Fabrication of low directional acoustic transducers for intravascular forward-looking imaging

This paper describes an intravascular ultrasound forward-looking imaging and a fabrication of low directional acoustic transducer. We used a forward-looking ultrasound probe (FLUP) as acoustic sources and receivers to make an ultrasound forward-looking image, but a clear image could not be obtained because of strong directivity of the FLUP. By using laser induced breakdown (LIB) as acoustic sources and the FLUP as receivers, a fine image of reflector was successfully obtained because of the LIB can provide an almost completely spherical ultrasound pulse wave. For using LIB in a human body, an intravascular fiber-optic ultrasound transmitter was fabricated. A low directional convex shape 1-3 composite PZT transducer (0.7 mm in diameter and 0.75 mm curvature radius) was fabricated. Decreased the directivity of the fabricated convex shape 1-3 composite PZT was confirmed, and an 8 ring-array convex shape 1-3 composite PZT transducers (3 mm in outside diameter and 1.5 mm in inside diameter) has been fabricated as receivers. These low directional acoustic transducers are suitable for decreasing the directional loss of the echo signal from the reflector.