This research uses ultrasonic standing waves to arrange sub-micron size particles within polymeric materials in layered or stratified configurations. Such composites have the potential to exhibit unique mechanical and transport properties. Through the combination of ultrasonics, polymer science, and particle science, it is hoped that a range of advanced thinfilm materials can be developed as ba...

We present the theory and some applications of the synthetic aperture focusing technique applied to single transducer ultrasonic data sets. In this technique a virtual source located at the geometrical focal point of the physical transducer is algorithmically generated and thus allows for tighter focusing over a geometrically larger scan volume. We present results from a structural test phantom...

Guided wave focusing has been developed as a promising technique for defect detection in pipeworks, where non-axisymmetric flexural modes are tuned so that ultrasonic energy can be focused at a target point in a pipe. If a defect is located at the target point, large amplitude reflected waves can be observed. In this study, the focusing phenomenon is analyzed using a semi-analytical finite elem...

For diagnostic or therapeutic technologies using femtosecond laser-induced optical breakdown (LIOB) in turbid biological tissues, pulses of sufficient fluence must be delivered to the site of interest. As light attenuates and diffuses rapidly due to wavelength-dependent absorption and scattering, it is important to develop penetration optimization schemes. In this study, we use a high frequency...

We report a photoacoustic imager that utilizes a focused laser beam in combination with a 20 MHz ultrasound focusing transducer to obtain micron-resolution tissue images over a long working distance. The imager is based on a ring transducer that combines ultrasonic and laser beams collinearly and confocally in a monolithic element. The combination of focused laser beam and short pulse irradiati...

The synthetic aperture focusing technique (SAFT) is often used for imaging in non-destructive ultrasonic testing. Conventional SAFT is well suited for contact testing of homogeneous objects because of the constant sound speed throughout the media, whereas the refraction present in the practically important case of immersion tests has so far prevented a widespread use of SAFT for such data. Fort...

The effects of high intensity focused ultrasound (HIFU)-induced continuously varying thermal gradients on sound ray propagation were modeled theoretically. This modeling was based on Fermat's variational principle of least time for rays propagating in a continuously varying thermal gradient described by a radially symmetric heat equation. Such thermal lenses dynamically affect HIFU beam focusin...