This study examines lighting design plans and the subsequent evaluation of the case of Kokura Castle and the peripheral area in Kitakyushu that was chosen as one of Japan’s New Three Most Spectacular Night Views. A social experiment was conducted, analyzed, and evaluated. Then, on the basis of the results, plans for a nightscape for the future were presented. Kitakyushu city developed guidelines for private companies that plan to execute the lighting designs. The guidelines state that urban development should first consider visitors’ perspectives and the lighting designs should be conducted carefully as each facility is an important “point” element. From the social experiment conducted at Kokura Castle and the peripheral area, it is clear that two things are present; Intent of Restriction, which is directly connected to the implementation of lighting plans, and Methods of Restriction, which suppress direct effects on the peripheral area. The results of Visual Thinking Strategies demonstrate that participants could fully understand the intent of the designer. Additionally, it is clear that people expect a high artistic quality in the lighting effects. For implementations of lighting designs, it is necessary not only to have the Intent of Restriction, which considers the structures of buildings and investigations of the surrounding environmental factors, but also to have a logical sensitivity philosophy that captures the stories behind places.

LED lighting technology has been advancing quite rapidly. The luminance distribution in LED floodlights is assumed to differ from that of high-intensity discharge (HID) floodlights. However, measuring the luminance of LED floodlights is difficult because of their high luminance and narrow beam. The purpose of this study was to clarify the problems with the luminance measurement of floodlights using digital cameras.

The modulation transfer function (MTF) characteristics of seven different camera systems were obtained, and the luminance distribution of different types of LED floodlights was measured using four different camera systems. The luminance distribution of the LED floodlights measured using by the camera systems with different MTFs showed different values of luminance. The results show that a higher resolution does not necessarily mean a better MTF is maintained. Identifying the MTF characteristics of the camera system is important to determine the accuracy of the luminance distribution measured with the system.

Consideration of nonlinearity properties of array-spectroradiometers is important in the fields of photometry, radiometry, and colorimetry. The nonlinearity properties of two commercial array-spectroradiometers were investigated, and the maximum nonlinear behavior of 24 % was observed. The errors in the measurement of chromaticity coordinates (x, y) by these array-spectroradiometers due to the nonlinearity were investigated using three white light sources based on light emitting diodes and laser diodes. It was found that 24 % nonlinearity caused the change of chromaticity coordinates up to 0.018. Correction of a spectroradiometer with respect to the nonlinearity would enable us to obtain accurate colorimetric data for light sources.

Low-pressure mercury–argon torus plasma generated in an inductively coupled fluorescent lamp was investigated. The temporal characteristics of the torus plasma from the ignition stage to the stable stage were analyzed by applying the transformer model. The power transfer efficiency was found to be over 90%, and the coupling coefficient was around 0.75. The current density and the electric field strength of the torus plasma were comparable to those of the positive column of a conventional fluorescent lamp. The finite element method was used to analyze the relative electron density distribution in the plasma. The absolute density profile of the electron was estimated by combining the average electron density experimentally determined with the calculated filling factor of the electron. The maximum electron density estimated was around 1.5×10¹² cm^－3 in the steady state, nearly equal to that experimentally determined by the double probe. The discharge took about one hour to reach the steady state. This can be explained by the mercury transport from the amalgam, which was fixed at the tip of a long, narrow glass tube that penetrated the excitation coil to the discharge vessel. The analysis technique presented in this paper is useful to explain the temporal characteristics of inductive torus plasma as well as the interaction between the plasma and the excitation coil.

Many studies on the effects of LED on living organisms have been performed recently thanks to the ease and precision with which the power and wavelength of the LED can be regulated. To investigate the effects of LED irradiation on Drosophila activity, we monitored the locomotive activity of Drosophila for six days continuously. The data showed that wild-type flies behave similarly under fluorescent light, incandescent bulb, and white LED irradiation, which is equivalent to the intensity of an incandescent bulb. We next investigated the effects of red, blue, and yellow-green LED irradiation under same intensity as white LED on the locomotive activity of a wild-type fly and a Drosophila model of autism spectrum disorder (ASD). The results showed that the amount of locomotive activity in the wild-type flies with red LED irradiation was significantly increased throughout the day (excluding morning peaks) while that with blue LED irradiation was decreased in evening peaks and at nighttime. Yellow-green LED irradiation increased the locomotive activity during the midday siesta but decreased the activity of the morning and evening peaks.

It is known that the rugose (rg) mutant, the Drosophila homolog of human Neurobeachin, shows locomotive hyperactivity. In our study, the red LED irradiation did not affect the locomotive activity of the rg mutant at all. Taken together with the effects of red LED irradiation to the wild-type, it seems that red LED irradiation enhances the neural circuit to positively regulate the locomotive activity, and rg functions in the neuronal cells by negatively regulating the neural circuit enhanced by red LED irradiation. Thus, the neuronal cells expressing the rg gene appear to play an important role for the regulation of activity during the midday siesta and while sleeping at night. In contrast, irradiation with yellow-green and blue LED to the rg mutant had similar effects to those of the wild-type. This demonstrates that irradiation with yellow-green and blue LED negatively regulates the locomotive activity through the neural circuit not related to rg, or downstream of the neural circuit actively regulated by red LED irradiation.

Lighting design is a wide-ranging field, that requires specialized knowledge. Recently, the importance of nightscape lighting has been increasing due to safety concerns as well as cultural demands. Many cities have created nightscape lighting guidelines tailored to their specific climate and weather, aiming for positive nightscapes. However, there are many unsolved problems regarding the production and application of guidelines. In order to gain insight into the problems seen in previous cases, we will review the social experiments conducted by a private entity in a city in Miyazaki Prefecture. Through this process, we will find a new method of creating city nightscape lighting guidelines and we will indicate the importance of “Lemma Lighting” by applying the “signifiers” concept.