
	Where results make sense

Topic: Speckle pattern

Related Topics

Coherence (physics)

Federal Standard 1037C

Laser

In the News (Thu 17 Dec 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	[No title]
		The attractiveness of speckle methods lies in the ability to measure large deformations, reduce sensitivity both in speckle photography and speckle interferometry, variable sensitivity to in-plane and out-of-plane displacements, displacement derivatives, and shape measurement.
		The contrast of the speckle pattern is a ratio of the variance to the average irradiance.
		Speckle pattern observed in the image of a diffuse object illuminated by a coherent beam is termed subjective speckle pattern..
	www.rose-hulman.edu /~joenatha/speckle1.html (847 words)

	ieo \| technical
		Two speckle patterns are produced which are identical except that one is displaced relative to the other by an amount, which depends on the extent of the displacement of the object and the magnification of the imaging system.
		This speckle pattern is imaged onto a CCD array where it is allowed to interfere with a reference wave, which may, or may not, be speckled.
		Phase-shifting is used to obtain a fringe pattern which depicts the phase change, in the range 0 and 2pi, that occurred between the two speckle patterns.
	www.ieo.dit.ie /technical_ndt.html (3951 words)

	Speckle pattern - Wikipedia, the free encyclopedia (Site not responding. Last check: )
		A speckle pattern is a random intensity pattern produced by the mutual interference of coherent wavefronts that are subject to phase differences and/or intensity fluctuations.
		Prominent examples include the seemingly random pattern created when a coherent laser beam is reflected off a rough surface, and the highly magnified image of a star through imperfect optics or through the atmosphere (see speckle imaging).
		The speckle phenomena also have analogues in other fields; examples are the reflection of radio waves from rough surfaces such as the ground, and ultrasonic imaging etc. The speckle pattern was initially considered the bane of holographers as holographic reconstructions were accompanied by grainy noise.
	www.sciencedaily.com /encyclopedia/speckle_pattern (586 words)

	Optical Elastography
		Thus, application of speckle techniques to assessment of strain in biological tissues often relies upon rapid sampling of the speckle patterns and the use of processing algorithms that are aimed at inferring strain rates rather than absolute strains.
		Due to the fast decorrelation of the observed speckle patterns as a result of random movements within the tissues (water, blood, etcÖ), the switching of the illumination angle and subsequent triggering of the CCD array must be rapid enough to acquire at least several records with minimal decorrelation between subsequent exposures.
		Stacked speckle histories are time series of one-dimensional views of the speckle patterns combined in a spatio-temporal array such that the spatial dimension (camera pixel) is along the abscissa and the temporal axis is the ordinate.
	omlc.ogi.edu /news/oct00/seansaratov2000/index.htm (3370 words)

	ieo \| technical
		Two speckle patterns are produced which are identical except that one is displaced relative to the other by an amount, which depends on the extent of the displacement of the object and the magnification of the imaging system.
		This speckle pattern is imaged onto a CCD array where it is allowed to interfere with a reference wave, which may, or may not, be speckled.
		The resulting interferogram is then displayed on the monitor as a pattern of dark and bright fringes, called correlation fringes, as the fringes are produced by correlating the intensities of the resultant speckle patterns taken before and after displacement.
	ieo.dit.ie /technical_ndt.html (3951 words)

	Vibrometer University - Surface Effects
		Speckle patterns are always produced when a coherent light source is focused onto a rough surface.
		The speckle noise produced depends on the rate of change in the speckle pattern and is therefore strong when measuring from rotating targets or surfaces that show a strong in-plane motion.
		In addition, speckle tracking routines and optimized scan mirror control are available with Polytec's scanning vibrometer to minimize noise effects coming from speckles.
	www.polytec.com /usa/158_1000.asp (556 words)

