Sur la Détermination Holographique de L'état de Déformation à la Surface D'un Corps Non-transparent
TL;DR: In this paper, les franges presentent des proprietes interessantes, en particulier celle de n'etre visibles qu'en certains endroits seulement, c'est-a-dire d'etres localisees.
Abstract: La reconstitution simultanee par holographie des images d'un objet avant et pendant une sollicitation mecanique fait apparaitre des franges d'interference. Ces franges presentent des proprietes interessantes, en particulier celle de n'etre visibles qu'en certains endroits seulement, c'est-a-dire d'etre localisees. Ces phenomenes ont deja ete examines en detail par plusieurs auteurs auxquels sont empruntes certains raisonnements. Pour chaque point de la surface du corps, on peut observer les franges avec un systeme optique visant dans une direction variable. Sur une courbe de l'espace est remplie la condition de localisation complete: les ondes se superposant en ces points ont meme difference de phase. Pour chaque direction, on peut aussi donner l'endroit ou le contraste des franges est maximum: on se trouve ainsi sur une surface de localisation partielle. Grâce a un critere sur l'orientation des franges, il est possible de determiner les points de localisation complete et d'en deduire par une relation lin...
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TL;DR: Holographic interferometry has some unique properties, which makes it superior to classical interferomet; wavefields from the same object, but under different conditions and at different times, can be compared.
Abstract: Publisher Summary Interferometry is an old and very powerful technique to measure the deviation between two wavefields with a sensitivity of a fraction of a wavelength. In holographic interferometry, at least one of the wavefields to be compared interferometrically is stored in a hologram. The hologram is usually recorded experimentally with the help of a reference wave. However, computer-generated holograms constructed theoretically may also be used to supply special, previously not existing wavefields. In most cases, the hologram itself also acts as the beamsplitter for the superposition of the two wavefields. Holographic interferometry has some unique properties, which makes it superior to classical interferometry; wavefields from the same object, but under different conditions and at different times, can be compared. This is an essential prerequisite to compare interferometrically different states of solid objects with opaque, diffusely scattering surfaces. Transient wavefields can be frozen instantaneously by short exposure times. Time averaged wavefields can be recorded and compared afterward. This results in reduction of noise and increase of accuracy and stability.
57 citations
TL;DR: In this paper, a survey on the formation of the fringe patterns observed in these methods is presented, which helps in deriving dependences of their shape and visibility on object deformation parameters and optical systems by starting from the correlation properties of the light scattered from diffuse objects.
Abstract: Publisher Summary This chapter focuses fringe formations in deformation and vibration measurements using laser light. The chapter discusses a survey on the formation of the fringe patterns observed in these methods. The chapter helps in deriving dependences of their shape and visibility on object deformation parameters and optical systems by starting from the correlation properties of the light scattered from diffuse objects, and discuss the mutual relationships and features of each method by putting physical interpretations on derived mathematical relations. In holographic interferometry and speckle interferometry, the fringe shape represents the distribution of the phase change of the scattered light caused by object deformation, while the fringe visibility depends on the overlap of the corresponding speckle pair, therefore, on speckle displacement and speckle size. In speckle photography, on the other hand, the fringe shape represents the speckle displacement, while the fringe visibility is affected by the speckle decorrelation accompanying the displacement. In addition the relations derived in the present chapter would deliver a quantitative basis for selecting an adequate method of measurement and the optimum manner of signal processing in these modem interferometric techniques.
56 citations
TL;DR: This review paper is an attempt to rationalize the field by classifying the many different interpretation schemes into four main techniques, and by offering guidelines for the choice of technique for different applications.
Abstract: Holographic interferometry is a very powerful technique for the measurement of small deformations and displacements of opaque solid objects. Unfortunately, the quantitative interpretation of the fringe patterns is somewhat involved, and the large number of papers published on this subject in the past 10 years has caused considerable confusion. This review paper is an attempt to rationalize the field by classifying the many different interpretation schemes into four main techniques, and by offering guidelines for the choice of technique for different applications.
55 citations
TL;DR: When an object undergoes a combination of minute rigid-body motion and homogeneous deformation, its vectorial displacements can be described by a general, 3 x 3 matrix transformation and this same matrix can be used to transform the sensitivity vector of hologram interferometry into a fringe vector that defines the fringes as laminae that are intersected by the surface of the object.
Abstract: When an object undergoes a combination of minute rigid-body motion and homogeneous deformation, its vectorial displacements can be described by a general, 3 × 3 matrix transformation. This same matrix can be used to transform the sensitivity vector of hologram interferometry into a fringe vector that defines the fringes as laminae that are intersected by the surface of the object. When fringes are observable on more than one surface of a three-dimensional object whose shape is known, it is possible to determine the fringe vector from the shape and spacing of the fringes on the object. If three holographic views are available, from which three fringe vectors can be determined for three known sensitivity vectors, it is possible to determine the transformation matrix, and this, in turn, can be decomposed into deformation and rotation matrices. More than three views allow the use of least-square-error theory to minimize errors in data taking.
