Acoustic lens for plane-wave to spherical-wave transformation - divides tubular acoustic waveguide between two media sepd. by eg polystyrene with conical and ellipsoidal faces

摘要

The biconcave lens (1) has rotational symmetry about its central axis (A) and presents to the medium (M1) in which the plane wave is propagated a surface (3) of revolution of a section of straight line (G) inclined at an angle (alpha) to the axis. The refracted wave enters the downstream medium (M3) via a surface (4) of revolution of a section of ellipse (E) having its major axis (H) inclined at a smaller angle (beta). The aperture angle (gamma) is double the inclination (delta) of the minor axis. USE/ADVANTAGE - In eg medical ultrasonic therapy, aberrations are minimised and losses by reflection are reduced.