Exterior caustics produced in scattering of a diagonally incident plane wave by a circular cylinder: semiclassical scattering theory analysis

Rie use the semiclassical limit of electromagnetic wave scattering theory t o determine the properties of the exterior caustics of a diagonally inciden t plane wave scattered by an infinitely long homogeneous dielectric circula r cylinder in both the near zone and the far zone. The transmission caustic has an exterior/interior cusp transition as the tilt angle of the incident beam is increased, and each of the rainbow caustics has a far-zone rainbow /exterior cusp transition and an exterior/interior cusp transition as the i ncident beam tilt angle is increased. We experimentally observe and analyze both transitions of the first-order rainbow. We also compare the predictio ns of the semiclassical approximation with those of ray theory and exact el ectromagnetic wave scattering theory. (C) 2000 Optical Society of America [ S0740-3232(00)01010-3]. OCIS codes: 080.1510, 290.4020.