Beam deflector for the transformation of a parallel rays - bundle in a constant incidence rays - bundle on a cylinder body

摘要

A deflector for exciting Lamb waves at the surface of a cylindrical part having a polygonal or circular directrix converts a beam of rays parallel to the generating-lines of the part into a beam of rays which impinge upon the surface at a constant angle of incidence in a family of broken helices. The deflector comprises a plurality of flat deflecting elements each associated with one face of the part and having an orientation defined by the direction of a normal. In order to produce excitation in phase of the Lamb waves from one face to another on the concurrent segments od a broken helix, the planes of two flat deflecting elements are deduced from each other by a movement of rotation about a parallel to the generating lines followed by a movement of translation parallel to the generating-lines of the part.