IEC 62127-2:2007/AMD2:2017

IEC 62127-2 ®
Edition 1.0 2017-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 2
AM ENDEMENT 2
Ultrasonics – Hydrophones –
Part 2: Calibration for ultrasonic fields up to 40 MHz

Ultrasons – Hydrophones –
Partie 2: Etalonnage des champs ultrasoniques jusqu’à 40 MHz

IEC 62127-2:2007-08/AMD2:2017-03(en-fr)

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IEC 62127-2 ®
Edition 1.0 2017-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 2
AM ENDEMENT 2
Ultrasonics – Hydrophones –
Part 2: Calibration for ultrasonic fields up to 40 MHz

Ultrasons – Hydrophones –
Partie 2: Etalonnage des champs ultrasoniques jusqu’à 40 MHz

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.140.50 ISBN 978-2-8322-3904-9

– 2 – IEC 62127-2:2007/AMD2:2017
© IEC 2017
FOREWORD
This amendment has been prepared by IEC technical committee 87: Ultrasonics.
The text of this amendment is based on the following documents:
CDV Report on voting
87/612/CDV 87/639/RVC
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC website under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
_____________
2 Normative references
Add the following new reference:
IEC 61689, Ultrasonics – Physiotherapy systems – Field specifications and methods of
measurement in the frequency range 0,5 MHz to 5 MHz
3 Terms, definitions and symbols
3.26
derived instantaneous intensity
(added by Amendment 1)
Delete the following text below the term:
"approximation of the instantaneous intensity"
Replace the existing four lines before Equation (1) by the following:
quotient of squared instantaneous acoustic pressure and characteristic acoustic impedance of
the medium at a particular instant in time at a particular point in an acoustic field

© IEC 2017
4 List of symbols
Replace:
ρc specific acoustic impedance
by
ρc characteristic acoustic impedance of the measurement liquid (water)
Add the following new symbols:
d distance between the auxiliary transducer and the reflector measured along the axis of
symmetry
d distance between the auxiliary transducer and the active element of the hydrophone
h
measured along the axis of symmetry
d distance between the auxiliary transducer and the last minimum of the acoustic
m
pressure amplitude along the axis of symmetry of the auxiliary transducer
R amplitude reflection coefficient for the reflector/water interface
RT
Z characteristic acoustic impedance of the reflector
RT
J reciprocity coefficient for plane waves
p
*
S apparent transmitting current response of an auxiliary transducer
t
*
M apparent receiving voltage response of an auxiliary transducer
t
p acoustic pressure generated by a transducer at its surface
a
p acoustic pressure incident on a transducer surface
i
p acoustic pressure incident on the hydrophone surface
h
I transmitting current driven to a transducer
t
U voltage generated by a transducer in the receiving mode
t
G correction that accounts for the diffraction in the propagation field and is related to the
th
waveform generation by the transducer and the reception by the hydrophone
G correction that accounts for the diffraction in the propagation field and is related to the
tt
generation and the reception by the transducer
U voltage measured with the transducer coupled to the system
load
I current measured over a short circuit jumper replacing the transducer
sc
9 Free field reciprocity calibration
9.1 General
Replace the existing text by the following:
This clause specifies the primary reference measurement procedure (see JCGM 200:2012,
2.8 [79]) calibration of hydrophones under free field conditions using the principle of
reciprocity.
Add the following new note:
NOTE The free field condition can be achieved in a confined water space by following any of a variety of
measurement procedures, such as with the use of tone-burst (time-gated sine wave – see 10.5.3), time-delay
spectrometry [63, 68], frequency modulated chirp [80, 81] or other techniques [82].

– 4 – IEC 62127-2:2007/AMD2:2017
© IEC 2017
9.4 Two-transducer reciprocity calibration method
9.4.1 Apparatus
Replace the existing subclause title and text by the following:
9.4.1 Auxiliary transducers
Circularly plane piston auxiliary transducers should be used to generate the ultrasonic field in
the frequency range of interest, limited to the maximum range between 1 MHz and 15 MHz.
The effective radiation area (A ) shall be determined, according to IEC 61689, for each
ER
transducer and at all frequencies the transducer is intended to be used. If a frequency
modulated chirp is to be used as excitation signal, the A shall be determined at least in the
ER
minimum, maximum and one intermediate frequency in the range of interest.
The position of the last minimum of acoustic pressure amplitude along the axis of symmetry,
d , shall be determined with an uncertainty not larger than 1 mm. It shall be done as an on-
m
axis line scan, according to IEC 61689, at the same frequencies the A was determined. The
ER
near field distance produced by the auxiliary transducer is defined as N = a /λ, where λ is
1 t
the ultrasonic wavelength in water at the frequency of operation and a = 2λd +λ is the
t m
effective radius of the ultrasonic transducer.
NOTE Focusing auxiliary transducers can be used, but several corrections need to be applied, and this document
is only intended for plane-piston transducers. A detailed implementation of a reciprocity-based calibration method
using focusing transducers can be found in [84].
The effective radiation area (A ) is used in the equations of Annex K to properly assess the
ER
diffraction correction and the reciprocity coefficient for plane waves, whilst the last minimum
) is used to indirectly define the near
of pressure amplitude along the axis of symmetry (d
m
field distance (N ), being N = (2λd + λ )/λ. Although both quantities A and d are directly
1 1 m ER m
linked for ideal transducers, both shall be determined experimentally according to IEC 61689.
9.4.2 Procedure
Replace the existing subclause title and text by the following:
9.4.2 Reflector
The reflector should comprise a flat surface whose smallest linear dimension shall be at least
four times the effective radius of the ultrasonic transducer a . The reflector shall also be flat to
t
±10 μm, with a surface finish good to ±5 μm (surface roughness: R < 5 μm; R < 5 μm;
v p
R < 1 μm). The thickness of the reflector shall be such that the first reflection from the rear
a
surface will not interfere with that directly from the front surface for any of the excitation
signals to be used. Special attention shall be given for long burst or low-rate frequency
modulated chirps, mainly at the lowest frequencies of interest.
The amplitude reflection coefficient for the reflector/water interface R shall be
RT
experimentally determined, for instance by the relation R = (Z – ρc)/(Z + ρc), were ρc
RT RT RT
is the characteristic acoustic impedance of the water and Z is the characteristic acoustic
RT
impedance of the reflector.
NOTE R is the maximum valley depth, R is the maximum peak height and R is the arithmetic average
v p a
describing the reflector profile roughness amplitude parameters.
Add the following new subclauses:
9.4.3 Measurement field
As both the auxiliary transducer and the hydrophone have finite apertures, a diffraction
pattern is present in the ultrasonic field. To minimize uncertainties due to the analytical or

© IEC 2017
numerical corrections to be applied to the measurement quantities, the nearest measurement
shall be performed at least at 0,9 × N , and the furthest distance shall not be larger than
2,2 × N . Water-air surface and tank walls shall be far enough from the ultrasonic path such
that any reflected waveform will not interfere with the direct waveform at the measurement
spot.
If any structure is too close to the direct ultrasonic waveform path, it shall be covered with
absorbing lining to minimize the interference with the measurement signal, and concern about
that interference shall be included in the uncertainty budget.
9.4.4 Reciprocity approach
Reciprocity can be established as a primary hydrophone calibration method provided some
practical and theoretical details are adopted. Annex K depicts the fund
...