Experimental Determination of the Depth of Focus of Transducers Using Elliptical and Modified Parabolic Reflector Systems

Abstract

When operating in the near zone of a large aperture transducer, one must use a focusing technique to realize the far-field resolving power of the aperture. For many applications the depth of focus is an important consideration. Experimental data will be presented showing the beam width, minor-lobe suppression, and sensitivity as a function of range near the far focus of an elliptic reflector. Data for similar conditions will also be presented for parabolic reflectors with the focal element shifted to obtain optimum directivity conditions. (This work is supported by the Bureau of Ships.)