The development of a sideways looking laser ultrasound probe for use in laser angioplasty procedures

A set of laser ultrasound directivity patterns have been presented for samples irradiated within a water medium. The forward-going pattern for aluminium was used to validate the experimental technique and showed reasonable agreement with theory. The backwards-going patterns measured in gelatine showed significant sideways going energy at angles of approximately 70° from the surface normal. This effect was particularly marked for small laser spot sizes but had little dependence on optical absorption coefficient over the range investigated. A pattern was measured for healthy fixed aorta and the pattern showed similar features to the pattern measured in gelatine under similar conditions. Hence, the results indicate that there is the possibility of designing a sideways imaging system using laser-generated ultrasound