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					LM   I N FOpecial
     LASER MEASUREMENT SYSTEMS                                               ISSUE 2/2005

     Polytec’s Vibrometers are Indispensable Tools to Investigate Natural
     Dynamic Processes and to Optimize Parts and Goods.
     The heart beats, wings flap, sounds are sent out and
                                                                     CONTENT                                          PA G E
     received – life would be much too quiet without vibrations.
     To investigate vibrating systems in nature requires sensitive   Polytec News                                         2
     and flexible measurements that don’t disturb the specimen.
     Originally developed to characterize manmade products,
                                                                     Product News
     technology and systems, non-contact Laser-Doppler Vibro-         MSA-400 Now with Topography Option                  4
     metry is now exploring measurements that unravel the             Vibration Measurement at 20 m/s and Beyond         13
     mysteries of biological structures.                              Scanning Vibrometry: New Milestones                20
     In this issue discover how complex biomechanical processes      Special Feature:
     in the middle and inner ear can be elucidated by Polytec        Vibration Measurement
     vibrometers (pages 5, 8 and 11). Another biological appli-      in Nature & Science
     cation involving insects is highlighted on page 14 with the      Interview: We Can “See” How the Patient Hears       5
     research on vibration-based communications in a beehive.         Hearing Research on the Inner Ear                   8
     Besides looking at bio-structures, the PSV Scanning Vibro-
                                                                      Tiny Sensors – Accurate Ear                        11
     meter can help maintain our health by optimizing dental
     ultrasonics (page 16) and other medical devices.                 Good Vibrations in the Beehive                     14
                                                                      Dental Scalers for Perfect Teeth                   16
     There are numerous other research applications in mech-
     anical and civil engineering. For example, please find an        Rotational Vibrations Unraveled                    18
     article about the Rotational Vibrometer applied to engine       Events         MEHR INFO?                           22
     development (page 18), and a companion tutorial about                          E-mail: Rotational
                                                                     Supplement: Basics
     measurement of rotational vibrations. All this and much                        oder
                                                                     Vibration Sensing
     more are included in this edition.

     Advancing Measurements by Light                        
          Polytec News


                     Dear Reader,
                     At one of our recent seminars,
                     the participants asked the
                     speaker which objects he would       New Polytec US Midwest Office
                     investigate with his vibrometers.
                                                          and Representatives
                     He replied: “Anything that
                                                          Polytec is continuously improving its worldwide sales network.
                     hasn’t taken to the trees on
Michael Frech
                                                          With a third US office just opened in Ann Arbor, MI, Polytec is
                     the count of three!”
                                                          ready to expand its support for the automotive industry.
                     We’d like to add that even on        Also, new local representatives have been chosen in Israel, South
                     moving objects the speaker           Africa, Norway, and, for the Laser Surface Velocimeter product
                     would have a sporting chance.        line, in the Peoples Republic of China. Please see back page and
                     Laser vibrometry is easily           inside of the tear-off form for a complete list of our world-wide
                     adapted to difficult measure-        offices and representatives or visit
                     ment tasks and can record data
                     even when the object is distant,
Dr. Helmut Selbach   delicate, rotating or very hot.
           Polytec’s non contact vibration meas-         New Corporate Video on Vibrometers
           urement technology can solve problems         Advancing Measurements by Light – Just what does this slogan really
           in many different markets including           mean? How does a laser vibrometer work? What are the features
           automotive, aerospace, industrial pro-        and benefits of the technology?
           duction, data storage and micro sys-          Now you can get answers to these questions with a short video
           tems (MEMS). In these core markets our        journey into vibration measurement and Polytec’s innovative solu-
           vibrometers help to improve the quality       tions. Please find the new Polytec video on the CD attached to
           of products and processes.                    this issue, or view or download it at

           Recently, the technology comprising
           our MSA-400 Micro Structure Analyzer
           received the 2005 Sensor Award for
           Innovation – a valuable acknowledge-
           ment of Polytec’s exceptional, applica-
           tion-related research and development
           activity in the field of light-based sen-
           sor technology.
           Besides our core markets mentioned
           above, there are many more fields of
                                                         Polytec Wins Sensor Award 2005
           application. In this issue, we have                       The AMA Fachverband für Sensorik e.V. sponsors the
           assembled interesting articles that apply                  Sensor Innovation Award for extraordinary applied
           Polytec technology to biology, medical                           research and development in the field of sensor
                                                                               and measurement technology. Its intention
           research and mechanical engineering.
                                                                               is to highlight outstanding R&D projects
           Have fun reading!                                                   which have a promising market
                                                                               potential. Recently, at the
                                                                               Sensor+Test 2005 tradeshow
                                                                               in Nuremburg, the fifth Sensor
           Michael Frech                                                       Innovation Award was given to
           Vice President                                                      Polytec for developing the inno-
           Laser Measurement Systems                                           vative MSA-400 Micro System
                                                         Analyzer. The MSA-400 is a unique all-in-one instrument
                                                         for quick and precise 3-D dynamic measurements
                                                         on MEMS devices (see page 4). It greatly enhances
           Dr. Helmut Selbach                            efficient development and cost-effective manu-
           Managing Director Polytec GmbH                facturing of reliable micro systems.

Polytec Partners

ANOVIS Makes Full Use of the Laser Vibrometer Bandwidth
The MEDAV group of companies concentrates           This is one good reason why MEDAV relies on laser
on innovative signal analysis and classification    vibrometry by Polytec. MEDAV solutions make full
methods for measurement data taken from different   use of the laser vibrometer bandwidth to optimally
industrial applications. For more than 10 years,    fulfill the most important requirements from the
MEDAV’s employees have been working on End          EoL environment: Failsafe fault identification.
of Line (EoL) testing of gearboxes and engines.     The Acoustic Noise and Vibration Signal Analyzer
Their consistently high level of performance has    (ANOVIS) from MEDAV supports a direct connec-
established their position as one of the leading    tion to laser vibrometers under production con-
suppliers of intelligent monitoring systems.        ditions. On the ANOVIS platform, MEDAV offers
Signal analysis covers a wide range of processes    Black Box systems for test bench operation, ana-
used to identify decision-relevant information in   lyzers for the QC/QA laboratory as well as a
                                                    mobile system for vehicle measurements.
the recorded data. In MEDAV applications such
as combustion engine or crack testing, wide         More Info:
signal bandwidths are often necessary.    

            THôT/Polytec Photonic Force Microscope
            Enables Picometer Measurements
THôT manufactures optical media inspection          resolution required to support
and measurement equipment to monitor vibra-         further advances in data
tions at the atomic level for the data storage      storage technology by
and semiconductor industry. THôT testers use        characterizing the
Polytec's vibrometer technology for automated       head/media mech-
production, process control, process develop-       anical interface.
ment and R & D applications. These test systems     To learn more
provide state-of-the-art measurements that can      about THôT
be adapted to a specific customer’s need.           Technologies and the use of
With a total system noise floor below 2 pm          vibrometry to understand complex
and phase differential detection                    mechanical relationships on hard disk drives,
of 0.6 pm, THôT's new                               please read THôT's article featured in the LM
LDV based Photonic                                  INFO Special issue 2/2004 found in PDF format
Force Microscope (PFM)                              at or visit
provides the picometer                    

Product News

Characterization of Micro Systems

3-D Topography Measurement is Now Available
for the MSA-400 Micro System Analyzer
In addition to its unique capability to measure MEMS and microsystem dynamics,
Polytec’s MSA-400 Micro System Analyzer can now perform high resolution topography
measurement on MEMS and micro-components.

The All-in-One Optical Instrument         In addition, static 3-D topography
                                                                                          All-In-One-instrument for meas-
for Measuring MEMS Dynamics and           measurements can now be made using
                                                                                          uring both dynamic response and
Topography                                white light interferometry to determine
                                                                                          static topography of MEMS
The award-winning MSA-400 Micro           structure heights and shape on both
                                          rough and specular surfaces. This is also       Rapid, non-contact measure-
System Analyzer uses light for non con-
                                          a non-contact measurement proce-                ment procedure
tact measurement of three-dimensional
motions in microstructures. Equipped      dure, free from any impact, feedback            Sub-nanometer resolution
with internal, precision microscope       or surface preparation to the sample.           Rough and specular surface
optics, the MSA-400 combines scanning     The MSA-400 Micro System Analyzer               compatibility
laser Doppler vibrometry to measure       is the ideal MEMS measurement tech-
out-of-plane vibrations orthogonal to     nology for determining the essential        tions and is suitable for both laboratory
the component’s surface with strobo-      static parameters – profile, shape,         R&D measurements and production
scopic video microscopy to capture        critical dimensions and roughness –         line, quality control applications.
in-plane displacement parallel to the     as well as dynamic parameters – reso-       Please visit
component’s surface. Taken together,      nance frequencies, deflection shapes,       microsystems for detailed information
these techniques allow fast and com-      damping, settling response and decay        or contact our product specialists and
plete dynamic characterization of         time. The MSA-400 is designed to            regional sales managers to arrange a
microstructures.                          mount to popular MEMS probe sta-            complete demonstration.

