Natl. Inst. of Standards and Technol., Rm. A 147, Bldg. 233, Gaithersburg, MD 20899
The diffraction correction factor for a transducer first acting as a transmitter and then receiving the signal reflected off a rigid plane is useful in determining the system transfer function of a pulse-echo system. The determination of the diffraction correction factor is well understood for flat disk transducers, but is more complex for focused transducers. Recently, a method was derived [Chen et al., ``Acoustic coupling from a focused transducer to a flat plate and back to the transducer,'' J. Acoust. Soc. Am. 95, 3049--3054 (1994)] for approximating the diffraction correction factor of a cylindrically focused transducer for the case when the rigid plane is close to the focal plane of the transducer. In this work, results are presented for cases when the rigid plane is not close to the focal plane of the reflector.