Development of speckle shearing interferometer error. 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. A common approach to generate two sheared images of the object in espsi systems is to use a michelson interferometric optical setup. The introduction of the shearing principle in the examination of optical wavefronts by interferometry 1 has led to a great simplification of the apparatus required. Digital shearing speckle pattern interferometry based on.
Divergent laser illumination is commonly used in current designs of commercial electronic speckle pattern shearing interferometry espsi or shearography, for qualitative nondestructive testing ndt of material defects. Electronic laser speckle interferometer for displacement. Interferometry in speckle light theory and applications. Speckle shearing interferometry, or shearography hung, 1982, is an interferometric optical measurement technique that utilises the laser speckle effect.
Pdf measuring displacement derivatives by electronic speckle. Instead of the phase change, we measure its gradient, the method falls into the category of speckle shear. Simple electronic speckle pattern shearing interferometer. An analysis of the outofplane shearing interferometer has been performed which shows that production of inplane strain partial derivatives, which are not affected by outofplane displacement function components, is possible. A new versatile electronic speckle pattern interferometer for. Interferometry is an important investigative technique in the fields of astronomy, fiber optics, engineering metrology, optical metrology, oceanography, seismology, spectroscopy and its. A common lateral shear interferometer uses a plane parallel glass plate as a shearing device. 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. Digital speckle pattern interferometry and related.
The observed speckle pattern could be thought of as a fingerprint of the illuminated area in the sense that the observed pattern is unique for the microstructure of the specific surface area. Analyses of both the imaging system and the opticalfiltering arrangement have been developed. Speckle interferometry 3 on the other hand includes methods that are based on the measurement of phase changes. Measurement of strain distributions in mouse femora with. Shearing speckle pattern interferometry is a fullfield speckle interferometric technique used to determine surface displacement derivatives. A simple phaseshifting lateral shearing interferometer. A present system consists of an image shearing camera using a fresnel biprism of small angles and a digital tvimage processing facility.
An imageshearing specklepattern interferometer for measuring bending moments to cite this article. The principles and system arrangement are described and the preliminary. Introduction electronic speckle pattern shearing interferometry espsi enables direct measurements of displacement derivatives to be made with variable sensitivity111. Digital inplane electronic speckle pattern shearing interferometry. The dsspi system which is based on temporal analysis is.
Pdf electronic speckle pattern shearing interferometry espsi is superior to electronic speckle pattern interferometry espi when strain. Digital speckle pattern interferometry dspi can achieve wholefield, noncontacting measurements of microscopic deformation for highresolution determination of 3d strain distributions. Shearography or speckle pattern shearing interferometry is a measuring and testing method similar to holographic interferometry. The dsspi system which is based on temporal analysis is attractive because of its ability to measure strain dynamically. Digital speckle pattern interferometry and related techniques. A present system consists of an imageshearing camera using a fresnel biprism of small angles and a digital tvimage processing facility. Osa digital specklepattern shearing interferometry. Application of electronic speckle pattern shearing. Digital speckle interferometry and related techniques provides a single source of information in this rapidly progressing field. Electronic speckle shearing pattern interferometry esspi is a technique that has been used for surface strain and vibration analysis, assuming that simple derivatives are obtained by.
Electronic speckle pattern shearing interferometry espsi. Quantitave strain analysis with image shearing speckle. Recording and 8 further use of strain response in the form of fields of two mutually orthogonal tangential components of displacements u and v is a preferred option from the standpoint of reliability of stress component measurement. Experimental demonstrations for each case of the applications are presented. Application of a photopolymer material in speckle pattern shearing interferometry. An application of digital image processing techniques to speckle shearing interferometry is described.
The electronic speckle pattern shearing interferometer espsi pr esented in this pap er is a very simple sy stem having a min imum of co mponents. In this paper, such a dsspi system with wollaston prism has been built. 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. Quantitative strain analysis with image shearing speckle. Wyant chapter 18 page 14 of 15 block diagram of electronic sequence of espi system. We place a piece of flat glass in front of the object and let the glass form an inclined angle with the zaxis. Electronic speckle pattern 29 interferometry espi is used for the measurement of displacement in the three orthogonal 30 axes, allowing the independent extraction of the two inplane displacement ip and one out31 ofplane oop displacement components. Guest editorial recent developments in digital speckle.
Osa digital speckle pattern shearing interferometry. The visualisation is in the form of fringes on the image where each fringe normally represents a displacement of half a wavelength. Three applications of the speckleshearing interferometric camera are described. Digital shearing speckle pattern interferometry dsspi has been recognized as a practical tool in testing strain. Digital holography dh is usually free of misinterpretation, but when an expression like imageplane digital. In traditional shearing interferometry, observation of fringes requires optical processing of doubleexposed interferograms. Related content a double exposure technique for speckle pattern interferometry j n butters and j a leendertz. Speckle photography 2 includes the methods where positional changes of the speckle are monitored.
