ZnS electroluminescent lamps calibrated for use as standard light sources.

Ceramic panelescent lamps of different colors have been investigated and calibrated as standard light sources for testing of potomultiplier equipment. Intensity and spectrum changes with voltage, frequency, and temperature have been studied. Inhomogeneities in the surface brightness have also been investigated. By use of a stabilized power supply very stable sources are obtained. For long term stability the most critical parameter is the working temperature of the lamp.