The speckle pattern is produced by the intereference of the light from both beams reflecting off the object and is captured by the video camera. Lockinspeckleinterferometry for nondestructive testing. Optical fullfield measurement techniques are increasingly being used in material testing, fracture mechanics, and vibration analysis. Winter experimentelle mechanik, technische universitit braunschweig, schleinitzstr. Dec 15, 2017 material testing by computer aided speckle interferometry. Development of electronic speckle pattern interferometry. First automated speckle interferometry was achieved on the 0. Se3 shearography isisys germany system was used for experiments, which consists of an array of laser diodes 4x100 milli watts, related optics, ccd camera, image card and software. We describe the experiment in detail, and demonstrate how surface. Fermi 6, 50125 firenze, italy received 12 september 2003. Electronic speckle interferometry, phasemapping, and.
This paper describes a brief outline of holographic and speckle methods for nondestructive testing applications, wherein the deformations of an object under load are measured in a noncontact way. Although a powerful technique, manual determination of deformations and. Espi can be used in arrangements where fringes will represent lines of either inplane or outofplane displacement. Does anyone out there know of open source software which can be used for speckle interferometry with normal digital cameras. This would also reduce many of the errors inherent in espi.
Electronic speckle pattern interferometry espi fea. In testing brittle materials special steel brushes have been successfully applied to transfer the load to the specimen. This paper describes how to use a speckle interferometry. Speckle interferometry experiments with a digital photocamera maurizio vannonia. Wyant chapter 18 page 14 of 15 block diagram of electronic sequence of espi system. The basis for the stress calculation is a set of coefficients for a cylindrical hole in a semiinfinite body and a plane stress state. Electronic speckle pattern interferometry espi, also known as tv holography, is a technique. Contact ams today to discuss your microscopic testing needs. Test methods, nondestructive evaluation, and smart materials. The shearography systems are applied for non destructive testing.
Speckle interferometry article about speckle interferometry. By using software program imagej program, the values of the mean intensity. Speckle interferometry experiments with a digital photocamera maurizio vannonia and giuseppe molesinib istituto nazionale di ottica applicata, largo e. It is to measure stressstrain curves of 15x15mm orthotropic samples but i dont need the strain fields within the samples so something less precise than speckle may well be appropriate. Shearography espi systems shearography and electronic speckle patter interferometry espi are laser based, optical measurement methods, working full field and non contact. High speed electronic speckle pattern interferometry espi. This paper discusses characterization of the electronic speckle pattern interferometer spsdspi developed for jwst to verify its capabilities to measure structural deformations in large composite. We are capable of stitching individual fields of view to enable form testing on larger samples. Both methods use the same basic techniques for nondestructive testing, but dspi processes speckle pattern data digitally in a computer instead of using analog electronics to enhance fringe contrast. Advances in speckle metrology and related techniques. The non contacting operation of optical metrology makes it attractive to solve the task of measuring geometric quantities of microparts. A standard multimode optical fiber can be used as a general. Electronic speckle pattern interferometry espi is a nondestructive optical method. While speckle seams to be the standard, im happy to use other systems as.
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. This short course gives an introduction to the field of interference and interferometry. Some rare amateurs use this technique on missions in observatories, but none seem to use it routinely with a classical amateur instrumentation. Allfiber spectrometer based on speckle pattern reconstruction brandon redding, sebastien m. Measurement principles of espi dantec dynamics precision. Laser speckle interferometry for conservation science. In this work, the principle of interferometry is used to assess the surface roughness of the machined surfaces. Pdf lockinspeckleinterferometry for nondestructive testing.
The visualisation is in the form of fringes on the image where each fringe normally represents a displacement of half a wavelength of the light used i. We offer a complete package including equipment and software. Electronic speckle interferometry for the deformation. It relies on the interference between diffusely reflected light from the test. Speckle interferometry measurements in testing halls for. Speckle techniques map deformation and displacement laser. Scientists from the getty conservation institute have developed a noninvasive method for detecting voids behind the surface of wall paintings, plasters and mosaics, using laser speckle. Electronic speckle pattern interferometry espi is a wellknown application of the speckle. Testing microcomponents by speckle interferometry nasaads. Popoff, and hui cao department of applied physics, yale university, new haven, connecticut 06520, usa. Electronic speckle pattern interferometry for vibrational. The optical properties of speckle waves strongly influence most of the methods scrutinised and serve as an intrinsic link between the chapters. Laser speckle photography for surface tampering detection.
