Apparatus for generating ultra violet light

Claim 1

Apparatus for providing a controlled light output in the ultra-violet range to provide an erythemal effect, comprising: lamp means for generating a generally continuous output for substantially the ultra-violet range, said lamp means comprising a housing having an opening at one end, at least one lamp mounted in said housing for transmitting light towards said opening, filter means connected to said housing over said opening for providing a filtered output from said lamp over a selected wave length range whereby the filtered output can be used to provide an erythemal effect, and calibration means separate from said lamp means for determining the intensity of the filtered output over said selected range, variable power supply means selectively actuable for varying the power to said lamp and hence for selectively controlling the intensity of the filtered output whereby the erythemal effect can be controlled, said lamp comprising a mercury vapor gas lamp with the gas doped with a small quantity of xenon being no greater than around four percent of the gas by volume, said lamp having closely spaced electrodes being spaced no greater than around 0.75 inch.