High speed electronic speckle pattern interferometry espi. Precise detection of wrist pulse using digital speckle. Fringe pattern reference beam holographic interferometry electronic speckle pattern interferometry object beam these keywords were added by machine and not by the authors. This interferometer can be built for a small fraction of the cost of a commercial version and is simple and inexpensive to build and understand. A portable electronic speckle pattern interferometer with integrated topometric surface analysis j. Nowadays, there are a large number of interferometric systems that allow to monitor a large variety of physical parameters. In relation with this thermal strain measurement method using electronic speckle pattern interferometry methodology was tested in lithuania for application to the graphite.
This is a phenomenon that occurs when coherent light strikes an optically rough surface. In the present work, application of digital speckle pattern interferometry dspi was applied for the measurement of mechanicalelastic and thermal properties of fibre reinforced plastics frp. Electronic speckle pattern interferometry espi, also known as tv holography, is a technique which uses laser light, together with video detection, recording and processing to visualise static and dynamic displacements of components with optically rough surfaces. A present system consists of an imageshearing camera using a fresnel biprism of small angles and a digital tvimage processing facility. Dspi, originally known as electronic speckle pattern interferometry, is an interferometry based method that allows achieving wholefield, noncontacting measurements of microscopic deformation 14. The objects displacement results in an optical phase shift.
Electronic speckle pattern interferometry espi non. Pdf phase stepping shearography and electronic speckle. List of papers this thesis includes the following papers. Electronic speckle pattern interferometry espi is becoming a very common test and measurement tool among industrial users. However, speckle interferometry has been thus far confined to the study of static deformation, or at most, periodic deformation in a timeaverage or timefrozen sense. However, it has been during the last 15 years that espi, boosted by the availability of affordable and increasingly powerful digital image processing systems, has grown into one of the leading optical measurement techniques, receiving new names such as tv holography or digital specklepattern interferometry. Espsi electronic speckle pattern shearing interferometry. Speckle pattern is a random granular pattern produced by the reflection of coherent light beam e. Methodology the principle of speckle interferometry uses the ability of laser light of interference.
Digital speckle pattern interferometric technique was used to characterize the material constants poissons ratio and youngs modulus of the. View electronic speckle pattern interferometry research papers on academia. The wavelength is written on the top and also marked by the red line in the bottom scale. 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.
The noncontact and fullfield measurement allows the calculation of the three. Development and application of a fibre optic electronic. 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. Speckle interference patterns need in any case a kind of further decoding step in order to become a source of useful information.
This is done by applying phaseshifting techniques to speckle interferometry, which will quantitatively determine the phase of doubleexposure. Allfiber spectrometer based on speckle pattern reconstruction. Electronic speckle pattern interferometry espi has been widely used for vibration. Electronic speckle pattern interferometry is a wellknown experimental technique for fullfield deformation measurements. Pdf a michelson interferometer based espi system for static and vibration out of plane displacement measurements is presented. 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. Dspi processes speckle patterns in a computer rather than with a frame grabber and analog electronics as in espi.
Defect detection in metals using electronic speckle pattern interferometry. Electronic speckle pattern interferometry espi is an optical technique which enables interferometric measurements of surface displacements on almost any surface and 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. Analysis of laser speckle severity, granularity, and anisotropy using the power spectral density in polarcoordinate representation desmond c. Pdf defect detection in metals using electronic speckle. Vibrationobservation techniques for digital speckle. Finite element contour map of predicted strain derivative distribution. However, the discussions usually center on methods to mitigate the effects of vibration either by isolation of thesystem or by limiting the sampling time of the detector 3. Such optical techniques include speckle shearing interferometry for measuring surface. The problems associated with electronic speckle pattern interferometry in the presence of ambient vibrations have been the subject of discussion for some time. Osa deformation reconstruction by means of surface. Dspi needs a phaseshifting setup and rotating the whole device for 3d deformation.
Electronic speckle pattern interferometry espi, also known as tv holography, is a technique which uses laser light, together with video detection, recording. Inplane electronic speckle pattern shearing inter ferometry 405 ao x. Carlsson, digital measurement of three dimensional shapes using lightinflight speckle interferometry, optical engineering. Speckle inter9, ferometry is often subdivided into two distinct techniques.
Pdf an electronic speckle pattern interferometer suitable for use in an undergraduate laboratory is described. Pdf a simple design for an electronic speckle pattern. Electronic speckle pattern interferometry espi is a wellknown application of the speckle effect. Wyant chapter 18 page 14 of 15 block diagram of electronic sequence of espi system. The development of a simple electronic speckle pattern interferometer espi for the noninvasive, noncontact detection and characterization of earlystage damage of painted surfaces, like fracturing and layer separation, is reported. With improvements in image quality it has the potential to become the definitive tool for nondestructive testing. An application of digital image processing techniques to speckleshearing interferometry is described. The espi system developed relies on the analysis of soundinduced vibration of the investigated surfaces. Ong sanjeev solanki xinan liang xuewu xu data storage institute astar agency for science, technology and research singapore 117608, singapore email.
