Ultrasonics - Surgical systems - Measurement and declaration of the basic output characteristics

This standard specifies: - the essential non-thermal output characteristics of ultrasonic surgical units; - methods of measurement ot these output characteristics; - those characteristics which should be declared by the manufacturers of such equipment. This standard is applicable to equipment which meets the requirements of a, b and c below: a) ultrasonic surgical systems operating in the frequency range 20 kHz to 60 kHz; and b) ultrasonic surgical systems, whose use is the fragmentation or cutting of human tissue, whether or not those effects are delivered in conjunction with tissue removal or coagulation; and c) ultrasonic surgical systems, in which an acoustic wave is conducted by means of a specifically designed wave guide to deliver energy to the surgical site.

General Information

Status
Published
Publication Date
29-Jan-1998
Technical Committee
Current Stage
PPUB - Publication issued
Start Date
29-Jan-1998
Completion Date
29-Jan-1998
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INTERNATIONAL
IEC
STANDARD
61847
First edition
1998-01
Ultrasonics – Surgical systems –
Measurement and declaration of the basic
output characteristics
Ultrasons – Systèmes de chirurgie –
Mesure et déclaration des caractéristiques
de sortie
Reference number
CEI/IEC 61847:1998(E)
---------------------- Page: 1 ----------------------
Numbering

As from 1 January 1997 all IEC publications are issued with a designation in the 60000 series.

Consolidated publications

Consolidated versions of some IEC publications including amendments are available. For example, edition numbers

1.0, 1.1 and 1.2 refer, respectively, to the base publication, the base publication incorporating amendment 1 and

the base publication incorporating amendments 1 and 2.
Validity of this publication

The technical content of IEC publications is kept under constant review by the IEC, thus ensuring that the content

reflects current technology.

Information relating to the date of the reconfirmation of the publication is available in the IEC catalogue.

Information on the revision work, the issue of revised editions and amendments may be obtained from IEC National

Committees and from the following IEC sources:
• IEC Bulletin
• IEC Yearbook
On-line access*
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Published yearly with regular updates
(On-line access)*
Terminology, graphical and letter
symbols

For general terminology, readers are referred to IEC 60050: International Electrotechnical Vocabulary (IEV).

For graphical symbols, and letter symbols and signs approved by the IEC for general use, readers are referred to

publications IEC 60027: Letter symbols to be used in electrical technology, IEC 60417: Graphical symbols for use on

equipment. Index, survey and compilation of the single sheets and IEC 60617: Graphical symbols for diagrams.

IEC publications prepared by the same
technical committee

The attention of readers is drawn to the end pages of this publication which list the IEC publications issued by the

technical committee which has prepared the present publication.
* See web site address on title page.
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INTERNATIONAL
IEC
STANDARD
61847
First edition
1998-01
Ultrasonics – Surgical systems –
Measurement and declaration of the basic
output characteristics
Ultrasons – Systèmes de chirurgie –
Mesure et déclaration des caractéristiques
de sortie
 IEC 1998 Droits de reproduction réservés  Copyright - all rights reserved

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in

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procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in

copie et les microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.

International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
PRICE CODE V
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 3 ----------------------
– 2 – 61847 © IEC:1998 (E)
CONTENTS
Page

FOREWORD ................................................................................................................... 3

INTRODUCTION ............................................................................................................. 4

Clause

1 Scope ......................................................................................................................... 5

2 Normative references.................................................................................................. 5

3 Definitions................................................................................................................... 6

4 List of symbols............................................................................................................ 9

5 General measurement requirements............................................................................ 9

5.1 Operating conditions .......................................................................................... 9

5.2 Load conditions.................................................................................................. 9

5.3 Preparation for measurements ........................................................................... 10

6 Measurement procedures............................................................................................ 10

6.1 Primary tip vibration excursion ........................................................................... 10

6.2 Secondary tip vibration excursion ....................................................................... 11

6.3 Drive frequency.................................................................................................. 11

6.4 Tip vibration frequency....................................................................................... 11

6.5 Derived output acoustic power and output acoustic power .................................. 12

6.6 Directivity pattern............................................................................................... 13

