医用超声阵列换能器波束容差分析与变迹处理

Tolerance Analysis and Apodization Processing of Medical Utrasound Array Transducer Wave Beams

用指向性函数研究了医用超声阵列换能器在具有幅度误差、相位误差及阵元失效情况下的波束特性，提出并应用幅度加权变迹处理、相位变迹处理和孔径变迹处理方法来改善阵列换能器的波束指向性．计算结果表明：相位误差和高斯分布幅度误差使旁瓣增大、栅瓣增多、波束特性变差，它们对声场特性的影响由误差的大小及分布情况共同决定．幅度加权变迹处理和孔径变迹处理都可以有效地抑制旁瓣，改变指向性；一个恒定孔径发射，可变孔径接收超声阵列系统存在一个最佳接收孔径，此时旁瓣最小．这一结论对医学超声和工业超声等领域都具有重要应用价值．

The directivity function is used for determining the beamforming wave properties of ultrasound array for medical use. It is affected by efficacy loss of elements, amplitude and phase error distribution of array elements. A method is developed by combining amplitude weighting, phase and aperture apodization for improving beam patterns. The computed results show that (1) Phase error and Gauss distribution amplitude error give rise to larger sidelobes, more grating lobes and deteriorating beam quality whose effect to sound field properties was determined by error distribution. (2) Amplitude weighting and phase apodization processing can restrain sidelobes and improve the directivity effectively. (3) In an ultrasound array system with fixed transmitting aperture and changeable receiving aperture, there exists a best receiving aperture, at which sidelobes are the lowest. This conclusion is important to the medical and industrial application of ultrasonic.