Cambridge Ultrasonics participated in the Cambridge Technology Exchange event on 24th May. The event aims to promote business contacts with the high technology businesses growing around Cambridge and with Cambridge University. We shared the stand with one of our clients - Marconi Applied Technology.
There are two reasons for participating:
Our clients include: oil majors, oil service companies, manufacturers of ultrasound equipment, communications companies, makers of coin recognition systems, UK government agencies, nuclear industry, universities, standards agencies. Recent experience shows that the life/biological sciences have a need for new products with ultrasonic functionality.
The common theme to our work is helping
our clients to innovate. We specialise in applying ultrasound
in novel or unconventional ways. By way of comparison, conventional
ultrasound businesses (NDT for example) want to sell systems based
upon their existing range of products, possibly customising them
to add value, so the range of innovation they are prepared to
offer is often limited. 
Cambridge Ultrasonics offers something different - we are often asked to go right back to first principles, to the physics of what our clients want to do. We take ideas and look into the physics to assess feasibility. It’s very much in the Cambridge-science model and Cambridge PhDs with many years of experience are the core of our personnel.
We often work with our clients’ R&D departments to leverage their expertise. However, we are happy to take a project right through to working prototypes on our own.
As well as bringing skills in ultrasound engineering and the supporting physics we can also provide: mathematical modelling, numerical modelling (Matlab, Mathcad and FE), development of signal processing, software engineering (C++ and Visual Basic), analogue circuit design (SPICE), digital circuit design and systems design. We also have equipment we have developed ourselves that renders visible ultrasonic waves, which we use regularly in developing ultrasonic systems (see example figures) - we believe this is a unique commercial service in the UK.
If you feel your business would benefit from more experience and knowledge of ultrasonic functionality then please contact us.
Ideas - we are a source of ideas and innovation
from the perspective of ultrasonics, physics, electronics and
software.
Brainstorming - we apply our knowledge and experience to your
problems in short sessions, leveraging the skills in your R&D
department. This is a low-cost way to get a project moving.
Feasibility analysis - we take initial ideas and go away and think
about them. We will do calculations and preliminary design work
then prepare a report. Save money early on in a project using
our experience and expertise.
Feasibility tests - we put together a quick prototype or a model
and evaluate it. Our schlieren visualization service can be used
to get quick results in many applications involving ultrasound
- this is a unique commercial service in the UK.
Transducer design - we can write target specifications, design
transducers for a specific applications and build prototypes.
You may have a transducer that doesn't work properly - we can
debug it for you.
Systems design - transducers need drive signals, drive amplifiers,
receiver amplifiers, signal processing and information needs to
be displayed. We can design all the elements in the chain to whatever
level of detail you require - we will stop at the point your R&D
department wants to take over.
Transducer investigation service - in one day our schlieren service
can give you an insight into the operation of your transducers
that you won't get by any other method. It is quite simply one
of the best ways to check the performance of your transducer at
low-cost.
Lectures - we give lectures on ultrasound brimming with practical
demonstrations that bring your staff up to speed quickly on the
fundamental principles of ultrasonic waves and inspection systems
of all kinds. Our schlieren visualization system is portable and
we can bring it to you and incorporate it into the lecture (see
our web-site for examples www.cambridge-en.com). We can even put
your transducers into the visualization equipment and see how
they are working.
Ultrasound is used to cause agitation in liquids and powders in processing technology. Significant power levels are needed so continuous ultrasound is used. Ultrasound can be used to nebulise liquids, it can also be used to trap and separate particles in a standing wave. High power ultrasound, at a frequency of approximately 40 kHz, can be focussed to a point using an acoustic lens, where the intensity can be sufficiently high to weld plastics. High power ultrasound is used to agitate sieves, increasing the rate of powder sieving in the manufacture of pharmaceutical products. Probably the most commonly used ultrasonic instrument in this field is the cleaning bath. It is a simple container filled with a liquid, usually water, and agitated by ultrasonic transducers attached to the outside of the bath. The working frequency range is 20 kHz to 150 kHz. The drive frequency, amplitude and cleaning time can be adjusted. Cleaning is caused by motion of the liquid or by more aggressive cavitating bubbles. During cavitation a bubble collapses and it can create an erosive, microscopic water-jet.
