Speckle Fluctuations as a Screening Test in the Holographic Measurement of Plant Motion and Growth

Briers, J. D.

doi:10.1093/jxb/29.2.395

Cited by 16 publications

(7 citation statements)

References 1 publication

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“…Time-varying speckle is frequently observed when biological samples are observed under laserlight illumination. Examples reported in the litera-ture include various botanical subjects [12][13][14][15] and the phenomenon is attributed to the flow of fluids inside the plant, or even to the motion of particles within the cells of the plant. 12,13 One of the most important potential applications arises when the fluctuations are caused by the flow of blood.…”

Section: Time-varying Specklementioning

confidence: 99%

Capillary Blood Flow Monitoring Using Laser Speckle Contrast Analysis (LASCA)

Briers¹,

Richards²,

He³

1999

J. Biomed. Opt.

182

134

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Coherent light scattered from an ensemble of moving scatterers produces a time-varying speckle pattern. The intensity fluctuations observed in a single speckle can be regarded either as a time-varying interference effect or as a Doppler beating effect. Techniques based on each of these approaches have been developed to analyze the fluctuations in an attempt to measure the velocities of the scatterers. Most of these methods measure the temporal statistics of the intensity fluctuations in a single speckle, i.e., at a single point. If a map of the velocity distribution is required, some form of scanning must be introduced. One way of avoiding the need to scan is to make use of the spatial statistics of time-integrated speckle. This is the basis of a technique, already described in the literature, called laser speckle contrast analysis (LASCA). In this article, we present a brief review of the theory linking the intensity fluctuations to the velocity and of the various techniques that have been proposed to measure them. We then describe the present configuration of our LASCA technique and describe some recent developments in our search for a real-time, noninvasive, full-field technique for visualizing capillary blood flow. © 1999 Society of Photo-Optical Instrumentation Engineers.

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Section: Time-varying Specklementioning

confidence: 99%

Capillary Blood Flow Monitoring Using Laser Speckle Contrast Analysis (LASCA)

Briers¹,

Richards²,

He³

1999

J. Biomed. Opt.

182

134

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“…Laser speckle is a random interference pattern generated by the addition of coherent scattered or reflected laser light with slightly different optical path lengths. The basic theory of laser speckle was developed in the 1960s, and in the 1970s a technique based on laser speckle-timevarying speckle-was developed and used by several groups for biomedical applications [1][2][3][4][5] . The relationship between the temporal fluctuations of the speckle pattern and the movement of scatters in living organisms is used as a basic model in this technique.…”

Section: Introductionmentioning

confidence: 99%

Study on blood flow pulsation using laser speckle contrast imaging

et al. 2011

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Laser speckle contrast imaging (LSCI) is becoming an established method for full-field imaging of blood flow dynamics in animal models. Blood flow pulsation originated from heart beat affects blood flow measurement results of LSCI and it is considered as major physiology noise source for most biomedical applications. But in some biomedical applications, the details of the pulsation process might provide useful information for disease diagnostics. In this study, we investigated the ability as well as the limitation of LSCI in monitoring flow pulsation in phantom study. Both intralipid (2% -5%) and human whole blood samples are used in phantom study. A syringe pump is controlled by a computerprogrammable motor controller and liquid phantom is pushed through a 400 μm ID capillary tube by the pump at different pulsation patterns, varied in frequency (1-7 Hz), valley-to-peak ratio (10%-50%), acceleration/deceleration rate, etc. Speckle contrast images are acquired at 15-30 frames-per-seconds. Our results show: (1) it is very hard for LSCI to pick up signals from high frequency pulsation (5-7 Hz), which is close to the heart back frequency of rats. This might be caused by the nature of fluid dynamics of blood during pulsation. LSCI might not work well for animal models in detecting pulsation. (2) With low frequency pulsation (1 Hz, close to human normal pulsation rate), our experimental results shows from most pulsation patterns, LSCI could catch the fine details of the blood flow change in a cycle. LSCI might be used for studying human blood flow pulsation.

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“…[1][2][3] The second order statistics of a spatial or temporal speckle pattern are usually associated with its autocorrelation function and the latter with the power spectrum of the light through the Wiener-Kintchine theorem. Several parameters have been proposed in the literature, [4][5][6] such as the full width at half maximum ͑FWHM͒, to characterize the autocorrelation function of the temporal history of a speckle pattern. In a recent work, 7 it was found that the width of the equivalent rectangle ͑WER͒ and X * log X parameters, which take into account several points of the autocorrelation function, give good results in the characterization of the speckle pattern that is produced in the drying of paint or fruit slices.…”

Section: Introductionmentioning

confidence: 99%

Statistics of the dynamic speckle produced by a rotating diffuser and its application to the assessment of paint drying

2000

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We explore alternative ways to assign a measure to dynamic speckle patterns produced by different phenomena. Both the power spectrum and the autocorrelation of the intensity are considered. First, we describe an experimental study of the statistics of the Fresnel speckle patterns produced by illuminating a diffuser with laser light as a phenomenon where some control can be maintained on the dynamic variables. The diffuser rotates in a plane with constant angular speed. A correlation is established between some parameters of the autocorrelation or the power spectrum of the intensity fluctuations of the speckle patterns and the tangential speed corresponding to different distances from the rotation axis. A scale correction is suggested to estimate the number of points of the autocorrelation function that should be included in the calculations before speckle crosstalk starts. The defined parameters are then applied to characterize the activity of the dynamical speckle produced in the drying of paint. This is considered as a starting point for the understanding and assessment of more complex situations including biological activity. © 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)01006-0] Subject terms: dynamic speckle; autocorrelation function; drying of paint.Paper 990004

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Speckle Fluctuations as a Screening Test in the Holographic Measurement of Plant Motion and Growth

Cited by 16 publications

References 1 publication

Capillary Blood Flow Monitoring Using Laser Speckle Contrast Analysis (LASCA)

Capillary Blood Flow Monitoring Using Laser Speckle Contrast Analysis (LASCA)

Study on blood flow pulsation using laser speckle contrast imaging

Statistics of the dynamic speckle produced by a rotating diffuser and its application to the assessment of paint drying

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