Atmospheric laser communication system with wide-angle tracking and adaptive compensation

Carhart, Gary W.; Vorontsov, Mikhail A.; Beresnev, L. A.; Paicopolis, Peter S.; Beil, Fabian

doi:10.1117/12.618363

Cited by 6 publications

(3 citation statements)

References 4 publications

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“…[1][2][3][4][5] In turn, these effects can severely impact the performance of Army free-space laser optics communication systems. [6][7][8] For most current lasercom systems, random fluctuations of signal intensity are assumed to be statistically homogeneous and isotropic. 9,10 Moreover, for weak turbulence (Rytov variance,…”

Section: Introductionmentioning

confidence: 99%

Analysis of free-space laser signal intensity over a 2.33 km optical path

Tunick

2007

Atmospheric Optics: Models, Measurements, and Target-in-the-Loop Propagation

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The probability distribution of aperture averaged signal intensity from free-space laser optical systems depends on the optical turbulence along the optical path. For most current free-space laser systems, random fluctuations of signal intensity are assumed to be statistically homogeneous and isotropic. Moreover, it is assumed that probability distributions are generally log-normal and that Kolmogorov -5/3 wave number turbulence power law represents the signal intensity data. In this paper, the Kolmogorov model is investigated for an optical path that traverses a complex non-uniform topography. Experimental research is conducted to determine the characteristic behavior of high frequency (2000 Hz) signal intensity data collected over a 2.33 km optical path at the Army Research Laboratory (ARL) Atmospheric Laser Optics Testbed (A_LOT) Facility. Results focus mainly on calculated power spectra and frequency distributions. In addition, a model is developed to calculate optical turbulence intensity (C n 2 ) as a function of receiving (and transmitting) aperture diameter, log-amplitude variance, and path length. Here, initial comparisons of calculated to measured C n 2 data are favorable. It is anticipated that this kind of signal data analysis will benefit laser communication systems development and testing at the ARL.

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Section: Introductionmentioning

confidence: 99%

Analysis of free-space laser signal intensity over a 2.33 km optical path

Tunick

2007

Atmospheric Optics: Models, Measurements, and Target-in-the-Loop Propagation

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“…A complex coarse-pointing system increases weight and volume of the optical receiver and reduces the tracking efficiency. Carhart et al 12 presented a compact bidirectional adaptive optical receiver with a wide angle tracking and adaptive compensation to improve the concentration of laser beam energy and reduce signal fading.…”

Section: Introductionmentioning

confidence: 99%

Off-axis catadioptric fisheye wide field-of-view optical receiver for free space optical communications

et al. 2012

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We propose a wide field-of-view optical receiver design based on a fisheye lens and an off-axis catadioptric structure for free-space optical communications. The design utilizes a novel fisheye lens group to compress a wide field angle into a narrow field angle and produce the appropriately collimated light that can effectively be coupled into the following aperture of a catadioptric telescope. An off-axis catadioptric telescope with aspheric surface mirrors is designed to compress the incident beam spot size, compensate for the high order optical aberrations and eliminate light loss due to an obstruction. The parallel exit rays are reflected on a double-level tracking mechanism by feeding the position signal from a quadrant detector to correct the pointing error and optimize the coupling efficiency into an optical fiber. The final wide field-of-view optical receiver design is presented along with the evaluation of optical performance results and tracking characteristics. The proposed optical receiver not only can provide a 60-deg wide field-of-view to expand the tracking range, but also mitigates optical aberrations to improve the tracking accuracy for free space optical communication systems in a turbulent atmosphere.

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“…In both of these system types, adaptive wavefront distortion compensation is performed in remotely located AO subsystems. In these wavefront control configurations the remotely located AO subsystems are quite difficult to synchronize without data exchange (e.g., using additional optical or rf communication channels 4 ). On the other hand, the absence of synchronization between remotely located wavefront control systems may result in undesired cross talk between their control loops and compensation process instability.…”

Section: Introductionmentioning

confidence: 99%

Adaptive wavefront control with asynchronous stochastic parallel gradient descent clusters

Vorontsov

Carhart

2006

J. Opt. Soc. Am. A

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A scalable adaptive optics (AO) control system architecture composed of asynchronous control clusters based on the stochastic parallel gradient descent (SPGD) optimization technique is discussed. It is shown that subdivision of the control channels into asynchronous SPGD clusters improves the AO system performance by better utilizing individual and/or group characteristics of adaptive system components. Results of numerical simulations are presented for two different adaptive receiver systems based on asynchronous SPGD clustersone with a single deformable mirror with Zernike response functions and a second with tip-tilt and segmented wavefront correctors. We also discuss adaptive wavefront control based on asynchronous parallel optimization of several local performance metrics-a control architecture referred to as distributed adaptive optics (DAO). Analysis of the DAO system architecture demonstrated the potential for significant increase of the adaptation process convergence rate that occurs due to partial decoupling of the system control clusters optimizing individual performance metrics.

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Atmospheric laser communication system with wide-angle tracking and adaptive compensation

Cited by 6 publications

References 4 publications

Analysis of free-space laser signal intensity over a 2.33 km optical path

Analysis of free-space laser signal intensity over a 2.33 km optical path

Off-axis catadioptric fisheye wide field-of-view optical receiver for free space optical communications

Adaptive wavefront control with asynchronous stochastic parallel gradient descent clusters

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