Optical filtering of airborne and ground magnetic data

Summary An optical processor has been used to filter ground and aeromagnetic or gravimetric maps in order to obtain information on magnetic or causative bodies buried in the ground. This is accomplished by directional filtering in the Fourier spectrum of the magnetic or gravimetric intensity as displayed on a contour map. Despite certain difficulties inherent to the use of contour maps instead of density maps, some promising results were obtained.The great advantage of this optical filtering technique resides in the fact that no digitization (which is a lengthy and expensive process) is required for the analysis. The optical processor used may carry out the Fourier transform of over ten million points almost instantaneously, and at a very low unit cost, because the required optical system is much cheaper and much faster than a digital system.