Optical detection techniques and light delivery with UV LEDs and optical fibres

Following the recent introduction of AlGaN/GaN based ultraviolet Light Emitting Diodes (UV-LEDs) in the 250 nm to 350 nm wavelength region, a wide range of research activities have begun. For example, using the high levels of power of available UV-light, chemical reactions can be stimulated. However, when optical detection techniques are considered, light intensity and wavelength accuracy are more important to achieve low detection limits. Using LED-based light sources in the ultraviolet instead of the classical deuterium, xenon, mercury or metal halide sources is very attractive due to their high power conversion, relatively simple electronic driving circuitry and low power consumption. For both absorption and fluorescence detection, such LEDs and complete detection systems are powerful tools both traditional and new applications in the field and laboratory. In this work, the electrical and optical properties of these new UV-LEDs will be described. Further, the flexibility of using optical fibres for UV-light delivery will be discussed with respect to the available UV-wavelengths and UV-induced damage. To exemplify the potential of UV LEDs, a self correcting fibre optic detection system over the wavelength range 260 and 280 nm, based on such LEDs will be shown. Further, an overview discussing flexible optical fibre UV-light delivery systems will be given and applications for both will be considered.