Novel Radiation Device for Application in the UV-A and UV-B Range

This work concerns an ultraviolet-A (UV-A) and UV-B emitting radiation unit. To this end, UV-A emitting light emitting diodes (LEDs) were combined with a Lu3Al5O12:Gd3+ (LuAG:Gd) coated Xe excimer discharge lamp. Prior to the application, the single-phase phosphor was optimized w.r.t particle size distribution and reflection spectrum before the photoluminescence properties were recorded. It turned out that LuAG:Gd is an intense emitting material in the UV-B spectral range. Afterwards, a phosphor paint was made and applied with an up-flush technique to a fused silica tube to create a uniform coating. For the excimer lamp a high voltage pulse generator in flyback topology was developed which allows to adjust the UV-B output from 1% to 100% without affecting the lamp efficiency. To maximize the UV output power the pulse width, pulse amplitude as well as the duty cycle of lamp was tuned. At last the complete set up was measured in front of an BaSO4 coated integrating sphere to record the radiation pattern and to show the scalability of the UV-A LEDs and UV-B excimer lamp. Overall, a fully adjustable and versatile radiation device for medical treatment, photochemistry and tanning purposes was engineered which could be an alternative to (coated) mercury discharge lamps and UV-B LEDs.