6.7 Primary tip vibration excursion modulation.......................................................... 13

6.8 Duty cycle.......................................................................................................... 14

6.9 Quiescent electrical power ................................................................................. 14

6.10 Maximum electrical power.................................................................................. 14

6.11 Primary acoustic output area.............................................................................. 15

6.12 Secondary acoustic output area ......................................................................... 15

6.13 Power reserve index .......................................................................................... 15

7 Declaration of output characteristics............................................................................ 15

Figures............................................................................................................................ 16

Annexes

A Measurement methods and conditions......................................................................... 21

B Theory of operation of ultrasonic surgical devices........................................................ 26

C Bibliography................................................................................................................ 29

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61847 © IEC:1998 (E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
__________
ULTRASONICS – SURGICAL SYSTEMS –
Measurement and declaration of the basic output characteristics
FOREWORD

1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, the IEC publishes International Standards. Their preparation is

entrusted to technical committees; any IEC National Committee interested in the subject dealt with may

participate in this preparatory work. International, governmental and non-governmental organizations liaising

with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization

for Standardization (ISO) in accordance with conditions determined by agreement between the two

organizations.

2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an

international consensus of opinion on the relevant subjects since each technical committee has representation

from all interested National Committees.

3) The documents produced have the form of recommendations for international use and are published in the form

of standards, technical reports or guides and they are accepted by the National Committees in that sense.

4) In order to promote international unification, IEC National Committees undertake to apply IEC International

Standards transparently to the maximum extent possible in their national and regional standards. Any

divergence between the IEC Standard and the corresponding national or regional standard shall be clearly

indicated in the latter.

5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with one of its standards.

6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject

of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61847 has been prepared by IEC technical committee 87:

Ultrasonics.
The text of this standard is based on the following documents:
FDIS Report on voting
87/114/FDIS 87/117/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.
Annexes A, B and C are for information only.
In this standard the following print types are used:
– Requirements: in roman type
– Test specifications: in italic type
– Notes: in small roman type
– Words in bold in the text are defined in clause 3.
A bilingual version of this standard may be issued at a later date.
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– 4 – 61847 © IEC:1998 (E)
INTRODUCTION

Ultrasonic surgical systems, operating in the 20 kHz to 60 kHz range, are used widely in

ophthalmology and neurosurgery to fragment or disintegrate and aspirate unwanted tissue.

Their commercial use in ophthalmology started in 1970. Their application in neurosurgery

followed about 10 years later. Ultrasonic surgical systems are also widely used in oncology

surgery.

This International Standard defines the parameters which characterize the output and

performance of open and closed site ultrasonic surgical systems, and indicates which

parameters should be declared. In addition, measurement procedures are described so that

technically qualified people will be able to report on the parameters in a uniform and

understandable fashion. An open surgical site is one in which the incision is large relative to

the size of the applicator tip being inserted thus precluding any increase in pressure of the

organ due to an imbalance of irrigant flow and suction flow. An example of a closed surgical

site is an eye where the incision is closely controlled.

This International Standard does not provide any guidance on what is the resultant safety or

efficacy of devices described by these parameters since very little scientifically controlled data

are available by which such judgements can be made.
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61847 © IEC:1998 (E) – 5 –
ULTRASONICS – SURGICAL SYSTEMS –
Measurement and declaration of the basic output characteristics
1 Scope
This International Standard specifies:
– the essential non-thermal output characteristics of ultrasonic surgical units;

NOTE 1 – One of the parameters of interest is output acoustic power. This standard addresses only the low-

frequency (under 100 kHz) component of the total delivered energy. The high-frequency component, which probably

relates to cavitation developed at the tip, is not addressed (see A.4).
– methods of measurement of these output characteristics;

– those characteristics which should be declared by the manufacturers of such equipment.

