Nearfield description of focusedunfocused transducers and transducerlens systems
Abstract
An algorithm is developed for calculating the field of focused ultrasonic transducers and transducerlens systems in the Fresnel approximation. The approach is based on expanding the sound field in terms of GaussianLaguerre functions. The structure of the sound field depends largely on the ratio of the focal length to a squared/lambda, where a is the radius of a circular transducer and lambda is the ultrasound wavelength. By placing the transducer one focal distance from the lens, one finds the greatest uniformity in the field for a given focal length. The calculations are for a uniform velocity distribution on the transducer, but the algorithm can be modified to accept other distributions.
 Publication:

12th Symposium on Nondestructive Evaluation
 Pub Date:
 1979
 Bibcode:
 1979syne.proc..202C
 Keywords:

 Lenses;
 Nondestructive Tests;
 Ultrasonic Flaw Detection;
 Ultrasonic Wave Transducers;
 Algorithms;
 Focusing;
 Fresnel Integrals;
 Geometrical Optics;
 Near Fields;
 Instrumentation and Photography