Thermographic imaging of the subcutaneous vascular network of the back of the hand for biometric identification

Access control systems require positive identification of authorised persons for entry to restricted facilities. Possession of a card by an authorised person has been the traditional approach to high security access control. These cards range from simple magnetic swipe cards through to proximity smart cards for identification. More recently, serious attempts have been made to identify appropriate biometric characteristics of individuals to provide positive identification. The more popular biometric access control techniques have included facial images, hand geometry, fingerprints and retina patterns. Also, the dynamics of keyboard input, handwritten signature and voice patterns have been reasonably successful in identifying authorised persons. This paper describes research that has been undertaken by the authors to use the subcutaneous vascular network (vein pattern) of the back of the hand as a unique personal biometric for identification. An outline will be given of a prototype low cost automatic thermographic imaging system which has been developed by the authors to obtain vein patterns for positive identification. The paper includes consideration of the image acquisition, image processing and vein pattern matching strategies. A summary of experimental results concerning the acceptance and rejection rates for the system is also provided.