Latent fingerprint imaging by spectroscopic optical coherence tomography

Abstract

Optical coherence tomography (OCT) is a non-contact and non-invasive optical method for evaluating semitransparent and scattering objects. Its unique features, such as non-destructive 3D measurements of tested objects with a fast scanning rate, make this technique interesting for latent fingerprint reading, which is the subject of this paper. So far, OCT has not found widespread use for reading fingerprints directly from surfaces due to its insufficient axial resolution. This problem has been overcome by applying spectroscopic analysis to the OCT measurements, which is based on retrieving the spatially resolved spectral characteristics of the recorded backscattered light directly from the OCT measurement data. The spectroscopic analysis is very sensitive to thin film thickness variations, improving the readability of the latent fingerprints by OCT, which is reported here as well. This study includes a description of spectroscopic analysis in combination with OCT and indicates the benefits for thin film evaluation, in particular, latent fingerprints. The example of latent fingerprint OCT measurements enhanced by spectroscopic analysis has been shown, as well as a brief discussion of the method's applicability. Finally, improving fingerprint OCT imaging contrast and readability by applying spectroscopic analysis have been confirmed.