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. A present system consists of an imageshearing camera using a fresnel biprism of. Simple educational tool for digital speckle shearography. Abstract an application of digital image processing techniques to speckle shearing interferometry is described. It uses coherent light or coherent soundwaves to provide. An application of digital image processing techniques to speckleshearing interferometry is described. A novel distance sensing technique using digital speckle shearing interferometry is outlined in this paper. The determination of dynamic deformation and strain fields form the phase map of shearogram is demonstrated, and some preliminary results are shown. A novel implementation of the method for obtaining the partial derivatives of inplane and outofplane displacement fields in the inplane electronic speckle pattern shearing interferometry espsi configuration is described. Shearography is a speckle interferometric method, also called speckle pattern shearing interferometry, which directly measures displacement derivatives 2. The former can measure 3d deformations in nanometric level.
The two shearing images interfere with each other and produce a speckle interferogram. Digital speckle pattern shearing interferometry limitations. Since shearing interferometry, also called shearography, does not depict fringes caused by object tilt, it is a tool well suited for either nondestructive testing of objects under load or for. There exists many types of optical systems which allow deformation and shape measurements which are based on interferometry. Vibration analysis by means of digital speckle pattern. Due to the shearing function on the ccd, this technique is called electronic speckle shear. Dspi processes speckle patterns in a computer rather than with a frame grabber and analog electronics as in espi.
Using shearography to find the flawsdigital speckle. Speckle interferometry nanophotonics and metrology lab epfl. Digital holography dh is usually free of misinterpretation, but when an expression like imageplane digital. However, the current system does not allow us to derive accurate strain distributions because of complex surface contours inherent to biological samples. Measurement of strain distributions in mouse femora with 3d.
The dsspi system which is based on temporal analysis is attractive because of its ability to measure strain dynamically. Digital speckle pattern interferometry applied to a. 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. Se3 shearography isisys germany system was used for experiments, which consists of. Digital speckle pattern shearing interferometry is described as a robust measuring method due to its simple optical setup and the insensitivity against ambient noise. A new versatile electronic speckle pattern interferometer for. Digital specklepattern shearing interferometry osa. Electronic speckle pattern shearing interferometer espsi for vibration.
The dsspi system which is based on temporal analysis is attractive because of. Espsi electronic speckle pattern shearing interferometry. Asnt ndt library overviewofdigitalshearographyforndt. A present system consists of an imageshearing camera using a fresnel biprism. Optical distance sensing using digital speckle shearing. In traditional shearing interferometry, observation of fringes requires optical processing of doubleexposed interferograms. Digital inplane electronic speckle pattern shearing interferometry digital inplane electronic speckle pattern shearing interferometry patorski, krzysztof 19970701 00. The list of mechanical applications of speckle interferometry is impressively long. We present theory, design, and preliminary experimental studies for a compact wavefront sensor based on lateral shearing interferometry using a binary phase grating, image sensor, and.
Lateral shear interferograms of object image fields generated by. A simple phaseshifting lateral shearing interferometer. This paper refers to two wholefield, noncontact experimental techniques. The dsspi system which is based on temporal analysis is attractive because of its. Speckle interferometry technique has been mainly developed for the purposes of experimental mechanics. Digital speckle pattern interferometry dspi can achieve wholefield, noncontacting measurements of microscopic deformation for highresolution determination of 3d strain. The determination of the dynamic deformation and the strain fields from the phase map of shearogram is demonstrated, and some preliminary results are shown. Digital speckle shearing interferometry use of linear ccd. Digital speckle pattern interferometry dspi can achieve wholefield, noncontacting measurements of microscopic deformation for highresolution determination of 3d strain distributions. Digital speckle shearing interferometry by use of linear ccd scanning can be effectively used to measure the outofplan deformation of the objects and get a wide filed of view in continuous. Speckle and digital holographic interferometry a comparison. Pdf electronic speckle pattern shearing interferometry using.
Pdf digital shearing speckle pattern interferometry. Guest editorial recent developments in digital speckle. An application of digital image processing techniques to speckleshearing interferometry is. Digital transform processing of carrier fringe patterns from. This interferometer makes it easy to measure in quasirealtime spatial derivatives of surface displacement and modal vibration amplitude of objects. Digital transform processing of carrier fringe patterns from speckleshearing interferometry. Digital inplane electronic speckle pattern shearing. This definition appears rarely and is found in the following acronym. Speckle photography 2 includes the methods where positional changes of the speckle are monitored. Guest editorial recent developments in digital speckle pattern interferometry the last 10 years have seen signi.
The digital version is faster than conventional shearography, and does not require any film or fourier filtering. Due to the shearing function on the ccd, this technique is called electronic speckle shear interferometry. The list of mechanical applications of speckle interferometry is impressively long 1. Digital specklepattern interferometry listed as dsp. Using shearography to find the flawsdigital speckle shearing. Application of electronic speckle pattern shearing. Osa digital specklepattern shearing interferometry. It uses coherent light or coherent soundwaves to provide information about the quality of different materials in nondestructive testing, strain measurement, and vibration analysis.
Dec 15, 1980 digital speckle pattern shearing interferometry. A polarized digital shearing speckle pattern interferometry system. Digital speckle pattern interferometry applied to a surface. Digital transform processing of carrier fringe patterns from speckle shearing interferometry.
