Multiple phase-screen simulation of oceanic beam propagation

Farwell, Nathan; Korotkova, Olga

doi:10.1117/12.2062683

Cited by 15 publications

(10 citation statements)

References 18 publications

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“…To further verify this interesting phenomenon, in this section, we refer to the phase screen method in Ref. [34] to demonstrate the propagation process of the beam containing two types of phase discontinuities through weak oceanic turbulence. The parameters are set to be the same as that in Figure 3 Each case in Figure 6 is the ensemble average of 500 realizations because the further increase of realizations has less impact on the error reduction.…”

Section: The Phase Screen Simulation Of a Beam With Two Types Of Phas...mentioning

confidence: 99%

Phase discontinuities induced scintillation enhancement: coherent vortex beams propagating through weak oceanic turbulence

Wang,

Zhang,

Ren

et al. 2021

Preprint

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Under the impact of an infinitely extended edge phase dislocation, optical vortices (screw phase dislocations) induce scintillation enhancement. The scintillation index of a beam consisting of two Gaussian vortex beams with ±1 topological charges through weak oceanic turbulence is researched via derivation and phase screen simulation. Different combinations of two types of phase discontinuities can be obtained by changing the overlapping degree and the phase difference of two coherent Gaussian vortex beams. The scintillation indexes for them verify that the formation condition of the phenomenon is the coexistence of two types of phase discontinuities. And the enhanced scintillation index can be several orders of magnitude larger than that of a plane wave under weak perturbation (Rytov variance). This phenomenon could be useful for both optical vortex detection and perturbation measurement.

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Section: The Phase Screen Simulation Of a Beam With Two Types Of Phas...mentioning

confidence: 99%

Phase discontinuities induced scintillation enhancement: coherent vortex beams propagating through weak oceanic turbulence

Wang,

Zhang,

Ren

et al. 2021

Preprint

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“…The main factors affecting the optical field in the target plane through an oceanic medium are the scattering and absorption occurring due to the various constituents in the ocean and the fluctuations of the refractive index of seawater, known as oceanic turbulence [27]. According to [28], we limit our discussion to the case where the ocean water is clear water, that is to say we only consider the optical turbulence, and will not be interested in the absorption and scattering effects. Then the power spectrum of the refractive index fluctuations of the oceanic waters is a linearized polynomial of two variables: The temperature fluctuations and the salinity fluctuations.…”

Section: Analytical Formulaementioning

confidence: 99%

Average spreading and beam quality evolution of Gaussian array beams propagating through oceanic turbulence

Zhi¹,

Chen²,

Tao³

et al. 2015

Laser Phys. Lett.

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The propagation properties of a radial Gaussian beam array through oceanic turbulence are studied analytically. The analytical expressions for the average intensity and the beam quality (power-in-the-bucket (PIB) and M 2 -factor) of a radial beam array in a turbulent ocean are derived based on an account of statistical optics methods, the extended Huygens-Fresnel principle, and the second order moments of the Wigner distribution function. The influences of w, ε, and χ T on the average intensity are investigated. The array divergence increases and the laser beam spreads as the salinity-induced dominant, ε decreased, and χ T increased. Further, the analytical expression of PIB and the M 2 -factor in the target plane is obtained. The changes of PIB and the M 2 -factor with three oceanic turbulence parameters indicate that the stronger turbulence with a larger w, smaller ε, and larger χ T results in the value of PIB decreasing, the value of the M 2 -factor increasing, and the beam quality degrading.

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“…The fluid field was analyzed by Doppler velocimeter and particle image velocimetry (PIV) system, and the measurement results were compensated by computational fluid dynamics model. Farwell et al [26,27] studied the intensity and coherent distribution of turbulence in underwater beam propagation based on the power spectrum model of ocean turbulence.…”

Section: Introductionmentioning

confidence: 99%

A Wavelet Based Deep Learning Method for Underwater Image Super Resolution Reconstruction

2020

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In order to solve the scattering degradation by turbulence and suspended particles in underwater imaging, traditional processing methods including image enhancement, restoration and reconstruction have been continuously researched. But most of them rely on degradation models, and there exist problems of ill-posed. Image super resolution reconstruction based on deep learning has become a hot topic in recent years. In order to further improve the effectiveness and efficiency of deep learning based methods, an improved image super-resolution reconstruction algorithm based on deep convolutional neural network is proposed in this paper. The wavelet basis which can effectively simulate the waveform and characteristics of underwater turbulence is selected to replace the neuron fitting function in order to improve the accuracy and efficiency of the algorithm. An improved dense block structure (IDB) is introduced into the network which can effectively solve the gradient disappearance problem of deep convolutional neural network and improve the training speed at the same time. The method proposed in this paper has been verified in laboratory flume, public data set and real water body. The experimental results show that under the same conditions, the proposed algorithm shows improvements on various evaluation parameters compared with DRFN, VDSR and DRCN method. So it can be concluded that the proposed method can effectively improve the quality of deep learning based reconstruction for imaging in natural water.

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Multiple phase-screen simulation of oceanic beam propagation

Cited by 15 publications

References 18 publications

Phase discontinuities induced scintillation enhancement: coherent vortex beams propagating through weak oceanic turbulence

Phase discontinuities induced scintillation enhancement: coherent vortex beams propagating through weak oceanic turbulence

Average spreading and beam quality evolution of Gaussian array beams propagating through oceanic turbulence

A Wavelet Based Deep Learning Method for Underwater Image Super Resolution Reconstruction

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