Using Near-Infrared Technique for Vein Imaging

Near-infrared (NIR) imaging technique has wide applications in biomedical field, in which the NIR vein image has considerably major benefits. NIR imaging allows visualizing the veins underneath the skin of patients having problem with vein visibility, mapping the normal and abnormal veins for diagnosis and treating. In addition, finger or palm vein recognition, as a highly secure and convenient technique of personal identification, has received increasing attention recently. In this study, NIR vein images of various parts of hand, including the finger, palm, wrist and arm were described using NIR imaging techniques in various modes such as transmission mode, reflection mode, and the combination of two mentioned modes. Wavelengths in the range of 750 to 940 nm, with low absorption window, provide higher contrast of vein imaging, which can be enhanced by use of crossed polarizers and neutral density filters to remove the glare from the skin surface. Finally, analysis and evaluation of advantages and disadvantages of these methods were presented.