The electronic speckle pattern interferometry espi method has been adapted for analyzing mechanical and thermal properties of thin metallic, polymer and composite films, metallized structures in. Vibration observation is a major application of digital specklepattern interferometry dspi, which is a variation on electronic specklepattern interferometry espi. The speckle pattern is optically mixed with a second coherent light field that is either another speckle pattern or a smooth light field. This interferometer can be built for a small fraction of the cost of a commercial version. Timeaveraged electronic speckle pattern interferometry in. Digital specklepattern interferometry systems for automatic measurement of deformations of a diffuse object are presented, which are based on a fringe scanning method with phaseshifted speckle interferograms. Pulse diagnosis is one of the four diagnostic methods of traditional chinese medicine. Evaluating the elastic modulus of bone using electronic. Our global network of friendly and knowledeable distributors. Moorea department of physics, rollins college, holt avenue, winter park, florida 32789 received 6 april 2004.
The incident light scatters in all directions from the surface and these scattered waves interfere and form an interference. Phase stepping shearography and electronic speckle pattern interferometry d findeis, j gryzagoridis, m matlali department of mechanical engineering university of cape town, rondebosch, 7700, south africa tel. If the inline pdf is not rendering correctly, you can download the. Espi can be used in arrangements where fringes will represent lines of either inplane or outofplane displacement. Electronic speckle pattern interferometry, ist ein interferometrisches messverfahren zur. Inplane electronic speckle pattern shearing interferometry. Holographic and speckle interferometry jones and c. The latter can measure small displacement in micrometric level. The incorporation of monomode fibre optics into an argon ion powered electronic speckle pattern interferometer espi is reported.
Introduction to speckle interferometry techniques youtube. The intensity is distributed according to a negativeexponential probability density function. The former can measure 3d deformations in nanometric level. An electronic speckle pattern interferometer suitable for use in an undergraduate laboratory is described. Digital speckle pattern interferometry applied to a. Speckle patterns have high frequency phase data, which make it difficult to find the absolute phase of a single speckle pattern. The method uses the spatialcarrier digital speckle pattern. Pdf electronic speckle pattern interferometry for vibrational.
The dantec dynamics elektronic speckle pattern interferometry espi systems are designed for complete three dimensional, full field and highly sensitive displacement and strain and stress analysis. Timeaveraged electronic speckle pattern interferometry in the presence of ambient motion. Pdf a simple design for an electronic speckle pattern interferometer. Electronic speckle pattern interferometry springerlink. These techniques can dramatically increase the resolution of ground. Electronic speckle pattern interferometry espi espi on the other hand, records the surface displacement of an object in response to the applied force.
Then, the speckle is interpreted as a statistical phenomenon. It has been stated as recently as 1989 thatdynamic speckle pattern interferometry is. Applications speckle pattern analysis provides a wide variety of applications. Methodology and results of these measurements are presented in this paper. A digital speckle pattern before deformation of an object is recorded in the mass storage device of a computer facility. This process is experimental and the keywords may be updated as the learning algorithm improves. Electronic speckle pattern interferometry wikipedia. Application of electronic speckle pattern interferometry. This definition appears rarely and is found in the following acronym finder categories. Analysis of laser speckle severity, granularity, and. Although speckle interferometry techniques were developed years ago and are widely used for the visualization of the operating deflection shapes of vibrating surfaces, methods for accurate reconstruction of the observed deflection shape are still an active topic of research.
A new versatile electronic speckle pattern interferometer for. Electronic speckle pattern interferometry espi is a technique for fullfield displacement measurement and has been well accepted in. Espsi stands for electronic speckle pattern shearing interferometry. Electronic speckle pattern interferometry research papers. This produces an interferometric speckle pattern that will be detected by sensor to count the change of the speckle pattern due to force given 9. A portable electronic speckle pattern interferometer with.
After object deformation an object point o is displaced by d to the point o. Phase shifting speckle interferometry for determination of. We propose a noncontact optical method to detect human wrist pulse, aiming at the precise determination of the temporal and spatial distributions of pulse. Phase stepping shearography and electronic speckle pattern. A mechanically stable laser diode speckle interferometer. Measurement of elastic and thermal properties of composite. Electronic speckle pattern interferometry for vibrational analysis of. The visualisation is in the form of fringes on the image where each fringe normally represents a displacement of half. Elektronische specklemusterinterferometrie wikipedia. Digital speckle pattern interferometry dspi and digital image correlation dic.
They can be divided into the shiftandadd image stacking method and the speckle interferometry methods. Wang department of civil engineering university of new mexico albuquerque, nm 871 introduction the fracture of rock and concrete is characterized by the formation and propagation of the fracture process zone. The measurement is performed noncontact on the whole measuring area on nearly any material and component. Mod01 lec06 hologram interferometry, speckle methods duration.
Digital holography dh is usually free of misinterpretation, but when an expression like imageplane digital. Electronic speckle pattern interferometry for vibrational analysis of cutting. Digital speckle interferometry and related techniques k. Theory and applications on free shipping on qualified orders. The visualisation is in the form of fringes on the image where each fringe. Review of electronic speckle pattern interferometry springerlink.
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