I reported on the acceptability dataset for color-differences in seven popular colors used in the ceramics tile industries. The performance of seven kinds of color-difference formulas was tested with this color-difference dataset using the just acceptable color-difference predicted by Probit analysis. I found that MLAB and NC-3C are significantly better than other formulas for acceptability dataset and a revision of the weighting between color-difference attributes for CIE94 and CIEDE2000 is necessary.
This paper describes a new-structure luminaire system with a xenon discharge lamp and a liquid crystal filter, that controls color temperature of illuminating light widely and continuously according to the voltage applied to the filter. We designed and fabricated a new optical filter by laminating two different types of liquid crystal devices, that individually decrease and increase color temperature of transmitted light by varying the spectral balance of incident light from the discharge lamp. Each liquid crystal device contains different dichroic dyes and absorbs short-or long-wavelength visible light. The degree of absorption can be varied by controlling the applied voltage. From the fundamental optical experiments, in which a high-pressure xenon discharge lamp of neutral color temperature of 5600K with almost flat radiation spectrum was combined with the liquid crystal filter mentioned above, we found that the color temperature of light radiated from the system can be varied from 3800K to 8200K. The presented luminaire system is especially useful for capturing video and photographic images and for appreciating art works when strict color temperature control is essential.
A method of determining the mercury transport coefficient in a small diameter discharge tube, used as a backlight lamp, has been developed using increase in light out-put after it is switched on. The diffusion coefficient of mercury in the phosphor-coated tube is about four times that in a clear i.e. non-phosphor-coated tube. The diffusion coefficient reduces as the tube diameter decreases. The absorption coefficient is negative just after the tube is switched on, and after that the value turns to positive.
A method is described for automatically detecting the optical axis using a genetic algorithm. The genetic approach was used to develop a basic model for automatically determining the parameters needed to adjust the optical axis. Application of this method to a model with two axes demonstrated that it is as accurate the conventional manual method.
The importance of urban landscape lighting has increased. In this study, by using the Semantic Differential Technique, we tried to analyze the effects and influence of urban landscape lighting that produces traditional landscapes. We also clarified the factor structure of an impression evaluation. We selected the cityscapes of Kanazawa as our model. From the results of a factor analysis for the traditional landscape, we identified four basic factors:“Evaluation”, Sensitivity, “Originality”, and “Refinement”. Moreover, we identified that “Originality” included the factor that was the evaluation scale of era. Also, we identified the factor structure, which is composed of two pair component factors: Evaluation/“Refinement” and “Originality”/“Sensitivity”. The nightscape's impression evaluation score was in most cases higher than the dayscape's.
The tungsten microcavity light source and the tungsten cluster light source have recently attracted interest as nextgeneration light sources that have a high luminous efficacy and a long lifetime. The complex index of refraction of tungsten requires a 2000 to 6500K operating temperature to evaluate the luminous efficacy and lifetime. Little is, known however, about the complex index of tungsten at such high temperatures. We consider that ellipsometry is an effective measuring method because it can measure complex index of refraction without metallic contact at these temperatures. We thus designed and fabricated an ellipsometer and used it to measure the complex index of refraction of tungsten at room temperature. As a result, we established that with an improved ellipsometer the complex index of refraction of tungsten could be measured at 2000-6500K. In this paper, we report on the problems of measuring metallic complex index of refraction precisely using ellipsometry and on the achieved measurement accuracy.