Phaseshifting dynamic holographic interferometry using bso photorefractive crystals. We discuss the behavior of reflection by the object surfaces due to the long wavelength. A diffractive optical element is described that can be used to implement a very simple selfaligning electronic speckle pattern interferometer and holographic interferometer that requires only a laser source and a camera in the optical setup. Speckle interferometry in the longwave infrared for. Dynamic holographic electronic speckle pattern interferometry. A metrology system combining three laser speckle measurement. They may be used to measure static or dynamic displacements, the shape of objects, and refractive index variations of. A simultaneous phaseshifting interferometer of the type shown above is also very useful as a digital speckle. Digital holographic speckle pattern interferometry dhspi is a nondestructive and noncontact optical technique which investigates deformation, deterioration and fracture mechanisms in order to evaluate the structural condition of materials and systems as a result of ageing, mechanical deterioration and materials failure. Holographic and speckle interferometry are optical techniques which use lasers to make noncontracting field view measurements at a sensitivity of the wavelength of light on optically rough i.
Espi can be used for stress and strain measurement, vibration mode analysis and nondestructi. Citeseerx document details isaac councill, lee giles, pradeep teregowda. In digital holographic and speckle interferometry devoted to solid object displacement measurement, the reflecting properties of the object under study are of importance in designing the observation and laser illumination systems. Holographically recorded photopolymer diffractive optical element for holographic and electronic speckle pattern interferometry. Phase stepping shearography and electronic speckle pattern. Digital holographic speckle pattern interferometry dhspi is a. In this report, we present a novel imaging technique, called speckle field digital holographic microscopy sdhm, which utilizes the speckle field for illumination. Read use of holographic interferometry and electronic speckle pattern interferometry for measurements of dynamic displacements, mechanical systems and signal processing on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. The combination of speckle interferometric and holographic methods will make possible to measure normal and tangential displacement components at a time. Speckle tend to degrade the fringe pattern, and a speckle noise.
They may be used to measure static or dynamic displacements, the shape of objects. Holographically recorded photopolymer diffractive optical. Digital holographic speckle pattern interferometry dhspi is a technique based in holographic interferometry hi and electronic speckle pattern interferometry espi 2, 3, which are wellknown nondestructive techniques used primarily in industrial sector for quality control 4, 5. This thesis presents the mathematical foundation of digital holography, namely digital sampling of holograms and numerical reconstruction of wavefronts. This article describes the principles and major applications of digital recording and numerical reconstruction of holograms digital holography. The outofplane setup can be briefly described as follows. In this wavelength range specklegrams are affected by the thermal radiation emitted by objects at room temperature. Seeing invisible defects with the portable digital. Strain and stress analysis by holographic and speckle interferometry. Holography and speckle in phaseshifting digital holography. Center for holographic studies and laser micromechatronics.
Introduction dennis gabor invented holography in 1948 as a method. Electronic speckle pattern interferometry holography interferometry. Fringe formations in holographic interferometry and speckle metrology are discussed in terms of correlation functions of randomly varying complex amplitude of light diffusely reflected from rough surface with the goal of surveying quantitative and automatic measurements by these methods. Speckle and digital holographic interferometry a comparison. Espi can be used in arrangements where fringes will represent lines of either inplane or outofplane displacement. Electronic speckle pattern interferometry wikipedia.
Analysis of holographic fringe formation and holospeckle. Keys so as to understand the differences between digital holography and speckle interferometry and examples of software for hologram reconstructions are also treated in brief. Threedimensional distributions of correlations of the complex amplitudes and intensities before and after the laser wavelength shift are calculated in numerical simulations where a rough surface is modeled with random numbers. A diffractive optical element is described that can be used to implement a very simple selfaligning.
Control unit, software, excitation mechanism, scanning mechanism. Introduction the speckle interferometry is a favorite professional tool for measuring double stars. In practical cases, the objects can show separate zones in which the surface property can simultaneously cause either scattering or specular reflectivity. Complimentarity of digital holographic speckle pattern. Dynamic interferometry neal brock, john hayes, brad kimbr ough, james millerd, michael northmorris.
The software for the image processing, phase calculation. The developments in electronic detection and processing further added wings to laser speckle methods giving rise to electronic speckle pattern interferometry espi, or tv holography 5,6. Bridging the gap between electronic speckle pattern. Despite this, a monograph on dspi has long been awaited, and here it is. 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. Speckle interferometry allows to measure static or dynamic displacement maps that occur. Using such wavelengths allows one to extend the measurement range and decrease the sensitivity of the techniques to external perturbations. Digital holographic speckle pattern interferometry iperion ch.
