Live scan fingerprint imagery using high resolution C-scan ultrasonography

High-frequency ultrasound is proposed as a means for performing live scan fingerprint imagery. Fundamental ultrasonic imaging concepts and their relationship to imaging the ridge structure of the finger are discussed. The ability to obtain an image of the fingerprint using ultrasound is based on the acoustical impedance difference between human tissue (i.e., a ridge) and air (i.e., a valley). This acoustic impedance difference is sufficient to affect the amount of acoustic energy returned to the receiver, thereby allowing a grey scale image of the fingerprint to be produced. Experimental results are given and an architecture for a prototype fingerprint reader is presented. Images obtained using the prototype reader are also presented. The feasibility of using high-resolution ultrasound to obtain fingerprint images directly from fingers is demonstrated.