Improving the effectiveness of fluorescence for the detection of semen stains on fabrics

The paper describes the use of the Polilight, a light source based on a xenon arc lamp, to exploit the fluorescence properties of semen as an aid to searching fabrics for stains in sexual assault cases. The broad excitation spectrum of semen allows the fluorescence to be generated at a range of wavelengths. This permits the excitation and emission conditions to be selected that minimize interference from background fluorescence of the fabric and thereby optimizes the contrast between the fabric and the stain. A common method for the observation of fluorescence is the use of colored plastic goggles or filters. The paper shows that the detection of fluorescence from semen stains is significantly enhanced using appropriate interference filters.