渐进式频率-波数域全聚焦超声成像

为了提高全聚焦超声成像的质量和速度,提出了渐进式频率波数域全聚焦超声成像方法（GTFM-FW）。首先通过逐次激励超声相控阵各阵元并全孔径采集回波,得到全矩阵数据;然后通过傅里叶变换将全矩阵数据中的一组或多组对角线数据变换到频率波数域,对各组对角线数据的变换结果进行对齐并叠加;最后利用Stolt变换和二维逆傅里叶变换得到全聚焦成像结果。为了验证算法的有效性,对仿真点目标以及试块进行了详细成像实验。结果表明:本文方法可以通过改变全矩阵数据的使用量来实现成像分辨率与旁瓣干扰间的折中。并且由于采用频率波数域处理,在成像分辨率优于传统全聚焦成像算法的情况下,运算量大大降低。 

Gradual total focusing method ultrasonic imaging in frequency-wavenumber domain

In order to improve the speed and quality of total focusing method,a Gradual Total Focusing Method ultrasonic imaging in Frequency-Wavenumber domain（GTFM-FW） is proposed.The method starts with a full-matrix capture by collecting the full aperture echo data preceded by sequentially activating each element on the ultrasonic transducer.The echo data located on one or multiple diagonals of the full matrix is selected and transformed to frequency-wavenumber domain spectrums by Fourier transform,which is then aligned and summed together.The final image is produced by a Stolt mapping and inverse Fourier transform.To verify the validity of this algorithm,detailed imaging experiments are performed both on simulated point targets and ultrasonic test blocks.The results show that the method proposed in this article enables imaging quality trade-off between image resolution and sidelobe interference by adjusting the proportion of full-matrix data used for imaging.Furthermore,the frequency-wavenumber approach yields better resolution performance than traditional total focusing method as well as lower computational cost.