The presence of an ultrasonic field can affect chemical reactions: it can accelerate the rate of reactions that occur in its absence and it can enable reactions to occur that otherwise would not happen. The latter is classed as sonochemistry.
Sononchemistry is closely related to sonoluminescence, which is the emmission of light when a liquid has an intense sound field in it. Sonochemistry occurs if there is an ultrasonic field with a frequency of approximately 300 kHz and the intensity is sufficiently great to cause cavitation. The liquid must also contain an inert, monatomic gas such as Argon. When a liquid cavitates it forms vapour bubbles. The bubbles collapse quickly as the pressure changes to compression and this is believed to be the cause of both sonoluminescence and sonochemistry. Bubbles collapse in about 1 us and pressures and temperatures as great as 5 x 108 Pa and 104 K have been measured. Temperatures of 103 K would be sufficient to account for some of the sonochemical effects reported so sonochemistry and sonoluminescence are believed to be thermochemical effects, caused indirectly by the high temperatures in the collapsing bubbles. Sonochemical effects are generally absent without the presence of the inert, monatomic gas mentioned earlier. Monatomic gases have higher ratios of specific heats (1.33 to 1.67) than either diatomic or polyatomic gases and therefore a collapsing bubble of a monatomic gas generates the highest temperature of any gas. Short duration spectroscopic analysis has shown there are generally two components in sonoluminescence: an infra-red component associated with black-body radiation, allowing temperature to be estimated and spectral lines associated with excited states of some active chemicals. Pressure broadening of the spectral lines is the basis of the pressure measurement.
Cambridge Ultrasonics has been helping the
Institute of Physics East Anglian branch (IoP EA) promote physics
with the public. On 20th December at the Cavendish Laboratory
(Cambridge University’s physics department) the IoP EA ran
three events on the same day: a lecture by David Andrews of Cambridge
Ultrasonics on the uses of ultrasound, an exhibition of robots
from the BBC TV series Robot Wars and a quiz game called Call
My Bluff - In Physics with a panel of celebrities. 
David Andrews’ lecture presented experiments with participation from children in the audience. It culminated in visualizing the ultrasonic waves from a medical, phased-array transducer of 128-elements. It showed how the waves could be brought to a focus and scanned to make an image. The scanner was then tried on a Buzz Lightyear toy inside a water-filled balloon to show how foetal scanning works. David Andrews was helped by Jeff Bamber of the Royal Marsden Hospital and Suk Pannu of Marconi Data Systems as well as members of the audience. Accuson helped transport their scanner as well as demonstrating a second scanner in the exhibition.
About 400 people came, which was the capacity of the lecture theatre. The head of the Cavendish, Professor Longair, who also helped on the day, invited the IoP EA back for Christmas 2001
In September Cambridge Ultrasonics will be providing a demonstration of its ultrasound visualizing experiment for 2000 A-levels students as a part of a 3-day event called Physics at Work.
We also manage the new IoP EA web site: www.iop-eastanglia.org as well as creating their posters. The robot image was created as a 3-D computer model and then rendered. Similar procedures were used for the crystal ball for the "Seeing into the future" event.
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The plan for the future of Cambridge Ultrasonics is to convert our considerable knowledge and reputation in the field of inspecting concrete into new products and services in a spin-off company. There are several business opportunities before us (Spring 2001) but to exploit them we need an injection of capital. With this capital we can grow the new business.
We expect to see exponential growth in turnover starting in 24 months time, which should be sustained for several years thereafter with the products we want to make and sell now. Demand to buy these new products and services, which we alone could deliver, has been growing and it is now higher than ever before. We have potential purchasers who want to evaluate with a view to buying now.
A large manufacturer of industrial ultrasonic inspection equipment, wants to sell our products throughout the world. The same company wants to be a major shareholder in the new business.
Our reputation, or brand image, in the field has been developing steadily over the last ten years. We are perfectly positioned to exploit this opportunity.
Our reputation is definitely in the public domain but key components of our know-how are not. One of the first steps we take will be to file patent applications on those key components. These patents will immediately add value to the business.
We want a partnership with private investors, institutional investors and corporate investors who would like to provide business capital and share in the opportunity to grow the business.
Investors who seek to make a capital gain over a period of two to five years should be able to sell their shares within this time for a substantial gain reflecting the increased value of the business.
