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The focus of light—linear polarization breaks the rotational symmetry of the focal spot

2003; Taylor & Francis; Volume: 50; Issue: 12 Linguagem: Inglês

10.1080/09500340308235246

1362-3044

Ralf Dorn, S. Quabis, Gerd Leuchs,

Advanced Electron Microscopy Techniques and Applications

Abstract We experimentally demonstrate for the first time that a linearly polarized beam is focused to an asymmetric spot when using a high-numerical aperture focusing system. This asymmetry was predicted by Richards and Wolf in 1959 and can only be measured when a polarization-insensitive sensor is placed in the focal region. We used a specially modified photodiode in a knife-edge-type set-up to obtain highly resolved images of the total electric energy density distribution at the focus. The results are in good agreement with the predictions of a vectorial focusing theory.