Introduction to speckle interferometry techniques youtube. Historical development of speckle interferometry techniques 4. In this paper we present two recent developments of speckle technique with applications to micromechanics problems using siem speckle interferometry with electron microscopy, to nondestructive evaluation of crevice corrosion and composite disbond and vibration of large structures using tads timeaverage digital specklegraphy. Speckle interferometry definition of speckle interferometry.
University of vigo for discussions about phase unwrapping software. The wavelength is written on the top and also marked by the red line in the bottom scale. The speckle phenomenon is a rapidly changing interferencediffraction effect seen in a highly magnified diffraction image of a star. This method can be applied to a lot of cases within a range of displacements between tens of nanometers and tens of micrometers. The image intensity of the speckle pattern formed by video signal subtraction is low.
However, in the undergraduate laboratory and for many research applications, fig. Holographic and speckle interferometry jones and c. 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. It is to measure stressstrain curves of 15x15mm orthotropic samples but i dont. Dec 10, 20 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. Effective development of advanced materials and components requires an understanding of. To fulfill these requirements our department developed the optics, electronics and software for our speckle interferometry observations. A simple design for an electronic speckle pattern interferometer. Speckle interference patterns need in any case a kind of further decoding step in order to become a source of useful information. Electronic speckle pattern interferometry espi fea validation. In interferometric fringe pattern analysis, specular and speckle fringe patterns are the two main. Speckle interferometry definition is a technique for generating a clear composite image of a celestial object blurred by atmospheric turbulence in which a large number of shortexposure photographs are. 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.
Image processing was therefore necessary to enhance the fringe clarity. Speckle interferometry experiments with a digital photocamera maurizio vannonia. The concept of a speckle imaging system spatial frequency cut off is developed and equations are derived to allow its calculation, including contributions from detector and sky background noise. Phaseshifting speckle interferometry katherine creath speckle patterns have high frequency phase data, which make it difficult to find the absolute phase of a sin. Among these methods, interferometry techniques mainly composed of specklegrating interferometry or. In this paper we present two recent developments of speckle technique with applications to micromechanics problems using siem speckle interferometry with electron microscopy, to. What is the abbreviation for electronic speckle pattern interferometry.
Speckle interferometry experiments with a digital photocamera. While speckle seams to be the standard, im happy to use other systems as well, but dont have easy access to lasers etc. 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. Gruter 1912 first observed development of keratoconjunctivitis in rabbits after. The reduction of the speckle patterns, which represent the random distribution of atmospheric. Optical full field techniques offt are more and more utilized by mechanical laboratories. The configuration of the correlation fringes is usually dim. Electronic speckle pattern interferometry with the phasecam 6100. This is a phenomenon that occurs when coherent light.
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. Budinichlecture hall winter college on optics 2017. This is done by applying phaseshifting techniques to speckle interferometry, which will quantitatively determine the phase of doubleexposure speckle measurements. Input of the image frames into the computer was made using the software. Speckle interferometry from eric weissteins world of physics. This chapter describes the application of two experimental techniques, based on the speckle effect, to damage identification. In speckle interferometry, the optimal integration time goes as. Calvo department of optics, complutenseuniversity of madrid 17thfebruary 2017, 11. Wyant chapter 18 page 14 of 15 block diagram of electronic sequence of espi system. Speckle interferometry from eric weissteins world of.
Stellar speckle interferometry is a technique for obtaining diffractionlimited resolution of stellar objects despite the presence of the turbulent atmosphere which limits the resolution of conventional longexposure pictures to approximately one arc second. A software with several functions is written using matlab. Mod01 lec06 hologram interferometry, speckle methods duration. I was in charge of automating the hardware of a meade 10 telescope with the intention of streamlining the process of speckle interferometry to. The use of a sequence of shortexposure snapshots to obtain images at a telescopes diffraction limit. Electronic speckle pattern interferometry wikipedia. Speckle interferometry article about speckle interferometry.
A more recent method, called speckle interferometry, has been developed to reproduce the true disks of red supergiant stars and to resolve spectroscopic binaries such as capella. Electronic speckle pattern interferometry espi is a wellknown application of the speckle effect. Closeup of the tai 24inch optical paths for speckle interferometry. Image processing was therefore necessary to enhance the fringe.
Diagram of the tai speckle interferometry components. Espi abbreviation stands for electronic speckle pattern interferometry. Electronic speckle pattern interferometry espi sciencedirect. On development of portable digital holographic speckle pattern interferometry system for remote. A new versatile electronic speckle pattern interferometer for. Thus, while classical interferometry ci is the unanimously accepted. It can be used to measure surface displacement 2 and related. Application of digital speckle interferometry to visualize. 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. A signal to noise optimization algorithm for speckle. Theory and applications on free shipping on qualified orders. Sean craft software developer selfemployed linkedin. Speckle interferometry with midsized amateur telescope.