We Can “See” How the Patient Hears

Interview with Professor Anthony W. Gummer about the Use of
Laser Vibrometers for Hearing Research and Clinical Diagnostics
                                            some and the measurement time pro-            I just mentioned the benefits to clinical
                                            hibitively long. In 1995, our research        diagnostics. Regarding our fundamental
                                            group succeeded in combining a highly         research on biophysical processes in
                                            sensitive Polytec vibrometer with all oth-    the cochlea, there is no other measure-
                                            er components to produce a so-called          ment technology providing appropriate
                                            Laser Audiometer that provides full           sensitivity and a resolution below 1 pm.
                                            diagnostics within a couple of seconds.
                                                                                          What are the clinical practice require-
                                            Which pathologies can be diagnosed by         ments for a LDV-based diagnostic
                                            LDV measurements, and which are the           device?
                                            regions of the ear that can be accessed
                                                                                          The system must be simple to operate
                                            via eardrum measurements?
 Anthony W. Gummer is director
                                                                                          by a technical assistant, the measure-
                                            Measurements on the eardrum can               ment time short so as not to unneces-
 of the Physiological Acoustics &
 Communication section of the Dept.         be used to diagnose pathologies of            sarily inconvenience the patient, and
 of Otolaryngology, University of           the middle ear, such as luxations of the      the laser power must be below 1 mW,
 Tübingen.            ossicles, otosclerosis or dysfunctions        as in the case of Polytec vibrometers.
 cochlea                                    of middle-ear implants and prostheses.
                                                                                          How would you rate the performance
                                            It also allows us to investigate the micro-
Professor Gummer, how has Laser-            mechanical function of the inner ear.         of the current Polytec product line?
Doppler-Vibrometry (LDV) found its way      The active amplification process inside       We are extremely satisfied with the
in to hearing research and diagnostics?     the cochlea, which generates an oto-          capability of Polytec’s single-point
The first experimental vibration meas-      acoustic emission, can be assessed            vibrometers. The depth-of-field is in
urements on the eardrum were in the         non-invasively by the highly sensitive        the µm range, enabling well-focused
seventies and eighties. Some years later,   single-point vibrometer as a vibration        high-resolution measurements. Our
the LDV started to provide insight into     of the ear drum. We can “see“ how             current experimental setup for the
the micromechanics of the inner ear         well or poorly the patient hears. This        investigation of hair cells involves an
with an article by Nuttall et al in 1991.   could have important applications in          OFV-505 Sensor Head and our newly
Since the nineties, the application of      screening infants for dysfunctional           developed AFM cantilever and has a
LDV in clinical diagnostics has been        hearing.                                      100-fold better sensitivity than the
continuously reviewed. At that time,        Can you outline the advantages of LDV         previous combination (see article on
the experimental setup was cumber-          compared to other methods?                    page 8).

Special Feature

I Can Hear the Grass Grow…
 Laser vibro-
 metry can
 answer many
 questions: How
 do ears work? How do
 insects communicate?
 Where Is the vibration
 source?                     Biology
 In our world, vibrations    For every living species on our planet      Other bio applications include measur-
 are everywhere. Did you     there are corresponding biological          ing communication between elephants,
                             applications of laser vibrometry. One       fruit ripeness, spider web motion, and
 know about honeycomb        of the most prominent is insect com-        the hearing mechanism in frogs and
 vibrations, silo honking,   munication. Some insect sounds are          fruit flies (see issue 1/2005, page 18).
                             quite loud, such as the singing of the
 bridge resonance failure    cicada; while others are supersonic
 and remote voice detec-     and can’t be heard. Some insects are
                             so small that their songs are transmit-
 tion? Read on to learn
                             ted mainly through a plant rather than
 more about vibrations       air. Entomologists can use vibrometers
 in nature and in man-       to record this unheard noise for later
                             study. Consider honeycomb vibrations
 made products and           in beehives; these signals can only be
 processes. Discover how     measured with highly sophisticated
                             equipment (see page 14).
 these vibrations are
 detected and studied
 using laser vibrometry.     Medical and Health Care
                             In this issue you will learn how laser      dental scalers (see page 16) and respira-
 To download previous        vibrometry can assist with eardrum          tors have been investigated using Polytec
 issues of the LM INFO       diagnostics and research on the middle      vibrometers. The vibrometer can also
                             and inner ear. In addition, vibrometers     function as a non-contact polygraph by
 Special quoted in this
                             have been used for vibration measure-       measuring muscle vibrations, or as a
 article, please visit       ments on artificial heart valves, mech-     remote voice detector as a part of a
                             anical properties of tendons, analysis of   multi-media surveillance system.
                             vibrations while bone drilling or medical
 usa/LM-INFO                 laser ablation, and detection of bone
                             crack propagation. Medical, safety and
                             health care devices like tooth brushes,

Acoustics                                                                            Metrology and Calibration
Musical instruments generate wonder-       portant in product design. The focus      Primary calibration of vibration and
ful, inspiring sounds through their vib-   is on how and where are undesired         shock sensors by laser Interferometry
rations. Polytec vibrometers can help      noises generated and at which point       has the unique advantage that meas-
us understand how this happens with        or location can countermeasures be        urements of surface acceleration,
early work already done on violins,        taken. Please read the article about      velocity or displacement are made
cembalos and dulcimers. Vibrometers        the joint project between Polytec and     with a precision that is traceable
are also indispensable tools for loud-     HEAD acoustics on                         directly to the wavelength of laser
speaker design, identifying diaphragm      “Binaural Transfer                        light (see issue 1/2003, page 8).
resonances that are deleterious to the     Path Analysis”                            Also, laser vibrometric velocity meas-
sound quality. Vibrometer measure-         (See issue 1/2004,                        urements offer the possibility to per-
ments provide an experimental basis        page 10).                                 form traceable impulse calibrations
for sophisticated acoustic investiga-                                                of transducers subjected to known
tions like structural-acoustic response                                              impulse loads (see issue 1/2004,
(sound field) predictions, acoustic                                                  page 16).
imaging and anti-sound research.
Acoustics are also increasingly im-

Industrial Research                        Materials Research, Mechanical and Civil Engineering
There are many areas of industrial         Laser vibrometry is an ideal tool for     “honking” noise (up to 110 dB) that
research where vibration issues are        the measurement of structural dynam-      occurred while discharging grain from
encountered. In the automotive and         ics and for non-destructive flaw detec-   a silo could be resolved by using a
aerospace industry there are undesired     tion (fracture, delamination, fatigue)    Polytec vibrometer. Geological appli-
vibrations of parts and bodies that        in all kinds of materials, parts and      cations include detection of land
must be eliminated.                        components. For instance, we report-      mines, rock failures and earthquake-
Laser vibrometry gives the opportunity     ed on non-linear scanning vibrometry      induced defects in concrete.
to optimize dynamic automotive FE          for non-destructive testing (see issue
models by matching the parameters          1/2004, p. 20) and on the investiga-
derived from vibration measurements        tion of ultrasonic wire bonding (see
on prototypes to the FE model. Simi-       issue 1/2004, p.18). Regarding build-
larly, for small moving or vibrating       ings and industrial plants, there are
components in electronic circuits,         many applications for in-the-field
data storage devices, and microelectro-    structural health monitoring on wind
mechanical systems (MEMS), FE model        turbines, building vibration and dis-
verification is essential for rapid cost   placement, and cable-stayed bridges
effective micro component designs.         to prevent bridge resonance failure.
See issue 1/2004 for automotive appli-     Even curious effects like the loud
cations, issue 2/2004 for data storage
applications and issue 1/2005 for
                                            More interesting applications on
MEMS applications.

Special Feature

Tiny Sensors – Accurate Ear

Laser-Doppler Vibrometers Probe the Basic Mechanism of Hearing
Intensive medical, molecular and biomechanical research activities have provided much insight into
the function of signal processing inside the ear. However, we are still far from a comprehensive
understanding of the hearing mechanism. Current research work deals with the details of electro-
mechanical signal transduction occurring in the cochlea of the inner ear. For the investigation of the
inner ear biomechanics, Laser-Doppler Vibrometers have proven to be highly sensitive vibration sen-
sors that don’t affect the specimen.

Ears and Hearing – Biological               The outer ear (A) includes the auricle,     a fluid medium and hair cells with
Miracles of Signal Processing               the earlobe and the ear canal.              their cilia either free-standing in the
Our ears are the most critical sensory      The middle ear includes the tym-            fluid or in contact with a covering
organs with regard to interaction with      panic membrane or eardrum (B)               membrane. Moving the fluid or
the environment and to communi-             and the ossicles (C), the three tiny        membrane, the cilia are deflected
cation. They process various spatially      bones of the middle ear known as            generating nerve impulses.
resolved signals in real time featuring a   the malleus, incus, and stapes.           The perception of acoustic signals
remarkable spectral resolution and a        These bones transfer the tympanic         depends essentially on how acoustic
tremendous dynamic range. From a            membrane motion to the inner ear          vibrations are transmitted and con-
biomechanical point of view, the ear        through the oval window.                  verted on their way from the outer
is a highly sophisticated acoustic sen-     The inner ear (D) comprises both          ear via the middle ear to the hair
sor converting sound pressure waves         the cochlea (the organ of hearing)        cells in the inner ear.
into electrical signals.                    and the labyrinth or vestibular           The details of biomechanical signal
There are three sections to the human       apparatus (the organ of balance).         processing in the cochlea are a current
ear (Figure 1):                             Inside the cochlea and labyrinth is       topic of medical research.