An application of digital image processing techniques to speckleshearing interferometry is described. Phase shifting speckle interferometry for determination of. Pdf simple phaseshifting lateral shearing interferometer. It uses coherent light or coherent soundwaves to provide information about the quality of different materials in nondestructive testing, strain measurement, and vibration analysis.
An imageshearing specklepattern interferometer for. In conventional spsi, observation of fringes requires an optical processing of double exposed interferograms and therefore, this technique is not in real time. Electronic specklepattern interferometry is the most effective optical method in analysis of residual stress 5. Application of a photopolymer material in speckle pattern. This paper explores the possibilities and limitations for real time shearing fringe observation using the electronic speckle pattern interferometry technique. These proceedings reflect the work presented at the conference interferometry in speckle light. Guest editorial recent developments in digital speckle pattern interferometry the last 10 years have seen signi. Application of photopolymer holographic gratings in electronic speckle pattern shearing interferometry.
Shearography is extensively used in production and development in. Deformation analysis of a shaft by a carrier method of speckleshearing pattern interferometry a. Abstract an application of digital image processing techniques to speckleshearing interferometry is described. Electronic speckle pattern shearing interferometry, also known as shearography, is a highly sensitive technique that can measure the distribution of the displacement derivatives of the object surface. Pdf digital shearing speckle pattern interferometry. Then, the speckle is interpreted as a statistical phenomenon. A phaseshifting electronic speckle pattern shearing interferometer with a very simple shearing device is proposed. It is derived from a similar technique, electronic speckle pattern interferometry espi sharp, 1989, which is related to holography. Inplane electronic speckle pattern shearing interferometry. Developed in the past decade, shearographyalso called speckle pattern shearing interferometryis a coherentoptical measuring and testing method, similar to holographic interferometry. Digital shearing speckle pattern interferometry based on rochon prism and its application article pdf available in applied sciences 912. The everincreasing requirements of product quality and reliability demand more efficient measuring and testing methods. Quantitative strain analysis with image shearing speckle pattern interferometry. In this paper, a new measurement system of realtime heterodyne shearography interferometry is presented.
Applications speckle pattern analysis provides a wide variety of applications. The angle between beam direction and the zaxis is called 8. However, the current system does not allow us to derive accurate strain distributions because of complex surface contours inherent to biological samples. Electronic speckle pattern interferometry wikipedia. The camera will be referred to as speckleshearing interferometric camera. 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. Electronic speckle pattern shearing interferometry espsi enables direct measurements of displacement derivatives to be made with variable sensitivity12. Electronic speckle pattern shearing interferometry espsi, also known as shearography, is a wholefield optical technique used to measure approximately the. Temporal heterodyne shearing speckle pattern interferometry. Design and experiment of electronic speckle shearing phase. An image shearing speckle pattern interferometer for measuring bending moments to cite this article. Another area will give rise to a totally different random speckle pattern.
Generally, a basic shearographic measurement system uses a shearing device, such as a michelson interferometer, a wollaston prism. This interferometer makes it easy to measure in quasirealtime spatial derivatives of surface displacement and modal vibration. Digital transform processing of carrier fringe patterns. Some of the experimental data were obtained using a relatively new technique called speckle diffraction interferometry. The intensity is distributed according to a negativeexponential probability density function. Such optical techniques include speckle shearing interferometry for measuring surface. Since speckle pattern shearing interferometry spsi allows derivatives of surface displacement to be measured directly, it is very useful for nondestructive testing and strain analysis. This interferometer makes it easy to measure in quasirealtime spatial derivatives of surface displacement and modal vibration amplitude of objects. This method has also been used to describe the mode shapes of vibrating objects. Digital transform processing of carrier fringe patterns from speckleshearing interferometry. Pdf application of photopolymer holographic gratings in. Quantitave strain analysis with image shearing speckle pattern interferometry shearography mendeley.
An analysis of the outofplane shearing interferometer has been performed which shows that production of inplane strain partial derivatives is possible, which. Speckle interferometry and correlation applied to large. Interferometry is a family of techniques in which waves, usually electromagnetic waves, are superimposed, causing the phenomenon of interference, which is used to extract information. The results of these experiments have shown that visible speckle correlation fringes related to the. Pdf electronic speckle pattern shearing interferometry using. The light beam propagates along the direction parallel to the xzplane. The visualisation is in the form of fringes on the image where each fringe normally represents a displacement of half. The inplane data is represented as substraction correlation fringes and can be formed using two designs of interferometer. Electronic speckle pattern shearing interferometer espsi for vibration. Lateral shear interferograms of object image fields generated by. Electronic speckle pattern shearing interferometry espsi and its applications electronic speckle pattern shearing interferometry espsi and its applications steinchen, wolfgang 19940805 00. A common glass plate has been shown to be an adaptable and effective tool for use in speckleshearing interferometry.
1630 328 1463 628 1255 107 1115 944 63 283 1185 1155 81 925 1618 934 450 73 1454 1170 921 687 1638 1322 1281 504 1264 1075 1061 1525 894 1430 621 293 615 407 1188 1414 529 1428 281 1446 1408 1233 1010 XML HTML