Lensing properties of rotational gas flow

Abstract

A negative lens comprised of a gas in steady axisymmetric flow is demonstrated experimentally and analyzed. The lens has potential applications in high-intensity laser optics and presents the possibility of adjusting the focusing properties of the lens on a sub-millisecond time-scale. It can be operated in environments where conventional optical elements are vulnerable.

Vortex dynamics and applications to gaseous optical elements

“…While the vortex lens can find applications in both negative (neutral gas) and positive (plasma) configurations [8], laser guiding is possible only in a plasma channel with a density minimum on axis. As shown above, the gas density in the vortex is already optimized for laser guiding and it is important to ionize the gas in a 'soft' manner, without significant changes to the density profile.…”

“…The neutral gas lenses have small useful aperture (the core) and long focal length, leading to effective f-numbers in the range of hundreds. Ionization, in addition to flipping the sign of the focal length, will shorten the focal length by an order of magnitude or more [8] and reduce the f-number to useful values. Such a plasma lens can be used for enhanced focusing of high intensity lasers [22] and for coupling of intense laser beams into guiding channels.…”

“…In previous work we experimentally demonstrated [8] and simulated [9] the lensing properties of spinning gases. We showed that near the axis of rotation the gas density profile (and refractive index) has a parabolic radial dependence.…”