<title>Analytical simulation of statistically inhomogenous intensity fluctuations of biospeckles using band-limited fractal model</title>

Band-limited fractal model of atmospheric refractivity fluctuation

Journal of the Optical Society of America A ◽

10.1364/josaa.5.000475 ◽

1988 ◽

Vol 5 (4) ◽

pp. 475 ◽

Cited By ~ 10

Author(s):

Y. Kim ◽

D. L. Jaggard

Keyword(s):

Fractal Model ◽

Band Limited

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Band-Limited Reference-Free Speckle Spectroscopy: Probing the Fluorescent Media in the Vicinity of the Noise-Defined Threshold

Applied Sciences ◽

10.3390/app10051629 ◽

2020 ◽

Vol 10 (5) ◽

pp. 1629

Author(s):

Dmitry Zimnyakov ◽

Elena Isaeva ◽

Anna Isaeva ◽

Sergey Volchkov

Keyword(s):

Fluorescence Intensity ◽

Random Medium ◽

Propagation Path ◽

Third Order ◽

Spatial Fluctuations ◽

Fluorescence Radiation ◽

Intensity Fluctuations ◽

Band Limited ◽

Finite Band ◽

Spectral Selection

A method of reference-free speckle spectroscopy based on the statistical analysis of intensity spatial fluctuations of the spectrally-selected multiple-scattered fluorescence radiation is examined in the case of the finite-band spectral selection of fluorescence light emitted by the laser-pumped random medium, and detection conditions far from the ideal case. Intensity fluctuations are recorded during point-to-point scanning of the surface of a random multiple-scattering medium, which is characterized by the dependences of the second- and third-order statistical moments of intensity on the wavelength of detected spectrally selected light. In turn, the statistical moments of intensity fluctuations are determined by the average propagation path of fluorescent radiation in the medium. This makes it possible to analyze the features of the light-medium interactions at a scale of the order of the transport mean free path of radiation propagation in the medium. Depending on the spectral selection conditions, the method is applicable for characterizing micro- or nano-structured fluorescent layers with thicknesses from tens of micrometers to several millimeters. In the examined case, the finite-band spectral selection results in the values of coherence length of the detected fluorescence radiation compared with the ensemble-averaged absolute value of the path-length difference between the stochastically interfering and spectrally selected partial contributions to the fluorescence field. In addition, non-ideal detection conditions (usage of a multimode optical fiber in the light-collecting unit) cause additional strong damping of the detected speckle intensity fluctuations. These factors lead to a remarkable suppression of spatial fluctuations of the fluorescence intensity in the course of spatially- and spectrally-resolved surface scanning of the laser-pumped probed random medium. Nevertheless, with appropriate procedures of the intrinsic noise reduction and data correction, the obtained spectral dependencies of the normalized third-order statistical moment of the band-limited fluorescence intensity clearly indicate the fluorescence propagation features in the probed multiple-scattering random media (such as a strong influence of the scattering strength and multiple self-absorption–re-emission events on the average propagation path of light in the medium).The possibilities of noise reduction and data correction in the case of applying the band-limited reference-free spectroscopic instrumentation with low spectral and spatial resolution are illustrated by the experimental results obtained using the Rhodamine-6G-doped and continuous wave (CW)-laser-pumped layers of the densely packed titania and silica particles.

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Spectral analysis of light intensity fluctuations caused by orientational fluctuations in nematics

Journal de Physique ◽

10.1051/jphys:01980004104035100 ◽

1980 ◽

Vol 41 (4) ◽

pp. 351-358 ◽

Cited By ~ 15

Author(s):

D.C. Van Eck ◽

R.J.J. Zijlstra

Keyword(s):

Spectral Analysis ◽

Light Intensity ◽

Intensity Fluctuations

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Method of estimation of hidden correlation of narrowband noise signals

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2019-12-34-39 ◽

2019 ◽

pp. 34-39 ◽

Cited By ~ 1

Author(s):

E.I. Chernov ◽

N.E. Sobolev ◽

A.A. Bondarchuk ◽

L.E. Aristarhova

Keyword(s):

Signal Processing ◽

Digital Signal Processing ◽

New Technology ◽

Digital Signal ◽

Measuring Instruments ◽

Central Frequency ◽

Pearson Criterion ◽

Useful Signal ◽

Band Limited ◽

Narrowband Noise

The concept of hidden correlation of noise signals is introduced. The existence of a hidden correlation between narrowband noise signals isolated simultaneously from broadband band-limited noise is theoretically proved. A method for estimating the latent correlation of narrowband noise signals has been developed and experimentally investigated. As a result of the experiment, where a time frag ent of band-limited noise, the basis of which is shot noise, is used as the studied signal, it is established: when applying the Pearson criterion, there is practically no correlation between the signal at the Central frequency and the sum of signals at mirror frequencies; when applying the proposed method for the analysis of the same signals, a strong hidden correlation is found. The proposed method is useful for researchers, engineers and metrologists engaged in digital signal processing, as well as developers of measuring instruments using a new technology for isolating a useful signal from noise – the method of mirror noise images.

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