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Speckle imaging and eye testing using speckle also use the speckle effect. Speckle is the chief limitation of coherent lidar and coherent imaging in optical heterodyne detection. In the case of near field speckles, the statistical properties depend on the light scattering distribution of a given sample.
Speckle variance optical coherence tomography (SV-OCT) is an imaging algorithm for functional optical imaging. Optical coherence tomography is an imaging modality that uses low-coherence interferometry to obtain high resolution, depth-resolved volumetric images. OCT can be used to capture functional images of blood flow, a technique known as ...
Speckle imaging in biology refers to the underlabeling [clarification needed] of periodic cellular components (such as filaments and fibers) so that instead of appearing as a continuous and uniform structure, it appears as a discrete set of speckles. This is due to statistical distribution of the labeled component within unlabeled components.
When a surface is illuminated by a laser beam and is viewed by an observer, a speckle pattern is formed on the retina. [ 2 ] [ 3 ] If the observer has perfect vision, the image of the surface is also formed on the retina, and movement of the head will result in the speckle pattern and the surface moving together so that the speckle pattern ...
Coherent Corp. (formerly II-VI Incorporated) is an American manufacturer of optical materials and semiconductors. As of 2023, the company had 26,622 employees. Their stock is listed at the New York Stock Exchange under the ticker symbol COHR. In 2022, II-VI acquired laser manufacturer Coherent, Inc., and adopted its name.
Compared with other existing imaging technologies, laser speckle contrast imaging has several obvious advantages. It can uses simple and cost-effective instrument to return excellent spatial and temporal resolution imaging. And due to these strengths, laser speckle contrast imaging has been involved in mapping blood flow for decades.
To visualize this effect, the image and reference beams are combined on a video camera and recorded. When the object has been displaced/deformed, the new image is subtracted point by point from the first image. The resulting image is a speckle pattern with black 'fringes' representing contours of constant 2nπ.
The origin of this effect is rapidly changing variations of the optical refractive index along the light path from the object to the detector. Seeing is a major limitation to the angular resolution in astronomical observations with telescopes that would otherwise be limited through diffraction by the size of the telescope aperture .