Stochastic interference of fluorescence radiation in random media with large inhomogeneities

Zimnyakov, Dmitry A.; Asharchuk, I.A.; Yuvchenko, S. A.; Sviridov, Аlexander P.

doi:10.1016/j.optcom.2016.11.045

Cited by 4 publications

(1 citation statement)

References 23 publications

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“…To obtain an accurate expression for the speckle contrast, knowledge of the PDF of optical path length,

, is required. In general, for more complex scattering media such as biological tissue,

would have to be simulated numerically, for example using a Monte Carlo approach [ 57 ]. For more well-defined scattering media, analytical expressions for

have been derived from to the diffusion equation that describes light transport in scattering media [ 58 ].…”

Section: Principles Of Speckle Imaging In Vivomentioning

confidence: 99%

Speckle-enabled in vivo demixing of neural activity in the mouse brain

Sarafraz,

Nöbauer,

Kim

et al. 2024

Biomed. Opt. Express

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Functional imaging of neuronal activity in awake animals, using a combination of fluorescent reporters of neuronal activity and various types of microscopy modalities, has become an indispensable tool in neuroscience. While various imaging modalities based on one-photon (1P) excitation and parallel (camera-based) acquisition have been successfully used for imaging more transparent samples, when imaging mammalian brain tissue, due to their scattering properties, two-photon (2P) microscopy systems are necessary. In 2P microscopy, the longer excitation wavelengths reduce the amount of scattering while the diffraction-limited 3D localization of excitation largely eliminates out-of-focus fluorescence. However, this comes at the cost of time-consuming serial scanning of the excitation spot and more complex and expensive instrumentation. Thus, functional 1P imaging modalities that can be used beyond the most transparent specimen are highly desirable. Here, we transform light scattering from an obstacle into a tool. We use speckles with their unique patterns and contrast, formed when fluorescence from individual neurons propagates through rodent cortical tissue, to encode neuronal activity. Spatiotemporal demixing of these patterns then enables functional recording of neuronal activity from a group of discriminable sources. For the first time, we provide an experimental, in vivo characterization of speckle generation, speckle imaging and speckle-assisted demixing of neuronal activity signals in the scattering mammalian brain tissue. We found that despite an initial fast speckle decorrelation, substantial correlation was maintained over minute-long timescales that contributed to our ability to demix temporal activity traces in the mouse brain in vivo. Informed by in vivo quantifications of speckle patterns from single and multiple neurons excited using 2P scanning excitation, we recorded and demixed activity from several sources excited using 1P oblique illumination. In our proof-of-principle experiments, we demonstrate in vivo speckle-assisted demixing of functional signals from groups of sources in a depth range of 220–320 µm in mouse cortex, limited by available speckle contrast. Our results serve as a basis for designing an in vivo functional speckle imaging modality and for maximizing the key resource in any such modality, the speckle contrast. We anticipate that our results will provide critical quantitative guidance to the community for designing techniques that overcome light scattering as a fundamental limitation in bioimaging.

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“…To obtain an accurate expression for the speckle contrast, knowledge of the PDF of optical path length,

, is required. In general, for more complex scattering media such as biological tissue,

would have to be simulated numerically, for example using a Monte Carlo approach [ 57 ]. For more well-defined scattering media, analytical expressions for

have been derived from to the diffusion equation that describes light transport in scattering media [ 58 ].…”

Section: Principles Of Speckle Imaging In Vivomentioning

confidence: 99%

Speckle-enabled in vivo demixing of neural activity in the mouse brain

Sarafraz,

Nöbauer,

Kim

et al. 2024

Biomed. Opt. Express

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Low-coherence reflectometry in applications to media structure characterization

Isaeva¹,

Исаева²,

Yuvchenko³

et al. 2019

Saratov Fall Meeting 2018: Laser Physics, Photonic Technologies, and Molecular Modeling

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Reference-free path length interferometry of random media with the intensity moments analysis

et al. 2017

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Stochastic interference of partially coherent light multiple scattered by a random medium is considered. The relationship between the second- and third-order moments of intensity fluctuations in random interference patterns, the coherence function of probe radiation, and the probability density of path differences for the interfering partial waves in the medium are established. The obtained relationships were verified using the statistical analysis of spectrally selected fluorescence radiation emitted by the laser-pumped dye-doped random medium. Rhodamine 6G water solution was applied as the doping agent for the ensembles of densely packed silica grains which were pumped by the CW radiation (532 nm) from the diode-pumped solid state laser. Experimentally observed abrupt decay of the second- and third-order moments of fluorescence intensity fluctuations for the wavelengths ranging from 620 nm to 680 nm is interpreted in terms of amplification of spontaneous emission at large dye concentrations. This paper discusses the new optical probe of random media defined as "the reference-free path length interferometry with the intensity moments analysis".

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Stochastic interference of fluorescence radiation in random media with large inhomogeneities

Cited by 4 publications

References 23 publications

Speckle-enabled in vivo demixing of neural activity in the mouse brain

Speckle-enabled in vivo demixing of neural activity in the mouse brain

Low-coherence reflectometry in applications to media structure characterization

Reference-free path length interferometry of random media with the intensity moments analysis

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