Digital speckle interferometry for assessment of surface. Laser speckle interferometry for conservation science. Topics covered include basic classical interferometers, coherence and source requirements, diffraction gratings and zone plates, holography, speckle interferometry, and phaseshifting interferometry. This short course gives an introduction to the field of interference and interferometry. Does anyone out there know of open source software which can be used for speckle interferometry with normal digital cameras. We discuss a simple experiment for detecting small deformations by speckle interferometry. Electronic speckle pattern interferometry espi, also known as tv holography, is a technique.
Basics of interferometry the following are non destructive testing methods typically used for the inspection of new tires and casings for retreading. Shearography espi systems shearography and electronic speckle patter interferometry espi are laser based, optical measurement methods, working full field and non contact. Pulse diagnosis is one of the four diagnostic methods of traditional chinese medicine. In testing brittle materials special steel brushes have been successfully applied to transfer the load to the specimen. Speckle interferometry experiments with a digital photocamera maurizio vannonia. 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.
These techniques have proven to be very useful in testing different materials in a nondestructive way. Speckle techniques map deformation and displacement laser. This is one of the most sensitive interferometric technique. Lockinspeckleinterferometry for nondestructive testing. Digital speckle pattern interferometry dspi using a 100x100. Electronic speckle pattern interferometry espi has been proven to be a. Electronic speckle pattern interferometry espi is an optical technique which enables interferometric measurements of surface displacements on almost any surface and material.
Sparse aperture speckle interferometry telescope active optics control system matthew clause a conventional large aperture telescope required for binary star research is typically cost prohibitive. Espi can be used for stress and strain measurement, vibration mode analysis and nondestructive testing. However it suffers from the lack of objective and efficient detection method. Although a powerful technique, manual determination of deformations and. Wellknown advantages of the phase shifting interferometry include high measurement accuracy. In speckle interferometry, an optically rough test surface is illuminated with an expanded. 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. Laser interferometers from zygo were first introduced commercially 47 years ago. Via appropriate image processing, the speckle pattern recorded. However, traditional speckle pattern interferometry. Jacquot nanophotonics and metrology laboratory, swiss federal institute of technology, ch1015 lausanne, switzerland abstract. Electronic speckle pattern interferometry espi fea. Pdf lockinspeckleinterferometry for nondestructive testing. 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.
Development of speckle interferometry algorithm and system. The speckle interferometry is a favorite professional tool for measuring double stars. 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. We offer a complete package including equipment and software. 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. 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. Ndt nondestructive testing and vibration applications. 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. Electronic speckle interferometry, phasemapping, and. These measurements can be applied to stress, strain and vibration analysis, as well as to nondestructive testing. The shearography systems are applied for non destructive testing. 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.
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 and generation of strainstress distribution with high resolution. Measurement principles of espi dantec dynamics precision. Pdf speckle interferometry as a tool for fine measurements. By using software program imagej program, the values of the mean intensity. Today, zygo continues to maintain the leadership role in surface form metrology using laser interferometry. Material testing by computer aided speckle 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. Electronic speckle pattern interferometry espi is a nondestructive optical method. Electronic speckle pattern interferometry for vibrational. They can be divided into the shiftandadd image stacking method and the speckle interferometry. Fermi 6, 50125 firenze, italy received 12 september 2003. 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. Contact ams today to discuss your microscopic testing needs.
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. The method uses the spatialcarrier digital speckle pattern interferometry. With its nearly 40 years of existence, speckle interferometry. Several optical interferometric techniques are currently used. Allfiber spectrometer based on speckle pattern reconstruction brandon redding, sebastien m. Materials testing by computer aided speckle interferometry article in experimental techniques 175. 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. Automated speckle interferometry of double stars meter telescope at kitt peak national observatory figure 2. The non contacting operation of optical metrology makes it attractive to solve the task of measuring geometric quantities of microparts. Large aperture optical testing requires a high quality reference optic, either a transmission flat tf or transmission sphere ts. Popoff, and hui cao department of applied physics, yale university, new haven, connecticut 06520, usa. 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 an array of laser diodes 4x100 milli watts, related optics, ccd camera, image card and software.
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. Speckle interferometry measurements in testing halls for. Testing microcomponents by speckle interferometry testing microcomponents by speckle interferometry aswendt, petra. This paper describes a brief outline of holographic and speckle methods for nondestructive testing. Holographic and laser speckle methods in nondestructive. Allfiber spectrometer based on speckle pattern reconstruction. In this work, the principle of interferometry is used to assess the surface roughness of the machined surfaces. We describe the experiment in detail, and demonstrate how surface. Speckle interferometry this technique is based on the coherence of laser illumination and allows to measure microdisplacements at the surface of an object. Laser speckle photography for surface tampering detection. 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. To fulfill these requirements our department developed the optics, electronics and software for our speckle interferometry observations. While speckle seams to be the standard, im happy to use other systems as. We propose a noncontact optical method to detect human wrist pulse, aiming at the precise determination of the temporal and spatial distributions of pulse.
Precise detection of wrist pulse using digital speckle. Electronic speckle pattern interferometry wikipedia. While speckle seams to be the standard, im happy to use other systems as well, but dont have easy access to lasers etc. Laser interferometers surface form metrology manufacturer. Mar 28, 2016 introduction to speckle interferometry techniques experimental stress analysis an overview. If you need material testing, fracture mechanics, and vibration analysis of advanced materials, see how espi can help. 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. Optical fullfield measurement techniques are increasingly being used in material testing, fracture mechanics, and vibration analysis. Custom software modules written by teiche consisted of a run manager, scheduler, database, andor emccd camera control, and monitorlogger. Test methods, nondestructive evaluation, and smart materials.
