A 2D optical ultrasound array using a polymer film sensing interferometer

P.C. Beard, T.N. Mills
2000 IEEE Ultrasonics Symposium. Proceedings. An International Symposium (Cat. No.00CH37121)  
A 2D optical ultrasound receive array has been investigated. The transduction mechanism is based upon the detection of acoustically-induced changes in the optical thickness of a thin polymer film acting as a Fabry Perot interferometer (FPI). A sensor head employing a medium finesse polymer film FPI has been fabricated and characterised. By illuminating the interferometer with a large diameter (12mm) laser beam and raster scanning a photodiode across the reflected output beam, a 2D ultrasound
more » ... a 2D ultrasound array was simulated. To demonstrate the concept, the ultrasound field distributions at various distances from the focus of a 5 MHz focussed ultrasound transducer were mapped. The system was also evaluated by performing transmission ultrasound imaging of several targets of known dimensions. The "array" aperture, defined by the dimensions of the incident optical field, was 12mm in diameter and spatially sampled in 0.1mm steps. Element sizes, defined by the photodiode aperture, were 0.4mm for the foucussed transducer measurements and 0.8mm for the transmission ultrasound images. The wideband (30MHz) noiseequivalent-pressure was 3kPa and the acoustic bandwidth 12MHz. It is considered that this approach has the potential to be used for transmission medical ultrasound, biomedical photoacoustic imaging and ultrasonic field characterisation applications. .
doi:10.1109/ultsym.2000.921534 fatcat:tk5d6un5onh5betj6clnjhkjpq