Some transducer manufacturers have lead in the development of
transducer characterization techniques and have participated in
developing the AIUM Standard Methods for Testing Single-Element
Pulse-Echo Ultrasonic Transducers as well as ASTM-E 1065 Standard
Guide for Evaluating Characteristics of Ultrasonic Search Units.
Additionally, some manufacturers perform characterizations according
to AWS, ESI, and many other industrial and military standards.
Often, equipment in test labs is maintained in compliance with
MIL-C-45662A Calibration System Requirements. As part of the documentation
process, an extensive database containing records of the waveform
and spectrum of each transducer is maintained and can be accessed
for comparative or statistical studies of transducer characteristics.
Manufacturers often provide time and frequency domain plots for
each transducer. The signals below were generated by a spiked
pulser. The waveform image on the left shows the test response
signal in the time domain (amplitude versus time). The spectrum
image on the right shows the same signal in the frequency domain
(amplitude versus frequency). The signal path is usually a reflection
from the back wall (fused silica) with the reflection in the far
field of the transducer.
Other tests may include the following:
- Electrical Impedance Plots provide important information
about the design and construction of a transducer and can allow
users to obtain electrically similar transducers from multiple
- Beam Alignment Measurements provide data on the degree
of alignment between the sound beam axis and the transducer
housing. This information is particularly useful in applications
that require a high degree of certainty regarding beam positioning
with respect to a mechanical reference surface.
- Beam Profiles provide valuable information about transducer
sound field characteristics. Transverse beam profiles are created
by scanning the transducer across a target (usually either a
steel ball or rod) at a given distance from the transducer face
and are used to determine focal spot size and beam symmetry.
Axial beam profiles are created by recording the pulse-echo
amplitude of the sound field as a function of distance from
the transducer face and provide data on depth of field and focal