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Digital Holographic Method for Piezoelectric Transformers Vibration Analysis
Psota, Pavel ; Kopecký, V. ; Lédl, Vít ; Doleček, Roman
The paper describes a holographic method for vibration analysis in nanometer range. The method was successfully applied on different types of piezoelectric transformers and the measurement results are introduced. To proof the reliability of the method it was done a comparing simultaneous measurement of a piezoelectric component by the holographic method and the well-established single-point interferometric method. Results showing the minimal deviation of both methods are presented in the final part of the paper.
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Irregular surfaces - measurements and ZEMAX simulations
Melich, Radek ; Psota, Pavel ; Lédl, Vít ; Václavík, Jan
Surfaces produced on optical elements are loaded by dierent kinds of irregularities whose allowable amplitudes are prescribed by optical tolerances defined by an optical designer. An important feedback between realized and designed surfaces can be achieved using interferometry or profilometry measurements for instance. This article discusses dierent kinds of representation and visualization of those measurements in ZEMAX, enabling optical designer to evaluate an impact of the irregular surface on the optical system performance.
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Measurement of Vibration Mode Structure for Adaptive Vibration Suppression System by Digital Holography
Psota, Pavel ; Lédl, Vít ; Doleček, Roman ; Mokrý, P. ; Kopecký, V.
Previously the frequency-shifted digital holographic interferometry (FSDHI) for measurement of vibration amplitudes in range of nanometers was introduced and verified by authors [1,2]. The method FSDHI addressed some of the drawbacks of the conventional methods and was used mainly for piezoelectric transformer vibration amplitudes and mode structures measurement [3]. The limiting factor for application of this method is the maximal measured value of the vibration amplitude without the risk of ambiguity. The value is approximately 80nm for the frequency doubled Nd: YAG line. Since FSDHI enables us to precisely measure vibration amplitudes over the whole inspected area with very high lateral resolution, it could also be a very useful tool for measurement of vibration amplitudes and mode structures for research in the field of adaptive suppression systems. Such a measurement would provide a necessary feedback about the system behavior.This was the reason why we put an effort
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Planar acoustic metamaterials with the active control of acoustic impedance using a piezoelectric composite actuator
Nováková, Kateřina ; Mokrý, P. ; Václavík, J. ; Marton, P. ; Cernik, M. ; Psota, Pavel ; Doleček, Roman ; Lédl, Vít
In the Paper, there are presented methods for a precise active control of the acoustic impedance of large planar structures, e.g glass plates or shells, by means of distributed flexible piezoelectric composite actuators which are connected to passive or active electronic shunt circuits. Design of tunable acoustic metamaterials is realized using Finite Element Method simulations and their acoustic properties are evaluated using acoustic transmission loss measurements. Static and dynamic displacements of the metamaterials produced by electric voltage are measured using Digital Holographic Interferometry. We believe that deep understanding of presented systems should result in future applications that improve the quality of everyday life.
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Comparison of holographic setups used in heat and mass transfer measurement
Doleček, Roman ; Psota, Pavel ; Lédl, Vít ; Vít, Tomáš ; Kopecký, V.
The authors of the paper deal with measurement of heat and mass transfer for several years and they have frequently used few techniqes for measurement of refractive index distribution based on holographic interferometry. Some of the well known techniques have been modified some and some new ones developped. Every technique could be applied with success in different type of meassurement and obviously every one has set of properties making them unique. We decided to digest few different basic techniques and describe its properties in this paper with the aim to help the reader select the proper one for their measurement. The list of techniques and its properties is not comprehensive but schould serve as a basic orientation in the field.
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Digital holografic interferometry used for identification of 2D temperature field
Lédl, V. ; Vít, Tomáš ; Doleček, R. ; Psota, P.
The presented paper shows the possibility of digital holographic interferometry application in measurement of unsteady 2D temperature field generated by pulsatile flow which is impinging heated surface. Special holographic setup with double sensitivity was developed instead of the commonly used Mach-Zehnder type of holographic interferometer in order to attain the parameters sufficient for the studied case. This setup is not light efficient like the Mach- Zehnder type but has double sensitivity. The results from the digital holographic interferometry experiments are perfected by measurement of the velocity field achieved by methods of hot-wire anemometry.
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Prospects of digital holographic interferometry in heat transfer measurement
Doleček, R. ; Lédl, Vít ; Kopecký, V. ; Psota, P. ; Václavík, Jan ; Vít, Tomáš
In the measurement of heat transfer problem, a holographic interferometry (HI) is often used mainly because of its unique properties and very high adaptability to different sort of problems under investigation. Although in the area of vibration or deformation measurement of solid body the standard HI is replaced massively by digital holography in the case of refractive index distribution the situation is quite opposite. In this paper we present two different types of digital holographic interferometers. The interferometers with different sensitivities have been build and successfully tested.
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