The production of an isotropic source or detector by fixing a small resin sphere onto one end of an optical fibre is discussed. The potential application of these fibres to Photochemotherapy is reviewed. Isotropic fibres are used as both sources and detectors in experiments designed to measure the amount of light loss in a 1% solution of Neutralipid (an intravenous nutrient supply). Determination of light loss in this solution is important in one application of Photochemotherapy where an estimate of the irradiation time is required. / Thesis / Master of Science (MSc)