Reliably handling demanding acoustic tasks

Acoustic optimization of loudspeakers

Sound quality is the focus of any loudspeaker development operation – and the membrane’s properties are crucially important in this regard. With their linear frequency response that extends far beyond the audible range, Scanning Vibrometers are hugely beneficial in loudspeaker design. Non-contact measurements guarantee undistorted measurement data across the entire frequency range, thereby enabling clear interpretation of the results of sound pressure level (SPL) measurements and hearing tests. Polytec’s measuring technology offers you unique ways of analyzing dynamic loudspeaker characteristics, whereby you can also include the interaction with the surrounding components. Scanning Vibrometers from Polytec - collecting areal 3D measurement data of entire loudspeaker panels -  have proven their worth with all major loudspeaker manufacturers.

Development tools for musical instruments

Musical instruments generate wonderful, inspiring sounds through their vibrations. For many years now, Polytec laser vibrometers have been helping to describe and shed light on this phenomenon during development and sound engineering. Vibrometers help in the acoustic optimization of violins, harpsichords, guitars, pipe organs or even steelpans. Understanding the vibrational character and resonances of musical instruments is key for optimizing and shaping the instruments very own character. Even “secret sounds” can be unveiled through testing with this measuring technology.

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Optical measurement for developing ultrasonic devices

Safety is the top priority in medical technology. Consequently, complete documentation of the development stages is indispensable for producing good products and providing legal certainty. Laser vibrometers are therefore extremely important in the development and quality assessment of medical instruments, such as dental or surgical ultrasonic devices and imaging methods. The efficiency and safety of healthcare products, such as inhalators, respirators and toothbrushes, can also all be improved by carrying out measurements with Polytec vibrometers. Laser vibrometers have also become indispensable for the development, inspection, calibration and certification of middle ear implants and implantable hearing aids.

Ultrasonic energy has to get to where it’s needed in medical devices. Polytec’s PSV Scanning Vibrometer quickly and clearly illustrates how energy is distributed by ultrasonic actuators and thus speeds up the development process. Localization of a particular operating frequency’s vibration nodes allows you to optimize the design and thereby reduce energy dissipation. Thanks to the high spatial resolution and measurement accuracy in the picometer range, high-frequency deflection shapes are quickly and reliably visualized too.

Laser vibrometry is the decisive key technology in the design and development of medical ultrasonic instruments. It is the ideal tool for verifying FE simulations – both for invasive and diagnostic medical ultrasonic instruments. Thanks to its linearity well into the high MHz range and the complete lack of feedback effects, coupled with high lateral resolution, this technology is suitable for nearly all structural dynamic tasks. Calculation methods derived from the basic technology for sound field visualization and for durability (strain / stress) open up further applications. Consequently, laser Doppler vibrometry is a tool suited to the development of efficient, reliable and effective instruments for the doctor and the researcher.

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Optimizing sensors for imaging ultrasonic measurement instrumentation

Nowadays an increasing number of micro-manufactured sensors, actuators and components vibrate at frequencies in the high MHz range. These include, for example, ultrasound sensors or transducers as used for imaging in medical applications. To test the functionality of these components, to check existing simulation models and to optimize the design of the systems, you have to measure their dynamic behavior. Laser Doppler vibrometry is one of the few available solutions for this. It allows for non-contact characterization across all frequencies – even for broadband excitation. The deflection shapes can be visualized in an impressive way. Crosstalk in arrays can be recorded and graphically illustrated, just like the timing of the individual array elements. Even transients and relaxation behavior can be examined with ease.

Being an optical measurement method, laser vibrometry also enables you to perform measurements through transparent liquids, so ultrasonic transducers can be characterized in the actual application-oriented loading case. With the UHF-120 Vibrometer from Polytec, you can determine the behavior of samples vibrating at frequencies of up to 2.4 GHz with relative ease and great precision. The small amount of time required for the measurement is a significant advantage of the measuring method that can be decisive in the development process in particular. As an alternative to measuring the three-dimensional sound field using a noise sensor installed in the room, you can now determine the resulting sound field simply with one or more scanned measurements and the subsequent simulation.

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Efficient ultrasonic validation and testing

Laser Doppler vibrometers help you to develop efficient tools for ultrasonic processes. The LDVs from Polytec are indispensable for FE model validation and have proven their worth in many industries and applications, such as wire bonding, ultrasonic welding or ultrasonic food cutting. A good sonotrode design and coordination of the same to the transducer saves energy and guarantees a good result. The sonotrode’s operational deflection shapes can be determined directly and compared with the simulations using scanning laser Doppler vibrometers, thereby enabling reliable implementation of optimum efficiency levels. Even during the welding process, LDVs are capable of measuring the vibration amplitude right at the tool-workpiece contact, which not only gives you important information in the development phase, but also when deviations arise in the production process.

Ultrasonic applications

• In addition to plastics technology, ultrasonics also enables metal ultrasonic welding or the joining of different materials, such as metal and fiber-reinforced plastics (CFRP). Wire bonding – which is fairly widespread in microelectronics contacting – is yet another application.
• Determination of the relative velocity and displacement amplitudes by performing a differential measurement, which is necessary for forming a highly stress-resistant joint.
• Reliable calculation of the vibration amplitudes under operating conditions – excellent for assessing the ultrasonic welding process.

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