Optical Processing, 2

A photographic reduction is made of the section to be processed (in VARIABLE DENSITY for example). Each white, linear element of a seismic EVENT, a REFLECTION for example, acts as a slit and will give a diffraction image made up of a succession of luminuous points aligned in a straight line cutting the optical axis and perpendicular to the straight line element corresponding to the section. The brightness of these different points is proportional to the spacing of the neighbouring linear elements on the section. From a central point at which the brightness is at an absolute maximum, the brightness of the following luminuous points (of the 1st, 2nd order, etc…) decreases rapidly.