The preparation of purified ScI₃ and ScI₃-Nal bi-component mixtures for use in metal halide lamps is described. The principles of controlled break-up of liquid jets are outlined, and applied to the preparation of precisely sized spheres of bi-component mixtures. Experimental optimization of the jet velocity and excitation frequency permit the attainment of high yields of precisely sized pellets. Lamp performance trials show much improved colour uniformity for lamps dosed with bi-component mixtures as compared to those dosed with individual components.

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In case a fluorescent discharge lamp radiates light by alternating current, the relation between the luminousity and the value and shaps of discharging current is not so simple. An appropriated cathode spot temperature would be attained easily by reasonable effective value of the lamp current only, having no relations with the shape of the current. But the luminousity of a fluorescent discharge lamp varies by the shape or the crest factor of the lamp current, and in general it would be well known that somewhat smaller value of a lamp current gives better value of luminous efficacy lm/W. The author tries to analize such phenomena in this paper. At first an experimental evidence shall be shown, when a fluorescent lamp is driven by DC current, the relation of luminousity vs lamp current is not linear but has a saturative nature, and it will give an experimental equation of luminousity vs lamp current. This experimental equation should be treated as a foundation of following calculations. The luminousity would be expressed as a function of instantaneous value of the lamp current. And the time mean of integlated luminousity gives the so called practical value of the luminousity. For example there shall be explained that when phase controlled lamp current which shows zero value area of phase angle is given to a lamp, it would give low value of luminousity even if the effective value of lamp current is increased up to equal or more than standard value of lamp current in the catalogue data.

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A method of evaluating effective irradiance is discussed for photoresist with the reciprocity law failure property irradiated by fluctuating radiation. The resultant formula for evaluating effective irradiance suggests that both reciprocity law failure and time response for the photochemical reaction should be considered when evaluating effective irradiance. This method is used in an irradiance meter which measures the distribution of near ultraviolet effective irradiance. This irradiance meter is applied to the photoresist exposure process in color TV picture tube fabrication. This meter automatically measures relative irradiance over 51 points on the phosphor screen of a color TV picture tube, in about 1 min. Reproducibility and accuracy for measured values are estimated to be about 0.2% and 1%, respectively. Absolute irradiance is measured at the center of the screen, with an accuracy of about 3%.

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We have tried to improve the spectral radiant characteristics of the metal halide lamps by controlling the arc temperature by means of an additional metal halide which emits almost no spectral lines in the visible range. This technique has been applied to two kinds of metal halide lamps, the red-colored lithium iodide lamp and the high color rendering thorium iodide lamp. The former has been improved in the purity of red color and the latter has been improved in color rendering property by the addition of aluminum iodide or lead iodide. In both lamps, the arc temperature is lowered, decreasing selectively the visible mercury atomic lines.

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A giant outdoor, full color display system has been developed, the display screen consisting of a matrix array of newly developed light emitting tubes. Each tube is a flood beam CRT, which works as a single picture element (one color), having a single red, green or blue phosphor. The tube is enveloped by a colored glass bulb, to maintain high contrast in bright daylight. It has many superior characteristics and features high color fidelity, low power consumption and long life. It is most suitable for outdoor color display.

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Luminous efficiencies obtained for a small test field of 2.3' showed a simple and narrow type of curve regardless of experimental methods, flicker photometry and heterochromatic brightness matching. Past available data of luminous efficiencies for small fields were collected from published papers and plotted together on one graph, from which a single curve was derived to represent the luminous efficiency function for point sources. The function resembled the CIE V(λ).

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Airport lights are installed in or around the runway in order to convey appropriate visual information to an approaching pilot. Such coloured lights as white, red, green or blue are used as appropriate to their functions as visual aids. The visual effectiveness of airport lights is a function of their colour, the background luminance (daytime, twilight or night) and the visibility. In the past, effectiveness has been investigated only at the visual threshold under clear visibility. For more precise and quicker pilot reaction during the actual approach phase, however, studies of the visual effect with far higher illuminance than visual threshold are required, furthermore the identification of lights under low visibility conditions must be taken into consideration. A fog chamber is used for this comparative analysis among 4 coloured light sources (white, red, yellow and green) with a 3-minute visual angle. As for visual effect levels, the 4 levels of illuminance at the observer’s eye using point sources are chosen, namely, illuminance threshold, chromatic threshold, optimum illuminance, and lower limit of glare. Each level is measured under various conditions background luminance and visibility. The following results were obtained from this study.
(1) Irrespective of fog condition, the illuminance required for each visual level increases as the background luminance increases. Larger increments are required after the background luminance exceeds 1 cd/m².
(2) Without fog in the chamber, the chromatic threshold of red is relatively low and that of green is comparativily high, while those of white and yellow fall between red and green. The ratios of optimum value to chromatic threshold for the 4 colours are 80 to 500 in dark background and those decrease as background luminance increases.
(3) With fog in the chamber, there are no remarkable differences relatively low chromatic thresholds. The ratios of optimum to chromatic threshold of the 4 colours are 15 to 40 in the dark.

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