| 摘要 |
An ultrasonic system and method for imaging a surface wherein a C-mode ultrasonic scan is performed over a fixed area of the surface and range gating is applied to that area to a given depth below the surface. For use of the system and method in fingerprint imaging, a live finger is placed upon a sensitive surface, the portion of the finger on the surface is scanned using the ultrasonic energy, and ultrasonic energy returned from the finger portion is received and converted into spatial frequency components to determine the pattern of ridges and valleys of the fingerprint. The ultrasonic imaging system comprises a probe for providing a directed output ultrasonic beam to scan the surface and to receive ultrasonic echos from the surface, a pulser-receiver to cause the probe to provide the output beam and to provide signals in response to the returned ultrasonic echos, a signal processing circuit for detecting and processing return echo signals from the pulser-receiver and a computer for storing and displaying information contained in signals from the processing circuit and for controlling operation of the processing circuit. The probe scans the surface along one direction, and then along another direction, the two directions preferably being orthogonal.
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