Noise Reduction Techniques for Electronic Speckle Interferometry

It is shown that the speckle nature of electronic speckle pattern interferometry images can be reduced in quasireal time with the use of only three consecutive video images. By use of additive-subtractive phase modulation processing the technique is essentially insensitive to environmental noise, and distortion of fringes does not occur. By further removing the random speckle phase we show, using speckle statistics, that the number of dark speckles in the resulting fringe pattern is close to zero.

In the current study, we used the method of electronic speckle pattern interferometry (ESPI) to measure polymerization shrinkage of composite resins. Standardized cavities were prepared and placed into the ESPI apparatus before the cavities were filled with composites (n=2) .The ESPI apparatus was constructed to measure the out-of-plane displacement of the resins surface during the polymerization. Experiments demonstrated that the ESPI technique was a viable method to measure the deformation of composite resins. It was responsive and sensitive to dimensional changes. We found that cavity shape, size and C- factor influenced the date of resins shrinkage. And the tooth deformation in response to polymerization of resins was measured by the ESPI too. We concluded that ESPI was a feasible method for assessing resins deformation induced by its polymerization shrinkage when it was bonded in tooth cavities. And the results were greatly influenced by the dimensions of cavities , or interface adhesive and so on. It could also measure the tooth deformation induced by shrinkage of bonded composite resins. We found that resins polymerization shrinkage date may overestimate shrinkage-induced tooth deformation.

The method and equipment of the electronic speckle pattern interferometry (ESPI) for studying a stress-deformation state (SDS) of elastic bodies and structures are presented. Examples of use ESPI for measurements of residual stresses in welded structures, microdisplacements related to delamination of thin coatings, diagnostics of shrinkage stresses in coatings, determination of their elastic characteristics, generalization of the ESPI method for measurements of displacements of the nanometer scale fulfilled in IPMech RAS are given.

A comprehensive ESPI based system for combined measurement of shape and deformation of electronic components

Electronic Speckle Pattern Interferometry (ESPI) is becoming a very common test and measurement tool among industrial users. In its present form it rivals any current techniques for speed and ease of use. With improvements in image quality it has the potential to become the definitive tool for non-destructive testing.

