Journal of Light
&
Visual Environment

Volume 26 Number 1, March 2002

CONTENTS

Papers

English Abstracts

The luminance distribution of surfaces plays an important role to perceive the closed space correctly and to ensure a visual comfort. Therefore, the luminance arrangement of the interior surfaces must always be harmonious with the architectural design of interior. The necessary luminance arrangement of the interior surfaces, however, can be set by control of illuminance distribution on these surfaces. To control the illuminance level and distribution, the choice of lamp and the reflector design should be carried out according to the properties of plane/surface that will be illuminated, such as distance and dimension. In other words, the light of a lamp should be redirected to control the illumination on a plane with a "certain distance and dimension". Faceted reflector is a kind of reflector used to control the illuminance distribution. The traditional approach for designing a faceted reflector is to radiate the light reflected from each reflector element into the angle with the same magnitude. In this study, a successive approach which is useful in the design of faceted reflector is proposed. Geometric constructions of faceted reflectors have been examined by the aim of redirecting the reflected light from each facet of reflector on a plane in a certain distance and dimension. To evaluate different approaches, examples of reflectors are designed according to both traditional and proposed approach and the simulation results of some of the properties of these reflectors are compared. Also, according to the proposed approach, application examples for various conditions are formed and the results are examined.

New types of light-controllable luminaires using a metal halide lamp or a xenon lamp with a liquid crystal light shutter have been developed and demonstrated for spot or beam spot lighting of television program production. We fabricated a novel liquid crystal light shutter using a heat-resistant composite film of polymer and liquid crystal materials with a wide range of operating temperatures up to 150 ¤¹. The light shutter can modulate a strong luminous flux from the high-intensity discharge lamps, instead of a conventional mechanical shutter which has problems such as generating acoustic noise and being slow and heavy. The light modulation of the light shutter is based on a light scattering effect and the degree of scattering is controlled by the voltage applied to the shutter. It exhibits attractive features such as high transmittance, high-speed response, and high extinction ratio. The luminous intensity of an object could be varied continuously using the luminaries with the shutter, and the chromaticity deviation was drastically decreased by driving it with pulse width modulation.
KEYWORDS: spot luminaire, liquid crystal light shutter, high-intensity discharge lamp,chromaticity

The author fabricated a plain type thermal radiation detector with evaporating gold-black as the surface absorbent attached to a thermoelectric detector. The spectral responsivity of the thermal radiation detector under different evaporating conditions was investigated and the best condition for the highest degree of spectral responsivity is reported. The relative spectral responsivity of the thermal radiation detector with gold-black absorber against the thickness of the gold-black was explained with proposed plain type models. In the proposed plain type models, incident radiant energy is absorbed near the surface and transmitted through the gold-black absorber as heat. There were two kinds of the proposed plain type models, one was called the lumped constant model and the other was called the distribution constant model. Each model has two types. The best proposed model to fit the measured results was the distribution constant model 2, which contained reflection at the interface of the absorber and the PVDF pyroelectric film. To attain a very sensitive thermal radiation detector with constant spectral responsivity, which is constant within ¤}1% over a measured wavelength region, conical cavity type detectors were fabricated. Experimental samples were made to study the dependence of the effective reflectance of a conical cavity type thermal radiation detector on reflectance of the absorbent on the cone and the cone apex. The decrease in the effective reflectance for a conical cavity type was explained using a proposed conical cavity type model, which contains the first reflection, and the second repeated mutual reflections.
KEYWORDS: thermal radiation detector, absorptance, reflectance, conical cavity, model, spectral responsivity

One recently apparent trend in increasing traffic accidents in Japan is the increase in nighttime accidents. To address this problem, various traffic safety measures have been introduced aiming at safer road traffic environments. Among these measures, road lighting, in particular 'local lighting' has been introduced in an increasing number as a countermeasure against nighttime accidents. However, in terms of number of fatal accidents by road profile, the 'at intersection' accounts for the largest portion of the fatalities. Therefore, a more effective intersection lighting measure must be studied.
This paper discusses the illuminance levels expected for intersection lighting from the viewpoint of traffic accident reduction effect and reports the review result. The means used in reviewing were accident data before and after introduction of accident countermeasure and statistical analysis. It was learned from the result of these review works that an average road surface illuminance at intersections maintained at 20 lx or higher, as a level expected for intersection lighting, can provide the effect of accident countermeasure, and that an average road surface illuminance of 30 lx can further positively develop a statistically significant result as to reduction in traffic accidents.
KEYWORDS:road lighting, traffic accident, intersection

As an application of dielectric barrier discharge(DBD) lamps, vacuum-ultraviolet(VUV) exposure systems of both Ar2* and Kr2* excimers have been developed and their basic performance has been evaluated. Each system comprises a 20-W DBD excimer lamp, a sinusoidal wave high-voltage power supply, and a cylindrical lamp holder. A high-voltage transformer and a lamp are designed to be set as close together as possible in the holder. The inside of the holder is purged and filled with nitrogen gas when it is in use. The excimer lamp has an MgF2 window at the lamp end and is a "head-on type" lamp. The head-on type Ar2* excimer VUV system produced monochromatic light at 127 nm (with a 9.8-nm FWHM). It's irradiance had an almost homogeneous distribution within a 15-mm diameter planar circle at 50 mm from the output window and was about 0.4 mW/cm2. The head-on type Kr2* excimer VUV system produced monochromatic light at 147 nm (with a 13.2-nm FWHM). It's irradiance had an almost homogeneous distribution within a 15-mm diameter planar circle at 50 mm from the output window and was about 1.4 mW/cm2. The lifetime of the lamps in these system is defined as the time point at which irradiance drops to 50% of its initial value. It was 500 and 1500 h, respectively, for the Ar2* and Kr2* excimer lamps.
KEYWORDS : Ar2* excimer, Kr2* excimer, excimer lamp, exposure system, dielectric barrier discharge, vaccume ultraviolet