Naked eye picometer resolution in a Michelson interferometer using conjugated twisted beams

Michelson interferometry is one of the most widely used techniques for accuracy measurements. Its main characteristic feature is to infer a displacement in one of the arms of the interferometer from a phase measurement. Two different twisted beams, also called vortex beams, with opposite twisted rotations in each arm of the interferometer interfere in a daisy flower-like pattern. The number of petals is twice the topological charge. Their position depends on the relative phase of the beams. Naked eye detection of 44 pm displacements is achieved. The sensitivity of such an interferometer together with possible further improvements, and applications are then discussed.