	Mercury has molten core
		The system involved sending a powerful radar signal at the planet, then receiving the signal's echo, which appeared as a unique pattern of speckles reflecting the roughness of the planet's surface, at two locations separated by about 2,000 miles.
		The metallic core extends from the center to a large fraction of the planetary radius.
		Measuring how long it took for a particular speckle pattern to reproduce at the two locations (about 10 seconds) allowed Margot to calculate Mercury's spin rate with an accuracy of one part in 100,000.
	www.news.cornell.edu /stories/May07/margot.mercury.html (701 words)

	Speckle pattern analysis method and system - Patent 7123363
		This ‘boiling’ speckle is referred to as the biospeckle and has been observable in objects such as fruit, vegetables, blood flow, and egg embryos.
		This speckle pattern is directly related to the rate at which the compositional elements within the structure move i.e., the bioactivity.
		This temporally varying speckle is characteristic to vibrations which have been observable in inanimate objects such as a vibrating surface on a micro-switch, micro-actuator, or micro-motor used in nanotechnology type devices.
	www.freepatentsonline.com /7123363.html (4957 words)

	Coherent anti-Stokes Raman scattering microscopy with dynamic speckle illumination
		The time-dependent speckle patterns are generated by randomly moving a multimode fiber delivering one of the excitation laser pulses.
		As expected, the result is smoother than in figure 2(A) (with a speckle contrast of 10%), due to the fact that in figure 2(C) the speckle pattern is not sharply imaged at the camera.
		Note that the numerical averaging over the 16 different speckle images in figures 2(E) and (G) is equivalent to the above mentioned speckle reduction method, where a dynamically changing speckle pattern is produced by attaching a fiber to a vibrating loudspeaker membrane, and the CARS image is integrated over a selected number of laser shots.
	www.iop.org /EJ/article/1367-2630/10/2/023029/njp8_2_023029.html (4145 words)

	Canadian Speckle Park Association - Contact Us
		Speckle Park come in a variety of colors but the preferred color pattern are the speckled animals.
		It is similar to the speckled pattern but there are definite fl spots on the animals instead of just speckles.
		Speckle Park made their debut appearance in the ‘Halter to Hook’ competition in 2002 with 1 heifer.
	www.specklepark.ca /Nmerits.html (1589 words)

	Wellman Center for Photomedicine: People
		The temporal characteristics of the speckle pattern from biological tissue are affected by moving scatterers within tissue.
		Unperfused biological tissue leads to a temporally static speckle pattern, while fully perfused tissue exhibits a temporally modulated speckle pattern.
		Laser speckle analysis is based on using the temporal and spatial characteristics of the speckle pattern to assess tissue perfusion.
	www.mgh.harvard.edu /wellman/people/achau.asp (186 words)

	SPECKLE METROLOGY
		The average size of the speckles in these patterns is determined primarily by the wavelength of the coherent light, the width of the original illuminating beam or equivalently, the size of the illuminated surface area, and the geometry involved.
		The use of speckle metrology is divided into two classes, depending on whether the measurement merely depends on the simple translation of speckle patterns with no use of phase information, or whether a coherent reference beam is added to the speckle pattern and phase information is utilized.
		The film plate is first exposed to the speckle pattern on the object surface when the surface is in its initial or preloaded state.
	academic.mu.edu /phys/matthysd/L1980414.htm (792 words)

	Basic ultrasound, echocardiography and Doppler ultrasound
		The emmitted or reflected waves are seen to generate a speckle pattern (oval dots) as the amplitude is increased where wave crests cross each other, while the waves are neutralised where a wave crest crosses a though.
		It is evident that many speckles are only visible during part of the heart cycle, but if the speckle pattern is compared from frame to frame, the changes will be small.
		As speckle trecking can track in both transverse and axial directions, with a sufficient number of kernels, deformation can in preinciple be measured in two dimensions, as as dicussed in the section about a new application called "2D strain".
	folk.ntnu.no /stoylen/strainrate/Ultrasound (5262 words)

