light scattering , perpendicular , penetration (warfare) , molecular physics , anisotropy , absorption (acoustics) , penetration depth , chemistry , laser , physics , anatomy , medicine , geometry , mathematics , pathology , operations research , engineering
From an optical point of view the outermost skin layers contain numerous structures by which penetrating radiation may be scattered as well as absorbed. The nature and strength of this scattering may strongly influence the extent of penetration. We illuminated samples of stratum corneum and full‐thickness epidermis with collimated radiation and measured the angular intensity distribution of the transmitted radiation; we did this in the ultraviolet for several angles of incidence, and in the visible for perpendicular incidence only. Skin samples were obtained from the skin of the lower back and upper leg of Caucasian volunteers. Epidermis and subsequently stratum corneum were separated by chemical methods. In the case of stratum corneum, the angular intensity distribution of the transmitted radiation peaks strongly at all wavelengths, in approximately the direction of the incident radiation, that has been refracted at the surface of the sample. With full‐thickness epidermis, the distribution of the transmitted radiation also peaks, though less strongly than with stratum corneum. These features suggest a forward oriented scattering mechanism. Both in the case of stratum corneum and full‐thickness epidermis, the angular distribution flattens towards the shorter wavelengths and with increasing thickness. The wavelength dependence suggests that both scattering and absorption increase towards the shorter wavelengths. The existence of a thickness dependence indicates that volume scattering occurs. Hydration of stratum corneum is found to influence its scattering properties. Dry samples scatter less than hydrated samples. The consequences of our findings for modelling skin optics are briefly discussed.