ABSTRACT
A forensic light source (FLS) is commonly used in the forensic setting to visualize evidence that may be difficult to detect with the naked eye. Fluorescence, phosphorescence, absorption, and reflection may all occur when evidence is illuminated with a light source creating contrast, thereby facilitating the recognition of evidentiary material. Many of the techniques used for ultraviolet (UV) and alternate light source (ALS) photography are similar and will be discussed in the same fashion. Documenting these findings, although challenging in the past where film cameras were used, is simplified with digital camera equipment. However, thorough knowledge of the camera equipment is essential. Because photography is being performed using narrow bands of light, the automatic focusing capabilities of the camera are not often usable. Documenting evidence under wavelength specific radiation often requires manual focusing with careful consideration for depth of field in the image. Additionally, working with narrow wavelengths of light means that exposure times will be much longer than usual. The use of a tripod or copy stand is often required under these conditions.
