Wide-angle diffraction of the laser beam by a sharp edge

Abstract

UDC 535.2:621Using a rigorous theory of diffraction, we explain the origin and analyze the structure of a wideangle illuminated area observed when a limited beam is diffracted by the sharp edge of an opaque screen. It is shown that the formed plume has the structure of a cylindrical wave traveling from the screen edge and its amplitude is proportional to the beam amplitude at this edge. The observed structure is Young's boundary wave produced by diffraction of the limited beam.

Trajectory-Based Interpretation of Laser Light Diffraction by a Sharp Edge

“…2(b), as the observation screen is displaced further away from the edge, the oscillations on the left-hand side of the diffraction pattern get weaker. These features are well [16,20] and are similar to the features seen in the diffraction pattern of a plane wave [13][14][15]. The phenomenon of long tails in Figs.…”

“…The phenomenon of long tails in Figs. 2(c) and (d) was not noted and studied until recently [20,21]. Anakhov et al [20] analyzed this phenomenon by writing the expression for the electric field as a sum of two contributions, namely a geometrical contribution and a diffraction one.…”

“…2(c) and (d) was not noted and studied until recently [20,21]. Anakhov et al [20] analyzed this phenomenon by writing the expression for the electric field as a sum of two contributions, namely a geometrical contribution and a diffraction one. Here, we have evaluated the total electric and magnetic field and the corresponding energy density for both the freely propagating Gaussian beam and the beam obstructed by the half plane.…”

“…Here it is we do not have a Gaussian, but half a Gaussian, as described by Eq. (20). So, taking this distribution as a whole, we have divided into two parts.…”

“…The theoretical solution for the diffraction of a plane wave by the edge of a perfectly conducting plane was given by Sommerfeld in 1896 [13], which has become a standard starting point in solving diffraction problems for various two dimensional obstacles [14,15]. The diffraction of a Gaussian beam by an edge has been studied since the 1960s [16], although attention was mainly focused on the bright central part [17][18][19] of the diffraction image, while the less pronounced long side tails have not been analyzed until more recently [20,21]. This less pronounced tail extends with decreasing intensity along the diffraction plane on both sides of the diffracted-beam axis.…”