Near the ground laser communication system: anisoplantic studies based on the PSF measurements

Sergeyev, Aleksandr; Roggemann, Michael C.; Demars, Casey

doi:10.1117/12.882576

Cited by 8 publications

(6 citation statements)

References 16 publications

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“…While Fig. 2 and previous research [15][16][17] supports the premise of physical size change as a function of r 0 , an examination of the PSF contours seen in Fig. 2 suggests that the overall structural characteristics of turbulent PSFs remain the same.…”

Section: Scalability Conjecturementioning

confidence: 83%

Scalability conjecture for the Fried parameter in synthesis of turbulent atmosphere point spread functions

Hunt

Iler

Rucci

2018

J. Appl. Rem. Sens.

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Abstract. A common method for synthesizing turbulent imagery is to model phase perturbations on a wavefront and then propagate the wavefront to the entrance pupil of an imaging system. The point spread function (PSF) that results from the wavefront in the pupil is then computed and used to synthesize images by the usual means of convolution. In a recent publication, a method was disclosed using sparse and redundant dictionaries of turbulent characteristics to construct PSFs directly in the image plane and simulate image formation without making phase models and computing wavefront propagation. However, the dictionary method, as disclosed in the recent publication, is limited to modeling PSFs characterized by the Fried parameter of the data used to construct the dictionary. Herein, we demonstrate that a dictionary constructed from data with a given Fried parameter can be scaled to construct turbulent PSFs corresponding to larger and smaller values of the Fried parameter. This enables a single dictionary, or a small number of dictionaries, to serve for the simulation of turbulent images over a range of turbulence conditions. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Scalability Conjecturementioning

confidence: 83%

Scalability conjecture for the Fried parameter in synthesis of turbulent atmosphere point spread functions

Hunt

Iler

Rucci

2018

J. Appl. Rem. Sens.

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“…The effects of turbulence anisoplanitism have been well studied in the fields of both astronomical imaging [17,18] and free-space optical communications [19][20][21][22][23]. Anisoplanatism appears in O-TWTFT much as it does in astronomical imaging: the same turbulence that produces spatial distortions across an astronomical image will also produce differential time-of-flight variations across the uplink and downlink paths.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the impact of turbulence anisoplanatism on precision free-space optical time transfer

et al. 2019

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Future free-space optical clock networks will require optical links for time and frequency transfer. In many potential realizations of these networks, these links will extend over long distances and will span moving platforms, e.g. ground-to-air or ground-to-satellite. In these cases, the transverse platform motion coupled with spatial variations in atmospheric optical turbulence will lead to a breakdown in the time-of-flight reciprocity upon which optical two-way time-frequency transfer is based. Here, we report experimental measurements of this effect by use of comb-based optical two-way time-frequency transfer over two spatially separated optical links. We find only a modest degradation in the time synchronization and frequency syntonization between two sites, in good agreement with theory. Based on this agreement, we can extrapolate this 2-km result to longer distances, finding only a few-femtosecond timing noise increase due to turbulence for a link from ground to a mid-earth orbit satellite.Work of the U.S. Government and not subject to copyright.

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“…The MFBD method used the cost function and gradients described in Eqs. (19), (31), and (32). provided.…”

Section: Multiframe Blind Deconvolutionmentioning

confidence: 99%

“…To make the optimization tractable and reduce run times, the limited-memory BroydenFletcher-Goldfarb-Shanno (L-BFGS) 15 method is used to optimize the cost functions in Eqs. (16) and (19) to find the object and aberration coefficients most likely to have produced the simulated images in the data set. One of the characteristics of line-search methods like L-BFGS is the need for an estimate of the Hessian ∇ 2 fðxÞ.…”

Section: Multiframe Blind Deconvolutionmentioning

confidence: 99%

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Comparison of bispectrum, multiframe blind deconvolution and hybrid bispectrum-multiframe blind deconvolution image reconstruction techniques for anisoplanatic, long horizontal-path imaging

2014

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Abstract. The potential benefits of real-time, or near-real-time, image processing hardware to correct for turbulence-induced image defects for long-range surveillance and weapons targeting are sufficient to motivate significant resource commitment to their development. Quantitative comparisons between potential candidates are necessary to decide on a preferred processing algorithm. We begin by comparing the mean-square-error (MSE) performance of speckle imaging (SI) methods and multiframe blind deconvolution (MFBD), applied to long-path horizontal imaging of a static scene under anisoplanatic seeing conditions. Both methods are used to reconstruct a scene from three sets of 1000 simulated images featuring low, moderate, and severe turbulence-induced aberrations. The comparison shows that SI techniques can reduce the MSE up to 47%, using 15 input frames under daytime conditions. The MFBD method provides up to 40% improvement in MSE under the same conditions. The performance comparison is repeated under three diminishing light conditions, 30, 15, 8 photons per pixel on average, where improvements of up to 39% can be achieved using SI methods with 25 input frames, and up to 38% for the MFBD method using 150 input frames. The MFBD estimator is applied to three sets of field data and representative results presented. Finally, the performance of a hybrid bispectrum-MFBD estimator that uses a rapid bispectrum estimate as the starting point for the MFBD image reconstruction algorithm is examined.

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Near the ground laser communication system: anisoplantic studies based on the PSF measurements

Cited by 8 publications

References 16 publications

Scalability conjecture for the Fried parameter in synthesis of turbulent atmosphere point spread functions

Scalability conjecture for the Fried parameter in synthesis of turbulent atmosphere point spread functions

Measurement of the impact of turbulence anisoplanatism on precision free-space optical time transfer

Comparison of bispectrum, multiframe blind deconvolution and hybrid bispectrum-multiframe blind deconvolution image reconstruction techniques for anisoplanatic, long horizontal-path imaging

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