Tamamushi iridescent fabrics were illuminated by means of a hemispheric diffuse illuminator devised by us, and their color luminance distributions were measured by means of a telescope. From the results obtained the optical properties of Tamamushi fabrics were discussed to find:
1) When Tamamushi fabrics are illuminated by means of the hemispheric diffuse illuminator (light source), their iridescent effect decreases.
2) When Tamamushi fabrics illuminated by the illuminator above-mentioned are measured of their color by the telescope with each interference filter, mixed color values due to both the warp and the filling are obtained at any receiving angle, though such values cannot be obtained by a goniophotometer.
3) When Tamamushi fabrics illuminated by the illuminator above-mentioned are measured of their luminance (reflective property) by the telescope with a filter, there is seen a different tendency between the luminance curves obtained in the warp direction and those in the filling direction, when the receiving angle is large. This is presumably because of the effect of the different surface structures and different colors in both directions.
4) When Tamamushi fabrics illuminated by the illuminator above-mentioned are measured of their color by the telescope with each interference filter, there is seen less difference in the measured values at different receiving angles than those by a parallel luminous flux (goniophotometer).
5) When the hemispheric diffuse illuminator is used together with the parallel luminous flux (goniophotometer), and if the former is larger in light quantity than the latter, there is seen no effect of the parallel luminous flux on the chromaticities measured.