	EVIGeM - Surface Characterization of optical...
		It is based on the statistical properties of speckle patterns emerging from an optical smooth surface, which is illuminated with a fully developed static speckle pattern.
		In the case of the smoothest specimen the illumination speckle pattern is nearly specularly reflected to the CCD-array (Figure 7.a).
		The ACF width is a measure for the mean speckle diameter in the scattered light distribution and, therefore, decreases with increasing roughness.
	www.evigem.org /index.php?id=381 (2632 words)

	Solution #15157
		In a conventional, coherent-light optical mouse, it is necessary to detect the motion of a speckle pattern by an image sensor.
		If the average speckle size in the speckle pattern is smaller than the pixel size, then during a small movement of the speckle pattern, most speckles can stay within one pixel.
		Unfortunately, the optical system of the mouse generates a speckle pattern in which the average speckle size is smaller than the size of the pixel in conventional semiconductor image sensors.
	consulting.effectivesoft.com /examples.php?bid=0&id=4 (743 words)

	Second Order Speckle Statistics
		In this manner, it is possible for a point target that has flat phase to appear as a localized speckle pattern to the imaging system, as its echo has taken on the phase characteristics of speckle across the aperture.
		In considering the autocorrelation operation applied to speckle, recall that the power spectrum is the Fourier transform of the autocorrelation operation, and that neither function has a phase component.
		Therefore, we expect in the autocorrelation functions of a point target (that has a target spectrum with flat phase) and a speckle pattern (that has a target spectrum with random phase) to be the same in both lateral and axial dimensions, since the autocorrelation function is phase independent.
	dukemil.egr.duke.edu /Ultrasound/k-space/node7.html (570 words)

	Speckle Imaging of CBF
		Laser speckle imaging was suggested as a method for blood flow imaging almost 20 years ago by Fercher and Briers.
		They demonstrated that by integrating the intensity fluctuations in a speckle pattern over a finite time, information about the motion of the scattering particles could be determined.
		In areas of higher blood flow the speckle intensity fluctuations are more rapid and when integrated over a finite time, these areas show increased blurring of the speckle pattern.
	www.nmr.mgh.harvard.edu /~adunn/speckle/Speckle_Imaging_of_CBF.html (205 words)

	lab
		Electronic Speckle Pattern Interferometry (ESPI) is a technique for measuring surface contours and deformation patterns to a high degree of precision and accuracy.
		The speckles are interference images created when the path lenghts of converging rays reflected off the illuminated surface differ by half the wavelength of the coherent light source.
		These speckle patterns are then computer filtered to reate high-resolution contour maps of the shape of the object.
	cronos.rutgers.edu /~pelegri/lab/index.html (1096 words)

	COPS - Onderwijs, Java Corner, Speckle
		Speckle is formed when laser light scatters from a random system such as white paint or paper.
		Speckle is the result of the interference of waves originating from scatter centers illuminated by a coherent laser source.
		Even without multiple scattering a speckle pattern develops which is put to good use in e.g.
	cops.tnw.utwente.nl /education/5_oc_speckle.html (204 words)

	Laser Laboratory: Some Old Works
		Speckle shearography is an interferometric method to measure displacement gradients at surfaces of engineering components.
		To measure the spatial derivative od surface displacement, a reference speckle pattern (relative to the initial state of the object) is stored.
		Subsequent frames are subtracted from the reference pattern to obtain the final fringe pattern depicting the slope of the normal displacement.
	dau.ing.univaq.it /~laser/Research/Old_Works/Old_Works.htm (1352 words)

