An experiment has been done to validate the accuracy of the silicon photodiode self-calibration technique using white light, based on the theoretical analysis already reported. The photometric responsivity [A/lm] of two types of silicon photodiodes, four each, were determined by measuring the surface reflectance and the recombination losses of each photodiode using white light, and compared with the responsivity [A/lm] determined by the conventional self-calibration technique using monochromatic light of several wavelengths in the visible region. The responsivity values determined by both methods agreed within a 0.2% difference. These calibrated photodiodes were then combined with V (λ) filters whose spectral transmittance was measured, and four photometric standard detectors were made. The luminous intensity values of an incandescent lamp, measured by the four detectors incorporating either type of self-calibrated photodiodes, agreed within a 0.6% difference.
The studies of whiteness have been so far done for the object mode color. This article deals with whiteness of a light source color. The psychological content of the whiteness was defined as the perceptual preference of white. It was found that perceptual brightness and colorlessness contributed to perceptual whiteness and that the perceptual brightness depended on the chromaticities of light sources only if the range of luminance was relatively small. In this experiment, the perceptual colorless point was calculated in the uniform color space and the degree of the perceptual colorlessness was defined as the distance from this point. The whitenessformula for light source color was developed by multiple regression analysis.
Recently, computer simulations of photometric performance of luminaires have improved, resulting in more suitable lighting. However, due to some approximations in the modeling of optical systems, the simulations have a restricted application, their applications are limited to quadric or rational surfaces. We have solved these problems by developing a new computer simulation system for three dimensional optical systems. This paper presents the method of simulation and validates it. To simulate an optical system which has an asymmetric shape, we have developed a ray-tracing method for parametric surfaces. Every geometric shape of an optical system can be transformed into parametric surfaces and can be analyzed by this system. It is efficient to express an optical system as parametric surfaces, in the aspect of computation time and accuracy and data imput time for simulation. This method can analyze optical systems which are intended to be nonquadric or which must be non-quadric for manufacturing reasons. To verify the validity of this method, we made some experiments. Luminous distribution by simulation agrees with the result of measurement.
A super high power HPS lamp with 50kW of input, 8000klm of output and 1601m/W of efficiency has been developed. The key to success is the reduction of sodium vapor pressure, which compensates, for the geometrical increase of absorption by a layer of cooler sodium vapor. Spectral measurements on larger diameter tubes suggest that in the condition of optimum efficiency, the charcteristics are similar to those of conventional HPS lamps up to 1kW. The measurements also imply differences such as lower arc core temperature, which decreases visible efficiency, and a relative increase of molecular radiation. The effect of a longer arc tube, such as efficiency and distribution of self reversed D line width along the tube length are also examined. Further development was tried by increasing Xe pressure with decreasing starting voltage helped by a starting aid. With the increase of the Xe pressure, efficiency steadily increased and finally reached 1751 m/W. Proper positioning of the starting aid proved to reduce the starting voltage effectively. This lamp serves commercially for photosynthesis of Nylon-6.
It is very useful to study brightness of airport light system under low visibility condition to analyze how much light is scattered by the atmospheric particles. In this paper a simulation program was produced to analyze the space distribution of scattered light by a Monte Carlo method, based on the scattering properties of a single particle as calculated by Mie theory. This program does not set a limit to the position of scattering particles, and can take account of not only the influence of visibility but also that of the distribution of particle size and the wavelength of light. By using the program, the variation of luminance distribution with visibility, observation position, etc. was investigated from the viewpoint of a pilot looking at the airport and its surroundings during approach. This result shows that additional luminance due to the scattering of the airport light may have an influence on brightness of airport light in the night and twilight. It also shows that calculated value by means of this simulation technique is not perfectly equal to that of Koschmieder formula for additional luminance by the scattering of daylight. The distribution of particle size has a great influence on the scattering of airport light. On the other side, it does not have a great influence on the scattering of daylight.
The properties of spatial summation by the eyes at suprathreshold levels are not clearly understood. An experiment on the brightness of a test stimulus as a function of its area and background luminance was carried out to clarify the properties. The luminous intensity of the test stimulus to match a point stimulus in brightness was measured. The results are as follows: (1) The spatial summation is complete regardless of the background luminance for an area of less than 10min2. It becomes gradually less complete as the area is more than 10min2. As background luminance increases, the effect of the spatial summation decreases, and little summation occurs for an area of more than 103 min2 at background luminance of 1cd/m2 and 10cd/m2. (2) The range of partial summation at suprathreshold levels is wider than that at threshold levels. (3) Log (It/Im) increases linearly with log (Lb). (4) It is necessary to treat a light as a surface source to obtain the brightness, in the case that we observe a traffic signal light from a short distance.
In recent years, the effect of far infrared radiation on water characteristics have drawn a strong attention. It is well known that this effect improves the flavor of food and beverage, and also keeps freshness of food. In the measurements of the water clusters using 17O-nuclear magnetic resonance (17O-NMR), it was observed that the line width of the water oxygen signal narrowed. This result implies that the hydrogen bond may have been broken because of the increase in the molecular degree of freedom, resulting in smaller water cluster and faster molecular movement. At present, however, the changes of water clusters caused by infrared heating have not been clearly understood. The objective of this research is to clarify the effect of infrared radiation on water clusters by means of 12MHz 17O-NMR. In this experiment, only slight changes of water cluster were recognized under infrared heating. It was found, therefore, that the effect of infrared radiation on water clusters was much smaller than expected, and that the molecular degree of water depended on the potential of hydrogen: pH.