Structure of the Cochlea
The cochlea is a spiraled, hollow,
conical chamber of bone (for a cross-
section see Figure 2, left) and consists
of three fluid-filled chambers (Figure 2,
right). Its core component is the Organ
of Corti, the sensory organ which sup-
ports the receptors of hearing.
Vibrations transmitted from the stapes
to the cochlea generate a wave travel-
ing along the basilar membrane. The
basilar membrane separates the scala
media and the adjacent scala tympani.
A certain sound frequency generates
a displacement maximum at a corres-
ponding location on the basilar mem-
brane. The stiffness of the basilar
membrane decreases from bottom              Figure 2: Cross-section of the cochlea (left) and enlarged view of the Organ
to top of the cochlea. Thus high fre-       of Corti with hair cells (right)
quencies cause a maximal displacement
at the base of the basilar membrane
                                            Three rows consist of outer hair cells      Electromechanical Transduction in
while lower frequencies maximally
                                            (OHCs) and one row consists of inner        Outer Hair Cells
affect more distant positions.
                                            hair cells (IHCs).                          How can the outer hair cells influence
The wave propagation inside the
                                                The inner hair cells (IHCs) provide     the traveling wave?
cochlea is influenced by active
                                                the main neural output of the cochlea   A change of membrane potential of
mechanical amplification processes
                                                and generate nerve impulses from        the outer hair cell (OHC) causes the
that are responsible for the extraor-
                                                the mechanical vibrations induced       cell body to contract and elongate.
dinary dynamic range and the fre-
                                                by the sound wave.                      This electrically induced motion, called
quency selectivity of hearing.
                                                The outer hair cells (OHCs), however,   somatic electromotility, is believed by
Transduction in the Cochlea                     are responsible for mechanical          many researchers to be the basis of the
The hair cells are arranged in four rows        amplification within the cochlea.       exquisite frequency selectivity, sensitivity
across the Organ of Corti and along             These are the object of current         and dynamic range of the cochlea.
the entire length of the cochlear coil.         research.                               The electromechanical force produced
                                                                                        by the cell is thought to counteract
                                                                                        damping forces in the cochlea, such as
                                                                                        those inherent to the motion of fluids
                                                                                        and cells, to produce the extraordinary
                                                                    Figure 1:
                                                                                        mechanical tuning of the cochlea.
                                                                    Structure of
                                                                    the human ear.      The motor molecule responsible for
                               C                                    (A) outer ear;      somatic electromotility is called prestin.
                                                                    (B) eardrum         There are at least 6,000 of these mole-
                                            D                       and (C) ossicles    cules per square micrometer of cell
                                   B                                of the middle
                                                                                        surface. It is not known how the motion
                                                                    ear; (D) cochlea,
               A                                                                        of all these molecules is coupled to the
                                                                    labyrinth and
                                                                    auditory nerve      cytoskeleton, to generate the somatic
                                                                                        electromotility. The process is exceed-
                                                                                        ingly fast and works up to ultrasonic
                                                                                        frequencies. Destruction of this trans-
                                                                                        ducer leads to deafness.


Special Feature

                                                                                         determined by placing a high-imped-
                                                                                         ance mechanical load, the reverse side
                                                                                         of a lever used in atomic force micro-
                                                                                         scopy (AFL), against the apical end of
                                                                                         the cell. The velocity of the AFL, VAFL,
                                                                                         in response to electrical induced force
                                                                                         by the excluded section of the cell
                                                                                         was measured with the Laser Doppler
                                                                                         Vibrometer (LDV) focused on the AFL.
                                                                                         The force is then calculated from VAFL
                                                                                         and the known mechanical impedance
                                                                                         of the AFL.
                                                                                         To measure the axial impedance of
                                                                                         the cell, the tip of an AFL was placed
                                                                                         against the apical end of the cell
                                                                                         (Figure 3, lower) and a known force
                                                                                         applied to the AFL using a magnetic
                                                                                         field. The impedance is then computed
                                                                                         from the resulting velocity VAFL meas-
                                                                                         ured by the LDV and the known
                                                                                         mechanical impedance of the AFL.
                                                                                         Velocity measurements were performed
                                                                                         using a contemporary OFV-505 Sensor
                                                                                         Head and an OFV-5000 Vibrometer

Figure 3: Layout and micro image of the experimental setups for electro-
                                                                                         The experiments show that isolated
mechanical force (upper) and impedance (lower) measurements of an                        OHCs can compensate for fluid forces
outer hair cell (OHC)                                                                    with nearly constant displacement am-
                                                                                         plitude and phase up to frequencies
                                                                                         exceeding their local frequency on the
The electromechanical transduction        it is particularly attractive for investiga-   basilar membrane. From this it follows
process was investigated employing        tion of biological structures in a fluid.      that electromechanical transduction in
laser Doppler vibrometry together         It was also applied to investigate mech-       the OHCs provides the high frequency
with atomic-force spectroscopy. Using     anical and cell biological properties of       capabilities that are necessary to amplify
the vibrometer the somatic electro-       cellular and membranous structures in          the traveling wave within the whole
motility was found to follow changes      the cochlea.                                   acoustic range.
of the membrane potential cycle-
                                          Dynamical Measurements
for-cycle up to at least 100 kHz. The                                                     CONTACT
                                          of an Outer Hair Cell
soma of the OHC turned out to have
                                          To investigate the dynamics of the              Prof. Anthony W. Gummer, Ph.D.
the necessary molecular machinery to
                                          OHC, a portion of the cell is sucked            Section Physiological Acoustics
generate electromechanical responses –
                                                                                          and Communication
with little attenuation and time delay    into a glass capillary (Figure 3). For
                                          determining electromechanical force,            Dept. Otolaryngology,
– well above the frequency limit of
                                                                                          University of Tübingen
hearing. Since these measurements         the transmembrane potential of the
                                                                                          72076 Tübingen, Germany
were completed, an innovative method      cell is modified by applying a voltage
to measure the mechanical properties      (USP) to the pipette solution inducing
of biological structures up to at least   voltage drops, U1 and U2, across those
40 kHz has been developed. This tech-     sections of the cell membrane exclud-
                                                                                          Visiting this address you will also find
nique employs an atomic force can-        ed from and contained in the pipette,
                                                                                          a comprehensive glossary about the
tilever and has general applications      respectively (Figure 3, upper). The
                                                                                          structure and function of the inner ear.
outside the area of hearing research;     somatic electromechanical force was

Illuminating Sound Transmission

Motion and Biomechanics of the Human Middle Ear
Significant advances are being made in our understanding of the structure and functional relation-
ships of normal and pathological middle ears. One reason for the enhanced understanding has been
the use of non-contact laser Doppler vibrometers to measure motions of the middle ear both in-vitro
(cadaver in laboratory) and in-vivo (patient in operating room).

Introduction                                clarity in interpreting otoacoustic         Measurement Setup
In the physiological range, motions of      emissions that travel from the cochlea      Dynamic measurements using a Polytec
the middle ear are typically less than      through the middle ear and are meas-        HLV-1000 Laser Doppler Vibrometer
100 nm. Thus, accurate measurements         ured in the ear canal.                      (Figure 2) are made in order to deter-
with good signal-to-noise in the acoustic   Experimental Approach                       mine the biomechanical parameters of
hearing range of 20 Hz to 20 kHz are                                                    the morphologically based sub mod-
                                            The Stanford OtoBiomechanics group
necessary to characterize the response      uses the approach of deconstructing         els. Without an eardrum or stapes the
of the human ear, and at higher fre-        middle ears of cadaver temporal bones       malleus-incus complex (Figure 3) can-
quencies for similar measurements           into sub systems that are each charac-      not be driven with sound.
on animals.                                 terized through a combination of phy-
We are now on the verge of understan-       siological and morphological meas-
ding the relationship between human         urements as well as three-dimensional
middle ear morphometry, tailored to         mathematical analyses. The subsystems
individual ears, and the biomechanical      are mathematically reconstructed for
processes that lead to physiological        comprehensive analyses representing
responses in individual subjects.           the intact middle ear of each individual.
Yet, despite all of the recent advances,    The sub systems are:
there exists a significant lack of know-       the tympanic membrane coupled
ledge about the relationship between           to the ear canal and isolated by
middle ear structures and sound trans-         removing the incus
mission. The goal of our new study is          the malleus-incus complex (Figure 1)
to make precision measurements that            isolated by dissecting the eardrum
result in a better understanding and           and the stapes from the temporal         Figure 1: Isolated malleus-incus
model of the middle ear and thus im-           bone                                     complex (microCT image) without
proved middle ear repairs and better           the isolated stapes footplate            suspensory ligaments.

