Foucault imaging of superconducting fluxons

The Foucault method, one of the classical Lorentz microscopy techniques, is here investigated in order to demonstrate its applicability to in-focus ob servations of superconducting fluxons. As the deflections involved are of t he order of 10(-5)-10(-6) rad, low-angle techniques, high brightness, coher ent illumination, and a low aberration magnetic stage are needed. The first experimental results are presented and discussed in relation with a theore tical model for the fluxon which allows the interpretation of the main feat ures of the observed patterns. (C) 1999 American Institute of Physics. [S00 21-8979(99)03708-1].