Abstract: Magnetic scanning apparatus including means for generating an excitation magnetic field 1 in a region in which a specimen to be scanned may be placed, a detector 3 for detecting a magnetic field originating from or modified by a specimen being scanned and a sheet of magnetic material 2 to nullify the excitation field in the region of the detector 3. The means for generating the excitation field 1 may be an array of permanent magnets 6. The detector 3 may be an array of galvom devices such as Hall Effect devices. A display 5 may be included in the detector. The display may include a number of pixels, one for each of the galvomagnetic devices of the detector 3.