DOI•
A New Versatile Electronic Speckle Pattern Interferometer For Vibration Measurements
01 Jan 2013-
About: The article was published on 2013-01-01 and is currently open access. It has received 8 citations till now. The article focuses on the topics: Speckle pattern & Electronic speckle pattern interferometry.
Citations
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Journal Article•
TL;DR: In this article, the theory and performance of rotating radial diffraction grating-based optical modulators are presented. But the performance of such devices is not discussed in detail, nor the theoretical analysis of their performance.
Abstract: The doppler frequency shift produced in the various diffraction orders of a rotating radial diffraction grating allows such a device to be used as an optical modulator. The theory and performance of such devices is presented.
108 citations
Journal Article•
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78 citations
TL;DR: Hariharan as mentioned in this paper provides a self-contained treatment of the principles, techniques and applications of optical holography with particular emphasis on recent developments with a wide range of topics at a level suitable for both the student and research worker.
Abstract: P Hariharan 1984 Cambridge: Cambridge University Press xii + 319 pp price £35 ISBN 0 521 24348 3 It is the declared aim of the author of this book to provide a 'self-contained treatment of the principles, techniques and applications of optical holography with particular emphasis on recent developments'. He has covered a wide range of topics in this expanding field at a level which is suitable for both the student and research worker.
74 citations
31 Mar 1989
TL;DR: The possibility of storing lightwaves on holographic material can not only be used for recording and reconstructing of three-dimensional objects, but also to deflect lightwaves in an unconventionally manner and for divergent an focusing properties.
Abstract: The possibility of storing lightwaves on holographic material can not only be used for recording and reconstructing of three-dimensional objects, but also to deflect lightwaves in an unconventionally manner and for divergent an focusing properties. This kind of specific holograms, which hold imaging properties are called Holographic Optical Elements (HOE). Moreover one can store several features of conventional optical functions in one HOE.
26 citations
07 Sep 2018
TL;DR: In this article, the treatment of problems involving depolarization of incident polarized light beam passing through a depolarizing medium and general physical phenomena associated with it, is investigated at the speckle scale.
Abstract: Many optical applications requires often totally polarized light. However there are an other applications, such as optical spectrum analyzer, in which incident polarized light is undesirable. Insertion of depolarizer in such devices may stabilize the optical signal of the measured light, in order to reduce offsets in measurements. Liquid crystal are functional materials possessing anisotropies originating from their inner molecular alignment. A vertically aligned nematic liquid crystal with zero pretilts in the off state is isotropic for light impinging at normal incidence. However, the liquid crystal orientation upon electric switching is undefined; therefore the cell usually generates disordered birefringent medium related to undefined switching direction of molecules which produce random polarization of the transmitted light by liquid crystal cell, therefore depolarization effect is produced. In this work, the treatment of problems involving depolarization of incident polarized light beam passing through a depolarizing medium and general physical phenomena associated with it, will be investigated at the speckle scale. A suitable tool for this treatment will be real time Young’s interferometer constructed with a new principle including the possibility to control the fringe pattern in real time with objective to study the dynamics of speckle fluctuation. Modulation of depolarization control with an applied voltage are reported, also.
3 citations
References
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TL;DR: In this paper, the distribution of scale sizes in a speckle pattern (i.e., the Wiener spectrum) is investigated from a physical point of view, and it is shown that adding M uncorrelated speckles on an intensity basis can reduce the contrast by 1/√M.
Abstract: A speckle pattern formed in polarized monochromatic light may be regarded as resulting from a classical random walk in the complex plane. The resulting irradiance fluctuations obey negative exponential statistics, with ratio of standard deviation to mean (i.e., contrast) of unity. Reduction of this contrast, or smoothing of the speckle, requires diversity in polarization, space, frequency, or time. Addition of M uncorrelated speckle patterns on an intensity basis can reduce the contrast by 1/√M. However, addition of speckle patterns on a complex amplitude basis provides no reduction of contrast. The distribution of scale sizes in a speckle pattern (i.e., the Wiener spectrum) is investigated from a physical point of view.
2,093 citations
TL;DR: An improved digital correlation method is presented for obtaining the full-field in-plane deformations of an object by numerically correlating a selected subset from the digitized intensity pattern of the undeformed object.
1,788 citations
01 Dec 1963
TL;DR: In this article, the first order statistics of the observed electric-field strength, the observed light intensity, and observed light phase are examined, and the autocorrelation functions of the complex field and intensity processes are investigated, and that of the electric field is found to be proportional to the Fourier transform of the light intensity distribution incident on the scattering surface.
Abstract: : When laser light strikes a diffuse object, such as paper, the scattered light has been observed to possess a granular spatial structure. The statistical properties of these so-called 'sparkle patterns,' as seen by an observer in the far field of the scattering spot, are investigated. The first order statistics of the observed electric-field strength, the observed light intensity, and the observed light phase are examined. The electric field is reasoned to be a complex normal random variable; the intensity a real, exponentially distributed random variable; and the phase a uniformly distributed random variable. Higher order statistics of these random processes are also discussed. The autocorrelation functions of the complex field and the intensity processes are investigated, and that of the electric field is found to be proportional to the Fourier transform of the light-intensity distribution incident on the scattering surface. Spatial averages of the light intensity are considered and are found to converge to corresponding ensemble averages when either the area of the scattering spot or the average area grows large.
1,526 citations
TL;DR: La difference de phase entre les 2 faisceaux interferant varie de maniere connue et on fait des mesures de the distribution d'intensite a travers la pupille correspondant a au moins 3 dephasages differents.
Abstract: La difference de phase entre les 2 faisceaux interferant varie de maniere connue et on fait des mesures de la distribution d'intensite a travers la pupille correspondant a au moins 3 dephasages differents
979 citations
Book•
31 Mar 1983
TL;DR: In this article, the authors present a technique for shape measurements using holographic and speckle pattern interferometry techniques, based on the concept of correlation interferometrics.
Abstract: Preface to the first edition Preface to the second edition 1. Basic optical principles 2. Holographic interferometry 3. Speckle pattern interferometry 4. Electronic speckle pattern correlation interferometry 5. Holographic and speckle pattern interferometry techniques for shape measurements 6. Experimental design and technique 7. Applications Appendices References Index.
897 citations
"A New Versatile Electronic Speckle ..." refers methods in this paper
...using the stroboscopic ESPI method [19]....
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...Another development was to use an ESPI system combined with DSPh for the measurement of all the three displacement components [19]....
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...Sjodahl and Saldner took a different approach by combining phase stepped ESPI with electronic speckle photography technique to measure out-of-plane and inplane displacement components simultaneously with the same set of images [19]....
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