Electronic speckle pattern interferometry espi, also known as tv holography, is a technique which uses laser light, together with video detection, recording. Electronic speckle pattern interferometry espi is an optical technique which enables interferometric measurements of surface displacements on almost any surface and material. A back scattered object beam of an object surface and a reference beam, originating from the same laser light source, are superimposed on a video. Characterisation of thermal expansion coefficient of. Review of electronic speckle pattern interferometry espi. Measurement of in plane strain with shearography and electronic speckle pattern interferometry. Uncertainty evaluation of outofplane displacements. Electronic speckle pattern interferometry is an optical fullfield measurement method for determination of deformations of object surfaces with sensitivity below fractions of the wavelength of light. Application of the electronic speckle pattern interferometry espi technique for the localisation analysis of damage development in composites. Pdf measurement of in plane strain with shearography and. Remarks on residual stress measurement by holedrilling. Wyant chapter 18 page 14 of 15 block diagram of electronic sequence of espi system. The noncontact and fullfield measurement allows the calculation of the three. Electronic speckle pattern interferometry espi use tv system to record speckle instead of film gives realtime measurements minimum speckle size limited by camera resolution can perform computer analysis of speckle data optics 505 james c.
It is based on the principle that drilling a hole in the material causes a local stress relaxation. Electronic speckle pattern interferometry wikipedia. Pdf an electronic speckle pattern interferometer suitable for use in an undergraduate laboratory is described. Electronic speckle pattern interferometry observation of. Electronic speckle pattern interferometry espi is a highly sensitive optoelectronic whole field technique used for measuring surface displacement strain analysis, surface roughness, surface contour etc. Diverse applications of the electronic speckle pattern interferometry can be found in the recent. They can be divided into the shiftandadd image stacking method and the speckle interferometry methods. Jul 17, 2006 this paper describes the application of electronic speckle pattern interferometry to full. The shearography method is less susceptible to environmental noise, and operating the. It relies on the interference between diffusely reflected light from the test object and a.
Strain measurement by threedimensional electronic speckle. The incident light scatters in all directions from the surface and these scattered waves interfere and form an interference. It relies on the interference between diffusely reflected light from the test object and a reference beam. Electronic speckle pattern interferometry an overview. The visualisation is in the form of fringes on the image where each fringe. The use of digital image processing techniques for electronic speckle pattern interferometry is discussed. Related content a systematic approach to tv holography angel f dovaluse of modulated reference wave in electronic speckle pattern interferometry o j lokberg and k hogmoen. Since its inception during the early 1970s espi has gradually evolved into different optical designs and has been applied to a range of. Electronic speckle pattern interferometry espi espi on the other hand, records the surface displacement of an object in response to the applied force. Electronic speckle pattern interferometry espi is a wellknown application of the speckle effect. The techniques applications for vibration and deformation testing within industrial and medical research are outlined. Electronic speckle pattern interferometry to cite this article.
Electronic speckle pattern interferometry and digital holographic interferometry are investigated at long infrared wavelengths. Moire interferometry, phase shift shearography, and electronic laser speckle interferometry espi were successfully adopted in many different situations to measure displacement fields. Application of electronic speckle pattern interferometry. Review of electronic speckle pattern interferometry springerlink. High speed electronic speckle pattern interferometry espi. Proceedings of the asme 2002 international mechanical engineering congress and exposition. Remarks on residual stress measurement by holedrilling and. This is a phenomenon that occurs when coherent light strikes an optically rough surface. The potentials and limitations are discussed, and some applications used in industry are shown. Electronic speckle pattern interferometry espi and digital shearography have been shown to be of great value for the nondestructive evaluation of the integrity of materials and manufactured components. This paper describes the application of electronic speckle pattern interferometry to full. Electronic speckle pattern interferometry can provide highspeed, realtime holography for industrial research and inspection. We discuss the behavior of reflection by the object surfaces due to the long wavelength. Principles and new developments of 3d electronic speckle pattern interferometry 3d espi for strain and stress analysis are presented.
This article discusses its basic principles, modes of operation and applications, and finally tries to assess its future importance for industry. Introduction electronic speckle pattern interferometry espi is a technique for fullfield displacement measurement and has been well accepted in experimental mechanics field 1,2. Vibrationobservation techniques for digital specklepattern. Pdf electronic speckle pattern interferometry espi.
Electronic speckle pattern interferometry espi non. Abstract an application of digital image processing techniques to electronic speckle pattern interferometry espi is described. Recent developments and applications in electronic speckle. Espi can be used in arrangements where fringes will represent lines of either inplane or outofplane displacement. In the experiments proposed full field displacement maps were acquired by means of optical noncontact electronic speckle pattern interferometry espi technology 1, 2, in order to obtain high spatial definition and locate small defects on the sample, like debondings, material. Electronic speckle pattern interferometry espi and digital shearography have been shown to be of great value for the nondestructive testing of the integrity of materials and manufactured components. Digital holography dh is usually free of misinterpretation. Vibrationobservation techniques for digital speckle. The ndt laboratory in the department of mechanical engineering at the university of cape town has an active research. Our global network of friendly and knowledeable distributors.
Using such wavelengths allows one to extend the measurement range and decrease the sensitivity of the techniques to external perturbations. It is derived from a similar technique, electronic speckle pattern interferometry espi sharp, 1989, which is related to holography. Osa electronic speckle pattern interferometry and digital. Espi employs a ccd camera instead of a holographic plate as in conventional holographic interferometry.
