Experimental determination of thermal turbulence effects on a
propagating laser beam

Ndlovu, Sphumelele C.; Chetty, Naven

doi:10.1515/phys-2015-0028

Cited by 2 publications

(2 citation statements)

References 27 publications

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“…The experimental setup used in this work was adapted from a previous work by Ndlovu and Chetty (2015). We have chosen to use a laboratory setup as it removes inconsistencies of the atmosphere, such as varying wind velocities, temperatures and flow directions.…”

Section: Methodsmentioning

confidence: 99%

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Wind tunnel simulations to detect and quantify the turbulent effects of a propagating He-Ne laser beam in air

Augustine

Chetty

2017

Atm

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RESUMENSe verifica la efectividad de un diseño experimental para detectar y cuantificar los efectos turbulentos experimentados por un haz de láser de He-Ne al pasar por un túnel de viento. El haz se difundió a través de una serie de componentes ópticos además del túnel de viento diseñado y fabricado en el laboratorio en condiciones controladas. La construcción del túnel obedeció a una configuración preexistente, cuya aptitud para detectar los efectos turbulentos de otros modelos se había comprobado previamente. El diseño experimental fue exitoso, ya que pudo detectar y medir las condiciones atmosféricas al interior del entorno turbulento y cuantificar con precisión las características del haz de láser. Mediante el uso de instrumentos de medición de alta precisión, se pudo medir de forma exitosa la función de la estructura del índice de refracción (C n 2 ) y el diámetro de coherencia (parámetro de Fried). Los valores de C n 2 variaron de 1.61 × 10 -16 m -2/3 a 6.77 × 10 -15 m -2/3 , lo cual puede catalogarse como un régimen de turbulencia moderado a intenso. Estos resultados muestran una buena correspondencia con los de varios trabajos que investigaron entornos atmosféricos similares, de modo que nuestro diseño fue capaz de detectar y medir con precisión las turbulencias térmicas y los efectos de la velocidad del viento en el haz de láser, utilizando para ello un interferómetro de punto de difracción. ABSTRACTIn this paper, we ascertain the effectiveness of our experimental setup in detecting and quantifying the turbulent effects experienced by a He-Ne laser beam as it passes through a wind tunnel. The beam propagated through a series of optical components as well as the in-house designed and manufactured wind tunnel under controlled laboratory conditions. The wind tunnel was built to fit within an existing setup, which has previously proven to be successful in detecting the turbulent effects from other turbulence models. For various wind speeds and temperature settings, the setup has been successful as it was able to detect and measure the atmospheric conditions within the turbulent environment and fully quantify the characteristics of the laser beam. With the use of highly accurate measuring devices, we were able to successfully measure the refractive index structure function (C n 2 ) and the coherence diameter (Fried's parameter , which can be classified under the moderate to strong turbulence regime. These results tie in well with various published works for similar atmospheric scenarios hence this setup was successfully able to fully detect and quantify the thermal turbulence and wind velocity effects on the laser beam using a point diffraction interferometer.

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Section: Methodsmentioning

confidence: 99%

“…By introducing a wind element into the setup, a new technique for characterizing the laser beam will be explored. As with previous works by Ndlovu and Chetty (2015) and Augustine and Chetty (2014), we set out to minimize the cost and time devoted to our testing procedures.…”

Section: Methodsmentioning

confidence: 99%

Wind tunnel simulations to detect and quantify the turbulent effects of a propagating He-Ne laser beam in air

Augustine

Chetty

2017

Atm

Self Cite

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Experimental analysis of a laser beam propagating in angular turbulence

Enoch

Chetty

2022

Open Physics

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In this work, a Gaussian laser beam is propagated through a thermally turbulent region before passing through a point diffraction interferometer to produce a circular interferogram. This was done to ascertain how turbulent windstreams of various wind speeds and temperatures affect a laser beam when directed at different angles to the beam axis. The interferometric results portray a clear dependence on the angle of application. That is, deviations away from 90° result in increased wavefront fluctuations. The refractive index structure constant, Rytov variance, and Fried’s parameter were computed to quantify each turbulent model. The attributed strength regimes of these atmospheric parameters were in varying degrees of agreement with the interferometric data. These contradictions and resulting conclusions were discussed in full.

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Experimental determination of thermal turbulence effects on a propagating laser beam

Cited by 2 publications

References 27 publications

Wind tunnel simulations to detect and quantify the turbulent effects of a propagating He-Ne laser beam in air

Wind tunnel simulations to detect and quantify the turbulent effects of a propagating He-Ne laser beam in air

Experimental analysis of a laser beam propagating in angular turbulence

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