A capillary discharge tube has been used for background lighting of liquid crystal displays and gaseous lasers. In these optical devices, the luminance and spectral characteristics play a very important role and usually depend on discharge conditions such as the tube radius, gas pressures, discharge currents, and the gases used. Furthermore, the optical characteristics of a gas mixture behave in a different manner from those of pure gases. Therefore, it is important to investigate the optical characteristics of gas mixtures for various discharge conditions. In this paper, measurement has been made of the fundamental optical properties of gas mixtures in a cylindrical capillary discharge tube. The gases used were mixtures of He-Ne, He-Ar, and Ne-Ar. The tube used in the measurements was 1 mm in diameter. The discharge current was 20 mA, while gas pressures were varied from 0.2 to 20.0 Torr. The results of the measurements are qualitatively discussed.

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This paper describes the developmental process of new prismatic panel for lighting fixture which satisfies both high efficiency and diffusion ability. Concretely, the result of improved opal panel for high efficiency and diffusion ability, the theory of accomplishing high diffusion ability by prismatic panel, the process of selecting prismatic element, the simulation of luminance of prismatic panel by inverse-ray tracing method and the specification of surface-mounted fluorescent lighting fixture applied with this prismatic panel are reported. The prismatic element is lozenge-shaped, with a length of 5.0 mm, a width of 2.9 mm and a height of 2.2 mm. The light which goes to the prismatic element just under the lamp is totally reflected at the internal prismatic surface, consequently apparent luminance of lamp through the panel is reduced. While the light which goes to the prismatic element between lamps is refracted downward, so luminance of panel between lamps is increased. Applying this prismatic panel, very thin surface-mounted fluorescent fixture has been developed.

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Lighting for streets should be designed in such a way that pedestrians on the street at night are able to identify the general characteristics of "other" persons still some distance away on the road. The illuminance level to be provided had been investigated experimentally in the laboratory by utilizing a lighting simulator. In the experiments, observations were repeated by 3 observers, 10 times each, for 30 different lighting conditions. As a result, a value of 2 lux for the vertical illuminance on the "other" person’s face has been obtained as the minimum value that allows pedestrians to identify "other" persons at a distance of 4 metres (whether he/she is an acquaitance or a stranger).

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