Espi can be used in arrangements where fringes will represent lines of either inplane or outofplane displacement. For the engineering run, a zwo asi290mm speckle camera was used in place of the zwo asi224mc seen here. Diffractionlimited images, of resolution many times finer than what is ordinarily obtainable through large earthbound telescopes, can be obtained by first measuring the modulus of the fourier transform of an. Article in proceedings of spie the international society for optical engineering 7019. Among these methods, interferometry techniques mainly composed of speckle grating interferometry or speckle grating shearography are more difficult to use in a mechanical lab context, because of their sensitivity to external vibrations except shearography, and because of the global lack of optical. 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. 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. Compared to the speckle photography method, speckle interferometry is more sensitive.
This would also reduce many of the errors inherent in espi. The first one, known as electronic speckle pattern interferometry or. Digital speckle pattern interferometry dspi is an optical nondestructive testing method allowing the visualization of the defects or the deformations of an object submitted to static deformation or to vibration. Electronic speckle pattern interferometry espi espi on the other hand, records the surface displacement of an object in response to the applied force. A more recent method, called speckle interferometry, has been developed to reproduce the true disks of red supergiant stars and to. Allfiber spectrometer based on speckle pattern reconstruction. Development of matlab filtering techniques in digital speckle pattern. Example image of electronic speckle pattern interferometry espi.
After deformation, four digital speckle patterns are recorded as. Electronic speckle pattern interferometry espi, also known as tv holography, uses video detection and recording to produce an image of the object upon which is superimposed a fringe pattern which represents the displacement of the object between recordings. Dynamic speckle interferometry of thin biological objects. Speckle interferometry is a highly sensitive tool used for making fullfield, noncontact measurements of surface properties at the microscale. Speckle interferometry is based on the coherent addition of scattered light from an object surface with a reference beam that may be a smooth wavefront or a scattered field from a reference object or from. Does anyone out there know of open source software which can be used for speckle interferometry with normal digital cameras. Proceedings volume 7019, advanced software and control for. Digital speckle pattern interferometry dspi is an optical nondestructive testing method allowing the visualization of the defects or the deformations of an object submitted to static deformation or to. Digital speckle pattern interferometry and related techniques. A pignal to noise optimization algorithm for speckle interferometry applications g. A software package for speckle interferometry of adaptive. Astronomical imaging by processing stellar speckle. Speckle interferometry nanophotonics and metrology lab epfl.
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. The electronic speckle pattern interferometry espi method has been adapted for analyzing mechanical and thermal properties of thin metallic, polymer and composite films, metallized. Introduction the speckle interferometry is a favorite professional tool for measuring double stars. Digital speckle interferometry and related techniques k.
Mar 28, 2016 introduction to speckle interferometry techniques experimental stress analysis an overview. Electronic speckle pattern interferometry espi is becoming a very common test and measurement tool among industrial users. A 30mm illuminated reticle eyepiece not shown was installed in the open path at left. On development of portable digital holographic speckle pattern. With improvements in image quality it has the potential to become the definitive tool for nondestructive testing. This talk shows how using interferometry methods provides routinely accurate measurements with a midsized amateur. Digital speckle pattern 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. Stellar speckle interferometry is a technique for obtaining diffractionlimited resolution of stellar objects despite the presence of the turbulent atmosphere which limits the resolution of conventional long. A digital speckle pattern before deformation of an object is recorded in the mass storage device of a computer facility. Schematic of an electronic speckle pattern interferometer that is sensitive to out of plane displacement. Application of speckle interferometry to damage identification. We present speckle interferometer measurements of 467 binary stars taken at. For exposures shorter than the coherence time 10 ms for the atmosphere in the optical. The digital image processing software imaster by robertson electronics 10 was used for this purpose.
Other articles where speckle interferometry is discussed. Introduction to speckle interferometry techniques experimental stress analysis an overview. Highly developed data analysis software and controlling computer provided. In its present form it rivals any current techniques for speed and ease of use. Pdf application of speckle interferometry to damage. Speckle interferometry definition is a technique for generating a clear composite image of a celestial object blurred by atmospheric turbulence in which a large number of shortexposure photographs are mathematically correlated by a computer. A speckle interferometry capability was added to ps3 in 20 that included adjustable high and low pass filters, an interference filter, and, of critical importance, the capability to.
Some rare amateurs use this technique on missions in observatories, but none seem to use it routinely with a classical amateur instrumentation. Sean craft software developer at selfemployed lacombe, louisiana 60 connections. 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. A mechanically stable laser diode speckle interferometer. Speckle patterns have high frequency phase data, which make it difficult to find the absolute phase of a single speckle pattern. Electronic speckle pattern interferometry espi non. 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. High speed electronic speckle pattern interferometry espi. Speckle interferometry is based on the coherent addition of scattered light from an object surface with a reference beam that may be a smooth wavefront or a scattered field from a reference object or from the sample.
Electronic speckle pattern interferometry in characterizing. Department of mechanical engineering, university of calabria, ponte p. For long exposures, the image is blurred to a seeing disk. Kyle hovey software developer atomic jolt linkedin. 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. Speckle pattern is a random granular pattern produced by the reflection of coherent light beam e.