ANALYSIS OF THE NUMERICALLY IMPLEMENTED ANGULAR SPECTRUM APPROACH BASED ON THE EVALUATION OF 2-DIMENSIONAL ACOUSTIC FIELD .1.2. COMMENT

The aim of this Comment Is to show that, when the normal velocity of t he transducer is no longer constant, the algorithm that has been recen tly proposed by Wu et al. [J. Acoust. Sec. Am. 99, 1339-1348 for Part I and 1349-1359 for Part II (1996)] cannot eliminate aliasing nor remo ve the phase error in the angular spectrum. In fact, in recent article s, Wu ef al. proposed and used a new numerical algorithm for eliminati ng the aliasing in the spectrum, Moreover, they have shown that the ph ase error can be easily removed. In their investigation they used a pl anar transducer and linear array. To show the effectiveness of their a lgorithm, the normal velocity of the planar transducer or of the eleme ntary transducers (in the case of the array) has been supposed constan t. (C) 1997 Acoustical Society of America.