Modified differential phase contrast Lorentz microscopy for improved imaging of magnetic structures

A modification to the differential phase contrast mode of Lorentz microscopy is proposed in which an annular quadrant detector is used instead of the standard solid quadrant detector. The new imaging mode allows a high degree of control over the relative efficiencies with which low and high spatial frequency information can be transferred from the specimen to the image. This makes it possible to effect a considerable separation of contrast arising from magnetic and nonmagnetic origins in thin polycrystalline magnetic films and thus reveals finer magnetic detail than was hitherto possible. Experimental details of the implementation of the technique, together with examples of its use for investigating thin-film recording media, are presented