NOTE 2 – In the interest of clarity, this standard does not address all of the complex surfaces and shapes possible

for applicator tips. A straight tubular shape is used in the description of the parameters and measurements to be

made. It is left to the user of this standard to adapt the basic methodology described to more complex designs if

required.

This International Standard is applicable to equipment which meets the requirements of a, b

and c below:

a) ultrasonic surgical systems operating in the frequency range 20 kHz to 60 kHz; and

b) ultrasonic surgical systems, whose use is the fragmentation or cutting of human tissue,

whether or not those effects are delivered in conjunction with tissue removal or coagulation;

and

c) ultrasonic surgical systems, in which an acoustic wave is conducted by means of a

specifically designed wave guide to deliver energy to the surgical site.

NOTE 3 – Examples of these types of systems are surgical aspirators, intracorporeal lithotripters, end-cutting

devices etc.
This International Standard is not applicable to:

– lithotripsy equipment which uses extracorporeally induced pressure pulses, focussed

through liquid conducting media and the soft tissues of the body;

– surgical devices used as part of the therapeutic process (hyperthermia systems);

– surgical devices whose acoustic application areas are not at the end of a longitudinally

vibrating applicator tip and therefore would not fit the monopole model used in this standard.

This International Standard does not deal with the effectiveness or safety of ultrasonic surgical

systems.

NOTE 4 – Throughout this standard, the term accuracy means the overall uncertainty expressed at the 95 %

confidence level.
2 Normative references

The following normative documents contain provisions which, through reference in this text,

constitute provisions of this International Standard. At the time of publication, the editions

indicated were valid. All normative documents are subject to revision, and parties to

agreements based on this International Standard are encouraged to investigate the possibility

of applying the most recent editions of the normative documents indicated below. Members of

IEC and ISO maintain registers of currently valid International Standards.
IEC 60500:1974, IEC standard hydrophone

IEC 61205:1993, Ultrasonics – Dental descaler systems – Measurement and declaration of the

output characteristics
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– 6 – 61847 © IEC:1998 (E)
3 Definitions
For the purpose of this International Standard, the following definitions apply.
3.1
applicator tip; applied part
that part of the surgical tool which comes into direct contact with body tissues
3.2
directivity pattern

normalized variation in acoustic pressure as a function of angle at constant range from the

applicator tip

NOTE – This parameter is important when operating adjacent to body structures which are sensitive to pressure

and motion such as the endothelial cells on the inside of the cornea or acoustic nerves.

Symbol: p
Unit: dimensionless plot
3.3
drive frequency
mean frequency of the driving voltage or current

NOTE – This parameter, coupled with tip vibration excursion, allows the user to compare the velocities of applicator

tips.
Symbol: f
Unit: kilohertz, kHz
3.4
duty cycle

for those systems which modulate the electrical drive power, the ratio of the voltage or current

pulse duration (on time) to the duration of one complete modulation cycle while the equipment

is active
Symbol: D
Unit: dimensionless
3.5
maximum electrical power

the peak input electrical power to the ultrasonic handpiece when the load on the applicator tip

is gradually increased from its quiescent condition

NOTE – The peak electrical power occurs at the point at which a reduction in the primary tip vibration excursion

from its value corresponding to the occurs (see 6.9 and 6.10).
quiescent electrical power
Symbol: P
max
Unit: watts, W
3.6
output acoustic power

the acoustic power delivered by the applicator tip into water, and measured using a

calorimetric method (see 6.5)

NOTE – Measurement of acoustic power delivered by applicator tips having different output areas and/or excursion

amplitudes will facilitate application of the ALARA principle, the use of exposure levels that are as low as

reasonably achievable.
Symbol: P
Unit: milliwatts, mW
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61847 © IEC:1998 (E) – 7 –
3.7
derived output acoustic power

the acoustic power delivered by the applicator tip into water, and derived from measurements

made using a hydrophone (see 6.5)

