1. Apparatus for producing ultraviolet radiation, particularly a quick-tanning sunlamp, comprising at least one source of substantially uniform ultraviolet radiation including at least five closely adjacent rod-shaped low-pressure mercury lamps; reflector means associated with said source and defining at least one exit opening for ultraviolet radiation, said reflector means including a discrete trough-shaped reflector for each of said lamps and each of said reflectors surrounding the respective lamp along an arc of at least 180.degree., said source and said reflector means being constructed and assembled to establish a high-density radiation field of predetermined area in the region of said exit opening and the heat output of said lamps being sufficiently low to insure that the temperature in the region of said field is within a range which is below the range of discomfort to a person exposed to said field; and means for intercepting at least the major percentage of wavelength bands of ultraviolet radiation below approximately 315 nm ahead of said field so that said field consists essentially of the remaining wavelength band of ultraviolet radiation.