Intensity fluctuation spectra of dynamic laser speckle patterns acquired by a full-field temporal modulation method

2012 ◽  
Vol 51 (31) ◽  
pp. 7576 ◽  
Author(s):  
Dake Wang ◽  
Adam Moyer ◽  
Matt Henderson
Keyword(s):  
Intensity Fluctuation ◽  
Laser Speckle ◽  
Modulation Method ◽  
Temporal Modulation ◽  
Full Field ◽  
Speckle Patterns

scholarly journals The Spectral Analysis of Dynamic Laser Speckle Patterns Generated by Brownian Particle Suspensions: A Stroboscopic Effect Based Filtering Technique

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Dake Wang ◽  
James Ranger ◽  
Adam Moyer
Keyword(s):  
Power Spectrum ◽  
Brownian Particle ◽  
Modulation Frequency ◽  
Colloidal Suspensions ◽  
Frequency Component ◽  
Laser Speckle ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Full Field ◽  
Speckle Patterns

The power spectrum of the time-varying intensity in the dynamic laser speckle patterns is determined by passing the shifted power spectrum through a low-pass filter which is implemented via the signal integration. The light intensity is modulated sinusoidally to induce the stroboscopic effect which shifts the resonant frequency component of the spectrum to 0 Hz. The homodyne dynamic laser speckles generated by the quasi-inelastic scattering of the Brownian motions in colloidal suspensions are investigated. Within the frequency range from 10 Hz to 10 kHz used in this work, the bandwidth of the Lorenztian power spectrums is shown to be inversely proportional to the particle size, which is in agreement with the prediction of the dynamic light scattering theory of diffusing particle. The spatial variation observed in the full-field power spectrum maps is caused by the nonuniform distribution of average speckle intensity and varies with the modulation frequency. However, the bandwidths measured at different locations are found to be intensity independent.

X-ray intensity fluctuation spectroscopy measurements of the charge density wave phases of NbSe3

2002 ◽  
Vol 12 (9) ◽  
pp. 3-8
Author(s):  
M. Sutton ◽  
Y. Li ◽  
J. D. Brock ◽  
R. E. Thorne
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Intensity Fluctuation ◽  
Speckle Pattern ◽  
Equations Of Motion ◽  
Density Wave ◽  
Electrical Currents ◽  
X Ray ◽  
Longitudinal Correlation ◽  
Speckle Patterns

An introduction to X-ray Intensity Fluctuation Spectroscopy (XIFS) is given by describing its relationship to speckle from coherent sources. A brief description of the relationship of XIFS measurements to the underlying equations of motion is given. Preliminary results for the charge density wave (CDW) system NbSe3 are then presented. Static speckle patterns are shown for the $\overrightarrow {Q}_1 = (0 .76$ 0) CDW peak showing that XIFS experiments are possible in this systom provided time constants are long enough. For electrical currents below threshold, a static speckle pattern is observed but for currents above threshold the speckles are smeared out showing movement of the CDW. It is also shown that above threshold, the longitudinal correlation length decreases.

scholarly journals Fourier transforms for fast and quantitative Laser Speckle Imaging

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
J. Buijs ◽  
J. van der Gucht ◽  
J. Sprakel
Keyword(s):  
Quantitative Data ◽  
Fourier Transforms ◽  
Imaging Technique ◽  
Laser Speckle ◽  
Frequency Range ◽  
Laser Speckle Imaging ◽  
Speckle Imaging ◽  
New Approach ◽  
Speckle Patterns ◽  
New Processing

Abstract Laser speckle imaging is a powerful imaging technique that visualizes microscopic motion within turbid materials. At current two methods are widely used to analyze speckle data: one is fast but qualitative, the other quantitative but computationally expensive. We have developed a new processing algorithm based on the fast Fourier transform, which converts raw speckle patterns into maps of microscopic motion and is both fast and quantitative, providing a dynamnic spectrum of the material over a frequency range spanning several decades. In this article we show how to apply this algorithm and how to measure a diffusion coefficient with it. We show that this method is quantitative and several orders of magnitude faster than the existing quantitative method. Finally we harness the potential of this new approach by constructing a portable laser speckle imaging setup that performs quantitative data processing in real-time on a tablet.

scholarly journals Separation of cortical arteries and veins in optical neurovascular imaging

2014 ◽  
Vol 07 (03) ◽  
pp. 1350069 ◽  
Author(s):  
Linna Zhao ◽  
Yao Li ◽  
Hongyang Lu ◽  
Lu Yuan ◽  
Shanbao Tong
Keyword(s):  
Cerebral Cortex ◽  
Optical Imaging ◽  
Signal To Noise Ratio ◽  
Vascular Diseases ◽  
Region Growing ◽  
Field Method ◽  
Laser Speckle ◽  
Cerebral Vessel ◽  
Full Field ◽  
Arteries And Veins

Separation of arteries and veins in the cerebral cortex is of significant importance in the studies of cortical hemodynamics, such as the changes of cerebral blood flow, perfusion or oxygen concentration in arteries and veins under different pathological and physiological conditions. Yet the cerebral vessel segmentation and vessel-type separation are challenging due to the complexity of cortical vessel characteristics and low spatial signal-to-noise ratio. In this work, we presented an effective full-field method to differentiate arteries and veins in cerebral cortex using dual-modal optical imaging technology including laser speckle imaging (LSI) and optical intrinsic signals (OIS) imaging. The raw contrast images were acquired by LSI and processed with enhanced laser speckle contrast analysis (eLASCA) algorithm. The vascular pattern was extracted and segmented using region growing algorithm from the eLASCA-based LSI. Meanwhile, OIS images were acquired alternatively with 630 and 870 nm to obtain an oxyhemoglobin concentration map over cerebral cortex. Then the separation of arteries and veins was accomplished by Otsu threshold segmentation algorithm based on the OIS information and segmentation of LSI. Finally, the segmentation and separation performances were assessed using area overlap measure (AOM). The segmentation and separation of cerebral vessels in cortical optical imaging have great potential applications in full-field cerebral hemodynamics monitoring and pathological study of cerebral vascular diseases, as well as in clinical intraoperative monitoring.

An artifact-metrics which utilizes laser speckle patterns for plastic ID card surface

2010 ◽  
Author(s):  
Manabu Yamakoshi ◽  
Xiaoying Rong ◽  
Tsutomu Matsumoto
Keyword(s):  
Laser Speckle ◽  
Speckle Patterns

Image synthesis from nonimaged laser-speckle patterns

1987 ◽  
Vol 12 (11) ◽  
pp. 858 ◽  
Author(s):  
Paul S. Idell ◽  
J. R. Fienup ◽  
Ron S. Goodman
Keyword(s):  
Image Synthesis ◽  
Laser Speckle ◽  
Speckle Patterns
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