Dual-channel low-coherence interferometry and its application to quantitative phase imaging of fingerprints

H. Gabai and N. T. Shaked

Abstract:

We introduce a low-coherence, dual channel and common-path interferometric imaging system for three dimensional imaging of fingerprints for  both biomedical and biomertical applications.The proposed system is simple to align, and requires no alignmet in order to obtain interference with low-coherence light source, thus enabling non-expert useres to benifit from the attractive advantages of low-coherence, common-path and dual-channel interferometry. In our case, we have used the dual-channel property in order to create a noise reduced and DC supressed equivalent hologram, from which we were able to derive a high quality, with nano-meter resolution depth profile of fingerprints

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The figure shows measurements of thick samples (up to 100 microns) using low-coherence, common-path, wide-field phase interferometry with two-wavelength unwrapping. (a) Two 180°-phase-shifted interferograms of a finger-print template, acquired simultaneously (dual imaging channel). The dashed white square indicates on the scar location. (b) Depth profile distorted by blurring (in blue). Significant distortion can be seen in the upper-right part of the image. (c) Final result with improved contrast obtained by using the two interferograms  to decrease noise. (d) Final result in three-dimensional view.
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