47 citations
TL;DR: In this paper, the possibility of using the speckle pattern decorrelation for determination of small deformation tensor components of an elementary object surface area in an optical image field is described.
Abstract: The paper describes the possibility of using the speckle pattern decorrelation for determination of small deformation tensor components of an elementary object surface area in an optical image field. The relationship between the small-deformation tensor and the speckle field displacement is analysed in detail. The studied problem is presented from the approximation viewpoint of both wave and geometrical optics.
26 citations
References
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TL;DR: A new method for the measurement of minute deformations of arbitrary three-dimensional objects, such as might occur due to applied stress, as well as the interpretation of the interference phenomena observed in terms of the translations and rotations undergone by a point on the object.
Abstract: This paper describes a new method for the measurement of minute deformations of arbitrary three-dimensional objects, such as might occur due to applied stress. The method is an application of the wavefront reconstruction technique, as developed by Leith and Upatnieks, to the interferometry of three-dimensional diffusely reflecting objects. The theory of wavefront reconstruction is sketched. A detailed theory for the interpretation of the interference phenomena observed in terms of the translations and rotations undergone by a point on the object is presented. Experimental results verifying the method and the theory are shown.
192 citations
TL;DR: In this article, a superposition de deux hologrammes sur a meme plaque donne lieu, dans le processus de restitution, a des phenomenes d'interference mettant en evidence les deplacements and, eventuellement, les deformations de faible amplitude of l'objet.
Abstract: La superposition de deux hologrammes sur une meme plaque donne lieu, dans le processus de restitution, a des phenomenes d'interference mettant en evidence les deplacements et, eventuellement, les deformations de faible amplitude de l'objet. Si l'on considere les franges qui apparaissent dans la direction de l'image restituee, leur localisation par rapport a celle-ci, leur forme et leur contraste fournissent une information quantitative sur les composantes du deplacement (translations et rotations) subi par la surface de l'objet. D'autre part, un reseau de franges de Fraunhofer, centrees sur la source de restitution (ordre 0), est observable dans certaines conditions et permet de preciser un critere de non-deformation de l'objet au cours d'un deplacement donne. On montre que le phenomene est identifiable au spectre de Fourier d'une transmittance constituee par deux pupilles complexes identiques legerement decalees l'une par rapport a l'autre. La validite du critere est verifiee experimentalement dans le ca...
42 citations
TL;DR: In this paper, it was shown that the complex amplitude of field one, in a small volume about a point P of observation, is identical (or proportional) to field two in a similar volume about P, close to P. The conditions for homology are given, and a proof is outlined with reference to a more detailed investigation carried out elsewhere.
Abstract: In holographic interferometry of diffusely reflecting surfaces the two interfering fields observed are homologous, provided certain observation conditions and idealizations are satisfied. The physical content of this statement, as it is given here, is that the complex amplitude of field one, in a small volume about a point P of observation, is identical (or proportional) to the complex amplitude of field two in a similar volume about a point P′, close to P. The conditions for homology are given, and a proof is outlined with reference to a more detailed investigation carried out elsewhere. A principal ray, and the locus of points satisfying homology of field two with respect to points along the principal ray in field one, constitute a pair of homologous rays. The concept of homologous rays was introduced by Vienot et al. [1] for surface movements coplanar with the illumination and observation directions. Its validity is extended here to more general movements, including strain and shear. It is shown how po...
38 citations
TL;DR: In this article, a double-exposure hologram interferometer using two reference beams is described which restores fringe visibility after processing and permits to obtain various fringe patterns from a single hologram.
Abstract: A double-exposure hologram interferometer using two reference beams is described which restores fringe visibility after processing and permits to obtain various fringe patterns from a single hologram. It has been successfully applied to the deformation measurements on an object of local variations in lateral translations. Experiments are also presented on changing fringe patterns suitable to interpretations. Expressions were derived for the localization of fringes of diffusely reflecting objects and compared with the experimental results. A good agreement was obtained between them.
35 citations
TL;DR: Two simultaneous holograms and several directions of observation are utilized to determine the components of displacement and strain in the disk.
Abstract: Two simultaneous holograms and several directions of observation are utilized to determine the components of displacement and strain in the disk. A reference strip is introduced to relate the fringe orders in the two holograms. A very good agreement is obtained between the holographic results and the elasticity theory solution. The obtained displacement field is estimated to be accurate to 8 x 10(-6) cm, which is approximately one-eighth the wavelength of the laser light utilized to obtain the holograms.
34 citations