High bright and white light emitting diodes(LEDs) were fabricated. White LEDs are the fourth color made for commercial use following blue, green and red. White LEDs typically have the efficacy of 10 lm/W and the color temperature of 3000K-10000K. This new technology was achieved by combining blue InGaN LED and YAG phosphor. Compared with incandescent lamps, advantages such as wide color variation, life beyond 10000hr, no burn-out, reduced sensitivity to variation and little heat generation are expected.

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Recently, it has been reported that the organic compounds such as dirt and odors can be decomposed by photocatalytic reaction of titanium oxide (TiO₂). In the daily use of lamps and luminaries, the accumulation of dirt often reduces a great amount of light output. We have developed a new type of fluorescent lamp coated with photocatalytic TiO₂ film to improve those problems on lighting. At first, we estimated the decomposition of cigarette dirt on the lamps coated with TiO₂ films. The loss rate of light output could be decreased to half by decomposition of dirt during operating. Furthermore, we investigated the change in concentration of acetaldehyde in sealed box during lighting. It was found that the lamp could deodorize the air in the box by decomposition. At the same time, UV radiation from the lamp were absorbed by TiO₂ films. Thus, it was found that the users could be provided with the comfortable environment by application of the photocatalytic reaction to the lighting systems.

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Characteristics of radiation from microcavities are investigated to verify the luminous efficacy of microcavity radiator that was estimated by John F. Waymouth in 1989. Electromagnetic waves in a rectangular microcavity and a cylindrical microcavity were analyzed based on the waveguide theory. The modes of electromagnetic waves in the microcavities are analyzed using a normalized eigenfunction. The conductivity and permittivity of metals are obtained by analyzing the motion equation of the free electron in the metals. The skin depth of tungsten is estimated with the emissivity of tungsten based on electromagnetic theory. Accordingly it is estimated that the luminous efficacy of radiation from the microcavity is expected to reach 118 lm/W.

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A new system of parametrisation defining exterior daylight changes was developed linking the real measured data with a new generation of sky standards. The concept of the sky standardisation with a simple change of gradation and indicatrix formulae is presented and some applications are demonstrated. The set of fifteen standard skies adopts also all existing CIE standards in a system covering the whole probable spectrum of skies existing world-wide while the importance and validity of any particular sky standard is to be decided in accordance with the local availability, occurrence frequency defined by cluster analysis as well as due to design needs and/or other reasons for a specific application. Thus either one critical sky standard can be applied e.g. in window design or glare studies or a chosen mixture of several standards can simulate the average or extreme, fluent or random changes of the exterior daylight climate e.g. in case of energy trade-off programs, when simulating reference month, season or year courses.

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This study intends to be a help for preparing design materials to ensure proper illuminance and work surface luminance taking into account the visual characteristics of workers. Experimental subjects were divided into two groups of the young and the aged from the point of sight characteristics to demonstrate differences in required lighting conditions to secure adequate legibility and brightness for both the young and aged groups. In addition, it is demonstrated that the effects of aging can be dealt with as the decrease in the visual acuity under uniform illumination at steady adaptation. Further, "Relative Acuity" is proposed so that visual acuity of workers can be assessed through the method of a legibility evaluation, of which conception is also presented based on the idea.

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When an interior space is illuminated non-uniformly, we perceive different levels of brightness. The strongly illuminated areas give a bright impression while the weakly illuminated areas give dark impression. In other words, the whole space is divided into several portions which have different levels of brightness. The purpose of this study is to estimate overall impression of brightness which is divided into such portions which have different brightness. Two experiments were carried out in this research to assess brightness of whole spaces those were illuminated non-uniformly. In the first experiment, luminance distribution images of an interior space were used as stimuli. In the second experiment, actual interior spaces of non-uniform lighting were used as stimuli. From these results, it could be concluded that the whole space that is illuminated non-uniformly is perceived darker than the space illuminated uniformly. The overall impression of brightness of the space that is illuminated non-uniformly could not explained on the basis of the quantitative average of the luminances. It could be corresponded with the psychological average of all portions’ brightness those were divided by the illumination level.

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This paper reports on the preliminary results of a series of experiments conducted to determine if the illuminances recommended, in Australia, for emergency evacuation lighting are sufficient for the detection of messages and for wayfinding by the aged. The stimulus for the work has been the increased lifeexpectancy and the number of people in aged care accommodation, now often large buildings and often multi-storey. The initial results indicate that the illuminances are a factor of ten too low and suggest that this should be considered when reviewing the emergency evacuation lighting standard.

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In an automatic inspection system, the improvement of image quality has a close relation with the detecting device and the inspected object. It is difficult to determine the relation among the detecting lens, the surface roughness, and the reflectance of inspected object by analytics or measuring methods. In this paper, the reflection characteristic of the inspected object in an automatic inspection system is studied by means of Monte Carlo (MC) method. The theoretical analysis and simulation results reveal as follows: if the inspected objects have the same reflectance and the same surface roughness, the number and the standard deviation of photon bundles are related to the radius of the lens and the shape of inspected object. A change in the specular reflectance has greater influence on the number of reflected photon bundles than that of the diffuse reflectance. However, with the increase of the surface roughness, the photon bundles received by the lens decrease, and the influence of the specular reflectance on the number of reflected photon bundles becomes similar in number to the diffuse reflectance.

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The chlorophyll fluorescence spectra of green plant leaves induced by a visible laser have strong emission peaks near 685 and 740nm. In order to examine the transverse distributions of the illuminating laser light and laser-induced chlorophyll fluorescence (687nm : F687 and 741nm : F741) within rice leaves, a micro-fluorescence imaging (MFI) system was devised using a microscope, a CCD camera with an image intensifier (I.I.), Ar⁺ lasers oscillating at 488 and 514.5nm, a He-Ne laser, an image processor, and a microcomputer. Transverse distributions of illuminated laser light and chlorophyll fluorescence in leaves, projected on the surface of rice leaves with different chlorophyll contents, were measured for laser lights with various wavelengths (488, 514.5, and 632.8nm). The distributions of light projected at 541.5 and 632.8nm were observed at a greater depth from the leaf surface than that projected at 488nm. The attenuation curve of the incident laser light in the mesophyll tissue was well approximated by an exponential function. As a result, the attenuation coefficient α for incident light of various wavelengths and of leaves of various chlorophyll contents could be determined. In order to examine the self-absorption from distributions of the chlorophyll fluorescence in leaves with different chlorophyll contents, the profiles of the F741/F687 ratio within the mesophyll tissue were measured at various wavelengths. The F741/F687 ratio increased in the case of light with a high chlorophyll absorption coefficient. We conclude that the MFI system is a useful method of study to select the spectral quality of light for plant irradiation.

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