Digital inplane electronic speckle pattern shearing interferometry. The time average digital speckle patten shearing interferometry in conjunction with the stroboscopic technique is suited well for both qualitative and quantitative vibration analyses. This method has also been used to describe the mode shapes of vibrating objects. The speckle techniques can be classified into three broad categories. Pdf integrated diffractive shearing interferometry for. Pdf electronic speckle pattern shearing interferometry espsi is superior to electronic speckle pattern interferometry espi when strain. An analysis of the outofplane shearing interferometer has been performed which shows that production of inplane strain partial derivatives is possible, which. Shearography or speckle pattern shearing interferometry is a measuring and testing method similar to holographic interferometry.
Digital speckle pattern interferometry and related techniques. The visualisation is in the form of fringes on the image where each fringe. Tilt measurement using digital speckle shear interferometry. Vibration analysis by digital speckle pattern shearing. Generally, a basic shearographic measurement system uses a shearing device, such as a michelson interferometer, a wollaston prism. This paper explores the possibilities and limitations for real time shearing fringe observation using the electronic speckle pattern interferometry technique. Digital shearing speckle pattern interferometry based on rochon prism and its application article pdf available in applied sciences 912. A relatively new variation, digital speckle shearing interferometry dssi, uses a chargedcoupled device ccd camera and computer image processing to capture and process the interferometric fringe patterns. Inplane electronic speckle pattern shearing interferometry. 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. Digital speckle pattern interferometry dspi and digital image correlation dic.
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 speckle pattern interferometry. Abstract an application of digital image processing techniques to speckleshearing interferometry is described. Digital speckle pattern interferometry dspi is the generic name for a class of important interferometric techniques such as tv holography, electronic holography or phase shifting pattern interferometry, all of which involve similar optical and electronic principles. Digital image correlation method dicm is described as a robust inplane deformation measuring method due to its simple optical setup and the insensitivity against. 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. Vibrationobservation techniques for digital speckle. Pdf digital shearing speckle pattern interferometry based.
Digital speckle pattern interferometry dspi is the generic name for a class of important interferometric techniques such as tv holography, electronic holography or phase shifting. Electronic speckle pattern shearing interferometry espsi enables direct measurements of displacement derivatives to be made with variable sensitivity12. Such optical techniques include speckle shearing interferometry for measuring surface. Electronic speckle pattern interferometry wikipedia. Digital speckle shearing interferometry is an optical, noncontactive and nondestructive method widely used for the stress and strain analysis of objects. A polarized digital shearing speckle pattern interferometry. Osa digital speckle pattern shearing interferometry. The primary incentive for the development of this technique is of one that can be. Squeezing interferometry for optical phase extraction in. A relatively new variation, digital speckleshearing interferometry dssi, uses a chargedcoupled device ccd camera and computer image processing to capture and process the. It has been sued in industry for nondestructive testing and strain measuring.
Squeezing interferometry for optical phase extraction in digital speckle pattern interferometry. Vibrationobservation techniques for digital specklepattern. Compared with holography and electronic speckle pattern interferometry espi, environmental disturbances, such as a random rigid body movement, have less of an effect on digital. Digital shearing speckle pattern interferometry dsspi has been recognized as a practical tool in testing strain. Phase shifting speckle interferometry for determination of. Digital shearing speckle interferometry is a laserbased, optical, noncontacting and nondestructive method widely used for the stress and strain analysis of loaded static objects. Vibration observation is a major application of digital specklepattern interferometry dspi, which is a variation on electronic specklepattern interferometry espi. Application of digital speckle interferometry to visualize. Digital speckle projection for vibration measurement by. Since shearing interferometry, also called shearography, does not depict fringes caused by object tilt, it is a tool well suited for either nondestructive testing of objects under load or for quantitative evaluation of flexural strains. Vibration observation is a major application of digital speckle pattern interferometry dspi, which is a variation on electronic speckle pattern interferometry espi. In this paper, linear ccd, instead of area ccd arrays, is presented to record large area speckle shearing interferogram.
Measurement of strain distributions in mouse femora with. Digital speckle pattern interferometry applied to a surface roughness study fig1 schematic representation of two plane waves, x and x, il luminating a rough surface at. 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. 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. An application of digital image processing techniques to speckle shearing interferometry is described. A present system consists of an image shearing camera using a fresnel biprism of small angles and a digital tvimage processing facility. Digital transform processing of carrier fringe patterns. Espsi stands for electronic speckle pattern shearing interferometry. The time average digital speckle pattern shearing interferometry in conjunction with the stroboscopic technique is suited well for both qualitative and quantitative vibration analysis. This paper explores the possibilities for vibration analysis using digital speckle pattern shearing interferometry. Digital specklepattern interferometry how is digital. Combination of digital speckle pattern interferometry and. Digital shearing speckle pattern interferometry based on.
1281 568 560 1079 644 224 1281 922 311 126 936 588 237 1075 595 1460 450 91 236 1502 1103 564 102 2 769 800 784 103 1451 956 284 1257 302 1095 1001 1106 442 1404 482 1131 126 572 397 866 628 1157 1249 150 255 1408