Progress with gas lenses

Michaelis, M.M.; Kuppen, M.; Prause, A.; Forbes, Andrew; Viranna, N.; Lisi, N.

doi:10.1017/s0263034600010156

Cited by 6 publications

(5 citation statements)

References 18 publications

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“…where n 0 is the refractive index along its axis, r is the radial distance from the axis and γ is a constant given by the parameters of the SPGL [4]. This implies that only defocus (curvature) is introduced to the wavefront of the passing beam.…”

Section: Spinning Pipe Gas Lensmentioning

confidence: 99%

“…4. The inverse relationship between focal length and rotation speed for a given pipe wall temperature is typical of such lenses [4]. At high rotation speeds (ω) and large temperatures (T) the lens is strong, typically in the range of a few meters.…”

Section: Spgl Lensingmentioning

confidence: 99%

“…Rather the lens is assumed to be perfect, while the propagating field is always assumed to be best described by the ray approximation. Mention is only made of so-called 'near diffraction limited' spots [4], but this is insufficient information to propagate the resulting beam.…”

Section: Introductionmentioning

confidence: 99%

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Optical aberrations in a spinning pipe gas lens

Mafusire¹,

Forbes²,

Michaelis³

et al. 2008

Opt. Express

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If a heated pipe is rotated about its axis, a density gradient is formed which results in the pipe acting as a graded index lens. In this study we revisit the concept of a spinning pipe gas lens and for the first time analyse both the wave propagation of optical fields through the lens, and determine the optical aberrations introduced by the lens to the laser beam. We show that such lenses are highly aberrated, thus having a deleterious effect on the laser beam quality.

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Section: Spinning Pipe Gas Lensmentioning

confidence: 99%

Section: Spgl Lensingmentioning

confidence: 99%

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Optical aberrations in a spinning pipe gas lens

Mafusire¹,

Forbes²,

Michaelis³

et al. 2008

Opt. Express

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show abstract

“…As stated previously, Martynenko 1 demonstrated the theoretical basis of the device which was later demonstrated as a possible practical tool for focusing high-power laser beams. [2][3][4] Using the device as a telescope objective 6 showed that the SPGL is an imperfect lens because the images produced were of low resolution, which we assume was a result of the large number of aberrations generated by the SPGL. This finding inspired us to characterise these aberrations using a CFD model 7,8,10 and direct measurement 7,8 .…”

Section: Discussionmentioning

confidence: 99%

“…It is well known that the resulting density distribution inside the pipe is conducive to focusing laser beams through the gradient index (GRIN) lens principle. [1][2][3][4][5][6][7][8] The spinning pipe gas lens was invented by Martynenko 1 , and was subsequently developed for use as a 'damage-free' lens for focusing of high-power laser fields, [2][3][4] and as a gas telescope for astronomical imaging 6 . The principle of operation is simple: the shear viscosity of air increases when heated, 9 such that when the outside wall of the pipe is heated, the layer of air next to the pipe's inner wall is heated as well.…”

Section: Introductionmentioning

confidence: 99%

Spinning pipe gas lens aberrations along the axis and in the boundary layer

Mafusire

Forbes

2013

S. Afr. J. Sci.

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When the walls of an open-ended horizontal steel pipe are heated before the pipe is rotated along its axis, the exchange of the expelled heated air with the incoming cooler air, sucked in along the axis, results in a medium capable of focusing a laser beam propagating along the pipe's axis-a spinning pipe gas lens. However, the interaction of the heated and cooler air generates local density fluctuations which generate aberrations on the laser beam wavefront. We present results for the characterisation of these aberrations using a Shack-Hartmann wavefront sensor. The measurements show that along the axis, rotating the pipe decreases y-tilt as a result of the removal of distortions caused by gravity, although there is an increase in higher-order aberrations. However, in the boundary layer, the dominant aberration is x-astigmatism which increases with rotation speed. The results are confirmed by the measurement of the beam quality factor which increases as a result of the increase in the size of the higher-order aberrations. The spinning pipe gas lens is a device which can be used to focus laser beams using air only, but, in the process, the air introduces distortions which reduce the quality of the beam.

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Gas and plasma structures

Michaelis

Conti

McKenzie

et al. 2000

High-Power Laser Ablation II

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The words of this title may at first seem incompatible. We review a range of experiments where dynamic structures have been created. We show that it is possible to construct gas and plasma shapes using colliding shocks cigars and cylinders, curved waveguides, and even waveguides with rectangular cross sections. The colliding plasma lens/isolator lead to the colliding shock lens. We now suggest that colliding shock waveguides could find application in laser acceleration and soft X ray schemes. Colliding shock waveguides can be as long as necessary unlike gas jets.

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Progress with gas lenses

Abstract: Three gas lenses appear promising for fusion and other applications. We review progress of the understanding and scaling of two of these lenses and discuss their potential for industry, advanced research, and fusion.

Cited by 6 publications

References 18 publications

Optical aberrations in a spinning pipe gas lens

Optical aberrations in a spinning pipe gas lens

Spinning pipe gas lens aberrations along the axis and in the boundary layer

Gas and plasma structures

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