NOTE – Measurement of acoustic power delivered by applicator tips having different output areas and/or excursion

amplitudes will facilitate application of the ALARA principle, the use of exposure levels that are as low as

reasonably achievable.
Symbol: P
Unit: milliwatts, mW
3.8
power reserve index
the ratio of maximum electrical power to quiescent electrical power

NOTE 1 – The power reserve index gives the user a measure of how much “extra” power is available to maintain a

constant tip excursion amplitude under various load conditions.
Symbol: P
Unit: dimensionless

NOTE 2 – The power reserve index will only allow direct comparison of different devices if those devices share the

same operating modality. Piezoelectric and magnetostrictive devices cannot be validly compared using the power

reserve index.
3.9
primary acoustic output area

the area of the projection of the solid part of the applicator tip in the direction of primary tip

vibration excursion

NOTE – Primary acoustic output area is used in determining the energy radiated from the end of an applicator

tip for different tips operating at the same vibration excursion and frequency.
Symbol: A
Unit: square millimetres, mm
3.10
primary tip vibration excursion

peak-to-peak displacement of the applicator tip in the direction of maximum amplitude, at a

point on the applicator tip not more than 1 mm from its free (distal) end (see 3.2 of IEC 61205)

NOTE – The ability to fragment tissue can be correlated to primary tip vibration excursion.

Symbol: s
Unit: micrometre, μm
3.11
primary tip vibration excursion modulation

for those systems which modulate the electrical drive power, the percentage change in the

primary tip vibration excursion from its maximum value to its minimum value
Symbol: M
Unit: dimensionless
3.12
pulse duration

for those devices which modulate the electrical drive power, the time interval beginning at the

first time the drive voltage or current exceeds a reference level and ending at the last time the

drive voltage or current returns to that level. The reference level is equal to the sum of the

minimum drive voltage or current and 10 % of the difference between the maximum and the

minimum drive voltage or current.
Symbol: t
Unit: milliseconds, ms
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– 8 – 61847 © IEC:1998 (E)
3.13
quiescent electrical power

The input electrical power to the ultrasonic handpiece with the applicator tip unloaded, for a

given primary tip vibration excursion.
Symbol: P
Unit: watts, W
3.14
reference primary tip vibration excursion

The maximum primary tip vibration excursion for the combination of applicator tip and

handpiece chosen for measurement.

NOTE – The reference primary tip vibration excursion is used to obtain the values of quiescent and maximum

electrical power needed to calculate the power reserve index of a device configuration.

Symbol: s
Unit: micrometre, μm
3.15
secondary acoustic output area

the area of the projection of the exposed part of the applicator tip in the direction

perpendicular to the direction of the primary tip vibration excursion and corresponding to the

second largest component of motion
Symbol: A
Unit: square millimetres, mm

NOTE – Definitions 3.9 and 3.15 are intended to give the basic areas of interest when considering acoustic output

of simple tubular applicator tips. They do not cover the infinite variety of complex end shapes which may be

available from individual devices.
3.16
secondary tip vibration excursion

peak-to-peak displacement of the applicator tip in a direction perpendicular to the direction of

the primary tip vibration excursion and corresponding to the direction of the second largest

component of motion, of a point on the applicator tip not more than 1 mm from its free (distal)

end
Symbol: s
Unit: micrometre, μm
3.17
tip vibration frequency

fundamental frequency at which the applicator tip oscillates (see 3.3 of IEC 61205)

