A magneto‐optic small spot Kerr photometer device with a sampling spot size in the range of 4 &mgr;m is described. Key design features of the instrument include long working distance, large air‐core electromagnetic field coils, a sample holder which accommodates large samples, and a modulation detection scheme. DirectBHloops or the derivative, susceptibility signals can be obtained from a local area illuminated by the laser spot. The instrument can be used to obtain variations in magnetic properties across a large sample and is particularly suitable in wafer level testing in a manufacturing as well as research environment. Some studies done on soft magnetic films using this equipment are presented as examples of the versatility of the instrument.