A tristimulus photoelectric colorimeter has been designed to measure the chromaticities of pyrotechnic smokes having highly saturated colors. To obtain a compact housing for three multiplier phototubes, “head-on” type (RCA 5819) phototubes are used. For high sensitivity and stability the photometric units are three Photovolt Multiplier Photometers, Model 520-M. To minimize edge effects and rear wall reflection, the smoke chamber was designed as a 36-inch cube. The chamber is illuminated by four 150-watt flood lamps placed to yield uniform illumination on the viewing window. Three filters were designed to approximate the daylight CIE standard observer functions for the source-filter-phototube combinations of the instrument. As the CIE and functions are unimodal, little difficulty was encountered in designing the filters to approximate these functions. The CIE function, which is bimodal, required a divided filter to approximate its two lobes. The filter constructed was composed of two sectors, one approximating the “blue lobe,” the other approximating the “red lobe,” of the function. Satisfactory results have been obtained with this colorimeter using Munsell papers as standards.
© 1954 Optical Society of AmericaFull Article | PDF Article
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