Special Feature

                                                                                         magnet/coil system. The mass matrix
                                                                                         M, the damping matrix C , and the
                                                                                         stiffness matrix K are obtained from
                                                                                         the basic relations from the methods
                                                                                         for linear systems. The challenge in the
                                                                                         above description is to estimate the
                                                                                         viscoelastic parameter values of each
                                                                                         ligament and tendon. These estimates
                                                                                         are obtained by 3-D velocity measure-
                                                                                         ments using the laser Doppler vibro-
                                                                                         Conclusion and Outlook
Figure 2: Polytec HLV-1000 Hearing           Figure 3: Preparation of the middle         By combining each of the sub models,
Laser Vibrometer                             ear ossicles, with reflective material      these studies result in anatomically-
                                                                                         based biocomputational models of the
                                                                                         intact middle ear. Furthermore, the
A magnet attached to the tip of the          can be compactly expressed in matrix        studies will provide a solid foundation
malleus is driven by a coil around the       form as:                                    for the structural basis for middle ear
tympanic annulus. The magnitude and                                                      sound transmission and will have
                                                      vm = A · v
phase-angle of the velocity are measured                                                 applications in many areas of hearing
at several points on the malleus and         where v is a vector with calculated xyz     health care including surgical recon-
incus. Each point is measured from five      components, vm is the measured velo-        struction of the middle ear, otoacous-
or more unique angles to allow decom-        city and A is the matrix determined         tic emissions and passive and active
position into three vector components:       from the measurement angles. The            prostheses. Laser Doppler vibrometers
in-plane (X,Y) and out-of-plane (Z)).        method of least squares is used to cal-     are a critical component in the battery
                                             culate v. For each sub system and for       of tests used to understand structure/
Once a cadaver middle ear preparation
                                             the intact middle ear, high resolution      function relationships of the ear.
is mounted with the medial side facing
                                             micro-CT images are used to describe
the laser, two stacked goniometers are
                                             individual temporal bone ears. The
used to provide two orthogonal axes
                                             micro-CT images are segmented and
of rotation around a common fixed
                                             combined to obtain three-dimensional
rotation point 17.5 mm above the
                                             volume reconstructions of the ear canal,
goniometer. Each goniometer has an
                                             eardrum, ossicles, ligaments and ten-
angular range of ±15 degrees around
                                             dons, which are further analyzed to
one-axis, and ± 20 degrees around the
                                             obtain the desired morphometry.
other. Angular resolution is 5 arc min-
utes. Care is taken to choose an xyz         Mathematical Model
coordinate system which is a body-axis       A mathematical model is formulated,
system, that is, fixed in the temporal       incorporating anatomical features of the
bone and rotated with it. Alignment of       eardrum, including its angular placement
the y-axis should be along the incus         in the ear canal, conical shape and its
handle with the x-axis in the plane of                                                   Figure 4: Mathematical model
                                             highly organized circumferential and        of the eardrum
eardrum. The z-axis is along the laser       radial fiber layers. The dynamic motion
measurement direction.                       of the ossicular chain is modeled by         AUTHOR
Geometry Model                               methods of the multi-body system:
                                                                                          Prof. Sunil Puria, Ph. D.
components of velocity are related as         ..       .                                  Stanford University
                                             Mx (t) + Cx(t) + Kx(t) = F(t),
follows:                                                                                  Departments of Mechanical
                                             where the vector x(t) denotes the dis-       Engineering and Otolaryngology-
 i   = –sin( i ) x + sin( i ) cos( i )   y                                                Head and Neck Surgery
                                             placement at time t, and the vectors
       + cos( i ) cos( i ) z                 ..        .                                  OtoBiomechanics Group
                                             x (t) und x (t) are the corresponding
                                                                                          Stanford, CA 94305
The relation between measured velo-          velocity and acceleration. The force
cities and xyz components of velocity        vector F(t) is the force generated by the

Basics of Rotational
Vibration Sensing

Polytec laser vibrometers are proven instruments for non-contact
measurement of surface vibrations. The 4000 Series Rotational Vibro-
meter is a variation on a standard vibrometer that allows engineers
to measure rotational vibration directly. The instrument uses two non-
contact laser probes for dynamic acquisition of the angular vibration
of rotating parts. Each laser probe is a separate laser interferometer.
A special differential technique uses both measurement beams and
allows only the rotational component to be acquired, independent of
the shape of the measurement object. At the same time translational
vibrations are virtually eliminated. The 4000 Series has a frequency
range of 0.5 Hz to 10 kHz, providing enough bandwidth for even the
most demanding measurement tasks.

                                                                          Polytec GmbH
                                                                          Polytec-Platz 1-7
                                                                          D-76337 Waldbronn
                                                                          Tel. +49 (0)72 43 6 04-0
                                                                          Fax +49 (0)72 43 6 99 44

Advancing Measurements by Light            
                                                      and maintenance sensitive. Conventional contact
                                                      transducers are also subject to wear and slippage.
                                                      In comparison, non-contact technologies, like
                                                      laser interferometers, are easy to mount even in
                                                      crowded places and are ideal for monitoring
                                                      purposes. The vibrometer’s large standoff distance
                                                      makes repositioning the laser probe fast and
                                                      convenient and enables the precision measure-
                                                      ment of operating machinery at several locations
                                                      without interruption. A specific advantage of the
                                                      Polytec design is its ability to measure anywhere
                                                      within the range of -7,000 RPM to +11,000 RPM
                                                      including directional changes, torsional transients
                                                      and rotational vibrations around the rest position.
                                                      The Rotational Vibrometer System
                                                      The 4000 Series Rotational Vibrometer includes
                                                      the OFV-400 Optical Sensor Head and the
                                                      OFV-4000 Controller. Polytec’s long-standing
                                                      experience in the development of laser vibro-
                                                      meters has been applied to the design of the
                                                      OFV-400 Measuring Head, with a compact dual
Many familiar mechanical systems such as engines,     interferometer whose high optical sensitivity
power trains and gearboxes are significant sources    enables precision measurements on untreated
of rotational vibrations. These systems generate      surfaces. Signals from the OFV-400 are processed
rotational motion and mechanically transmit the       by the OFV-4000 Controller/Power Supply.
torque, movement, speed and acceleration from         The controller bandwidth is large enough to
one place to the other. Besides creating torsional    handle fast transients such as sudden accelerations
and bending vibrations in the generation of the       of a shaft during gear changes. All instrument
rotation motion there are many vibrations created     settings are shown on the OFV-4000’s backlit
in its transmission to the point of usage.            display including signal strength from both
Additional vibrations are generated by mismatched     laser beams and RPM.
gearing, unbalanced shafts, and poorly aligned
articulate joints. All of these unwanted vibrations   Principle of Operation
result in undesirable noise and premature fatigue     The 4000 Series Rotational Vibrometer uses two
of the mechanical systems.                            parallel laser beams which exit the OFV-400’s
                                                      front lens and strike the rotating surface. Each
Measurement Challenges
                                                      back-scattered laser beam is DOPPLER shifted in
To minimize the rotational vibrations and their       frequency by the surface velocity vector in the
harmful effects in the engineering design,            beam direction. This velocity is made up of
measurements are made to discover how torque          rotational and lateral components. Raw velocity
and kinematics are carried across the drive system,   information from each beam is independently
and to describe the nature of the deviations in       sent to the OFV-4000 for processing. The dif-
terms of elasticity, inertia, torque and contact.     ference between the two velocity components
Traditional measurement of torsional and rota-        is a direct measure of the pure rotational velocity
tional motion is not easy because the system          of the object and eliminates lateral vibrations.
components are continually moving relative to         Polytec’s dual interferometer design has signif-
the sensor platform and large portions of the         icantly greater optical sensitivity than competing
system reside in inaccessible places.                 designs using only one interferometer operating
There are both invasive and non-invasive sensing      in an optically differential mode. This optical
techniques. Invasive methods use devices mounted      sensitivity advantage allows measurements on
to the rotating part that transmit a signal to an     poorly reflecting surfaces, thereby increasing
opposing receiver or sensor, for instance RF          the range of applications and ease of use. For
telemetry combined with shaft mounted strain          measuring positive and negative rotations as
gauges or accelerometers. While these techniques      well as vibrations around zero RPM, a BRAGG
give direct physical measurements, they are skill     cell is incorporated into the dual interferometer.

                                        E 18
The Bragg cell produces a constant angular velocity   the back scattered beams. According to the
offset by frequency shifting the laser beams.         drawing in the figure, the lower beam measures
                                                      a Doppler shift from the surface moving towards
Optical Setup
                                                      the sensor head. The upper beam measures a
The OFV-400 Sensor Head contains two indepen-         Doppler shift with opposite sign from the surface
dent laser interferometers cleverly designed into     moving away from the sensor head.
a compact, lightweight package, utilizing several
                                                      Here the following formulas apply:
shared components. Each of these two interfero-
meters emits a measurement beam through the           fDA = 2       A/ = 2 ( RA cos ) /
OFV-400 front lens. The two beams are parallel        fDB = 2       B/ = 2 ( RB cos ) /
and come to a focus at a specified distance from
                                                      The geometrical relationship between the beam
the sensor head, where they strike the rotating
                                                      separation distance d and the angles and at
object with a separation, d. One beam strikes the
                                                      given radii RA and RB, is given by:
rotating object above the axis of rotation while
the other strikes it at an approximately equal        d = RA cos            + RB cos
distance below.                                       and thus the following formula is is obtained for
Each point on the circumference of the rotating       the frequency difference between the two Doppler-
part, with angular velocity , has a tangential        shifted beams that depends on the system con-
velocity t which is dependent on the rotational       stants d, and the angular velocity :
radius R. This tangential velocity can be broken
                                                      fD = fDA + fDB = 2 d /
down into two orthogonal translational velocity
components. In the figure, the vectors are shown      Hence, the angular velocity is
for one such break down of velocity for two points      = fD / 2d
A and B, where one of the velocity components
is arranged to point along the direction of the       Signal Processing
measurement beam ( A and B).                          Signals from the OFV-400 are processed by the
As shown in the following, it is possible to          OFV-4000 Controller to obtain the complete
determine the angular velocity by measuring           angular velocity information from the frequency
two parallel, translational velocity components.      of the analog output signals of both interfero-
By projecting the tangential velocity vectors         meters and to separate the static component
along the measurement beam, the following             (DC fraction) from the dynamic component
formulas were determined:                             (AC fraction) of the rotational speed.

   =      cos =      RA cos                           After separate signal conditioning, the output
 A     tA
                                                      signals of both interferometers are merged in a
 B =   tB cos =      RB cos                           mixer stage, followed by a preprocessing block.
As described above, the velocity components           Here static and dynamic frequency components
along the direction of the measurement beam           are separated and supplied to separate decoders,
produce the Doppler frequencies fDA and fDB in        which operate as frequency-to-voltage converters.


