Coherent magnetic imaging by TEM

A novel transmission electron microscope optimised for the study of magnetic material is described. Using this instrument, a new method for revealing magnetic structures, coherent Foucault imaging, can be realised. Images appear directly in the form of magnetic interferograms and provide immediate access to a quantitative description of the induction distribution across the specimen. A simple analytical approach is given to the underlying theory and the main features are confirmed by computer modelling. Experimental images of small regular permalloy elements illustrate the power of the technique for studying domain structures