Optical aberrations have been studied for centuries, placing fundamental limits on the achievable resolution in focusing and imaging. In the context of structured light, the spatial pattern is distorted in amplitude and phase, often arising from optical imperfections, element misalignment, or even from dynamic processes due to propagation through perturbing media such as living tissue, free-space, underwater and optical fibre. Here we show that the polarisation inhomogeneity that defines vectorial structured light is immune to all such perturbations, provided they are unitary. By way of example, we study the robustness of vector vortex beams to a variety of complex channels, demonstrating that the inhomogeneous nature of the polarisation remains unaltered from the near-field to far-field, even as the structure itself changes. We go on to show how this can be used for noisy free optical communication across noisy channels.
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