Four methods for characterizing ultrasonic transducers are reviewed. These methods have been or are being developed at the National Bureau of Standards (NBS) for characterizing the performance of ultrasonic devices operating into a water load. The nominal frequency range for the methods considered here is 0.5 to 30 MHz, which corresponds to devices used in nondestructive testing, medicine, and animal science. The principles upon which these methods are based are electrical measurements related to the equivalent circuit of a quartz transducer, a thermal equivalent calorimetric method, a measurement of total radiation force, and an electroacoustic method involving sampling the acoustic field of a directive device. It is helpful to thoroughly understand the physical theory which applies to each measurement method so that appropriate methods can be developed and analyzed for errors or uncertainties. Studies of errors and their basis constitute an important part of measurement science or “metrology,” and metrology is a principal interest of the National Bureau of Standards. Consistent with this interest, and to provide continuity among the measured quantities, linear and second-order acoustic relationships are tabulated in terms of the pressure and particle-velocity variables for lossless fluids. This provides an outline which interrelates measured quantities and suggests other derived quantities, or measurements, that may also be of interest. A formally economical method for obtaining such nonlinear acoustic relationships is outlined briefly in the Appendix. This provides the basis for the brief analyses which pertain to the radiation force method and to the scanning technique in the body of the paper. Aspects of the treatment of radiation force appear to be novel. References are given which relate to more fundamental theory and to more extensive intercomparison of methods and consideration of errors. © 1979, IEEE. All rights reserved. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.
