【摘要】 我们提出一种用阵元面加权压缩旁瓣的方法,理论计算和实验结果表明:这种方法简单。应用这种方法,可以使阵列的旁瓣降低到-26db以下。与主机配合,能够获得2～3mm的横向分辨率。 本文叙述了这一方法的原理和压缩旁瓣的实验结果,给出了用阵元面加权换能器进行相控扫描所获得的人体器官切面图象和横向分辨率照片。与未加权的换能器相比,图象清晰度和横向分辨率都有所提高。更多还原

【Abstract】 <ABSTRACT>The problem of side-lobes compression is quite important in an ultrosonic scanning system of phased array used in medicine.The existence of side-lobes may reduce the signal-noise ratio and blur or distort the image,and even give rise to a false target, so measures must be adopted to compress the side-lobes.At present, the measures of electronic focussing are always adoqted in medicine to get the side-lobes in the near field to be close to or coincide with the main lobe. But the problem of compressing the side-lobes in the zone beyond the focal area and the problem of compressing the receiving side-lobes haven’t been resolved completely yet. In acoustics the so-called : amplitude-weighing is, in essence, to compress the side-lobes by controll ing the distribution of the sensitivity of the array elements by: means of electronic technic for the purpose of improving the directivity. Now we present a method of compressing the side-lobes by controlling the distribution of the sensitivity by weighting of element area.Using such a method, we have overcome ;not only the difficulty ,of the. symmetrical arrangement of the element sensitivity in the amplitude weighting but also avoided the troubles in circuit compensation. Both the experimental resultand theoretical analysis have shown that such a method of element area weighting is effective not only for compressing of The transmitting side-lobes but also for compressing of the receiving ones; The side-lobes can be red uced lower than-26db, and in combination with the main unit,a lateral resolution of 2-3 ( mm ) can be obtained.In this paper,the principles and the experimental results in compressing the side-lobes are described.The section images of human organs and photos showing lateral resolution taken in phased scanning by a transducer of weighted area of .elements are also given in this paper. In comparison with a transducer of not-weighted areas.The clarity of the images and the lateral resolution are increased.更多还原