Irradiance tailoring as a method of reducing thermal blooming in an absorbing medium

Wallace, James; Itzkan, Irving; Camm, Jacqueline

doi:10.1364/josa.64.001123

Cited by 16 publications

(5 citation statements)

References 6 publications

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“…[90]. These results, described as preliminary, showed advantages to tailoring of the laser-beam intensity contours by using an intensity ramp with the intensity increasing in the wind direction and cylindrical focusing optics to counteract the defocusing of the beam in the direction transverse to the wind.…”

Section: G Effects Of Beam Shapementioning

confidence: 71%

High-power laser propagation: Thermal blooming

Smith¹

1977

Proc. IEEE

165

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Absrmcr-This paper presents a tutorial review of the self-induced thermal distortion of laser radiation propagating in absorbing media.The distortion of the laser beam is the result of heating of the path by absorption of a small fraction of the laser beam power by the medium which changes the index of refraction and therefore distorts the beam. Thermal-blooming effects can limit the laser powen which can be effectively propagated through the atmosphere, or in media which absorb laser power such as industrial or laboratory environments, Muid or gas cells, or even laser active media themselves. In this paper, we review the steadystate thermal blooming of CW beams including laboratory-simulation experiments and computer-code results. The thermal distortion of pulsed-laser radiation is also covered including single-pulse thermal distortion and the distortion of a train of laser pulses In these discussions, we derive and identify the scaling laws and determine the important nondimensional parameters so that the results can be interpreted and applied to other propagation conditions. The thermal-blooming problem can be complicated by a number of circumstances, such as the geometry of the propagation path, and these special cases are also reviewed. Among those covered a r e : the influence of stagnation zones, transonic flow, the kinetic cooling effect, molecular and aerosol absorption and relaxation, laser-beam jitter, and atmospheric turbulence. In addition, the techniques utilized to minimize blooming, such as laser-beam shaping, and adaptivmptics phase conection, are also discussed.

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Section: G Effects Of Beam Shapementioning

confidence: 71%

High-power laser propagation: Thermal blooming

Smith¹

1977

Proc. IEEE

165

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“…Figures 12 to 18 reveal that there is some correlation between the DODFM and ~rF(03C1, 0). 5. Conclusions.…”

Section: Resultsmentioning

confidence: 96%

“…3.1 TEMPERATURE DISTRIBUTION. -Assuming that the coupling between laser and air is only at the entrance of the medium, the heat equation is written as Taking equation (5) into consideration, substituting T. = T/To, p = r/R (for Gaussian distributions R is the 1/e radius), and F(r, z) = F(r, 0) exp(u. z), and assuming as a solution for equation 15equation 15 17is assumed as a power series :…”

Section: Te20 Modementioning

confidence: 99%

“…Based on the paraxial approximation, they reduced the problem to a nonlinear differential equation in a single characterizing parameter, namely, the « beamwidth parameter ». Wallace et aL [5] evaluated the impact of irradiance tailoring as a method of reducing the influence of the refractive effects caused by the heating of the medium. The process is to create, by irradiance shaping, only correctable phase changes along the propagation path.…”

Section: Introductionmentioning

confidence: 99%

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On atmospheric optical communications

El-Badawy

El-Halafawy

1984

Rev. Phys. Appl. (Paris)

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2014 La diffraction d'une porteuse puissante qui se propage dans une chaine de communication non guidée (atmosphère sèche) est plus rigoureusement étudiée. Quatre points pertinents sont examinés i) distribution radiale de la température, ii) paramètre « largeur moyenne du faisceau », iii) facteur de mérite normalisé de distortion optique, et iv) mise en forme d'un champ optique pour réduire la diffraction créée par les effets réfractifs. Abstract 2014 This paper investigates, more rigorously, the diffraction of a powerful optical carrier propagating in an unguided communication channel (dry atmosphere). Four main relevant topics are considered i) the radial temperature distribution, ii) the average beamwidth parameter, iii) a dimensionless optical distortion figure of merit, and iv) the irradiance tailoring technique as a method to reduce the diffraction caused by refractive effects.

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“…The advent of very intense lasers has led to a number of theoretical and experimental investigations of the distortion of intensity profiles (thermal blooming) in nonlinear media [Gebhardt and Smith, 1972;Wallace, 1972;Al[erness, 1974;Buser and Rohde, 1975;Gebhardt, 1976]. Some [Fried, 1974;Wallace et al, 1974] have specifically considered the question of tailoring the initial intensity profile to minimize thermal blooming. However, the studies have been limited to the geometrical-optics approximations, neglecting diffraction effects, or have relied on extensive computer solutions; no satisfactory optimization of the beam-tailoring problem has been obtained.…”

Section: Introductionmentioning

confidence: 99%

Theory of laser beam intensity profile distortions in turbulent media

Taylor¹

1977

Radio Science

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Analytical expressions are obtained for the mean-square nth moments of beam intensity profile, for the mean-square perturbation of the spatial spectrum, and for the variance of intensity integrated over an aperture for finite beams propagating in turbulent media. The theory is based on the assumption of the existence of a phase autocorrelation which is a function of the transverse difference coordinates and is illustrated using the approximation of linear optics and the Rytov approximation. The theory can be applied to determine the capabilities of optical beam systems in the presence of turbulence. LASER BEAM INTENSITY PROFILEDISTORTIONS 645

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Irradiance tailoring as a method of reducing thermal blooming in an absorbing medium

Cited by 16 publications

References 6 publications

High-power laser propagation: Thermal blooming

High-power laser propagation: Thermal blooming

On atmospheric optical communications

Theory of laser beam intensity profile distortions in turbulent media

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