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    Moisture effect of fingerprint using total internal reflection digital in-line holography
    (2014-01-01)
    Plaipichit, Suwan
    ;
    Buranasiri, Prathan
    Total internal reflection (TIR) is normally important in an optical fingerprint scanner. The moisture effect in a fingerprint scanner based on TIR has been explored by using digital in-line holography (DIH). First, the reflection and the transmission technique set up for DIH have been explored by using a positive resolution test target with a line width of 200 μm. From experimental results, the reconstructed image of the reflected DIH is perfect as the image of the transmitted DIH. Due to the advantage for opaque object imaging of the reflected DIH, reflected DIH based on TIR has been selected to investigate the moisture effect of the fingerprint. Fingerprints with moistures of 39%, 54%, 69%, and a soaked finger have been observed. A laser diode of 635 nm and a complementary metal oxide semiconductor camera were used in all of the experimental setups in this research. The reconstructed image of the fingerprint gives a sharper image than the directed recorded image. The fingerprint with higher moisture provided a darker fingerprint image, while the optimum amount of moisture that gives the most complete finger pattern is 54%. © 2014 Society of Photo-Optical Instrumentation Engineers.
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    Fingerprint verification by using low coherence digital holography
    (2013-09-18)
    Plaipichit, S.
    ;
    Atta, P.
    ;
    Buranasiri, P.
    ;
    Ruttanapun, C.
    ;
    Jindajitawat, P.
    In this paper, we have proposed the novel prototype of the portable fingerprint scanner. Using this method, the low coherence digital holography technique has been used to verify fingerprints. In our experiment, the Michelson's interferometer has been setup first for determining the coherence length of a laser diode with wave length of 635 nm. In our model, the light transmission and reflection properties of the glass slide have been applied. Then, the glass slide has been used as a beam splitter for separating the light to two beams, which are the reference beam and fingerprint image bearing beam. The results show fingerprint pattern, which are reconstructed with numerical method. © 2013 SPIE.