                      Interferometer A
        f   DA

                                                                            R A

                                          d                 tB

                       Interferometer B

        f   DB

                                                                 E 19
                                                                      Thus, measurements with a Polytec Rotational
                                                                      Vibrometer, enhanced by data processing soft-
                                                                      ware like VSI Rotate, can help identify individual
         Interferometer I
                                            d                         vibration frequencies solving problems in noisy
         Interferometer II                                            signals with closely spaced and crossing orders,
                                                                      and creating impressive plots and tables to use
                                                                      in reports and presentations.
                                                 FDoppler = –––––
             RF Preprocessing                                         For more information about VSI Rotate from Vold
                                                     = wavelength
                                                                      Solutions please visit For more
        D.C. Decod.      A.C. Decod.                                  information about Polytec Rotational Vibrometers,
                                                                      please visit


                 After decoding, the static RPM and the dynamic        P O LY T E C T U T O R I A L S E R I E S
                 signal (   ) are fed to separate outputs:
                                                                       Principles of Vibrometry
                   DC stationary rotation DC:
                                                                       (Issue 1/2003) E1 – E4
                   A constant component of the tangential
                   velocity which is proportional to the speed         Principles of Velocimetry
                   or RPM. The combination of both beams               (Issue 1/2004) E5 – E8
                   yields the correctly scaled RPM information,        Basics of Digital Vibrometry
                   independent of radius.                              (Issue 2/2004) E9 – E12
                   AC rotational vibration     :                       3-D Dynamic Analysis of Microstructures
                   The fluctuating component of the shaft              (Issue 1/2005) E13 – E16
                   rotation, which indicates the angular or
                                                                       Rotational Vibration Sensing
                   rotational vibration.
                                                                       (Issue 2/2005) E17 – E20
                   The vibrational velocity signal (   ) is also
                   sent to an integrator block to provide the
                   angular displacement       .                       Each LM INFO Special contains a pull-out
                                                                      tutorial section written to educate those
                 The gross, lateral movement of the shaft towards
                                                                      interested in the basic technology and
                 or away from the sensor head is not measured
                                                                      application of non contact laser Doppler
                 because it is common to the two laser beams,
                                                                      vibrometry and other light-based
                 that cancel in the differencing process.
                                                                      measurement techniques.
                 Data Processing                                      Please download previous issues at
                 Angular vibrational velocity, angular vibrational
                 displacement and RPM are provided as analog
                 outputs via three BNC jacks. These outputs can
                 be examined further with signal processing
                 software, such as an order tracking analyzer.
                 VSI Rotate is such a software package, provided
                 by our partner company Vold Solutions, for ana-
                 lyzing noise and vibration from time waveform
                 and tachometer signals. It is able to post-process
                 vibration data and provides high-resolution
                 spectral and order-based analysis that enable
                 a detailed diagnosis of machinery problems.
                 VSI Rotate features spectrograms, color contour
                 plots, phase plots, order tracking, 2-D and 3-D
                 plotting, and bode diagrams.

                                                              E 20
Product News

For Vibrations at 20 m/s And Beyond

New Modular to Formula 1
Proven High Speed Vibration Measurement Systems
Optimized for high vibrational velocities:   light sensitivity, a remote focus control   The specialist for developing Formula 1
Modular 20 m/s Vibrometer                    function, auto focus as well as the         racing engines:
                                             option of locking the focus position.       HSV-2000 High Speed Vibrometer
The new OFV High Speed Vibrometer
                                             With an OFV-5000-S and OFV-525              up to 30 m/s
series expands the number of options
                                             combination, it is possible to upgrade
known from the proven OFV-5000                                                           The HSV-2000 system allows single
                                             to a Polytec PSV-400-H4-S Scanning
Modular Vibrometer System. Now you                                                       point and differential displacement
can make vibration measurements at                                                       as well as velocity acquisition up to
vibrational velocities up to 20 m/s (pre-    Scanning extremely high velocities:         ± 30 m/s. Typical applications are valve
viously 10 m/s), for highly demanding        PSV-400-H4-S Scanning Vibrometer            train measurements as well as examin-
applications such as engine develop-         up to 20 m/s                                ing shock, impact and other high
ment. The new High Speed System is           The high velocity scanning system is        velocity effects. This system is widely
composed of the OFV-5000-S Vibro-            based on the PSV-400-H4 and allows          used in Formula 1 racing to optimize
meter Controller and the OFV-525             vibration measurements up to 20 m/s         their high performance engines. Using
High Speed Sensor Head.                      with a vibration frequency of up to         a special microscope adapter, high
                                             80 kHz. This, for example, allows sim-      velocity measurements are also possi-
The OFV-5000-S is based on the OFV-
                                             ple and intuitive operational deflection    ble on small objects, e.g. droplets of
5000 Vibrometer Controller and can
                                             shape analysis of engine components         ink in bubble jet printers.
likewise be configured with a wide
range of decoders and decoder com-           or other parts and aggregates in the        You will find more information at
binations for very different tasks.          high velocity range.              
This means that vibration frequencies
up to 1.5 MHz or vibrational displace-
ments that range from sub-nanometer
to meters can be measured.
The OFV-525 single-point Sensor
Head is based on the OFV-505 stan-
dard model. Like the basic model, the
OFV-525 adheres to an eye safe laser
output performance < 1 mW (Class 2)
and offers a very high optical scatter

Special Feature

Good Vibrations

Dancing Bees Generate Vibrations in the Honeycomb
as a Means of Communication
Honeybees live in colonies containing about 50,000 individuals. We are just beginning to understand the
wealth of information exchange in this “super organism”. Modern measurement methods allow us to signif-
icantly extend our understanding of the use of mechanical signals for communication between honeybees.

Feeding Ground Recruitment                 moving a few bee lengths apart from        ment directly on the honeycomb next
among Honeybees                            each other, whereby different feeding      to a dancer, providing we aligned the
Collecting bees which have discovered      grounds can be shown at the same time.     movement phases of the bee and the
a new feeding ground perform the so-       The enticing signals which these dancers   time window of analysis very precisely.
called bee dance or waggle dance in        emit should only have a short range so     The frequencies caused by the dance
the dark hive. The information on the      as to minimize disruptions to each other   which can thereby be measured are in
geographical position of the feeding       and so as not to attract too many bees.    the range between 200 and 300 Hz
ground is in the time-space construction                                              and produced in pulses of approx.
                                           The Dancer as a Source of
of the dance move. This information is                                                30 – 50 milliseconds in length. These
                                           Honeycomb Vibrations
                                                                                      pulses are generally in the time sequence
transferred during the dance movements     This function is fulfilled by honeycomb    of the abdominal movement so that
from the dancer to the follower bees       vibrations which are generated by the      the reverse phase of the abdominal
which are dancing in direct body           dancers. Measuring these honeycomb         movement is emphasized. This leads
contact with her.                          vibrations has proved to be extremely      to the assumption that an important
The highly complex chain of informa-       difficult, as an active colony generates   role of the movement of the abdomen
tion transmission starts in the hive by    an incredible continuous level of noise.   we can see is to effectively couple the
the other bees noticing a dancer and       Using non-contact laser Doppler vibro-     vibration pulse of the flight muscles to
going to her. Often several dancers are    metry, we managed to make a measure-       the honeycomb.

How Well do Honeycombs Conduct                                                          opposite walls of every individual cell
Vibrations?                                                                             are vibrating in the same direction.
Subject to a few simplifying assumptions,                                               However, in every row of cells, there is
it has been calculated that a dancer                                                    a single cell whose walls vibrate precise-
                                                                                        ly in the counter-phase (vibration node).
exerts a force of a maximum of 1 mN
on the edges of the cells during the                                                    Depending on the position of the exci-
waggle phase. On this basis an expe-                                                    tation point, this cell is between one
riment was conducted in which the                                                       and seven cells away from the point of
edges of the cells of an empty honey-                                                   excitation. It is plausible that the bees
comb were examined while being                                                          standing or walking in the edges of the
excited with this force and the fre-                                                    cells recognize this particular cell and
                                                                                        know it indicates the proximity of a
quency and time pattern as measured
                                                                                        dancer. Because the maximum distance
for the dancers to see how, which and
                                                                                        from which follower bees are still attrac-
how well vibrations are conducted via
                                                                                        ted to the dancer is precisely seven cells.
the honeycomb.
In doing so, it could be seen that the                                                  Conclusions
                                            Figure 2: Measurement results from a
honeycomb best conducts the vibra-          row of adjoining cells. The opposite        Social insects are excellent subjects for
tions in the frequency range examined       walls of the individual cell marked with    study. Understanding their mechanical
as a horizontal shift of the net made       "!” are vibrating in the opposite beat      systems and the evolution of differentia-
up of the edges of cells. A problem                                                     ted meaningful communication signals
appears if one considers that in a noise-   comb vibration itself also offers options   is important. The use of innovative
type excitation as occurs through the       to solve this signal/noise problem.         methods for quantitative acquisition
activity of all the bees on a honey-                                                    of signals and their transmission has
                                            Bees are standing on six feet on the
comb, vibrations of the honeycomb                                                       shown how brilliantly the honeybees
                                            edges of the cells and thus have six
also occur in the transmission range of                                                 have utilized the vibration signals they
                                            sensors working simultaneously. With
                                                                                        produce, the way in which they trans-
the dancers. The signal can thus be         the aid of two identical Polytec OFV
                                                                                        mit such signals via the honeycomb
hidden in the noise. The behavioral         Laser Vibrometer single-point Sensor
                                                                                        and the respective size of the audience
reaction of the bees standing or walk-      Heads, the vibration of the cell edges
                                                                                        for each dancer.
ing near a dancer on the honeycomb          were measured on empty honey-
however shows that the dancer is very       combs in two places at the same time.        AUTHOR
reliably recognized. Apart from the         Thus, it was possible to duplicate what
                                                                                         Prof. Dr. Jürgen Tautz
high probability that in parallel to the    at least two of the six bee legs can
                                            perceive at the same time.                   Beegroup Würzburg
“dance” there are other information                                                      Biozentrum, Universität Würzburg
channels used such as air movement,         It was apparent that at the frequency
                                                                                         97074 Würzburg. Germany
higher body temperature of the dancer,      transmitted best, in a whole row of
and chemical stimulants, the honey-         cells across the entire honeycomb, all

Figure 1: Test setup. The colony is
covered with a clear plastic window
with moveable circular panes. With the
aid of other moveable and transparent
elements and 90° deflecting mirrors,
almost every position on the honey-
comb can be measured without bees
walking into the measurement beam.

