Abstract

Diffraction from perfectly conducting wedges having angular and rounded edges was investigated using geometrical diffraction theory. Both plane and cylindrical incident waves were considered. In all cases, the illumination was assumed to strike the edge at right angles, with the electric vector polarized parallel to the diffracting edge. Several exact solutions are available for comparison with the geometrical approximation to the diffracted field, e.g., Sommerfeld’s solution for a thin screen. On either side of the shadow boundary, outside of a narrow transition region where the geometrical field is singular, the agreement with these exact solutions proves to be excellent. Wedge diffraction patterns, computed on the basis of the geometrical theory, were found to display a dependence on edge radius but no significant dependence on wedge angle. A particularly simple quadratic relationship between fringe visibility and edge radius was uncovered which could provide a practical basis for measuring edge radii ranging as small as the wavelength of the incident radiation. Such measurements would, for example, be useful for characterizing surgical scalpel blades.

© 1985 Optical Society of America