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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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Proceedings ArticleDOI
16 Jun 2012
TL;DR: A new imaging technique that combines computational photography and laser speckle imaging that provides a reliable way of detecting subtle surface contact at a level that was previously only possible under laboratory conditions is introduced.
Abstract: It is often desirable to detect whether a surface has been touched, even when the changes made to that surface are too subtle to see in a pair of before and after images. To address this challenge, we introduce a new imaging technique that combines computational photography and laser speckle imaging. Without requiring controlled laboratory conditions, our method is able to detect surface changes that would be indistinguishable in regular photographs. It is also mobile and does not need to be present at the time of contact with the surface, making it well suited for applications where the surface of interest cannot be constantly monitored. Our approach takes advantage of the fact that tiny surface deformations cause phase changes in reflected coherent light which alter the speckle pattern visible under laser illumination. We take before and after images of the surface under laser light and can detect subtle contact by correlating the speckle patterns in these images. A key challenge we address is that speckle imaging is very sensitive to the location of the camera, so removing and reintroducing the camera requires high-accuracy viewpoint alignment. To this end, we use a combination of computational rephotog-raphy and correlation analysis of the speckle pattern as a function of camera translation. Our technique provides a reliable way of detecting subtle surface contact at a level that was previously only possible under laboratory conditions. With our system, the detection of these subtle surface changes can now be brought into the wild.

34 citations

Journal ArticleDOI
TL;DR: It is successfully demonstrated that the sum of two negatively correlated images from DOEs can effectively reduce the image speckles and improve the image quality in HPD systems.
Abstract: Speckles on images in holographic projection displays (HPDs) were efficiently suppressed by the temporal sum of two diffractive images generated from diffractive optical elements (DOEs). Using a modified iterative Fourier transform algorithm, we obtained pairs of phase-only DOEs that generated the diffractive images with high negative correlation coefficients of -0.827 and -0.490 in the one-dimensional and the two-dimensional simulations, respectively. The suppression ratios of the speckles in the two simulations were 0.301 and 0.457, which were 61% and 35% lower, respectively, than the sum of the two uncorrelated images. We have successfully demonstrated that the sum of two negatively correlated images from DOEs can effectively reduce the image speckles and improve the image quality in HPD systems.

34 citations

Journal ArticleDOI
TL;DR: Spatial and temporal characteristics of the mesenteric blood-flow response were achieved with high resolution and suggested that LSI might provide a new approach to microcirculation studies.
Abstract: We present a noninvasive full-field method--laser speckle imaging (LSI)--for measuring the regional mesenteric blood flow without scanning. A system of LSI was designed and validated in a model experiment. Dynamics of regional blood flow in the rat mesentery under the influence of noradrenaline were monitored by this method. Spatial and temporal characteristics of the mesenteric blood-flow response were achieved with high resolution. These suggested that LSI might provide a new approach to microcirculation studies.

34 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of the wavefield intensities on the reliability of phase measurements was investigated for phase-shifting speckle interferometry using a smooth reference wave, and the first-order statistics of the background intensity and the modulation of the interference pattern were calculated and then used to determine the efficiency of the measurement, defined as the fraction of points that yield an interference signal exceeding a given modulation threshold.

34 citations

Journal ArticleDOI
TL;DR: This work presents a phase-diversity speckle imaging scheme, based on recording a sequence of intensity Speckle patterns at various imaging planes, and experimentally demonstrates that in addition to being able to retrieve the image of hidden objects, it can also simultaneously estimate the pupil function and the PSF of a highly scattering imaging system without any guide-star nor reference.
Abstract: Recently introduced angular-memory-effect based techniques enable non-invasive imaging of objects hidden behind thin scattering layers. However, both the speckle-correlation and the bispectrum analysis are based on the statistical average of large amounts of speckle grains, which determines that they can hardly access the important information of the point-spread-function (PSF) of a highly scattering imaging system. Here, inspired by notions used in astronomy, we present a phase-diversity speckle imaging scheme, based on recording a sequence of intensity speckle patterns at various imaging planes, and experimentally demonstrate that in addition to being able to retrieve the image of hidden objects, we can also simultaneously estimate the pupil function and the PSF of a highly scattering imaging system without any guide-star nor reference.

34 citations


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