Special Feature

Perfect Teeth

Laser Vibrometry Helps to Improve Efficacy in Dental Ultrasonics
Visualizing the motion of dental ultrasonic scalers is challenging due to their high frequency vibrations
and small associated displacement amplitudes. Laser vibrometry has made it possible to study, in
detail, the vibration patterns of dental ultrasonic scaling equipment, and to determine which may
be the most effective designs.

Introduction                              of the patient at home, treatment of         maneuvered over the tooth surface.
Dental plaque is a major factor in the    periodontitis is only possible through       Because of this, the magnitude of the
initiation of gum disease. Plaque may     the thorough cleaning of teeth by a          vibration displacement amplitude has
be removed easily through regular         clinician using hand curettes and anti-      regularly been used as an indicator of
tooth brushing but, if allowed to grow    microbials. Another instrument available     the efficacy of the ultrasonic scaling
                                          to the clinician for tooth debridement       system. The motion of dental ultrasonic
undisturbed, may become mineralised,
                                          is the ultrasonic scaler.                    scalers is difficult to visualize due to
forming a deposit known as calculus.
                                          Ultrasonic scaling units are present in      their high frequency vibrations and
This is a much harder substance, re-
                                          almost every dental practice in the UK.      small associated displacement ampli-
quiring professional intervention by a
                                          Generators drive scaler tips (Figure 1),     tudes. Therefore it is not simple to
dentist for its removal to help prevent
                                          using magnetostriction or piezoelectrici-    determine whether or not the instru-
gum disease. Whereas early gingivitis
                                          ty, to produce tip vibrations in the lower   ments are working correctly or which
may be reversed by improved oral care
                                          kilohertz range (usually 20 – 30 kHz).       may be the most effective designs.
                                                                                       However, laser vibrometry has made it
                                          Laser Vibrometry and Dental                  possible to study, in detail, the vibration
                              Figure 1.   Ultrasonics                                  patterns of dental ultrasonic scaling
                    Selection of ultra-
                 sonic scaler tips used   Ultrasonic scalers remove deposits from      equipment. The laser vibrometer used
                  for removing plaque     tooth surfaces via the mechanical chip-      in our investigations is a PSV-300-F/S
                          and calculus.   ping action of the scaler tip as it is       Scanning Vibrometer system, which

enables us to evaluate the vibration
characteristics of the whole scaler probe.
Initial scans (Figure 2) were performed
on scalers oscillating in an unloaded
environment (in air). The effect of water
flow rate and generator power setting
on tip displacement amplitude was then
evaluated for a range of instruments.
To make investigations more clinically
relevant, scaling instruments were
then scanned while in contact with
tooth surfaces under known loads.
In Figure 3 the displacement data is         Figure 3. Ultrasonic scaler tip vibration data mapped over an image of the scaler.
shown as a color map and in Figure 4
a snapshot from an animated deflection
shape is superimposed over a video
image of the scaler tip. The computer-
generated animation of the vibration
allows tip motion to be assessed quick-
ly and easily. From the data the maxi-
mum vibration displacement amplitude
of a scaler tip is seen to occur at the
unconstrained end of the tip. Further-
more, the scanning laser vibrometer
enables the evaluation of how water
flow, generator power and tip/tooth
contact load affects scaler oscillation
characteristics.                             Figure 4. A snapshot from an animated deflection shape of the vibration
                                             data, superimposed over a video image of the scaler.
Clinical Implications
One of the most significant results of       It is clear that vibration data acquired      Future use of the laser vibrometer in
this work is the high degree of varia-       using laser vibrometry can highlight to       this field may enable new scaler tips to
bility that was observed between tips        manufacturers that the current range          be designed whose vibrations are better
of the same design. New and unused           of ultrasonic instruments exhibit a high      understood, improving clinical efficacy.
scaler tips of the same style will respond   degree of variability. The lack of standar-   Following the successful characteriza-
differently in response to applied load,     dized instrument response makes it dif-       tion of dental ultrasonic scalers, the
an adjustment in water flow rate or          ficult for a clinician to familiarize them-   scanning laser vibrometer has found
generator power setting.                     selves with the instruments properly and      further application for measuring the
                                             this may affect clinical procedures. An       response of endosonic files, ultrasonic
                                             improved scaler tip design, based on the      retrograde tips and even powered
                                             evidence gained through laser vibro-          toothbrushes.
                                             metry, may lead to the manufacture
                                             of instruments with more consistent            AUTHOR
                                             operational characteristics, leading to
                                             improved patient treatment and care.           Dr. Simon Lea
                                                                                            School of Dentistry
                                             Conclusion                                     University of Birmingham
                                             Laser vibrometry has increased current         Birmingham, B4 6NN
                                             knowledge in the field of dental ultra-
Figure 2. The laser from the Scanning        sonics. In particular, this research has
Vibrometer is scanned over the sur-          highlighted the significant variability        dentalultrasonics
face of a dental ultrasonic scaler.          of these instruments.

Special Feature

Rotational Vibrations Unraveled

Using Rotational Vibrometers to Make
NVH Measurements on Combustion Engines
An engine’s combustion process induces rotational inhomogeneity and torsional vibrations in the
drive shaft resulting in unwanted vibrations and noise emission. By examining the rotational move-
ments of the different components, the drive train for the motor vehicle can be optimized to reduce
the unwanted vibrations. Rotational vibrometers using non-contact measurement procedures allow
for a quick and simple examination of the torsional vibrations during operation.

Components in the Combustion Engine         the mechanical effort involved, this      increase the light scatter by applying
A combustion engine contains a large        technique loads the pulley causing a      reflective sticky tape (negligible mass).
number of rotating parts, starting with     change in its mass and the moment of      Measurements with the Rotational
the crankshaft, the camshaft, the drive     inertia. At best, these changes dimin-    Vibrometer
shafts and differential shafts to the       ish the accuracy of the measurement;
                                                                                      Rotational vibrometers measure angular
auxiliaries such as the starter, electric   at worst, they can lead to completely
                                                                                      vibrations on surfaces rotating from
generator and turbo charger. In the         false results.
                                                                                      –7,000 to +11,000 RPM. They sense
following examples, measurements            The Polytec OFV-4000 Rotational           the rotation using the Doppler shifted
on the crankshaft pulley are shown.
                                            Vibrometer makes a simple, non-contact    laser light. The basic principles of rota-
Comparison of Measurement                   measurement that preserves the original   tional vibrometry are explained in the
Procedures                                  mass and moment of inertia. As a          detailed insert contained in this booklet.
The traditional method for measuring        general rule, the surfaces to be meas-    The example in Figure 1 shows simulta-
rotational vibrations uses the angular      ured do not need to be prepared,          neous measurement of two movements
displacement encoder mounted to a           only on material which is highly light-   of the pulley: the rotational vibrations
pulley using an adapter. Apart from         absorbent (black) it is necessary to      are acquired using the OFV-4000

Rotational Vibrometer and the axial
movements of the shaft are acquired
with a Polytec Single-Point Vibrometer.
The measurement data is used to per-
form an order analysis. The orders are
multiples of the rotational speed. If the
engine is turning at 3000 RPM (50 Hz)
then the first order is at 50 Hz, the
second order at 100 Hz and so on.
If the signal power of the rotational
vibration is plotted against the rota-
tional speed and frequency (spectro-
gram shown in Figure 2), then you can
see that the maxima occur primarily
at a resonant frequency of 490 Hz.
The corresponding order spectrum
(Figure 3) shows that in the RPM             Figure 1: Measurements of rotational vibrations and out-of-plane vibrations
range between 1000 RPM and 6000              on a crankshaft pulley
RPM, primarily resonances of the 6th,
8th and 10th order are excited.              attained using the filter setting FAST in    CONTACT
                                             which the discontinuities and disruptions
Signal Quality                                                                            Dipl.-Ing. Andreas Dittmar
                                             shown in the example on the left side
The OFV-4000 Rotational Vibrometer           (Filter setting SLOW) are filtered out.      IAV GmbH Chemnitz
offers you the option of conditioning                                                     09120 Chemnitz, Germany
the input signal using a tracking filter
                                             The Rotational Vibrometer is very easy
to improve the high-frequency carrier
signal. It is particularly suitable for      to use, has a high optical sensitivity
bridging short dropouts which can            and maintains a large dynamic range.         About IAV Group
occur during rotational measurements         No adapter or flange is necessary for        Ingenieurgesellschaft Auto und Ver-
due to the speckle effects of the re-        making measurements, leaving the             kehr offers the automotive industry
flected light. This effect is in principle   object under examination unaffected.         the full spectrum of hi-tech engi-
better with a larger time constant           The Rotational Vibrometer prevents           neering. IAV's activities encompass
(SLOW) but when tracking highly              stoppage time which occurs when              production vehicle development,
dynamic signals you have to switch           using contact processes. In the car          advanced engineering as well as in-
to FAST. The most favorable setting          industry it supports the development         company basic research. In addition
is often found by trial and error and        of torsional vibration dampers and           to its headquarters in Berlin, IAV
varies from case to case.                    helps solve all kinds of rotational          also operates from other locations
                                             vibration problems.                          in Europe, USA and Brazil. See
In Figure 4 the right picture shows
                                                                                 for further information.
how a smoother signal progression is

Figure 2: Spectrogram graph of the           Figure 3: Order spectrum of the rota-       Figure 4: Application of the tracking
measurements on the crankshaft               tional vibrations                           filter

Product News

Scanning Vibrometry:
New Milestones

Enhanced Hardware and Software Open Up New Possibilities
in the Area of Surface Vibration Measurement
The new eight-channel PSV-400 data acquisition system and the greatly enhanced PSV Scanning
Vibrometer Software are powerful tools that simplify experimental modal analysis. With newly
designed, intuitive and simple handling of geometry data MIMO measurements can be significantly
improved. For large objects, 3-D measurement of the vibration dynamics of the entire surface can be
made in pieces, with different views, and then stitched together to make a global data set that can
be visualized together. Once again, Polytec takes non-contact vibration metrology to the next level.