Electronic speckle pattern interferometry espi is an optical technique which. Winter experimentelle mechanik, technische universitit braunschweig, schleinitzstr. 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. Design, manufacturing and test of microcomponents generate new challenges for measurement techniques in general. Speckle pattern analysis provides a wide variety of applications.
Osa simultaneous 3d measurement of deformation and its. A digital phasemapping method has been developed for application in realtime electronic speckle interferometry studies. Electronic speckle pattern interferometry espi is a wellknown application of the speckle. 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. First automated speckle interferometry was achieved on the 0. Advanced photonics journal of applied remote sensing. Osa electronic speckle interferometry, phasemapping. Speckle interferometry experiments with a digital photocamera maurizio vannonia and giuseppe molesinib istituto nazionale di ottica applicata, largo e. Electronic speckle pattern interferometry espi espi on the other hand, records the surface displacement of an object in response to the applied force. Espi can be used in arrangements where fringes will represent lines of either inplane or outofplane displacement. 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. Some rare amateurs use this technique on missions in observatories, but none seem to use it routinely with a.
Speckle interferometry allows to measure static or dynamic displacement maps that occur. Wyant chapter 18 page 14 of 15 block diagram of electronic sequence of espi system. We are capable of stitching individual fields of view to enable form testing on larger samples. 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. Introduction to speckle interferometry techniques youtube. Materials testing by computer aided speckle interferometry. 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. Some rare amateurs use this technique on missions in observatories, but none seem to use it routinely with a classical amateur instrumentation.
Advances in speckle metrology and related techniques. Popoff, and hui cao department of applied physics, yale university, new haven, connecticut 06520, usa hui. The software for the image processing, phase calculation. A prototype active optics system was created and fitted to a telescope frame using relatively low cost components. Electronic speckle pattern interferometry espi fea validation. Its principles and application to a continuously deforming object are described. Electronic speckle pattern interferometry espi is a nondestructive optical method for studying surface deformations. Electronic speckle interferometry for the deformation. A new technique using digital speckle correlation for. This paper describes how to use a speckle interferometry. 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. Speckle interferometry in the lo ngwave infrared for combining holography and thermography in a single sensor. Jul 01, 1995 electronic speckle interferometry, phasemapping, and nondestructive testing techniques applied to realtime, thermal loading. Electronic speckle pattern interferometry espi effective development of advanced materials and components requires an understanding of their behaviour under load at various conditions.
The noncontact and fullfield measurement allows the calculation of the three dimensional distribution of the displacement and strainstress of the object under test as. Interferometry produces an interference fringe pattern when two or more light waves interact with each other. Introduction the speckle interferometry is a favorite professional tool for measuring double stars. Here, the speckle technique offers an excellent potential. Digital speckle pattern interferometry and related techniques. Both testing methods are an outgrowth of holography and speckle interferometry. It is one of the important tool for precision optical metrology and testing. 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.
Electronic speckle pattern interferometry an overview. It relies on the interference between diffusely reflected light from the test. Introduction to speckle interferometry techniques experimental stress analysis an overview. It relies on the interference between diffusely reflected light from the test object and a reference beam. The noncontact and fullfield measurement allows the calculation of the three dimensional distribution of the displacement and strainstress of the object under test. Keywords speckle behavior deformation development experiment fields holography information interferometry nondestructive testing. Outofplane deformation speckle interferometry can be used to measure outofplane deformation i. Development of electronic speckle pattern interferometry. A standard multimode optical fiber can be used as a general. An alternate approach using spectral amplitude and phase information, proc. Development of a portable system for determination of residual stresses by espihd method, compact shearographic system for ndt, application of the shearography method for nondestructive testing of. Gathering and processing a terabyte of data during a speckle interferometry run in an orderly, reasonably errorfree manner by human operators was difficult as explained by teiche 2014. Testing microcomponents by speckle interferometry nasaads.
This would also reduce many of the errors inherent in espi. Speckle interferometry article about speckle interferometry. Laser speckle, long viewed as a limit to spatial resolution, is the basis for a family of powerful nondestructive testing techniques. Digital speckle pattern interferometry dspi is a variation of electronic speckle pattern interferometry espi. Speckle interferometry experiments with a digital photocamera. Speckle interferometry in the longwave infrared for.
High speed electronic speckle pattern interferometry espi. Electronic speckle pattern interferometry for vibrational analysis of cutting tools piotr mrozek p. The optical properties of speckle waves strongly influence most of the methods scrutinised and serve as an intrinsic link between the chapters. Jacquot nanophotonics and metrology laboratory, swiss federal institute of technology, ch1015 lausanne, switzerland. 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 non. This speckle pattern is a fing erprint of the surface, i. 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.
Conference proceedings papers presentations journals. 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. With ams optical testing and interferometry services, your samples will be measured accurately by an expert optical. Analysis of speckle pattern interferometry system ipcbee.
Dynamic speckle interferometry of thin biological objects. 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. Sparse aperture speckle interferometry telescope active. Dec 15, 2017 material testing by computer aided speckle interferometry. Speckle interferometry is an interesting tool for the measurement of microdeformations and has found application in many different fields ranging from material testing to structural assessment.