Portable low-coherence holography creates 3D fingerprint images

Compact, easy-to-align interferometric setups using common-path, low- coherence interferometry can obtain nondestructive thickness measurements with subnanometer accuracy. The low-cost, simplified, and noise-reduced low-coherence interferometric imaging system has been designed, which can produce accurate depth profiles of fingerprints and be operated by common users. A tilted beamsplitter has been positioned in the output of the imaging system, which acts as a single-element interferometer. This common-path design is less sensitive to environmental noise factors such as mechanical vibrations and temperature fluctuations, as the object and reference beams propagate together. The tilted positioning of the beamsplitter also enables dual-channel imaging of two phase-shifted interferograms using a single camera.