Topic
Speckle imaging
About: Speckle imaging is a research topic. Over the lifetime, 3730 publications have been published within this topic receiving 62354 citations.
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TL;DR: In this paper, the authors discuss the triple-correlation imaging in optical astronomy, including speckle masking, spectroscopy, and optical long-baseline interferometry with arrays of large telescopes.
Abstract: Publisher Summary This chapter discusses the triple-correlation imaging in optical astronomy. The chapter discusses the high-resolution imaging methods of speckle masking (bispectrum or triple correlation processing), speckle spectroscopy, and optical long-baseline interferometry with arrays of large telescopes. The speckle spectroscopy methods have the advantage that they yield the spectrum of each resolution element of the object in addition to the high-resolution image. The additional spectral information is important for the study of the physical nature of astronomical objects. The advantage of the optical long-baseline interferometry with three or more telescopes is that, it can yield images and spectra with excellent angular resolution. Speckle masking is useful in the multi-speckle case, in experiments at visible wavelengths, and with interferometers consisting of large telescopes, such as the very large telescope (VLT) of the European Southern Observatory.
34 citations
TL;DR: This work presents the simultaneous measurement of three-dimensional deformations by electronic speckle pattern interferometry using five object beams and three colors to validate out-of-plane and in-plane deformation measurements and demonstrate sensitivity on the order of 10 nm.
Abstract: We present the simultaneous measurement of three-dimensional deformations by electronic speckle pattern interferometry using five object beams and three colors. Each color, corresponding to an orthogonal direction of displacement, is separated through dichroic filtering before being recorded by a separate CCD camera. Carrier fringes are introduced by tilting the beam path in one arm of each of the three interferometers. The measured deformation modulates these carrier fringes and is extracted using the Fourier-transform method to achieve high displacement sensitivity. The field of view is on the order of a millimeter, making the system suitable for study of microstructural deformations. We compare experimental results with calculated values to validate out-of-plane and in-plane deformation measurements and demonstrate sensitivity on the order of 10 nm.
34 citations
TL;DR: In this paper, a method of obtaining high-resolution time-averaged fringe patterns through digital holography has been described, which includes the elimination of the multiplicative high-frequency phase noise by synchronous detection followed by low-pass filtering.
Abstract: In digital holography, a challenge inherited from speckle interferometry is the quantitative data processing of time-averaged holograms in view of estimating the full field of vibration amplitudes. Fundamentally, the greatest obstacle comes from the orthogonal components of time-averaged digital holograms, corrupted by multiplicative, high-frequency phase noise covering the deterministic vibration-related phase. The paper describes a novel method of obtaining through digital holography high-resolution time-averaged fringe patterns. The three-level approach includes the elimination of the multiplicative high-frequency phase noise by synchronous detection followed by low-pass filtering. The high-frequency information needed by this procedure is taken from the digital hologram of the object at rest. The complete procedure includes an automatic correction of the environmental phase drift introduced by the synchronous detection. The different stages of data processing are illustrated by experimental results.
34 citations
TL;DR: In this article, the laser speckle strain gauge is described and several problems for practical application of the gauge are presented, together with some proposals for solving them, and the gauge optoelectronically detects speckles displacements caused by deformation of a diffuse surface and separates strain by means of a differential optical system.
Abstract: Basic principles and advances of the laser speckle strain gauge are described The gauge optoelectronically detects speckle displacements caused by deformation of a diffuse surface and separates strain by means of a differential optical system The method is noncontacting and automatic Several problems for practical application of the gauge are presented, together with proposals for solving them
34 citations
TL;DR: In this paper, four hundred-forty measurements of 232 binary stars observed during 1981 by means of speckle interferometry with the 4m telescope at KPNO are represented.
Abstract: Four hundred-forty measurements of 232 binary stars observed during 1981 by means of speckle interferometry with the 4-m telescope at KPNO are represented. Newly resolved systems include Xi-1 Cet, Rho Her A, HD 187321, and 59 Cyg A.
34 citations