Phase-resolved fluorescence technique with heterodyne signal processing for imaging of latent fingerprints

摘要

This paper describes the formulation and implementation of signal processing and experimental details of a system incorporating the heterodyne concept with a phase-resolved fluorescence technique for the detection and separation of latent fingerprint fluorescence emission from background fluorescence. The excitation laser source and gain of the detection device, which are modulated at megahertz frequency, are employed together with a heterodyne signal processing technique to separate the fingerprint fluorescence from the background fluorescence. The method provides improved contrast of fingerprint ridges. Experiments have been carried out on fingerprints deposited on various surfaces.