Figure 5.  Interference patterns created when a point source illuminates an edge.

A.Illumination intensity and interference patterns relative to an edge (X0) based on Cornu’s spiral.  (Feynman, R. P., R. B. Leighton, and M. Sands. 1963. The Feynman Lectures on Physics.  Addison-Wesley Publishing Company, Reading Massachusetts. Volume I.  p. 30-8.)

B.Model adapted by Wood, as originally proposed by Young, to account for the observed interference patterns associated with an edge is based on a circular wave front originating at the edge that interacts with a parallel wave front passing the edge. No explanation for the occurrence of the edge source was presented.  (Wood, R.W. 1934.  Physical Optics. The MacMillan Company. p. 221.)  In accordance with the pulson model such interference patterns are a function of interactions of the primary signal with secondarily generated pulsons as indicated in Fig. 4-B.  Since secondary pulsons are emitted in arcs, the magnitude of their interference effects with the primary signals should decrease with increased distances from the edge as their arcs expand.