scispace - formally typeset
Search or ask a question

Showing papers on "Speckle imaging published in 1975"


Book
01 Jan 1975
TL;DR: Dainty et al. as mentioned in this paper described statistical properties of laser speckle patterns and proposed a method to reduce the number of sparseness of the laser beam in Partially Coherent Light (PCL).
Abstract: Contents: Dainty, J. C.: Introduction. - Goodman, J. W.: Statistical Properties of Laser Speckle Patterns. - Parry, G.: Speckle Patterns in Partially Coherent Light. - McKechnie, T. S.: Speckle Reduction. - Francon, M.: Information Processing Using Speckle Patterns. - Ennos, A. E.: Speckle Interferometry. - Dainty, J. C.: Stellar Speckle Interferometry. - Dainty, J. C.: Recent Developments. - Subject Index.

1,254 citations


Book ChapterDOI
01 Jan 1975
TL;DR: Stellar speckle interferometry is a technique for obtaining diffraction-limited resolution of stellar objects despite the presence of the turbulent atmosphere which limits the resolution of conventional long-exposure pictures to approximately one arc second as mentioned in this paper.
Abstract: Stellar speckle interferometry is a technique for obtaining diffraction-limited resolution of stellar objects despite the presence of the turbulent atmosphere which limits the resolution of conventional long-exposure pictures to approximately one arc second. It was invented by Labeyrie [7.1] and the first results using the 5 m Hale telescope at Mount Palomar were presented in 1972 [7.2]. Speckle interferometry can be regarded as a method of finding the modulus of the degree of coherence in the far field of an incoherent source and is essentially the same as a method suggested independently by Asakura et al. [7.3] for the determination of the spatial coherence of light emitted by laboratory sources. There is also a very close relationship between stellar speckle interferometry and some of the information processing and engineering applications of speckle patterns described in Chapters 5 and 6.

81 citations


Journal ArticleDOI
TL;DR: A review of speckle interferometry techniques can be found in this article, where the authors set the various techniques into context, point out their similarities, and delineate their differences.
Abstract: Since its discovery in 1969, speckle interferometry has be-come a very active area of research, so much so that there now exists quite a collection of techniques that are applicable to a wide variety of problems. Because of the surprising versatility offered by such a wide range of techniques, the potential user of such technology may become con-fused as to what can and cannot be done, and, further, what process is suitable for what task. This review is provided, therefore, to set the various techniques into context, point out their similarities, and delineate their differences.

64 citations


Journal ArticleDOI
TL;DR: A simple calibration procedure is described and its use in measuring in-plane displacements in deformable solids is demonstrated and some limitations on the range of sensitivity that can be effectively utilized with holographic films, simple procedures, and a small laser are given.
Abstract: Speckle interferometry involves making a high resolution double-exposure photograph of an object that is illuminated with coherent light. When observed in a Fourier optical data processor, fringes are observed that are indicative of the changes, such as displacements, occurring in the body between exposures. Sensitivity of the measurement is variable and may be chosen after the data are recorded. A simple calibration procedure is described and its use in measuring in-plane displacements in deformable solids is demonstrated. Also given are some limitations on the range of sensitivity that can be effectively utilized with holographic films, simple procedures, and a small laser.

32 citations


Journal Article
TL;DR: Speckle imaging as discussed by the authors is a technique for recovering diffraction limited images from sequences of atmosphere-degraded, short exposure photographs obtained at a large telescope, which is derived from speckle interferometry and shares many of the characteristics of that process, including dependence of the output signal-tonoise on number of frames processed and relative insensitivity to fixed telescope aberrations and noise in the image record.
Abstract: Speckle imaging is a technique for recovering diffraction limited images from sequences of atmosphere-degraded, short exposure photographs obtained at a large telescope. The technique is derived from speckle interferometry and shares many of the characteristics of that process, including dependence of the output signal-to-noise on number of frames processed and relative insensitivity to fixed telescope aberrations and noise in the image record. Speckle interferometry has been demonstrated to yield telescope-diffraction-limited information, but only in the form of spatial power spectra. Speckle imaging averages a different quantity, the statistical autocorrelation of the image Fourier transform, which contains all the information in the averaged power spectra plus the transform phase information required to recover an image. Two-dimensional digital simulations of the process for extended continuous-tone objects are presented, and include the case where severe static telescope aberrations are present.

22 citations


Journal ArticleDOI
L.C. De Backer1
TL;DR: In this article, the authors describe the way in which the speckled appearance of laser-illuminated objects is used to determine in-plane displacement components, and the detection of cracks in small concrete models is treated as an application of the technique described.
Abstract: This article starts with a brief description of the way in which the speckled appearance of laser-illuminated objects is used to determine in-plane displacement components. The detection of cracks in small concrete models is treated as an application of the technique described.

17 citations



Journal Article
01 Jan 1975-Optik

15 citations


Journal ArticleDOI
TL;DR: In this paper, the utility of speckle interferometry for overcoming the atmosphere-induced resolution limit is investigated with a laboratory simulation, and various geometric object shapes verify reported field measurements for single and binary stars and demonstrate the usefulness of this technique for quantitative measurement of more complex shapes.
Abstract: The utility of speckle interferometry for overcoming the atmospherically induced resolution limit is investigated with a laboratory simulation. Studies of various geometric object shapes verify reported field measurements for single and binary stars and demonstrate the usefulness of this technique for quantitative measurement of more complex shapes.

8 citations



Journal ArticleDOI
TL;DR: In this paper, a two-telescope prototype is described, as well as preliminary plans for the construction of a full-size array of a large telescope working in the speckle interferometry mode.
Abstract: Interference fringes have recently been obtained with two small telescopes operated as a Michelson stellar interferometer. With the availability of photon-counting television cameras, it now becomes possible to build synthetic aperture arrays of large telescopes working in the speckle interferometry mode. Details of the two-telescope prototype are given, as well as preliminary plans for the construction of a full-size array.

Journal ArticleDOI
01 Jul 1975-Strain
TL;DR: In this paper, a simplified theory of speckle interferometry as a means of measuring localised displacement, was presented, and a simple experiment good correlation was obtained between strains determined by this method and strain gauge readings.
Abstract: A simplified theory of speckle interferometry as a means of measuring localised displacement, is presented. In a simple experiment good correlation was obtained between strains determined by this method and strain gauge readings. A special automated camera capable of monitoring a continuously varying displacement is described.

01 May 1975
TL;DR: In this article, an experimental program was carried out to see if holographic interferometry could be used to determine Young's modulus and Poisson's ratio of ice using the ring test.
Abstract: : An experimental program was carried out to see if holographic interferometry could be used to determine Young's modulus and Poisson's ratio of ice using the ring test Spurious rigid body deflections of up to 05 microinch were found when the sample was compressed These motions are of such magnitude that they will affect the accuracy of the bore gauge measurements of ice strength The technique most suited to measurements of the deformation of the ice ring is speckle interferometry This technique is most sensitive to motions of the magnitude found when using the ring test on ice and it allows measurement of motion in each of the three orthogonal directions separately so that Young's modulus and Poisson's ratio may be obtained easily