Eight-Channel Data Acquisition for MIMO Measurements                              MIMO is a measurement method in
                                                                                  which energy is introduced simultane-
An 8-channel data acquisition system   optional for the PSV-400-H4 Scanning       ously into a test structure at multiple
is now standard equipment on the       Vibrometer. Of these eight channels        points (Multiple Input) while the
PSV-400-3D Scanning Vibrometer and     three are taken by each of the vibrom-     system response is acquired at differ-
                                       eter heads leaving five measurement        ent sample points on the structure
                                       channels available for parallel acquisi-   (Multiple Output). Thus, a matrix of
                                       tion of reference signals such as load     transfer functions can be determined
                                       cells (seven available for the PSV-400-    between all power flows and sample
                                       H4). This provides completely new          points. MIMO measurements are
                                       possibilities for Principal Component      made
                                       Analysis (PCA) within the framework of       on large structures to be able to
                                       MIMO (Multiple-Input-Multiple-               couple more measurement energy
                                       Output) measurements.                        into different areas of the structure,

  where resonances fall very close                                                       .svd files. The Frequency Band Definition
  together (degeneration) so that                                                        can be extracted (“Save As...”) or
  superimposed modes can be                                                              dragged using Drag & Drop into an
  uniquely identified.                                                                   open frequency band editor.
Both the PSV-400-H4 and the PSV-400-                                                     PDA remote control
3D have up to four different internal
                                                                                         As of now a PDA (mobile handheld
generator channels available and now
                                                                                         computer) can be used to remotely
have the required number of reference
                                                                                         control the PSV software. The PDA
channels. Determining the FRFs (Fre-
                                                                                         thereby supports the same functions
quency Response Functions) is done
                                                                                         as the handset PSV-Z-051. The con-
directly in the PSV software so that only
                                                                                         nection with the PSV PC is made
the complete MIMO FRF matrix is
                                                                                         using WLAN.
exported into a downstream modal
analysis system.                                                                         Eight channel signal processing

PSVSoft Release 8.3                                                                      The 8-channel data acquisition men-
                                                                                         tioned before is fully supported by
The Scanning Vibrometer Software                                                         the new software release,
represents the “Intelligence” of the                                                     including user-friendly
vibrometer system and guides all            Simplified handling of geometry              management and
measurement, control, regulation and        data and measurement points                  configuration options
analysis tasks in the data acquisition      The 3-D geometry view is now available       for all measurement
system.                                     in acquisition mode so that the meas-        channels.
The PSV software has significantly          urement grid can be spatially visualized
expanded and improved the data              before making the vibration measure-          How do You Get
acquisition, analysis and presentation      ment (by using 3-D coordinates). Fur-         the Most from the
modes with the release of version 8.3.      thermore, by using specific color codes,
Numerous requests and suggestions           the status of a geometry or measure-
from the user community have been           ment point can be clearly shown with          As a user with a service agreement,
incorporated in the new release to make     regards to geometry acquisition, focus        Polytec will make the new software
surface vibration measurements even         and vibration measurement. The sample         available to you directly. Please note
more powerful, easier and more user-        points can now be selected according          that within the framework of the
friendly. Among other things, the fol-      to their status and their point numbers       new Uni-Vib program, Polytec is also
lowing performance characteristics have     and, then, modified through diverse           making the respective current releases
been implemented in version 8.3:            processing methods. Thus, for example,        of the PSV software available to users
                                            certain points can be selected, blocked       in university groups free of charge.
Bringing measurement data together
                                            or renumbered for geometry acquisition,       Please contact us for specific details.
The 3-D vibration dynamics acquired
                                            focus definition or vibration measurement.    If you are an end user and want to
in several individual measurements on
                                                                                          use the attractive new performance
large spatial structures can now be         Management of settings, browser
                                                                                          features in the current software
grouped together directly in the eva-       upgrades
                                                                                          release, but do not yet have a serv-
luation mode of the PSV software to         A project-oriented work sequence is           ice agreement with Polytec, then
form a global data set (3-D geometry        made significantly easier by the newly        please contact us as soon as possible.
and 3-D vibration data). This can then      designed filing system which places           As part of our commitment to you,
be analyzed, visualized and exported,       settings and measurement files in a           we will outline the attractive advan-
allowing simple and intuitive access to     common location (e.g. in a project            tages of our service concept and
the whole 3-D structural dynamics and       folder). Settings can now be filed in         make you an offer tailored to meet
contributing towards simplified data        any directory. The PSV browser uses a         your requirements.
analysis.                                   tree structure to allow the hierarchical
                                                                                          For more information about Polytec
The example shows an operational            access to the settings from settings          MEHR INFO?
                                                                                          Scanning Vibrometers please visit us
deflection shape of a car body that has     and measurement files. In addition,
                                                                                          on the Internet at
been stitched from 10 data sets and         the browser also shows the Frequency
has about 3000 measuring points.            Band Definition in the tree structure of


On the Spot with Cutting-Edge Products
Polytec is there! – trade fairs, conferences, user meetings and road shows are opportunities where
Polytec shares its unique expertise in vibrometry with customers and specialists all over the world.

  MEMS Workstation
  Seminar Series
  On April 6th, Polytec, Inc. and
  The Micromanipulator Co. (TMMC)
  began a six-stop seminar series to
  introduce the new MSA-400 Micro
  System Analyzer for dynamic MEMS
  characterization coupled to a high
  performance probe station from
  TMMC. This combination is known
  as a MEMS workstation and allows
  the user to characterize MEMS
  dynamics, position the device with
  motorized translation stages, work
  on wafer level or packaged devices,
  and utilize a variety of probes for
  electrical and mechanical stimula-
  tion. The first seminar was in Irvine,   North American Tradeshows
  CA followed by Dallas, TX on May
                                           The intense 2005 event schedule           with Geometry Scan for large object
  18 and Boston, MA on June 30.
                                           included Smart Structures/NDE in          experimental modal analysis, the
  The final three seminars will be
                                           March, Quality Expo in April, AISTech     MSA-400 Micro System Analyzer for
  September 23 in Sunnyvale, CA
                                           in May, SAE Noise and Vibration in        dynamic MEMS characterization, and
  at the North American Vibrometer
                                           May, Semicon West in July and Mech-       the TMS-300/320 Scanning White
  Users Meeting, October 25 in
                                           anics of Hearing Workshop in July.        Light Interferometer for precision
  Detroit, MI and November 16 in
                                           Polytec’s outstanding products were       machined part inspection.
  the Baltimore/Washington D.C.
                                           enthusiastically received including new   Information on upcoming tradeshows
  area. For more info visit
                                           products such as the PSV-400-3D Three-    is available on
                                           Dimensional Scanning Vibrometer

2005 North American Vibrometer Users Meeting
The North American Vibrometer Users Meeting will be
held at the Four Points by Sheraton in Sunnyvale, CA on
September 20 -23. This will be an exciting event featuring
both a two-day software training class and a two-day
technical seminar. The Users Meeting commences with
the two-day scanning vibrometer software training class
on September 20 – 21. This training is a first for North
America. Often requested by our users, the training has
become necessary due to the growing complexity and
sophistication of the software and the intended applica-
tions. The technical seminar follows the software training
and features many invited speakers discussing their appli-
cations on September 22 – 23. For complete info:

                                                                                      UK Vibrometer
                                                                                      Users Meeting
                                                                                      On November 22nd and 23rd the
                                                                                      UK Vibrometer Users Meeting will
                                                                                      be held at the Photonics Cluster site
                                                                                      on Aston Science Park in Birming-
                                                                                      ham. The first day will cover users'
                                                                                      work with vibrometers in the fields
                                                                                      of automotive development and
                                                                                      testing, microstructures (including
                                                                                      manufactured and natural structures),
                                                                                      the analysis of acoustic and ultra-
                                                                                      sonic waves in fluids (including air),
                                                                                      plus other vibrometry applications.
                                                                                      Day two will be a technology day,
                                                                                      covering the hardware and software,
                                                                                      methods and practices that make
                                                                                      Polytec vibrometers so powerful and
                                                                                      useful in vibration measurement.

