A system and method for coupling acoustic energy within a waveguide provides highly efficient and sensitive acoustic energy generation and detection. In particular, an ultrasound angioplasty system is described which makes use of an end-fire array of ring transducers to produce highly directionalized...http://www.google.co.uk/patents/US5813998?utm_source=gb-gplus-sharePatent US5813998 - Method and system for coupling acoustic energy using an end-fire array
