Toward fiber-based high-frequency 3D ultrasound imaging

We present a fiber-based optical detection system for high-frequency 3D ultrasound and photoacoustic imaging. Optically probing the surface of a thin polymer Fabry-Perot etalon defines the acoustic array geometry and element size. We have previously demonstrated wide bandwidth signal detection (>40 MHz) and element size on the order of 15 mu m. By integrating an etalon into a photoacoustic imaging system, high-resolution 3D images were obtained. However, the previous system is limited for clinical applications because the etalon is rigidly attached to a free-space optical scanning system. To move etalon detector technology toward a practical clinical device, we designed a remote-probe system based on a fiber bundle. A fiber bundle, composed of 160,000 individual light guides of 8-mu m diameter, delivers the optical probe to the etalon. Light coupled into a single guide creates an active element on the etalon surface. We successfully measured the ultrasound signals from 10 MHz and 50 MHz ultrasound transducers using a laser tunable around 1550 nm. With further progress on reducing the size of the etalon, it will be possible to build a practical device for in vivo high-frequency 3D ultrasound and photoacoustic imaging, especially for intravascular and endoscopic applications.