نتایج جستجو برای: speckle

تعداد نتایج: 8844  

Journal: :Applied optics 2012
Lucien Pouget Julien Fade Cyril Hamel Mehdi Alouini

We address an experimental Stokes imaging setup allowing one to explore the polarimetric properties of a speckle light field with spatial resolution well beyond the speckle grain scale. We detail how the various experimental difficulties inherent to such measurements can be overcome with a dedicated measurement protocol involving a careful speckle registration step. The setup and protocol are t...

2017
Orly Liba Matthew D Lew Elliott D SoRelle Rebecca Dutta Debasish Sen Darius M Moshfeghi Steven Chu Adam de la Zerda

Optical coherence tomography (OCT) is a powerful biomedical imaging technology that relies on the coherent detection of backscattered light to image tissue morphology in vivo. As a consequence, OCT is susceptible to coherent noise (speckle noise), which imposes significant limitations on its diagnostic capabilities. Here we show speckle-modulating OCT (SM-OCT), a method based purely on light ma...

Journal: :Optics express 2008
Haiying Cheng Yumei Yan Timothy Q Duong

Temporal-statistical analysis of laser-speckle image (TS-LSI) preserves the original spatial resolution, in contrast to conventional spatial-statistical analysis (SS-LSI). Concerns have been raised regarding the temporal independency of TS-LSI signals and its insensitivity toward stationary-speckle contamination. Our results from flow phantoms and in vivo rat retinas demonstrated that the TS-LS...

2014
V. SrinivasaRaghavan

A.Mohanapreethi, Dr. V. SrinivasaRaghavan M.E, Communication Systems, Loyola Institute of Technology 2 Chennai, India 2 . Abstract─In diagnosis of diseases, ultrasound imaging is the most commonly used imaging system in medical field. The main issue related to this imaging technique is the presence of speckle noise which degrades the quality of the image. Image denoising is an important pre-pro...

2015
Yiming Ding Huisung Kim Euiwon Bae

Carbon Nano Petals (i.e. CNPs) are cantilevered multilayer grapheme sheets that are seeded from core graphite fibers. The resulting structure offers a possibility of minimizing interfacial losses in transport application, improved interactions with surrounding matrix materials in composites, and a route toward substrate independence for device applications. The mass production of CNPs on the su...

2017
Sivasubramanyam Medasani G. Umamaheswara Reddy

Synthetic Aperture Radar (SAR) data are affected by speckle noise, because of coherent integration of back scattered signals from different targets. For one-dimensional SAR data the speckle noise is already a solved problem, due to its multiplicative nature. SAR polarimetry is an extension to multidimensional data by the use of polarization wave diversity. Any speckle filter has to suppress the...

2015
Jayachandra Bingi Vadakke Matham Murukeshan

Laser speckle pattern is a granular structure formed due to random coherent wavelet interference and generally considered as noise in optical systems including photolithography. Contrary to this, in this paper, we use the speckle pattern to generate predictable and controlled Gaussian random structures and quasi-random structures photo-lithographically. The random structures made using this pro...

Journal: :IEEE Trans. Geoscience and Remote Sensing 2003
Carlos López-Martínez Xavier Fàbregas

Synthetic aperture radar (SAR) data are affected by speckle noise, originated by the SAR system’s coherent nature. The problem of speckle noise in one-dimensional (1-D) data is already solved, as speckle has a multiplicative characteristic. SAR polarimetry represents an extension to multidimensional data by the use of polarization wave diversity. As a consequence of the existence of a correlati...

Journal: :Optics express 2009
Dongyel Kang Eric Clarkson Tom D Milster

Optical aberration effects up to the second moment of Gaussian laser speckle are theoretically investigated for both partially and fully developed speckle. In the development, a plane-wave illuminated diffuser generates a phase-perturbed random field in the object plane that creates speckle in the image plane. Theoretical derivations show that image field statistics are generally non-circular G...

Journal: :Optics express 2012
Roarke Horstmeyer Richard Y Chen Benjamin Judkewitz Changhuei Yang

Optical speckle is commonly observed in measurements using coherent radiation. While lacking experimental validation, previous work has often assumed that speckle's random spatial pattern follows a Markov process. Here, we present a derivation and experimental confirmation of conditions under which this assumption holds true. We demonstrate that a detected speckle field can be designed to obey ...

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