An indirect skin emissivity measurement in the infrared thermal range through reflection of a CO$_{2}$ laser beam

C. Villaseñor-Mora, F.J. Sanchez-Marin, S. Calixto-Carrera


An indirect procedure to measure human skin emissivity is proposed. This
procedure uses a 10.6 $\mu $m CO$_{2}$ laser, to project a controlled energy
on the skin, and a power meter to measure the projected, reflected, emitted
and background energies. To eliminate the effects of background radiation,
two power measurements are taken: one of the skin and background emission
and another that includes the skin emission itself, the background radiation,
as well as the reflection of the laser beam by the skin. Those two
measurements are subtracted to obtain the reflected energy and, with this,
the corresponding reflectivity of the skin. With such subtraction,
background and other sources of noise are eliminated, and using the
Kirchhoff law the emissivity is calculated. The emissivity values obtained
with this procedure were corroborated using a theoretical blackbody. Both
methods give practically the same values, which validates our procedure.
In addition, our values are in accordance with those previously reported by
other researchers, but our procedure is simpler, faster and innocuous. An
additional contribution of this work is the analysis of the way the skin
reflects the infrared radiation, in the mid range. It was found that the
reflection of the skin is more specular than Lambertian, for the wavelength
that was used in this work.


Skin emissivity; skin reflection; skin reflectivity; emissivity without blackbody; Lambertian surfaces

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Revista Mexicana de Física

ISSN: 2683-2224 (on line), 0035-001X (print)

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