	ABOUT LASER SPECKLE AND OTHER PHENOMENA (Site not responding. Last check: )
		Speckle is a mottled pattern that arises when laser light falls on a non-specular reflecting surface.
		As for the speckle pattern, that is usually called the interference pattern.
		Speckle noise arises because of the highly coherent nature of the laser light and can thus be reduced or eliminated by reducing the coherence of the source.
	www.cat.gov.in /others/lasinfo/specle.html (520 words)

	speckle \| English \| Dictionary & Translation by Babylon
		A speckle pattern is a random intensity pattern produced by the mutual interference of coherent wavefronts that are subject to phase differences and/or intensity fluctuations.
		Prominent examples include the seemingly random pattern created when a coherent laser beam is reflected off a rough surface, and the highly magnified image of a star through imperfect optics or through the atmosphere (see speckle imaging).
		Each point in the intensity pattern is a superposition of each point of the rough surface contributing with a random phase due to path length differences.
	www.babylon.com /definition/speckle (281 words)

	ELECTRONIC SPECKLE PATTERN INTERFEROMETRY (ESPI)
		Electronic speckle pattern interferometry is a method of speckle correlation interferometry that is growing in popularity because it simplifies the process of obtaining specklegrams.
		The basic idea is to take a picture of the speckled surface under study in its initial state, save this picture in a frame grabber or in computer memory, deform the surface, and take another picture.
		The fringe pattern describing the deformation that has occurred between the initial and final states is obtained by subtracting the second picture from the stored initial picture.
	www.marquette.edu /~matthysd/L1980428.htm (760 words)

	Volker Tolls @ Center for Astrophysics
		The concept of the Labeyrie multi-step speckle reduction method is a potential technique to reduce these challenging surface requirements to more achievable accuracies of λ/100 to λ/1000 by correcting and removing speckle light after the initial coronagraphic step.
		Instead of correcting the telescope wavefront before the coronagraph, Labeyrie suggested (Labeyrie 2002) that measurements are made of “the phase of the speckle pattern” in the image plane of a Lyot coronagraph.
		The speckle pattern is the result of phase errors introduced by the telescope system and the occulter mask in the coronagraph (all following optical elements contribute only negligible amounts to the speckle light since the bright stellar light has been mostly suppressed at this point).
	cfa-www.harvard.edu /~tolls/labeyrie.html (1392 words)

	The American Society for Nondestructive Testing (Site not responding. Last check: )
		This paper presents an electronic speckle pattern interferometric technique which can be used for the quantitative measurement of displacement and strains at very high temperatures.
		lectronic speckle pattern interferometry is an attractive technique for the characterization of materials at elevated temperatures.
		Electronic speckle pattern interferometry is an attractive technique for the characterization of materials at elevated temperatures.
	www.asnt.org /publications/materialseval/solution/jan98solutions/jan98sol.htm (2024 words)

	FOIL Lab -Research-
		We have used laser speckle contrast imaging to image blood flow changes in the cortex during a number of physiological conditions including stroke and migraine headache models as well as functional activation of the normal brain.
		Laser speckle is a random interference pattern produced when coherent light that has traveled different pathlengths is combined together on a detector such as a CCD camera.
		The blood flow in the cortex alters the speckle pattern and as a result, the spatial variations in the raw speckle image are encoded with information about the blood flow.
	www.bme.utexas.edu /research/dunn/research.html (458 words)

	Optical Testing Digest 04/06
		First, an illuminating speckle pattern is generated by optical low-pass filtering of the image of a diffuser plate.
		The illuminating speckle pattern is scattered from the rough surface under investigation.
		The mean speckle diameter of the pattern used for illumination is influenced by the edge frequency of the low-pass filter, realized by a pinhole in the Fourier-plane.
	www.spie.org /otd/OTD_1jun99.html (2238 words)

	[No title]
		The speckle fringe fields are analyzed using specialized methods of fringe processing for determination of the transverse displacements.
		Speckle fringe patterns are obtained from a "superposition" of the speckle patterns before and after application of the dead weight loads according to the subtraction method of fringe processing.
		We are also using ESPI to examine the influence of amalgam and composite fillings on the mechanical behavior of restored molars and their contribution to restored tooth failures.
	www.umbc.edu /engineering/me/lamp/optics.html (864 words)

Try your search on: Qwika (all wikis)