Limited diffraction array beams

Limited diffraction beams have a large depth of field infinite aperture. Because of their high side lobes and complex and could have many applications. In this article, new limited diffracbeam patterns near the cone surface, these devices are not curtion beams are developed. They are composed of multiple parallel rently used in clinics. Ring antenna [42] or transducer [43,44] is beams and are thus called array beams. A broadband synthetic array another type of device that increases the depth of field. However, experiment is used to produce these beams of a finite aperture, and the depth of field is increased only in the far field of the rings results are in excellent agreement with theory over a large depth of [45,46] where beams diffract significantly. Near the surfaces of field. In addition, potential applications of the new beams to real-time the rings, beams do not even have a central peak. In addition, volumetric imaging and measurement of transverse velocity of blood ring devices have a low energy efficiency because they must be flow are described. q 1997 John Wiley & Sons, Inc. Int J Imaging Syst thin. Dynamic focusing [47] is another method to increase the Technol, 8, 126–136, 1997 depth of field, in which the focal length of a receiver increases