A Standard Source of Ultraviolet Radiation for Calibrating Photoelectric Dosage Intensity Meters

The advantages and disadvantages of sources emitting either a continuous or a discontinuous spectrum are considered in connection with the use of such lamps as a standard of ultraviolet radiation. It is shown that because of the high intensity and favorable distribution of the ultraviolet emission lines at 2967 to 3132 A, the quartz mercury-arc lamp is well adapted for standardizing photoelectric ultraviolet dosage intensity meters in absolute units. A description is given of the installation of a commercial lID-volt vertical quartz mercury Uviarc lamp, and of methods of calibrating its ultraviolet output in absolute units. By calibrating photoelectric ultraviolet intensity meters against a laboratory standard, a great reduction is effected in equipment required for field measurements of ultraviolet solar radiation. CONTENTS Page