偏光による紙の反射特性の測定

抄録

An apparatus has been devised with which scattered flux of light from surface of paper is decomposed into specular and diffuse components. The incident light is plane polarized and the scattered flux is passed through a rotating polaroid sector, a polaroid analyzer and directed to a photomultiplier generating A. C. signals which are amplified, rectified and indicated. The indicator is set to zero reading by turning the analyzer to an angle A which, when the electric vector of the incident polarized light is perpendicular to the plane of incidence, is given by D/M=sin 2A-l, where D and M are specular and diffuse components respectively. The polaroid sector and analyzer are then removed and goniophotometric measurement enables the resolution of the scattered light into specular and diffuse components by the above equation.
The following results are obtained.
1. A fairly satisfactory conclusion is arrived at by assuming that the specular component remains polarized with unchanged plane of polarization and that the diffuse component is completely depolarized.
2. The diffuse component from coated paper follows Lambert's law but that from uncoated paper does not.
3. The specular component does not follow Fresnel's formula due probably to the fact that the reflection from paper is not explained by geometrical optics alone which makes Barkas' analysis not applicable to paper in general.
4. In some cases, the angle of maximum intensity of reflection is not equal to the angle of incidence which is explainable if the diffuse component and both relative area and reflection coefficient of mirror facets are considered.