Model human epidermal samples are used for transmission measurements at varying ambient humidity. Light is used from four different light emitting diodes (LEDs), of UVA wavelength of 365nm, and three visible wavelengths of 460nm, 500nm, and 595nm. A humidity-controlled chamber was used to house the samples while transmission measurements were taken. Many different types of measurements were taken, including raising ambient humidity from 20% to 75% then adding 0.5mL of water to the sample; lowering humidity from near 100% to 60%; and alternately raising and lowering of the ambient humidity. The results show higher transmission of light through the samples at very high ambient humidity, about 100%; whereas the transmission is much lower at lower ambient humidity. A simple model of epidermis as a turbid medium and reduced light scattering by refractive index matching is used to explain the results. Implications of these results are discussed.

Date Published: 5 September 2014
PDF: 7 pages
Proc. SPIE 9205, Reflection, Scattering, and Diffraction from Surfaces IV, 92050W (5 September 2014); doi: 10.1117/12.2062154

Published in SPIE Proceedings Vol. 9205:
Reflection, Scattering, and Diffraction from Surfaces IV
Leonard M. Hanssen, Editor(s)