The effective intensity of flashing lights has been calculated by using the Blondel-Rey-Douglas formula. However, the effective intensity calculated by using this formula can only be applied to the threshold in a dark background. Furthermore, the effective intensity of flashing lights in peripheral vision at the threshold level has not been clarified. Therefore, a visual experiment was conducted to obtain the threshold for flashing lights and steady lights in eccentricities of 1 degree, 5 degrees, and 10 degrees under a background luminance of 0.13 to 10 cd/m2. The results show the experimental values are higher than the Blondel-Rey-Douglas value under all conditions. The effective intensity calculating method for flashing lights in peripheral vision of the Blondel-Rey-Douglas formula with a revised visual time constant “a” was investigated.
In Japan, small tomatoes have high quality. Soluble solids content is a critical factor for palatability. A non-destructive method for determining the soluble solids content in larger tomatoes using near-infrared (NIR) spectroscopy has been developed. However, a new spectral measurement method was needed to measure different-sized tomatoes including very small fruits (less than about 10 g) using an instrument. The introduction of interactance-transimission mode may improve the efficiency of collecting light from the small tomatoes. Therefore, the objective of this study is to develop a new spectral measurement method for small tomatoes using NIR spectroscopy. Multiple linear regression (MLR) analysis of spectra (800-1000 nm) of tomatoes (numbers of samples (n) = 60) gave a calibration equation using 2nd derivative values of absorbance at 856, 876, 900, and 952 nm with a multiple correlation coefficient of 0.97. The MLR calibration was validated using other small tomato sample lots. Nevertheless, they were predicted well with a root mean square of 0.41 (n = 36).
To evaluate the performance of white LEDs as museum lighting, the authors have conducted research and reported on the effect of illuminance level and color temperature on textiles dyed with natural dyes. In this research, four additional white LEDs with various correlated color temperatures and different material constructions and three types of conventional fluorescent lamp were tested yellow textiles that were sensitive to light and ranked in the highly responsive category of the CIE Technical Report (CIE-157-2004) for blue and red dyes. The color degradation degree caused by white LEDs was almost larger than that caused by conventional NU fluorescent lamp. Among the white LEDs, the degradation degree was LED/D (7483K) > LED/UV+RGB (5265K) > LED/B+YAG (5098K) > LED/L (3633K). For the same illuminance level when the content of the 400-500 nm radiation became larger, the degradation degree became larger. When the correlated color temperature was the same, the degradation degree was larger with LED/UV+RGB than with LED/B+YAG. The acceleration degree of degradation differed depending on the LED construction (combination of LED chip and fluorescent material) . From these results, it can be determined that for introducing white LEDs to museum lighting, not only the annual maximum exposure but also the material construction (combination of LED chip and phosphor) should be considered.
To promote energy saving for office lighting, effective utilization of daylight illumination is necessary. It is very important to evaluate the brightness of a room taht is illuminated by both daylight and ceiling lamps. In this case, even if the average horizontal illuminance is kept constant, it is difficult to estimate the brightness perception of the room because of the very high intensity of daylight and the uneven distribution of light flux. In this paper, we investigated the effect of window size and intensity of daylight on the brightness perception of an office room with a window on one side. We examined the brightness perception and expressed it as a function of average horizontal illuminance attributed to the daylight and to the ceiling lamps.