High Frequency Optoacoustic Transducers for Ultrasonic and Photoacoustic Imaging

Abstract

This chapter explores methods for high efficiency optoacoustic transduction using modern fabrication and materials technologies developed primarily for the communications industry. It presents methods to generate high-frequency ultrasound using the thermoelastic effect and detect ultrasound using resonant optical detectors. The front end of all ultrasound and photoacoustic imaging systems includes an ultrasonic transducer to convert pressure waves into electric signals. Etalon detectors have many advantages for both ultrasound and photoacoustic imaging. The spatial resolution of an etalon sensor is limited first by the resolution of the optical system used with the probe laser. Measuring the reflected optical power modulation in response to an ultrasonic pulse for a calibrated transducer yields the etalon sensitivity in units of watts per megapascal. An etalon-based imager could be embedded into the catheter guide-wire, providing image guidance and image-monitored positioning and deployment of angioplasty catheters.