Detrimental effects of speckle-pixel size matching in laser speckle contrast imaging

Kirkpatrick, Sean J.; Duncan, Donald D.; Wells-Gray, Elaine M.

doi:10.1364/ol.33.002886

Cited by 251 publications

(212 citation statements)

References 18 publications

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“…(4), the speckle size can be controlled by the ratio between the size of the clear aperture and the size of matrix W, similar to Kirkpatrick's work [2]. But when this ratio is too small, i.e.…”

Section: Synthesis Of Correlated Speckle Patternsmentioning

confidence: 92%

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Simulation of speckle patterns with pre-defined correlation distributions

Song¹,

Zhou²,

Xueyan³

et al. 2016

Biomed. Opt. Express

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Abstract:We put forward a method to easily generate a single or a sequence of fully developed speckle patterns with pre-defined correlation distribution by utilizing the principle of coherent imaging. The few-to-one mapping between the input correlation matrix and the correlation distribution between simulated speckle patterns is realized and there is a simple square relationship between the values of these two correlation coefficient sets. This method is demonstrated both theoretically and experimentally. The square relationship enables easy conversion from any desired correlation distribution. Since the input correlation distribution can be defined by a digital matrix or a grayscale image acquired experimentally, this method provides a convenient way to simulate real speckle-related experiments and to evaluate data processing techniques.

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Section: Synthesis Of Correlated Speckle Patternsmentioning

confidence: 92%

“…The Fast Fourier transform of a phase matrix is a common approach [2], but this method can only synthesize independent speckle patterns. Since many applications of laser speckle are based on their correlation properties, simulation of speckle patterns with a predefined temporal correlation is desirable.…”

Section: Introductionmentioning

confidence: 99%

Simulation of speckle patterns with pre-defined correlation distributions

Song¹,

Zhou²,

Xueyan³

et al. 2016

Biomed. Opt. Express

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“…The second-order statistics of a speckle pattern provide a description of the spatial structure of the pattern, with the minimum size of a speckle, or the minimum correlation length of the pattern, being an important parameter in the characterization of this structure [9]. It has been noted in the literature that proper spatial sampling of the intensity of the scattered field is an important experimental consideration in speckle-based metrology applications [10]. In order to meet the spatial Nyquist criteria, the minimum speckle size of the measured intensity pattern should be at least two pixels [8].…”

Section: J Of Biomedical Photonics and Eng 3(3)mentioning

confidence: 99%

Spatial Poincaré Plots as Descriptors of Speckle Pattern Second-Order Statistics

Majumdar

Kirkpatrick

2017

JBPE

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Abstract. It is demonstrated herein that the use of spatial Poincaré plots provides an efficient means to describe short and long-range correlations in the spatial structure of the measured intensity distribution of scattered coherent fields. The intensity distribution over a row of pixels in single frames of speckle fields with varying speckle sizes was considered. Statistical descriptors from the spatial Poincaré plots for these intensity data with variable lags were used to estimate the short and long-term variations in the measured intensities, and from these descriptors, the minimum speckle size in the speckle patterns was estimated. This approach yielded similar results for speckle size estimates as the more standard method of calculating the power spectral density of the intensity pattern and simultaneously provided information on the relative contributions of short-term and long-term variations in the measured intensity to the spatial structure of the scattered fields.

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“…The imaging region of interest (ROI) covering an 8 × 8 mm area of the sample was imaged to 512 × 512 pixels of the CMOS sensor (5.5 × 5.5 μm pixel size). The speckle size was adjusted to at least twice the CMOS pixel size to ensure sufficient spatial sampling of each speckle spot and to avoid averaging of multiple speckles over a single pixel that could increase blurring and reduce speckle contrast in the measured speckle intensity autocorrelation curve [29][30][31]. To evaluate temporal speckle intensity fluctuations during coagulation, time series of laser speckle patterns were acquired at a frame rate of 480 frames per second (fps) for 0.5 s at a time, at 30 s time increments during coagulation.…”

Section: Lsr Evaluation During Blood Coagulationmentioning

confidence: 99%

Assessing blood coagulation status with laser speckle rheology

Tripathi

Hajjarian

Cott

et al. 2014

Biomed. Opt. Express

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Abstract:We have developed and investigated a novel optical approach, Laser Speckle Rheology (LSR), to evaluate a patient's coagulation status by measuring the viscoelastic properties of blood during coagulation. In LSR, a blood sample is illuminated with laser light and temporal speckle intensity fluctuations are measured using a high-speed CMOS camera. During blood coagulation, changes in the viscoelastic properties of the clot restrict Brownian displacements of light scattering centers within the sample, altering the rate of speckle intensity fluctuations. As a result, blood coagulation status can be measured by relating the time scale of speckle intensity fluctuations with clinically relevant coagulation metrics including clotting time and fibrinogen content. Our results report a close correlation between coagulation metrics measured using LSR and conventional coagulation results of activated partial thromboplastin time, prothrombin time and functional fibrinogen levels, creating the unique opportunity to evaluate a patient's coagulation status in real-time at the point of care. (2013). 11. M. Kaibara, "Rheology of blood coagulation," Biorheology 33(2), 101-117 (1996). 12. C. E. Dempfle, T. Kälsch, E. Elmas, N. Suvajac, T. Lücke, E. Münch, and M. Borggrefe, "Impact of fibrinogen concentration in severely ill patients on mechanical properties of whole blood clots," Blood Coagul.

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Detrimental effects of speckle-pixel size matching in laser speckle contrast imaging

Cited by 251 publications

References 18 publications

Simulation of speckle patterns with pre-defined correlation distributions

Simulation of speckle patterns with pre-defined correlation distributions

Spatial Poincaré Plots as Descriptors of Speckle Pattern Second-Order Statistics

Assessing blood coagulation status with laser speckle rheology

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