G. Howells et al., DETECTION OF PRINTED MAGNETIC INKS USING A ROOM-TEMPERATURE SCANNING MAGNETIC MICROSCOPE, Measurement science & technology, 8(7), 1997, pp. 734-737
We describe a room-temperature scanning magnetic microscope of novel d
esign which can be used at a spatial resolution of a few microns to im
age information stored on magnetic inks used in a variety of printing
processes. We suggest that this imaging technique could find general a
pplication in the inspection of currency notes and credit cards.