Development of Ultrasonic Finger Reader Based on Ultrasonic Holography Having Sensor Area with 80 mm Diameter

摘要

This paper describes finger reader, that generates a fingerprint image using ultrasonic waves travelling parallel to the sensor surface in concert with the principle of acoustic holography. The idea realized in this unit allows for the creation of devices based on thin plates of varying sizes, from smaller than a postage stamp, to the largest live scan applications that can be integrated with typical touch screens. The device is able to recognize the type of material that comes into contact with sensor surface, allowing it detect features consistent with living fingers and, therefore, differentiate between live and fake fingerprints. The sensitive sensor plate, or platen, used in the device can be constructed from a variety of different solid materials, such as glass and metals. The transducers are placed on the rim of the sensor plate The working principle of the device is based on the directions of ultrasound waves and not on pixels, hence the complexity of the device does not depend on the size of the sensitive area. Achievable resolution can be much higher than necessary for finger recognition. The device referenced in this presentation achieves resolution that is comparable to 1000 dpi.