Beam forming in solids using monolithic ultrasonic arrays

Experimental and theoretical results are presented to show that monolithic arrays can be used to produce attractive beam characteristics of particular relevance to real-time nondestructive testing (NDT) applications and for defect imaging. Segmented annular and linear monolithic arrays can produce attractive beam profiles with small beamwidths and little or no sidelobe activity.However, the arrays exhibit significantly different steering characteristics as a result of the dissimilar directivity properties of the basic elements from which the arrays are constructed. Linear-array profiles exhibit a narrower beamwidth than the corresponding segmented annular-array profiles. This is due to the larger number of elements and the higher operating frequency of the linear array, rather than degraded performance of the segmented-annular array. Hence, no absolute comparison can be made