Ultrasound transducer with extended focus

摘要

An ultrasound transducer having an extended focus for enabling an ultrasound imaging catheter to image features at a distance from the transducer with a high resolution and a high penetration depth. The ultrasound transducer is configured such that the acoustic path-length from the periphery of the transducer is increased relative to the acoustic path-length from the center of the transducer thereby increasing the transition length and focal length of the transducer. The ultrasound transducer may include an acoustic element having a convex surface on a side which transmits and receives ultrasound waves. An acoustic backing material may be attached to the acoustic element opposite the side where ultrasound waves are transmitted and received, and an acoustic matching layer may be provided on the convex surface of the acoustic element. The acoustic matching layer may have a substantially uniform thickness such that it also has a convex outer surface. The radius of curvature of the convex surface of the acoustic transducer element will determine the focal length for a given size and frequency of operation of the ultrasound transducer.