It is possible that we will receive offers to license our products or to buy certain product lines. Since the skills we are bringing to the new business is in developing new products rather than providing an international distribution and marketing chain we will look favourably on partnerships that allow us to focus on what we do best.
Investors seeking a longer period of growth can expect more new products and services to emerge.
The market for industrial inspection does not have the same annual growth as, say, the communications industry did in 1999/2000. One benefit of the industrial inspection market is that it is not as volatile as other sectors such as e-commerce or the communications industry in 2001. But the new products and services we will develop and sell are expected to result in growth that out-performs the average for industrial inspection.
We are preparing a confidential business
plan for the offer. If you would like to receive a copy then please
register your interest by e-mailing: 
.
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Our web-site www.cambridge-en.com contains information about our range of services and it has back issues of Innovation News.
Our Hot Hints section is proving to be very popular so if you want to find out what other hot hints we have revealed then look on the web-site.
The web-site has some video sequences taken using our schlieren visualizing equipment. So if you have never seen ultrasonic waves in motion before - this is the easiest way to get started.
Waves can be used to carry information. Ultrasound and electro-magnetic waves are the two commonest waves used by man for carrying information. The same theory of encoding information applies to both types of wave but it has found more applications with electro-magnetic waves than with ultrasound.
Figure 1 shows a carrier wave passing a point in space. The wave is called the carrier because it carries the information as a code or modulation - a wave of a single frequency has constant frequency and amplitude, it lasts forever and carries no information. A simple form of modulation is Morse code (see figure 2) - switching the carrier on and off. This is the form of encoding that is effectively used in many non-destructive testing (NDT) applications of ultrasound, when a flaw has to be detected. The problem is to decide when the carrier is on and when it is off.
A more modern form of modulation is called amplitude modulation (AM). Most radios receive AM stations on Medium wave and Long wave. Let's suppose the information (the modulation signal) we want to send is in figure 3. The modulation is used to vary the amplitude of the carrier - see figure 4. AM signals after de-modulation are the basis of most ultrasonic imaging systems, such as the B-mode sector scans familiar from medical scanners.
Another kind of modulation used with radio is to keep the amplitude constant but instead vary the frequency of the carrier; it's known as frequency modulation (FM). This has the advantage of low-noise after reception, because most propagation disturbances affect the amplitude and not the frequency. Figure 5 is the FM equivalent of figure 3. There are very few applications of FM in ultrasound technology despite the advantages it offers. Cambridge Ultrasonics has used linear sweep frequency chirp signals, a combination of FM and Morse code, in systems it has developed for inspecting concrete.
Three numbers are needed to describe a wave: frequency, amplitude and phase. We have seen applications of coding information using frequency (FM) and amplitude (AM and Morse). Phase modulation lends itself to digital communications when a restricted number of phase changes are used - this is the basis of digital mobile telephone technology. There are a few applications of phase change detection in ultrasound, for example phase changes from the echoes from crack-tips are used to estimate the size of the cracks in some advanced nuclear inspection systems.
How do receivers get rid of the carrier and get back to the original modulation? Firstly, the receiver has to create a copy of the carrier then compare it with the signal received. The way the comparison is made depends on whether its AM, FM or one of the other methods used for modulation.
With AM the simplest thing to do is multiply the received wave with the local carrier wave (figure 6). Can you see that multiplication results in two waves: one is the difference of the two carrier frequencies before multiplication (modulation frequency) and the other is the addition of the two carrier frequencies? That's why the carrier looks like it's frequency has doubled. Then we pass the wave through a filter to block the high frequencies (the doubled carrier) and let through the low frequencies (the modulation). After filtering we get figure 7 - we have got back to the modulation signal. Compare figure 3 with figure 7: the recovered amplitude is a constant scaling factor multiplied by the modulation signal; the frequency is the same; there is a phase shift in this example caused by the filter (not normally a problem). It takes the filter a short time to respond to the input signal (particularly in this case - why?) so the early time gets distorted in this example.
There is much to be learnt from other fields and applied successfully when designing ultrasound systems. At Cambridge Ultrasonics we follow developments in radar, sonar and medical ultrasound, looking for ways to apply the principles to give our clients’ innovative solutions.
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