International Journal of Computational Engineering ScienceVol. 04, No. 03, pp. 467-470 (2003) Testing and CharacterisationNo AccessSTATIC AND DYNAMIC CHARACTERIZATION OF MEMS VIA ESPIAndreas H. Foitzik, Wolfgang Kaese, Thomas Vogt, Michael Sommerer, and Serguei ArkhipovAndreas H. FoitzikUniversity of Applied Sciences Esslingen, Department for Mechatronics, Robert-Bosch-Str. 1, D-73037 Goeppingen, Germany Search for more papers by this author , Wolfgang KaeseUniversity of Applied Sciences Esslingen, Department for Mechatronics, Robert-Bosch-Str. 1, D-73037 Goeppingen, Germany Search for more papers by this author , Thomas VogtUniversity of Applied Sciences Esslingen, Department for Automotive Technology, Esslingen, Germany Search for more papers by this author , Michael SommererUniversity of Applied Sciences Esslingen, Department for Automotive Technology, Esslingen, Germany Search for more papers by this author , and Serguei ArkhipovMOSCOW AVIATION INSTITUTE (MAI), MOSCOW, Russia Search for more papers by this author https://doi.org/10.1142/S1465876303001538Cited by:2 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractGenerally unaltered surfaces stemming from IC- or MEMS-production (Micro Electro Mechanical Systems) cannot be investigated with ESPI (Electronic Speckle Pattern Interferometry) due to the lack of any interference from the extremely flat surfaces of devices made of silicon. In order to enable ESPI for such devices additional "rough" layers can be added to the MEMS surfaces, while these relatively "thick" layers alter the mechanical properties of such small devices considerably. Utilizing a new surface preparation technique (Goeppingen Procedure®) allows to create a nm-sized roughness onto the surfaces of MEMS, thus enabling interference originating from such altered surfaces and subsequently allowing ESPI.Static ESPI on commercially available micro-sized tilt-sensors as well as read-write head of a hard disk drive showed that elastic deformations can be determined with a lateral accuracy in the μm-range and an axial accuracy in the nm-range, respectively. The static investigations allowed the identification of defect sensors in terms of quality assurance. Dynamic ESPI on MEMS showed different normal modes as well as the dynamic behaviour at the occurence of the first and the second harmonic.Keywords:MEMSESPI - Electronic Speckle Pattern InterferometryGoeppingen Procedure References J. A. Leendertz, J. Phys. E (Sci. Instrum.) 3, 214 (1970). Crossref, Google Scholar H. Marwitz , Praxis Holographie ( Expert-Verlag , 1990 ) . Google ScholarP. Aswendt and R. Höfling, Measurement 23, S. 205 (1998). Crossref, Google ScholarD. Holsteinet al., Composite Structures 40, S. 257 (1998). Crossref, Google Scholar K. Hariri , Bruchmechanisches Verhalten jungen Betons: Laser-Speckle-Interferometrie und Modellierung der Rißprozeßzone ( Techn. Univ. Braunschweig , 2000 ) . Google ScholarZ. Yanget al., Optics and Lasers in Engineering 28(6), 443 (1997). Google Scholar Höfling, R.; Aswendt, P.; Liebig, V.; Brückner, H.: Synthesis of experiment and simulation in speckle interferometry: a medical application; Akademie Verlag Series in Optical Metrology, Vol. 2, S. 261-268, Berlin 1996 . Google Scholar Foitzik, A.H.; Kümmel, M.; Schmid, M.; Kaese, W.; Vogt, T.; Groth, P.; "ESPI on MEMS", 13.Intern. Wissenschaftlich-technische Konferenz SENSOR 2001, Sudak/Krim 2001 . Google Scholar FiguresReferencesRelatedDetailsCited By 2An Experimental Study of the Vibrational Characteristics of a Diamond Circular Blade Using Electronic Speckle-Pattern Interferometry and FEMMykhaylo Tkach, Yurii Halynkin, Arkadii Proskurin, Irina Zhuk and Volodymyr Kluchnyk et al.15 May 2021 | Acta Mechanica et Automatica, Vol. 15, No. 1Electronic Speckle Pattern Interferometry for Vibrational Analysis of Cutting ToolsPiotr Mrozek, Ewa Mrozek and Andrzej Werner17 July 2018 | Acta Mechanica et Automatica, Vol. 12, No. 2 Recommended Vol. 04, No. 03 Metrics History KeywordsMEMSESPI - Electronic Speckle Pattern InterferometryGoeppingen ProcedurePDF download

Experimental results obtained by applying both technique, Electronic Speckle Pattern Interferometry (ESPI) and Electronic Speckle Pattern Shearing Interferometry (ESPSI) were compared in the study of composite materials. We found that the difference between the strain fields obtained by ESPSI and ESPI was roughly a constant. This result was expected since, although ESPI in turn allows computing absolute strain values, the strains measured by ESPSI are relative to a reference that must be measured by an additional method.

The high resolution technique of electronic speckle pattern interferometry (ESPI) can be very useful in determining deformation of laboratory specimens and identifying initiation of failure. The in-plane ESPI theory is described and the fringe pattern of the processed ESPI image is analyzed to determine deformation and crack opening displacement. Fringes on the ESPI image represent lines of equal intensity, which relate to surface displacement. An ESPI system was constructed and calibrated for measuring uni-directional displacements. Several types of the experiments, such as uniaxial compression and fracture testing, were conducted to demonstrate the utility of ESPI.

