Speckle imaging

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

Application of laser speckle contrast imaging in laparoscopic surgery.

Abstract: Anastomotic leakage is a worldwide problem in gastrointestinal surgery which seems to be related to the state of microcirculation. Laser speckle contrast imaging (LSCI) could give surgeons insight in the state of microcirculation to attune the site of anastomosis. This work studies the feasibility of LSCI as a tool for this purpose. An experimental setup was developed using a commercially available laparoscopic video system. Laser speckle contrast imaging is capable of detecting ischemic areas on the large intestine. Further research and development are required before adaptation of this technique in the operating room.

Decorrelation functions in laser speckle photography

Abstract: The recording and filtering processes of speckle photography are analyzed in detail using statistical optics. We show that the Fourier transforms of the autocorrelation and cross-correlation functions of speckle fields result, respectively, in the diffraction halo function and the Young fringe pattern enveloped by the halo function. A generalized decorrelation factor, defined as the ratio of the Weiner spectra of the cross-correlation and autocorrelation functions, is introduced to explain the degradation of Young’s fringes. It is shown that this factor’s magnitude controls the fringe contrast, whereas its phase may distort the fringe shape. Examples including the effect of lens aberration are presented to show the utility of this decorrelation factor and of that introduced by Yamaguchi [ J. Opt. Soc. Am. A1, 81 ( 1984)].

Disks around Pre--Main-Sequence Binary Systems: The Case of Haro 6-10

Abstract: Subarcsecond KLM images of the pre-main-sequence star Haro 6-10 obtained with the CIRCUS IR camera attached to the Canada-France-Hawaii Telescope are presented. They are the first images where both components of the Haro 6-10 binary system are resolved. We confirm the results by Leinert & Haas (1989), obtained from speckle interferometry, that the projected separation of the two stars is 1″.25 at position angle 356°. We also present new polarization measurement and models that suggest the presence of a flat circumbinary envelope (possibly a disk) associated with the system

Three-dimensional speckle size in generalized optical systems with limiting apertures.

Abstract: Correlation properties of speckle fields at the output of quadratic phase systems with hard square and circular apertures are examined. Using the linear canonical transform and ABCD ray matrix techniques to describe these general optical systems, we first derive analytical formulas for determining axial and lateral speckle sizes. Then using a numerical technique, we extend the analysis so that the correlation properties of nonaxial speckles can also be considered. Using some simple optical systems as examples, we demonstrate how this approach may be conveniently applied. The results of this analysis apply broadly both to the design of metrology systems and to speckle control schemes.

Three-dimensional speckle suppression in optical coherence tomography based on the curvelet transform

Abstract: Optical coherence tomography is an emerging non-invasive technology that provides high resolution, cross-sectional tomographic images of internal structures of specimens. It holds great potentials for a wide variety of applications, especially in the field of biomedical imaging. OCT images, however, are usually degraded by significant speckle noise. Here we report a 3D approach to attenuating speckle noise in OCT images. This approach is based on the 3D curvelet transform, and is conveniently controlled by a single parameter that determines the threshold in the curvelet domain. Unlike 2D approaches which only consider information in individual images, 3D processing, by analyzing all images in a volume simultaneously, has the advantage of also taking the information between images into account. This, coupled with the curvelet transform's nearly optimal sparse representation of curved edges that are common in OCT images, provides a simple yet powerful platform for speckle attenuation. We show the approach suppresses a significant amount of speckle noise, and in the mean time preserves and thus reveals many subtle features that could get attenuated in other approaches.