A research team from TU Wien (Vienna) and Utrecht University (Netherlands) has now been able to show that tailor-made light beams can be constructed that are practically not changed by a disordered medium, but only attenuated. The light beam penetrates the medium, and a light pattern arrives on the other side that has the same shape as if the medium were not there at all.
This idea of "scattering-invariant modes of light" can also be used to specifically examine the interior of objects. The results have now been published in the journal “Nature Photonics”.
The waves on a turbulent water surface can take on an infinite number of different shapes – and in a similar way, light waves can also be made in countless different forms. "Each of these light wave patterns is changed and deflected in a very specific way when you send it through a disordered medium," explains Prof. Stefan Rotter from the Institute for Theoretical Physics at TU Wien.
Together with his team, Stefan Rotter is developing mathematical methods to describe such light scattering effects. The expertise to produce and characterise such complex light fields was contributed by the team around Prof. Allard Mosk at Utrecht University. "As a light-scattering medium, we used a layer of zinc oxide – an opaque, white powder of completely randomly arranged nanoparticles," explains Allard Mosk, the head of the experimental research group.
This method of finding light patterns that penetrate an object largely undisturbed could also be used for imaging procedures.
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