2005 German Tradeshows and TechDays                                                   Information
Polytec’s non-contact 3-D vibrometer      the 2005 Sensor Innovation Award for        Storage Week 2005
technology attracted numerous automo-     developing this outstanding technology
                                                                                      in Tokyo
tive experts attending the Automotive     at Sensor+Test 2005 in Nuremberg
Testing Expo in Stuttgart and the Laser   (see page 2).                               Information Storage Week (ISW 2005)
2005 Exhibition in Munich. In addition,   Also highlighting Sensor+Test 2005 was      is the largest data storage conference
Polytec visited four of Germany’s best-   the new LSV-300 Laser Surface Veloci-       and exhibition in Japan. It draws the
known car manufacturers and presented     meter. Featuring high performance           top professionals in the data storage
special Automotive TechDays on-site.      laser-Doppler based velocity and length     industry to the world-class sessions
These events have become an important     sensing technology, the LSV-300 is          and exhibits. As a pioneering data sto-
forum for our experts to learn about      offered at an extremely attractive price/   rage test and measurement company,
the requirements our current and          performance ratio.                          Polytec exhibited several innovative
future vibrometer users need in next      Its versatile interfaces                    instruments including the PSV-400
generation products.                      enable a simple and rapid                   Scanning Vibrometer, the MSV-400
Polytec premiered the new MSA-400         integration into typical                    Microscope Scanning Vibrometer and
Micro System Analyzer to Europe at        production processes.                       the VDD Digital Vibrometer, the latter
Control 2005 in Sinsheim and received                     operates at the threshold range of
                                                                                      data storage performance by utilizing
                                                                                      the latest technology in digital signal
Third Vibrometry Seminar in Korea                                                     acquisition and processing. This ex-
                                                                                      hibition was complemented by a cor-
In March, Polytec’s Korean representative had its Third Vibrometry Seminar en-        porate seminar named “Targeting the
titled “Advancing Laser Vibrometry”. It attracted over 60 participants from indus-    Limits of Laser-Doppler Vibrometry”
try and research including large computer and car manufacturers (GM Daewoo,           which taught about 20 participants
Samsung, LG). Presentations covered the basics of heterodyne demodulation
                                                                                      about the technology and the usage
as well as live demonstrations of the PSV-400-3D Scanning System and the
                                                                                      of Laser-Doppler Vibrometers.
MMA/MSA product line The success of this seminar has resulted in a planned
4th seminar entitled “Modal Analysis and Micro World”.

Polytec Representatives
For Polytec’s Global Sales Offices please see Back Page

Australia and New Zealand             Italy
Warsash Scientific Pty Ltd            BPS s.r.l. (Vibrometers)
Fax ++61-2-9318-2192                  Fax ++39-02-339 12 334     
Austria, Hungary, Slovenia, Czech     Sensortech S.r.l. (LSV)
Republic, Slovak Republic, Romania,   Fax ++39-02-9673-2431
Croatia, Yugoslavia         
LB acoustics Messgeräte GmbH          Korea
Fax ++43 1 2593-444 3400              Hysen Corp. (Vibrometers)         Fax ++82-31-728-0049
Belgium, The Netherlands and
Luxembourg                            VIGtools Co. Ltd. (LSV)
K. Peeraer B.V.B.A.                   Fax ++82-2-456-4369
Fax ++32-3-232-8098         
Brazil                                Acoutronic AB
Parstec Comércio de                   Fax ++46 - 227 285
Equipamentos Ltda.          
Fax ++55-16-3307 5327
                                      Energocontrol Spólka z o.o.
China (P.R.) and Hongkong             Fax ++48-12-411 07 11
Pacific Optoelectronic Inc. 
Fax ++86-10-6568 8291
                                      Octava+, Ltd.
                                      Fax ++7-095-799-90-93
LOKE Engineering (LSV)      
Fax ++86-21-68690 054
                                      Singapore, Thailand, Malaysia,
                                      Philippines, Vietnam, Indonesia,
Fax ++86-10-8580 1235
                                      Myanmar, Laos, Cambodia
                                      Millice Private Limited
Denmark                               Fax ++65-6552-7311
B&L Butina & Larsen technic 
Fax ++45-4970 7590
                                      South Africa
                                      K. Peeraer B.V.B.A.
Finland                               Fax ++27-12-362 5087
Cheos Oy                    
Fax ++358-201 986465
                                      Spain and Portugal
                                      ALAVA Ingenieros S.A.
Greece                                Fax ++34-91-570-2661
Paragon Ltd.                
Fax ++30-210-222-0019                 Fax ++34-93-459-4262          
India                                 Sweden
Techscience Services PVT LTD          Alvetec AB
Fax ++91-44-2231-1264                 Fax ++46-8-445-7676         
A. O. Ezra Electronics 2002
Fax ++91-44-2231-1264
Fax ++972-3-5525169
     Rep71y 850-183014-320
FAX tates: +1 49 7243 6
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                                 2nd – 6th Prize

                     1st Prize

                                      7th – 16th Prize

  ■ Yes,              I want to participate in the Polytec contest.

            What is the Maximum Vibration Velocity that can
            be Measured with the current Polytec Vibrometers?

            The right answer is _____________________.     (see back page)
                                                                                                Watch & Win with Polytec!
                                                                                                                                                                                                            Polytec GmbH (Germany)
                                                                                                                                       2nd – 6th Prize                                                      Polytec-Platz 1-7
                                                                                                                                                                                                            76337 Waldbronn
                                                                                                                                                                                                            Tel. + 49 (0) 7243 604-0
                                                                                                                                                                                                            Fax + 49 (0) 7243 69944
                                                                                                                     1st Prize                                                                    

                                                                                                                                                7th – 16th Prize
                                                                                                                                                                                                            Polytec-PI, S.A. (France)
                                                                                                                                                                                                            32 rue Délizy
                                                                                                Win a 20 GB iPod Color, a Laser                        iPod benefits from sophisticated hard disk drive     93694 Pantin
                                                                                                                                                       technology made possible with Polytec vibro-         Tel. + 33 (0) 1 48 10 39 34
                                                                                                Pointer Pen or a CityBag!                              meters! Interested in an exciting chance to win an   Fax + 33 (0) 1 48 10 09 66
                                                                                                All Polytec vibrometer users are winners – every       outstanding prize just for you? Here’s the deal.
                                                                                                day, creatively using our versatile, simple-to-use,    Watch our new corporate video and see if you
                                                                                                high performace vibrometers – even the famed           can find the answer to the following question:       Lambda Photometrics Ltd.
                                                                                                                                                                                                            (Great Britain)
                                                                                                What is the Maximum Vibration Velocity that can be                                                          Lambda House, Batford Mill
                                                                                                Measured with the current Polytec Vibrometers?                                                              Harpenden, Herts AL5 5BZ
                                                                                                                                                                                                            Tel. + 44 (0) 1582 764334
                                                                                                You can find the video on the CD that is attached and your comments. We will put the names of               Fax + 44 (0) 1582 712084
                                                                                                to your copy of the LM Info Special or you can view all respondents into a drawing for an Apple iPod,
                                                                                                it on our web site.                                 five Laser Pointer Pens and ten CityBags.
                                                                                                Please use the fax feedback form inside this issue     Please note the deadline for a response is           Polytec KK (Japan)
                                                                                                or our feedback web page              December 1st, 2005. Thanks in advance for            Hakusan High Tech Park
                                                                                                usa/contest to send the answer to the question         your comments!                                       1-18-2 Hakusan, Midori-ku
                                                                                                                                                                                                            Yokohama-shi, 226-0006
Technical specifications are subject to change without notice. LM_IF_Special_2005_02_7.500_US

                                                                                                Trade Fairs and Events – Laser Measurement Systems                                                          Tel. +81 (0) 45 938-4960
                                                                                                Reference our web site for the most up-to-date information and links                        Fax +81 (0) 45 938-4961
                                                                                                on trade fairs and events!                                                                        

                                                                                                 Sept 17 – 20, 2005     IEB Inner Ear Biology Workshop 2005              Tübingen, Germany                  Polytec, Inc. (USA)
                                                                                                 Sept 20 – 21, 2005     Diskcon 2005                                     San Jose, CA, USA
                                                                                                                                                                                                            North American Headquarters
                                                                                                 Sept 20 – 23, 2005     US Vibrometer Users Meeting                      Santa Clara, CA, USA
                                                                                                                                                                                                            1342 Bell Avenue, Suite 3-A
                                                                                                 Sept 27 – 29, 2005     MesurExpo 2005                                   Paris, France
                                                                                                                                                                                                            Tustin, CA 92780
                                                                                                 Sept 27 – 29, 2005     MeasComp 2005                                    Wiesbaden, Germany
                                                                                                                                                                                                            Tel. +1 714 850 1835
                                                                                                 Oct 05 – 06, 2005      Japan Modal Analysis Conference                  Tokyo, Japan
                                                                                                                                                                                                            Fax +1 714 850 1831
                                                                                                 Oct 05 – 06, 2005      Vibrometer User Meeing Sopemea                   Vélizy, France
                                                                                                 Oct 11, 2005           SIMTEC Journée Test & Mesure                     Nancy, France
                                                                                                 Oct 17 – 19, 2005      Noise-Con 2005 and ASA Meeting                   Minneapolis, MN, USA
                                                                                                                                                                                                            Midwest Office
                                                                                                 Oct 25 – 26, 2005      Astelab 2005                                     La Défense, France
                                                                                                 Oct 26 – 28, 2005      Automotive Testing Expo US                       Detroit, MI, USA
                                                                                                                                                                                                            3915 Research Park Dr.,
                                                                                                 Nov 03, 2005           Engineering Integrity Society Meeting            Coventry, UK                       Suite A-12
                                                                                                 Nov 05 – 11, 2005      ASME Congress and Exposition                     Orlando, FL, USA                   Ann Arbor, MI 48108
                                                                                                 Nov 08 – 10, 2005      Aerospace Testing Expo US                        Long Beach, CA, USA                Tel. +1 734 662 4900
                                                                                                 Nov 09 – 11, 2005      Micromachine 2005                                Tokyo, Japan                       Fax +1 734 662 4451
                                                                                                 Nov 22 – 23, 2005      Vibrometry User Group Workshop                   Birmingham, UK
                                                                                                 Jan 21 – 26, 2006      Photonics West 2006                              San Jose, CA, USA                  East Coast Office
                                                                                                 Jan 22 – 26, 2006      MEMS 2006                                        Istanbul, Turkey                   25 South Street, Suite A
                                                                                                                                                                                                            Hopkinton, MA 01748
                                                                                                                                                                                                            Tel. +1 508 544 1224
                                                                                                                                                                                                            Fax +1 508 544 1225

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