Electronic speckle pattern interferometry for vibrational analysis of. Electronic speckle pattern interferometry for vibrational analysis of cutting tools piotr mrozek p. If the inline pdf is not rendering correctly, you can download the. Uncertainty evaluation of outofplane displacements measured. A digital tvimage processing system with a large frame memory allows us to perform precise and flexible operations such as subtraction, summation, and level slicing. The ndt laboratory in the department of mechanical engineering. The electronic speckle shearing phaseshifting pattern interferometer essppi1 is a precise measuring technology developed on electronic speckle interferometry2,3, it has the merits of high accuracy, nondestructive testing and fullfield measurement.
Pdf remarks on residual stress measurement by hole. Electronic speckle pattern interferometry, ist ein interferometrisches messverfahren zur. In 1970, the french astronomer antoine labeyrie showed that fourier analysis speckle interferometry can obtain information about the highresolution structure of the object from the statistical properties of the speckle patterns. Comparative measurement of in plane strain by shearography. Electronic speckle pattern interferometry espi is a nondestructive optical method for studying surface deformations. Electronic speckle pattern interferometry for vibrational analysis of cutting. Phase stepping shearography and electronic speckle pattern. For example, electronic speckle pattern interferometry espi, also known as tv holography, records the speckle data with a tv or ccd camera. Osa electronic speckle pattern interferometry using digital. Pdf phase stepping shearography and electronic speckle. Speckle interferometry techniques for doubleexposure measurements such as electronic speckle pattern in terferometry espi which measure deformations and contours have been in use for about 15 years.
Espi concerns generating a phase fringe pattern modulo 2. Electronic speckle pattern interferometry isa full. Electronic speckle pattern interferometry espi is becoming a very common test and measurement tool among industrial users. Strain measurement by threedimensional electronic speckle pattern interferometry. A new versatile electronic speckle pattern interferometer for. The basic principles of electronic speckle pattern interferometry espi are described, stressing its close similarity to hologram interferometry. The aim of this study was to demonstrate electronic speckle pattern interferometry espi as a powerful tool in determining diffusion coefficients and partition coefficients for proteins in gels. Recently optical techniques were introduced to measure strain. These techniques can dramatically increase the resolution of groundbased telescopes, but. The objective of this research is to show that holographic speckle interferometry is applicable to dynamic problems, and more importantly, to demonstrate how this technique can be realized. This process is experimental and the keywords may be updated as the learning algorithm improves. Electronic speckle pattern interferometry observation of brickmortar interface behaviour under compression. Widearea imaging of ultrasonic lamb wave fields by. Electronic speckle pattern interferometry for vibrational.
Hole drilling is the most widespread method for measuring residual stress. Electronic speckle pattern interferometry espi is a technique for fullfield displacement measurement and has been well accepted in. For the space limit, the measurement principle of espi method is not introduced in this paper, the readers can refer the literature 11 for detail. Since electronic speckle pattern interferometry espi has the attractive merits such as noncontact, fullfield, highly sensitive, etc. Speckle interferometry methods do not produce an intermediate hologram but record the speckle patterns directly on a low resolution recording medium151 unsuitable for holographic reconstruction. Design and experiment of electronic speckle shearing phase. Pdf a michelson interferometer based espi system for static and vibration out of plane displacement measurements is presented. The list of acronyms and abbreviations related to espi electronic speckle pattern interferometry. Study of rubber blends by electronic speckle pattern. Speckle imaging describes a range of highresolution astronomical imaging techniques based on the analysis of large numbers of short exposures that freeze the variation of atmospheric turbulence. Damage location assessment in a composite panel by means. Electronic speckle pattern interferometry espi introduction electronic speckle pattern interferometry espi is an optical technique which enables interferometric measurements of surface displacements on almost any surface and material. The sinusoidal vibration is measured during a frequency sweep using the optical setup illuminated in figure 2.
Electronic speckle pattern interferometry using digital. The topics such as correlation fringes tilt and influence of small rigid body rotation were theoretically described and experimentally verified. Electronic speckle pattern interferometry espi has been widely used for vibration. Translation find a translation for electronic speckle pattern interferometry in other languages. Pdf remarks on residual stress measurement by holedrilling. Vibration observation is a major application of digital speckle pattern interferometry dspi, which is a variation on electronic speckle pattern interferometry espi. Pdf a simple design for an electronic speckle pattern interferometer. Electronic speckle pattern interferometry espi is a wholefield noncontact optical metrology technique for displacement measurement, based on the optical physics of surfacegenerated laser speckle. Pdf electronic speckle pattern interferometry for vibrational. Speckle shearing interferometry, or shearography hung, 1982, is an interferometric optical measurement technique that utilises the laser speckle effect. A special digital facility with a large frame memory for processing a tv image is developed, allowing one to perform precise and flexible operations such as subtraction, summation, and level slicing. Electronic speckle pattern shearing interferometry is very similar to electronic speckle pattern interferometry, and it is typically used for nondestructive testing in material analysis and strain measurement 3.
Vibration observation is a major application of digital specklepattern interferometry dspi, which is a variation on electronic specklepattern interferometry espi. Digital image processing techniques make it easy compared with analog techniques to generate high contrast fringes. Applications of electronic speckle interferometry esi. In nde applications, the defects are identified as anomalous regions in the interference fringe. Fringe pattern reference beam holographic interferometry electronic speckle pattern interferometry object beam these keywords were added by machine and not by the authors. Elektronische specklemusterinterferometrie wikipedia. Esi techniques such as electronic speckle pattern interferometry espi and electronic speeckle shearographic interferometry essi are widely applied for testing of engineering structures in industry. Espi was used to measure displacement field in anisotropic specimen made by selective laser melting 18, sinterization 19, or laminated wood 20. Ole lekberg 1980 physics in technology 11 16 view the article online for updates and enhancements. Electronic speckle pattern interferometry springerlink. The noncontact and fullfield measurement allows the calculation of.
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