Extending detection reach with a new narrow bandpass filter

Fingerprints have been detected and photographed by fluorescence for four decades. The technique has required the use of a barrier filter, in most cases orange, to block the light source reflection and isolate fluorescence. In some cases, however, the substrate also exhibits fluorescence, which can partially or totally obscure the fingerprint. A new narrow bandpass filter, used in combination with the standard barrier filter, can add significantly to both the extent and clarity of inherently and chemically treated fluorescing fingerprints. Moreover, in certain borderline cases, the chemical solution alone may be insufficient, but tailored optics can save the situation by converting an otherwise useless stain to an identifiable impression.