Symbol: f
Unit: kilohertz, kHz
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61847 © IEC:1998 (E) – 9 –
4 List of symbols
A secondary acoustic output area
A primary acoustic output area
c speed of sound in the medium
D duty cycle
f drive frequency
f tip vibration frequency
M primary tip vibration excursion modulation
p directivity pattern
p(r) pressure amplitude at position r
P output acoustic power
P derived output acoustic power
P power reserve index
P quiescent electrical power
P maximum electrical power
max
s primary tip vibration excursion
s reference primary tip vibration excursion
s secondary tip vibration excursion
t pulse duration
ρ density of the measuring medium
5 General measurement requirements
5.1 Operating conditions
Measurements shall be performed with parameters set to values recommended by the
manufacturer. The parameters to be considered are:
– ambient temperature;
– tip irrigant flow rate;
– tip vibration excursion;
– tip aspiration flow rate.

The parameters listed above are not set independently during actual surgical use. Therefore,

when a particular surgical environment is to be studied, the parameters listed above shall be

specified so that meaningful comparisons of performance can be made (see clause B.5).

5.2 Load conditions
5.2.1 For measurement of derived output acoustic power

Measurements of derived output acoustic power or output acoustic power shall be made

using degassed water (see clause A.6 for rationale and references to degassing techniques) in

a tank, lined with sound absorbing material and having a suitable size to render it essentially

anechoic for the tip vibration frequency of concern i.e. free field condition. In addition, for

devices which have suction available, sufficient flow through tip can be used to minimize the

accumulation of bubbles on the front surface of the tip.
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– 10 – 61847 © IEC:1998 (E)
5.2.2 For measurements of quiescent electrical power

Measurements of quiescent electrical power to the ultrasonic handpiece shall be made with

all system fluid flow operational and with the distal end of the applicator tip in air.

5.2.3 For measurements of maximum electrical power

Measurements of maximum electrical power (the power just prior to stall) to the ultrasonic

handpiece shall be made as indicated by 5.2.2 but with the distal end of the applicator tip

loaded with a suitable acoustically absorbing material capable of loading the applicator without

damaging it.
5.3 Preparation for measurements
5.3.1 Preparation of the applicator

Prior to any measurements all surfaces and parts of the applicator shall be free from

contamination. The applicator tip, the ultrasonic handpiece and the measurement devices

which come into contact with the water and irrigant shall be cleaned with detergent and rinsed

with warm water (see also [1] and [2]).
5.3.2 Preparation of the water

Degassed water shall be used (see annex A for reference to suitable degassing techniques,

see also [2] and [3] of annex C).
5.3.3 Preparation of the system

The apparatus shall be allowed a warm-up period as specified by the manufacturer. If a warm-

up period is not specified by the manufacturer, a warm-up period shall be allowed which is long

enough to allow stable operation to be achieved, up to a maximum of 15 min.
6 Measurement procedures
6.1 Primary tip vibration excursion

One of the following methods shall be used for measuring the primary tip vibration

excursion. The accuracy of the vibration excursion measurement shall be better than ±10 %.

6.1.1 Optical microscope method

A microscope shall be focused on a point not more than 1,0 mm from the free end of the

applicator tip which shall be illuminated by a light beam. When the equipment is energized,

the point traces a line. The relative orientation of the applicator tip and the microscope shall

be altered until the maximum line length is observed. The line length, equal to the primary tip

vibration excursion, shall be measured to an accuracy of ±10 % by means of a calibrated

eyepiece reticule or micrometer movement. If transverse vibrations occur simultaneously then

the point on the applicator describes an elliptical path and the length of the major axis of the

ellipse shall be measured (see figure 1).
6.1.2 Laser vibrometer method

A laser vibrometer shall have an output beam spot size small enough to focus on the end of the

applicator tip. The beam shall be directed parallel to the longitudinal axis of the tip vibration

i.e. in line with the direction of tip vibration excursion to be measured. The output of the

vibrometer control module can be displayed and recorded on instruments as specified by the

laser vibrometer manufacturer.
–––––––––
Figures in square brackets refer to the bibliography given in annex C.
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61847 © IEC:1998 (E) – 11 –
6.1.3 Feedback voltage method

For devices which have a feedback system which is directly coupled to the mechanical tip

excursion, the feedback voltage is proportional to the primary tip vibration excursion. The

optical microscope method of 6.1.1 shall be used to calibrate the feedback voltage in terms of

tip vibration excursion for a particular combination of ultrasonic handpiece and applicator.