Electronic speckle pattern interferometry espi non. Several optical interferometric techniques are currently used. An alternate approach using spectral amplitude and phase information, proc. This speckle pattern is a fing erprint of the surface, i.
Electronic speckle pattern interferometry an overview. This paper describes a brief outline of holographic and speckle methods for nondestructive testing. Automated speckle interferometry of double stars meter telescope at kitt peak national observatory figure 2. Introduction to speckle interferometry techniques youtube. Popoff, and hui cao department of applied physics, yale university, new haven, connecticut 06520, usa hui. Electronic speckle pattern interferometry wikipedia. In speckle interferometry, an optically rough test surface is illuminated with an expanded laser beam creating a laser speckle pattern in the space surrounding the illuminated region. 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 and digital shearography are widely used in nondestructive testing due to their advantages of high speed, full field, and high sensitivity.
To fulfill these requirements our department developed the optics, electronics and software for our speckle interferometry observations. Laser interferometers surface form metrology manufacturer. Speckle interferometry experiments with a digital photocamera. Electronic speckle pattern interferometry espi is an optical technique which enables interferometric measurements of surface displacements on almost any surface and material. Today, zygo continues to maintain the leadership role in surface form metrology using laser interferometry. Digital speckle pattern interferometry dspi using a 100x100. In speckle interferometry, an optically rough test surface is illuminated with an expanded. Electronic speckle pattern interferometry espi is a full field noncontact experimental measuring technique that allows rapid and highly accurate measurement of the three components of deformation. Jul 01, 1995 electronic speckle interferometry, phasemapping, and nondestructive testing techniques applied to realtime, thermal loading. Keywords speckle behavior deformation development experiment fields holography information interferometry nondestructive testing. Speckle interferometry this technique is based on the coherence of laser illumination and allows to measure microdisplacements at the surface of an object. With ams optical testing and interferometry services, your samples will be measured accurately by an expert optical. Large aperture optical testing requires a high quality reference optic, either a transmission flat tf or transmission sphere ts.
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. Laser speckle, long viewed as a limit to spatial resolution, is the basis for a family of powerful nondestructive testing techniques. The speckle interferometry is a favorite professional tool for measuring double stars. 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. Holographic and laser speckle methods in nondestructive. Interferometry produces an interference fringe pattern when two or more light waves interact with each other. Material testing by computer aided speckle interferometry. Testing microcomponents by speckle interferometry testing microcomponents by speckle interferometry aswendt, petra. Espi can be used for stress and strain measurement, vibration mode analysis and nondestructive testing. Speckle interferometry allows to measure static or dynamic displacement maps that occur. Via appropriate image processing, the speckle pattern recorded. A new technique using digital speckle correlation for. Laser interferometers from zygo were first introduced commercially 47 years ago.
Speckle interferometry in the longwave infrared for. 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. The method uses the spatialcarrier digital speckle pattern interferometry. Osa electronic speckle interferometry, phasemapping. Electronic speckle pattern interferometry espi fea validation. Speckle pattern analysis provides a wide variety of applications. Allfiber spectrometer based on speckle pattern reconstruction. With its nearly 40 years of existence, speckle interferometry.
Electronic speckle pattern interferometry for vibrational analysis of cutting tools piotr mrozek p. Design, manufacturing and test of microcomponents generate new challenges for measurement techniques in general. Ultra sonics low resolution xray other anomalies interferometry interferometry is the core technology in our applications and therefore it is declared in more detail now. In plane object displacement causes the relative beam path lengths between both laser beams to vary, which results in an alteration of the speckle pattern. Ndt nondestructive testing and vibration applications. Digital speckle pattern interferometry and related techniques. It is one of the important tool for precision optical metrology and testing. Pdf speckle interferometry as a tool for fine measurements. A digital phasemapping method has been developed for application in realtime electronic speckle interferometry studies. Osa simultaneous 3d measurement of deformation and its.
