Speckle contrast measurements with changeable coherence length: the method of scattering media probing

2002 ◽  
Author(s):  
Jung-Taek Oh ◽  
Dmitry A. Zimnyakov ◽  
Garif G. Akchurin
Keyword(s):  
Coherence Length ◽  
Scattering Media ◽  
Speckle Contrast

scholarly journals A Robust Method for Adjustment of Laser Speckle Contrast Imaging during Transcranial Mouse Brain Visualization

Photonics ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 80 ◽  
Author(s):  
Vyacheslav Kalchenko ◽  
Anton Sdobnov ◽  
Igor Meglinski ◽  
Yuri Kuznetsov ◽  
Guillaume Molodij ◽  
...  
Keyword(s):  
Biological Tissues ◽  
Laser Speckle ◽  
Robust Method ◽  
Scattering Media ◽  
Contrast Imaging ◽  
Speckle Contrast ◽  
Non Invasive ◽  
Sagittal Sinus ◽  
Brain Vasculature

Laser speckle imaging (LSI) is a well-known and useful approach for the non-invasive visualization of flows and microcirculation localized in turbid scattering media, including biological tissues (such as brain vasculature, skin capillaries etc.). Despite an extensive use of LSI for brain imaging, the LSI technique has several critical limitations. One of them is associated with inability to resolve a functionality of vessels. This limitation also leads to the systematic error in the quantitative interpretation of values of speckle contrast obtained for different vessel types, such as sagittal sinus, arteries, and veins. Here, utilizing a combined use of LSI and fluorescent intravital microscopy (FIM), we present a simple and robust method to overcome the limitations mentioned above for the LSI approach. The proposed technique provides more relevant, abundant, and valuable information regarding perfusion rate ration between different types of vessels that makes this method highly useful for in vivo brain surgical operations.

scholarly journals Guidelines for obtaining an absolute blood flow index with laser speckle contrast imaging

2021 ◽  
Author(s):  
Smrithi Sunil ◽  
Sharvari Zilpelwar ◽  
David A Boas ◽  
Dmitry D Postnov
Keyword(s):  
Blood Flow ◽  
Speckle Pattern ◽  
Quantitative Measure ◽  
Laser Speckle ◽  
Flow Index ◽  
Scattering Media ◽  
Contrast Imaging ◽  
Laser Speckle Contrast Imaging ◽  
Speckle Contrast ◽  
Blood Flow Index

Laser speckle contrast imaging (LSCI) is a technique broadly applied in research and clinical settings for full-field characterization of tissue perfusion. It is based on the analysis of speckle pattern contrast, which can be theoretically related to the decorrelation time - a quantitative measure of dynamics. A direct contrast to decorrelation time conversion, however, requires prior knowledge of specific parameters of the optical system and scattering media and thus is often impractical. For this reason, and because of the nature of some of the most common applications, LSCI is historically used to measure relative blood flow change. Over time, the belief that the absolute blood flow index measured with LSCI is not a reliable metric and thus should not be used has become more widespread. This belief has resulted from the use of LSCI to compare perfusion in different animal models and to obtain longitudinal blood flow index observations without proper consideration given to the stability of the measurement. Here, we aim to clarify the issues that give rise to variability in the repeatability of the quantitative blood flow index and to present guidelines on how to make robust absolute blood flow index measurements with conventional single-exposure LSCI. We also explain how to calibrate contrast to compare measurements from different systems and show examples of applications that are enabled by high repeatability.

scholarly journals Визуализация кровотока методом лазерных спекл-контрастных измерений в условиях неэргодичности

2020 ◽  
Vol 128 (6) ◽  
pp. 773
Author(s):  
А.Ю. Сдобнов ◽  
В.В. Кальченко ◽  
А.В. Быков ◽  
А.П. Попов ◽  
Г. Молодый ◽  
...  
Keyword(s):  
Exposure Time ◽  
Imaging Technique ◽  
Laser Speckle ◽  
Scattering Media ◽  
Contrast Imaging ◽  
Laser Speckle Contrast Imaging ◽  
Speckle Contrast ◽  
Brain Vasculature ◽  
Temporal And Spatial ◽  
The Given

In current work, the influence of static structural inclusions in heterogeneous highly scattering media such as biotissue on the results of laser speckle contrast imaging using both temporal and spatial processing algorithms has been investigated. The applicability of laser speckle contrast imaging technique has been studied in case of non-ergodic conditions. It was shown using the phantom model that increment of amount of static scatterers comparing to the dynamic ones in tissue causes significant error in results of temporal and spatial speckle contrast processing for the given camera exposure time. At the same time, the analysis of the spatial and temporal speckle contrast values, values of coefficient of speckle dynamics as well as results of Monte Carlo simulation of sampling volumes showed that presence of relatively thin static layer (up to 30% of all volume) cannot cause significant changes in results of laser speckle contrast imaging. The camera exposure time, as well as amount of frames for image processing can vary depending on the experiment goals. Finally, the proposed spatial and temporal algorisms of laser speckle contrast imaging were verified during transcranial visualization of the mouse brain vasculature.

Practical Picture Processing

1974 ◽  
Vol 32 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Radiation Damage ◽  
Coherence Length ◽  
Spatial Information ◽  
State Of The Art ◽  
Coherent Radiation ◽  
The State ◽  
Energy Spread ◽  
Electron Micrograph ◽  
Picture Processing ◽  
Molecular Skeleton

Various authors have emphasized the spatial information resident in an electron micrograph taken with adequately coherent radiation. In view of the completion of at least one such instrument, this opportunity is taken to summarize the state of the art of processing such micrographs. We use the usual symbols for the aberration coefficients, and supplement these with £ and 6 for the transverse coherence length and the fractional energy spread respectively. He also assume a weak, biologically interesting sample, with principal interest lying in the molecular skeleton remaining after obvious hydrogen loss and other radiation damage has occurred.

Impact of Scattering on Transfer of Radiation in Emitting, Absorbing, and Scattering Media

2002 ◽  
Vol 33 (3-4) ◽  
pp. 4
Author(s):  
M. L. German ◽  
E. P. Nogotov ◽  
V. P. Necrasov
Keyword(s):  
Scattering Media
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