En-face Full Field Optical Coherence Tomography for fast and efficient fingerprints acquisition

Optical coherence tomography (OCT) has been recently proposed by a number of laboratories as a promising tool for fingerprints acquisitions and for fakes discrimination. Indeed OCT being a non-contact, non-destructive optical method that virtually sections the volume of biological tissues that strongly scatter light it appears obvious to use it for fingerprints. Nevertheless most of the OCT setups have to go through the long acquisition of a full 3D image to isolate an "en-face" image suitable for fingerprint analysis. A few "en-face" OCT approaches have been proposed that use either a complex 2D scanning setup and image processing, or a full-field illumination using a camera and a spatially coherent source that induces crosstalks and degrades the image quality. We show here that Full Field OCT (FFOCT) using a spatially incoherent source is able to provide "en-face" high quality optical sectioning of the fingers skin. Indeed such approach shows a unique spatial resolution able to reveal a number of morphological details of fingerprints that are not seen with competing OCT setups. In particular the cellular structure of the stratum corneum and the epidermis-dermis interface appear clearly. We describe our high-resolution (1 micrometer, isotropic) setup and show our first design to get a large field of view while keeping a good sectioning ability of about 3 micrometers. We display the results obtained using these two setups for fingerprints examination.