The feedback voltage shall be displayed on an oscilloscope with a time base accurate to ±2 %

and vertical deflection amplifiers accurate to ±2 % while optical measurements are taken in

accordance with 6.1.1. Once calibrated in this fashion only the feedback voltage need be

observed to record the magnitude of tip vibration excursions.
6.2 Secondary tip vibration excursion

The following method shall be used for measuring the secondary tip vibration excursion.

The accuracy of the vibration excursion measurement shall be better than ±10 %.
6.2.1 Optical microscope

The method shall be as described in 6.1.1 but the applicator tip shall be first rotated about its

primary vibration axis while monitoring the length of the minor axis of the ellipse. The maximum

observed length of the minor axis of the ellipse shall be measured as the secondary tip

vibration excursion (see figure 1).
6.3 Drive frequency
One of the following methods shall be used. The accuracy of the drive frequency
measurement shall be better than ±2 %.
6.3.1 Frequency counter method

An electronic frequency counter shall be used to determine the frequency of the driving voltage

or current applied to the ultrasonic handpiece. The signal can be obtained either by connecting

a suitably shielded cable to the circuit locations specified by the manufacturer or by winding a

coil around the body of the ultrasonic handpiece and feeding the induced signal to a frequency

counter.
6.3.2 Spectrum analyzer method

A spectrum analyzer with a frequency range of 10 000 Hz to 100 000 Hz shall be used to

determine the frequency of the driving voltage or current. This shall be connected to the circuit

locations specified by the manufacturer.
6.4 Tip vibration frequency

One of the following methods shall be used to measure the primary tip vibration frequency.

The accuracy of the tip vibration frequency measurement shall be better than ±2 %.

6.4.1 Vibrometer method

A non-contacting vibrometer shall be used to indicate the frequency of oscillation of the applicator

tip. This shall be measured from the output of the vibrometer using an electronic frequency

counter, a spectrum analyzer or an oscilloscope with a calibrated time base (see IEC 60782).

6.4.2 Hydrophone method

A hydrophone which satisfies IEC 60500 shall be used to measure the frequency of the

radiated acoustic pressure from the applicator tip. The hydrophone shall be placed in the

range from 30 mm to 100 mm of the applicator tip to reduce the effects of nonlinear

propagation. The frequency of the hydrophone output shall be measured using an electronic

frequency counter, a spectrum analyzer or an oscilloscope with a calibrated time base.

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– 12 – 61847 © IEC:1998 (E)
6.5 Derived output acoustic power and output acoustic power

Derived output acoustic power or output acoustic power shall be determined using the

method specified in 6.5.1 or 6.5.2, respectively.
6.5.1 Derived output acoustic power – Hydrophone method

This method is based on the use of a calibrated hydrophone. The uncertainty of the

determination of derived output acoustic power shall be ±20 %. As a method based on a

single point sensor and a measurement at a single distance from the applicator tip, it is

chosen to eliminate the ideal requirement of integrating the pressure field and to avoid the

possibility of cavitational shielding (see clause A.4). A hydrophone which satisfies IEC 60500

shall be used to measure pressure at a known distance from the applicator tip. Then, using

the model of a monopole or a dipole source (see below), the derived output acoustic power

can be calculated for any tip vibration excursion desired. The applicator shall be positioned so

that the axis of symmetry of the primary tip vibration excursion coincides with the plane of

the geometric axis of the hydrophone track.

An applicator tip which reciprocates in the direction of its primary tip vibration excursion

(see figure 2) and which acts as a source which is small compared to the wavelength in the

acoustic medium c
...

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