The amplitude range for vibration measurement by time-average recording in electronic speckle pattern interferometry (ESPI) has been extended by sinusoidal phase modulation of the reference wave. The technique is, in part, similar to the reference wave modulation technique known from holography. The low resolution of the ESPI system results in a greater need for an extension of the measuring range. In addition, the technique is more convenient to use combined with ESPI, because of the instantaneous presentation of interferograms by this system. The modulation technique also provides information about the vibration phase. Fringe patterns illustrating applications of this technique are presented.

A method is proposed for checking the reliability of a quantitative estimate of longitudinal displacements in metallic beam samples when they are investigated by electronic speckle interferometry and phase-shifting speckle interferometry. Theoretical and experimental results are presented for the investigation of longitudinal surface displacements of samples by electronic difference speckle interferometry and phase-shifting speckle interferometry. © 2004 Optical Society of America

The use of holographic interferometry (HI) has been available for whole field testing of components for nearly twenty years. As an experimental technique it was limited to a laboratory environment but with the incorporation of a pulsed laser the possibility existed to attempt this type of analysis on the component operating in its usual environment. This should have provided the scientific and engineering community with the necessary tool to investigate many different difficult problems. The reality is holographic interferometry consumed billions of dollars globally, produced few real results and interest dwindled. Why? A number of reasons have been proposed which include experimental difficulties, data reduction and cost. Combined with the vast research effort in holography, interest in the allied field of speckle interferometry developed a video based technique which could rival holographic interferometry. This technique known as electronic speckle pattern interferometry (ESPI)1 provided equipment with similar capabilities to holographic interferometry but used the television camera directly as the imaging transducer rather than the photographic system. However this technique, which overcame a number of the experimental problems of holographic interferometry, still did not find immediate favour as an analysis tool. The end user was still not hammering on the door of the research laboratories. Laser costs have reduced and supporting digital electronics have substantially reduced to the extent where fully ruggedised commercial ESPI equipment costs approximately $30-50K. This makes it comparable with other experimental analysis packages, the cost argument therefore no longer strictly holds. The availability of image processing computer's has enabled a great deal of research into automated fringe data reduction and analyis, this was reviewed at a recent symposium by the Fringe Analysis Special Interest Group 4. The final major problem now outstanding is the availability of a handA¢â‚¬â€?held portable instrument capable of providing the computer with suitable data. The work this paper reports is an effort in this direction, to produce such a system. The application areas envisaged are: (i) displacement measurement of strain fields (ii) vibration measurement of resonant objects (iii) vibration measurement of non-resonant conditions (iv) refractive index changes in fluids, eg convective heat and fluid flow.

We show that it is possible to perform electronic speckle pattern interferometry (ESPI) using, for the first time to our knowledge, vortex beams as the reference beam. The technique we propose is easy to implement, and the advantages obtained are, among others, environmental stability, lower processing time, and the possibility to switch between traditional ESPI and spiral ESPI. The experimental results clearly show the advantages of using the proposed technique for deformation studies of complex structures.

Review of electronic speckle pattern interferometry (ESPI) for three dimensional displacement measurement

Out-of-plane displacement measurement by electronic speckle pattern interferometry in presence of large in-plane displacement

High-resolution deformation measurement method, which requires only two speckle patterns in electronic speckle pattern interferometry, is proposed by using fringe analysis based on specklegram. In fringe analysis using the proposed optical system, a pair of real- and imaginary-part components concerning the deformation information is extracted from one speckle pattern by Fourier transform in the same manner as the off-axis digital holography processing. A specklegram is calculated as a fringe image by multiplying the components of the real and imaginary part of speckle patterns in order to perform a high-resolution deformation analysis. Then, the phase map concerning deformation is detected from the specklegram, and the influence of speckle noise is also reduced by shifting the component on frequency domain. Furthermore, the amplitude of the intensity distribution of speckle pattern is normalized in order to reduce the influence by speckle noise much more. It is confirmed that the accuracy of the deformation measurement is efficiently improved by the proposed noise reduction methods.