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Speckle imaging

About: Speckle imaging is a research topic. Over the lifetime, 3730 publications have been published within this topic receiving 62354 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, a new residual stress determination method in two directions simultaneously is presented, which is based on stresses relaxation in a groove that is machined incrementally, and the residual stresses relaxation occurs simultaneously from both the depth and the length of the groove.
Abstract: In this study a new residual stress determination method in two directions simultaneously is presented. This method is based on stresses relaxation in a groove that is machined incrementally. The residual stresses relaxation occurs simultaneously from both the depth and the length of the groove. Thus, measuring the surface strain field generated by the relaxation enables to determine the stress gradient both along the depth and the length of the groove. To measure the surface strain in a direction perpendicular to the groove, a digital speckle pattern interferometer is used. This method is suitable when the residual stress field in the structure varies in the depth as well as along the surface of the part, like for example in a welded structure. The method is tested here on an aluminium plate in which a central band has been shot peened.

16 citations

Journal ArticleDOI
TL;DR: In this paper, the authors introduce a space-time analysis in which both spatial and temporal fluctuations are taken into account; the aim is to measure the power spectrum of the image with an increased signal to noise ratio.
Abstract: The standard method of stellar speckle interferometry, in which short exposure photographs are individually analyzed, is not the most general method of extracting object information from the time-varying image intensity. We introduce a space-time analysis in which both spatial and temporal fluctuations are taken into account; the aim is to measure the power spectrum of the image with an increased signal to noise ratio. Surprisingly, our more general space-time analysis does not yield an improved signal to noise ratio at very low light levels.

15 citations

Journal ArticleDOI
TL;DR: An algorithm for stellar object reconstruction without a reference star based on parallel application of the iterative blind deconvolution method to several speckle frames permits reconstruction of an object that satisfies the convolution relation in all the frames used.
Abstract: An algorithm for stellar object reconstruction without a reference star is described. The algorithm is based on parallel application of the iterative blind deconvolution method to several speckle frames, and it permits reconstruction of an object that satisfies the convolution relation in all the frames used. Computer simulations with noisy speckle images are carried out to demonstrate performances of the algorithm. The algorithm is applied to observational data of binary stars, and high-resolution images are clearly reconstructed. Binary parameters extracted from the images show good consistency with those obtained both with the power spectrum analysis and with the shift-and-add method.

15 citations

Journal ArticleDOI
TL;DR: In this article, a 1MHz focused sound field emitted by a hemispherical piezotransducer in water is imaged as an example, and the pressure at focus determined by this method agrees with measurements from a fiber-optic probe hydrophone.
Abstract: Interferometric imaging is a well-established method to image phase objects by mixing the image wavefront with a reference one on a CCD camera. It has also been applied to fast transient phenomena, mostly through the analysis of single interferograms. It is shown that, for repetitive phenomena, multiphase acquisition brings significant advantages. A 1MHz focused sound field emitted by a hemispherical piezotransducer in water is imaged as an example. Quantitative image analysis provides high resolution sound field profiles. Pressure at focus determined by this method agrees with measurements from a fiber-optic probe hydrophone. This confirms that multiphase interferometric imaging can indeed provide quantitative measurements.

15 citations

Patent
29 Mar 2010
TL;DR: In this paper, a system for imaging a textured surface includes a light source that is configured to project an electromagnetic radiation beam onto the textured surfaces, wherein the projected beam generates first radiation reflected from a first portion of the texture to form a speckle pattern, and second radiation reflected by the reflected first and second reflected radiation is received by an optical detector.
Abstract: A system for imaging a textured surface includes a light source that is configured to project an electromagnetic radiation beam onto the textured surface, wherein the projected beam generates first radiation reflected from a first portion of the textured surface to form a speckle pattern, and second radiation reflected from a second portion of the textured surface which is substantially uniform in intensity. The reflected first and second reflected radiation is received by an optical detector, and may be processed to generate an image of the textured surface from the first and second reflected radiation. Methods for textured surface sensing are also disclosed.

15 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202332
202249
202162
202079
201972
201895