Formulation and implementation of a phase-resolved fluorescence technique for latent-fingerprint imaging: theoretical and experimental analysis

摘要

A theoretical and experimental study of the imaging of latent fingerprints by a phase-resolved fluorescence techniques along with associated signal-processing analysis is described. The system configuration is optimized by incorporation of a novel approach of homodyne-assisted even-step phase shifting in a signal-processing concept. The excitation laser source and gain of the detection device, which are modulated at megahertz frequency followed by sensitive signal-processing concepts, are employed to separate the fingerprint fluorescence from background fluorescence. Experiments are carried out with fingerprints deposited upon different types of substrate surfaces. Later. a quantitative image-quality assessment is carried out, which confirms the improvement in the quality of the phase-resolved fingerprint image. Imaging of older fingerprints with better contrast is also carried out with the proposed novel technique. (C) 2005 Optical Society of America.