Non-contact imaging of thermal properties of the skin.

Non-contact measurement of thermal properties of the skin was performed by using a thermovision camera and a mechanical system that provides a step change in ambient radiation temperature. A hood maintained at 20 degrees C was initially placed so as to cover the object surface towards which a thermovision camera was directed. Then the hood was quickly replaced by another hood maintained at 40 degrees C. Thermograms before, immediately after and 20 s after switching the hoods were taken. Then the image of emissivity was computed from thermograms taken before and immediately after hood switching, and the emissivity-corrected thermograms were computed by using the emissivity value obtained at each pixel. The images of the square root of the product of thermal conductivity, density and specific heat were computed from thermograms taken immediately after and 20 s after hood switching. While images of the emissivity obtained and the thermal parameter defined above contained significant noise, differences in these quantities between sites could be clearly demonstrated.