The principle of holography is based on the fact that, via simultaneously recording a reference light laser beam split by a beam splitter and a returned, scattered light beam from the surface of a target on a holographic plate, reconstruction of an exact replica of the target can be achieved. Digital holographic speckle pattern interferometry dhspi, is based on o axis digital holographic speckle pattern interferometry. Results confirm the effectiveness of both techniques in the conservation field and examples are here in presented. Discusses holographic and speckle interferometry techniques which are the most advanced optical methods used in the analysis of materials deformation and fracture processes, enabling noncontact measurements to be carried out of 3d field on rough surfaces. Application of holographic interferometry and speckle. Applications of holographic and electronic speckle. Electronic speckle pattern interferometry espi non. Electronic speckle pattern interferometry espi fea. Nowadays, it deserves a chapter in almost every book that is published on speckle techniques, holographic interferometry or optical metrology. Dynamic holographicelectronic specklepattern interferometry. Thus a hologram records the phase and the amplitude of the incident. Relations and combinations between holographic interferometry and speckle correlation in contouring by phaseshifting digital holography are discussed. 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. Fringe resolution in digital holographic interferometry 2001.
At this stage the combination of holographic interferometry, electronic speckle interferometry and noncontact laser methods for acoustic waves and local heating fields generation is used. Digital holographic interferometry dhi is a wellestablished method for the. Digital speckle pattern interferometry and related techniques. We offer a complete package including equipment and software. 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. 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 and digital holographic interferometry are investigated at long infrared wavelengths. In a recent publication, professor vivi tornari from the institute of electronic structure and laser at the foundation for research and technology hellas designed a new digital holographic speckle pattern interferometry dhspi portable system with the main focus being to resolve existing shortcoming in existing techniques in art conservation. Digital holographic interferometry and speckle correlation. Holographic and speckle interferometry by robert jones. Sridhar reddy guntaka, vincent toal, and suzanne martin. Chapter 23 holography and holographic instruments lloyd huf f research institute uni y ersity of dayton dayton, ohio 2 3.
Ndt nondestructive testing and vibration applications. Electronic speckle pattern interferometry espi espi on the other hand, records the surface displacement of an object in response to the applied force. Then it investigates the minimum fringe separation resolvable in digital holographic interferometry. This paper describes a brief outline of holographic and speckle. These proceedings reflect the work presented at the conference interferometry in speckle light. The book holographic and speckle interferometry by robert jones and. Digital holographic speckle pattern interferometry. Holographic and laser speckle methods in nondestructive. 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. Furthermore, hi can be performed with one, two, or more reference waves, which can be of the same or different wavelengths. Phaseshifting dynamic holographic interferometry using. On development of portable digital holographic speckle pattern.
The speckle interferometry is a favorite professional tool for measuring double stars. Espi and holographic interferometry allow to measure deformations and vibrations in the micrometer and submicrometer ranges. Read applications of holographic and electronic speckle interferometric techniques for nde of spacecraft components, proceedings of spie on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. In spite of definite similarities they differ chiefly in the methods of acquiring and presenting optical data. Keys so as to understand the differences between digital holography and speckle interferometry and examples of software for hologram reconstructions are also. Simultaneous acquisition of 3d shape and deformation by.
The speckle beam was also used in widefield fluorescence imaging 15, 16 to improve resolution and sectioning ability. Mod01 lec06 hologram interferometry, speckle methods duration. These are promising to provide the mechanical engineer with commercial products based on automated noncontacting optical measurement systems, for applications in industrial design and testing. There exists many types of optical systems which allow deformation and shape measurements which are based on interferometry.
Holographic interferometry an overview sciencedirect. Application of holographic interferometry and speckle photography in the evaluation of mandible stabilization techniques 71 fringe images were recorded in the optical system for hologram reconstruction figure 10. This allows simultaneously capturing temperature and. Phase stepping shearography and electronic speckle pattern interferometry d findeis, j gryzagoridis, m matlali department of mechanical engineering university of cape town, rondebosch, 7700, south africa tel. Introduction to speckle interferometry techniques youtube. Some rare amateurs use this technique on missions in observatories, but none seem to use it routinely with a classical amateur instrumentation. Strain and stress analysis by holographic and speckle. While mathematical techniques for differentiation of experimental data are presented, no mention is made of modern computer software used to automate the. Proceedings of spie the international society for optical engineering. Both electronic speckle pattern interferometry espi and holography are rather powerful tools for nondestructive testing of materials and products. Jonathan huntley makes a remarkably neat approach to the automated analysis of speckle interferograms, describing both temporal and spatial phase evaluation and phase unwrapping techniques, as well as postprocessing methods to convert the optical phase maps into measurements of the parameter under study. Furthermore the software for managing the equipment, usually supplied by the seller with the hardware, provides only heavily processed output data. Calvo department of optics, complutenseuniversity of madrid 17thfebruary 2017, 11. Laser holographic interferometry is a technique combining laser interferometry and holography.
The metrological applications at the chslt concentrate on holographic interferometry, laser speckle metrology, fiber optic sensors, analytical and computational modeling of structural behavior under static as well as dynamic loading conditions, and other areas of current interest. Society of photooptical instrumentation engineers, 1997. These measurements can be applied to stress, strain and vibration analysis, as well as to nondestructive testing and radiation dosimetry. Holographic interferometry hi, which provides interferometric comparison of real objects or events separated in time and space, is a technique of unparalleled applications.
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