Spectral Radiative Properties of Fibrous Materials in Visible and Near Infrared Regions

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In visible and near infrared wavelength regions, spectral radiative properties of fibrous material such as a carbon fiber sheet(CF-sheet), clothes of several kinds, a glass wool insulator and an aluminum fiber were measured and investigated from 1996 to 1998.The results obtained through measurements and analyses can be summarized as follows.1. Using the radiation transfer equation, directional spectral transmittance and a reflectance of the fibrous materials were estimate by given characteristics parameters of fibrous material such as diameter of fiber and its distribution, void ratio, optical constant and specimen thickness.2. The directional spectral transmittance and reflectance were measured with a goniometer and a multi-purpose spectroradiometer. The hemispherical spectral radiative properties of fibrous material were measured with an integrating sphere and the spectroradiometer.3. The calculated values and the measured values on the spectral properties of the fibrous materials were well agreements except the wavelength range a shorter than 0.35 mu m and a longer than 0.8 mum.4. The hemispherical properties measured with the integrating sphere and the hemispherical properties calculated from the data measured directional properties of the CF-sheet agreed well. But the hemispherical transmittance of single CF-sheet measured with the integrating sphere are greater than about two times the calculated values from the data of the directional transmittance measured.5. The influences of material and color on the hemispherical spectral properties of the clothes were evaluated by measured data with the integrating sphere.6. The spherical spectral transmittance and the reflectance of the glass wool insulators were measured. Absorptances of the glass wool insulator increase with increasing the specific gravity. The absorptances are nearly constant in range of specific gravity are greater than 48kg/m_3.