Non-contact skin emissivity: measurement from reflectance

Reference Title:Non-contact skin emissivity: measurement from reflectance using step change in ambient radiation temperature Citation: T Togawa 1989 Clin. Phys. Physiol. Meas. 10 39-48 doi: 10.1088/0143-0815/10/1/004

Article by T Togawa of Inst. for Med. & Dental Eng., Tokyo Med. & Dental Univ., Japan

Abstract.

A method of estimating skin emissivity based on reflectance measurement upon transient stepwise change in the ambient radiation temperature was proposed. To effect this change, two shades at different temperatures were switched mechanically, and the change in radiation from the skin surface was recorded through an aperture for each shade by a high-resolution, fast-response radiometer having a sensitivity the 8-14 mu m range. Measurements were made on the forehead, forearm, palm and back of the hand in 10 male and 10 female subjects. No significant differences in emissivity were observed among sites and between sexes. The overall average of the skin emissivity obtained was 0.971+or-0.005 (SD). This result is inconsistent with most reported skin emissivity values. However, as the former studies had many inherent inadequacies, both theoretical and experimental, it is considered that most of these reported skin emissivities are unacceptable. The method proposed in the study has the following advantages: (1) relative calibration between instruments in unnecessary, (2) noncontact measurement can be achieved, and (3) each measurement can be made within one minute.

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