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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.
The optical arrangement is the same as for out-of-plane displacement above. The object is vibrated at a specific frequency. Those parts of the object which do not move will continue to be speckled. It can be shown that parts of the object which vibrate with amplitudes of nλ/4 have higher speckle contrast than those parts which vibrate at (n+½ ...
It was later realized that speckle patterns could carry information about the object's surface deformations. Butters and Leendertz developed the technique of speckle pattern interferometry in 1970, [97] and since then, speckle has been exploited in a variety of other applications. A photograph is made of the speckle pattern before deformation ...
The size of each speckle pattern should smaller than the photodetector's pixel size to avoid the decrease of contrast. The minimum speckle diameter for an LSCI system depends on the wavelength of light, imaging system magnification, and imaging system f-number: d min ≈ 1.2 ( 1 + M ) λ f / # {\displaystyle d_{\min }\thickapprox 1.2(1+M ...
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.
Shearography or Speckle pattern shearing interferometry is a measuring and testing method similar to holographic interferometry. It uses coherent light or coherent soundwaves [ 1 ] to provide information about the quality of different materials in nondestructive testing , strain measurement, and vibration analysis.
Optical configuration for reflection or Bragg ptychography This geometry can be used either to map surface features or to measure strain in crystalline specimens . Shifts in the specimen surface, or the atomic Bragg planes perpendicular to the surface, appear in the phase of the ptychographic image.
Speckle tracking is one of two methods for Strain rate imaging, the other being Tissue Doppler. Twist or torsional deformation define the base-to-apex gradient and is the result of myocardial shearing in the circumferential-longitudinal planes such that, when viewed from the apex, the base rotates in a counterclockwise direction.