Some rare amateurs use this technique on missions in observatories, but none seem to use it routinely with a. On the basis of the material discussed above, we can conclude that a dynamic speckle interferometry technique that allows studies of processes in thin transparent biological media has been theoretically. Wellknown advantages of the phase shifting interferometry include high measurement accuracy. Conference proceedings papers presentations journals. Dynamic speckle interferometry of thin biological objects. The noncontact and fullfield measurement allows the calculation of the three dimensional distribution of the displacement and strainstress of the object under test. Outofplane deformation speckle interferometry can be used to measure outofplane deformation i. The noncontact and fullfield measurement allows the calculation of the three dimensional distribution of the displacement and strainstress of the object under test as a response to a mechanical or thermal loading. Introduction to speckle interferometry techniques experimental stress analysis an overview. Jacquot nanophotonics and metrology laboratory, swiss federal institute of technology, ch1015 lausanne, switzerland abstract. Custom software modules written by teiche consisted of a run manager, scheduler, database, andor emccd camera control, and monitorlogger. Sparse aperture speckle interferometry telescope active.
We propose a noncontact optical method to detect human wrist pulse, aiming at the precise determination of the temporal and spatial distributions of pulse. They can be divided into the shiftandadd image stacking method and the speckle interferometry. This is one of the most sensitive interferometric technique. Measuring with light long applied to optical shop testing, interferometry is now used to measure many different types of parts in a variety of applications, such as optical system. Pulse diagnosis is one of the four diagnostic methods of traditional chinese medicine. Materials testing by computer aided speckle interferometry article in experimental techniques 175. Electronic speckle pattern interferometry espi has been proven to be a. The software for the image processing, phase calculation. The basic principle of speckle interferometry involves the comparison of speckle patterns recorded before and after a load or displacement is applied to the component under test. Speckle interferometry in the lo ngwave infrared for combining holography and thermography in a single sensor. Mar 28, 2016 introduction to speckle interferometry techniques experimental stress analysis an overview.
These techniques have proven to be very useful in testing different materials in a nondestructive way. We discuss a simple experiment for detecting small deformations by speckle interferometry. Topics covered include basic classical interferometers, coherence and source requirements, diffraction gratings and zone plates, holography, speckle interferometry, and phaseshifting interferometry. A prototype active optics system was created and fitted to a telescope frame using relatively low cost components. However it suffers from the lack of objective and efficient detection method. Materials testing by computer aided speckle interferometry.
Development of speckle interferometry algorithm and system. If you need material testing, fracture mechanics, and vibration analysis of advanced materials, see how espi can help. However, traditional speckle pattern interferometry. Here, the speckle technique offers an excellent potential. Introduction the speckle interferometry is a favorite professional tool for measuring double stars.
Both testing methods are an outgrowth of holography and speckle interferometry. Advanced photonics journal of applied remote sensing. These measurements can be applied to stress, strain and vibration analysis, as well as to nondestructive testing. 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. Electronic speckle pattern interferometry espi method is a wholefield, non destructive measurement method widely used in the industries such as detection of defects on metal bodies, detection of defects in intergrated circuits in digital electronics components and in the preservation of priceless. Its principles and application to a continuously deforming object are described. Digital speckle pattern interferometry dspi is a variation of electronic speckle pattern interferometry espi.
Jacquot nanophotonics and metrology laboratory, swiss federal institute of technology, ch1015 lausanne, switzerland. Basics of interferometry the following are non destructive testing methods typically used for the inspection of new tires and casings for retreading. Electronic speckle pattern interferometry espi is a nondestructive optical method for studying surface deformations. It relies on the interference between diffusely reflected light from the test object and a reference beam. 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. Speckle metrology includes various optical techniques that are based on the speckle fields generated by reflection from a rough surface or by transmission through a rough diffuser. Holographic interferometry hi is a technique which enables static and dynamic displacements of objects with optically rough surfaces to be measured to optical interferometric precision i. Digital speckle interferometry for assessment of surface.
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