玻璃层下指纹的高频超声成像

分层介质结构中,各层声阻抗的差异很大,层间材料常常存在较高的声衰减和频散特性,普通超声的扫描图像较难反映出介质的层间结构信息。对高频超声波透过水和玻璃层后进入模拟人体指纹形状的树脂介质中的传播特性进行分析,使用高频超声换能器,以C扫描的方式激发与采集分层介质中的超声波宽频谱信号,得到时域波形数据,然后通过传播理论得到波形特征,使用特定时域峰值成像算法提取出玻璃层下的界面特征信息,从而得到高成像精度指纹的超声检测图像。

High Frequency Ultrasonic Imaging for Fingerprint Under Glass Layer

The acoustic impedance of each layer in the multilayer media structure varies greatly. The interlayer materials are often have characteristics of high acoustic attenuation and frequency dispersion. The general ultrasound scanning images are not sufficient to determine the structural information between layers. In this paper, the propagation characteristics of high frequency ultrasonic waves entering the resin medium simulating human fingerprint after passing through the water and glass layers are analyzed. The high frequency ultrasonic transducer is used to stimulate and collect the ultrasonic signals with wide spectrum in the multilayer medium by C-scan to gain the time domain waveform data. By virtue of the waveform characteristics obtained by the propagation theory, the characteristic information of the interface under the glass layer is extracted by using a specific time domain peak imaging algorithm, thereby obtaining a high precision ultrasonic image for fingerprint under glass layer.