Fluorescence optimisation and lifetime studies of fingerprints treated with magnetic powders.

Fluorescence study plays a significant role in fingerprint detection when conventional chemical enhancement methods fail. The basic properties of fluorescence emission such as colour, intensity and lifetime could be well exploited in the detection of latent fingerprints under steady state and in dynamic methods. This paper describes a systematic study of fluorescence emission intensity from fingerprint samples treated with different magnetic powders. Understanding of suitable excitation wavelength required for getting maximum fluorescence emission intensity could be beneficial when selecting the appropriate fluorescent powders for the fingerprint detection. Lifetime study of fingerprints treated with various magnetic powders was also carried out. The importance of lifetime study is well explained through the time-resolved (TR) imaging of fingerprints with nanosecond resolution. Results from the TR imaging study revealed an improvement in the fingerprint image contrast. This is significant when the print is deposited on fluorescing background and its emission wavelength is close to that of treated fingerprint.