Power Reduction and Fluctuations Caused by Narrow Laser Beam Motion in the Far Field

Titterton, Paul J.

doi:10.1364/ao.12.000423

Cited by 51 publications

(25 citation statements)

References 2 publications

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“…͑ii͒ Titterton 17 was the first author, to our knowledge, who dealt with the scintillation and beamwander phenomena simultaneously and, in fact, as two independent effects. He showed that the power fluctuations caused by beam tilt can be substantially greater than those caused by scintillation.…”

Section: Rytov's Theory and Beam Wandermentioning

confidence: 99%

Scintillation and beam-wander analysis in an optical ground station-satellite uplink

et al. 2004

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In an optical communication link between an optical ground station and a geostationary satellite the main problems appear in the uplink and are due to beam wander and to scintillation. Reliable methods for modeling both effects simultaneously are needed to provide an accurate tool with which the robustness of the communication channel can be tested. Numerical tools, especially the split-step method ͑also referred to as the fast-Fourier-transform beam propagation method͒, have demonstrated their ability to deal with problems of optical propagation during atmospheric turbulence. However, obtaining statistically significant results with this technique is computationally intensive. We present an analyticalnumerical hybrid technique that provides good information on the variance in optical irradiance with an important saving of time and computational resources.

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Section: Rytov's Theory and Beam Wandermentioning

confidence: 99%

Scintillation and beam-wander analysis in an optical ground station-satellite uplink

et al. 2004

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“…Propagation of the beam through turbulent conditions has shown that it undergoes a loss of coherence, focus and beam spread (Chernov, 1967;Esposito, 1967). The extent to which scintillation and beam wander occur depends largely on the combination of temperature, wind velocity and convection factors (Titterton, 1973). The key to obtaining information about the way in which beams are affected by turbulence is to determine the refractive index structure coefficient C 2 n given by (Andrews and Phillips, 1988) …”

Section: Theorymentioning

confidence: 99%

Experimental verification of the turbulent effects on laser beam propagation in space

Augustine¹,

Chetty²

2014

Atmósfera

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RESUMEN óíntegramente los efectos térmicos de un rayo láser que se propaga en el aire. Las mejoras incorporadas al diseño previo incluyeron un láser más potente, un sistema de formación de turbulencias de alta precisión, un sensor de presión integrado, y una plataforma para ajustar la altura entre el rayo láser y el modelo de turbulencia. Este diseño no sólo puede reproducir resultados previos con exactitud, sino que además permitió la medición exitosa de nuevos datos sobre la intensidad de la turbulencia C 2 n , la varianza de Rytov (cintilación) y el diámetro de coherencia (parámetro de Fried). Los interferogramas resultantes se analizaron utilizando transformadas rápidas de Fouse incrementan en relación con la temperatura. La región turbulenta mostró perturbaciones muy intensas, en el rango de 1.1 × 10 -12 m -2/3 a 2.7 × 10 -12 m -2/3 . A pesar de la intensidad de la turbulencia, con relación a la cintilación se demostró algo diferente, ya que la condición para un entorno de turbulencia débil se determinó en el laboratorio y se esperaba un bajo índice de cintilación. Esto es resultado de las distancias de propagación relativamente cortas obtenidas en el laboratorio. En la atmósfera abierta las trayectorias cubren grandes distancias y, para determinar los efectos de la turbulencia, el modelo debe generar turbulencias de mayor efectos térmicos de la turbulencia en un rayo láser en propagación. ABSTRACT beam propagating in air. Improvements made to the setup include a new, more powerful laser, a precision designed turbulence delivery system, an imbedded pressure sensor, and a platform for height adjustability between the laser beam and the turbulence model. The setup was not only able to reproduce previous results exactly but also allowed new data for the turbulence strength C 2 n , the Rytov variance (scintillation) and the coherence diameter (Fried's parameter) to be successfully measured. Analysis of the produced interferograms disturbances, in the range of 1.1 × 10 -12 m -2/3 to 2.7 × 10 -12 m -2/3 . In spite of the strong turbulence strength, scintillation proved otherwise, since the condition for a weak turbulence environment was determined in the laboratory and a low scintillation index was to be expected. This is as a result of the relatively short propagation distances achieved in the laboratory. In the open atmosphere, path lengths extend over vast distances and in order for turbulent effects to be realized, the turbulence model must generate stronger turbulence. The model was, therefore, able to demonstrate its ability to fully quantify and determine the thermal turbulence effects on a propagating laser beam.

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“…22 The distribution of the vertical component of the wander signal for the data run under discussion here is shown in Figure 7. Marked asymmetry about the mean is noted, which is probably a manifestation of slow, large-scale, vertical refractive effects.…”

Section: Wander Distributionmentioning

confidence: 99%

Propagation of Multiwavelength Laser Radiation through Atmospheric Turbulence

Kerr¹,

Elliott²,

Holmes³

et al. 1973

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Power Reduction and Fluctuations Caused by Narrow Laser Beam Motion in the Far Field

Cited by 51 publications

References 2 publications

Scintillation and beam-wander analysis in an optical ground station-satellite uplink

Scintillation and beam-wander analysis in an optical ground station-satellite uplink

Experimental verification of the turbulent effects on laser beam propagation in space

Propagation of Multiwavelength Laser Radiation through Atmospheric Turbulence

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