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Transparent Fabry Perot polymer film ultrasound array for backward-mode photoacoustic imaging

Beard, PC; Zhang, EZ; Cox, BT; (2004) Transparent Fabry Perot polymer film ultrasound array for backward-mode photoacoustic imaging. In: Oraevsky, AA and Wang, LV, (eds.) PHOTONS PLUS ULTRASOUND: IMAGING AND SENSING. (pp. 230 - 237). SPIE-INT SOC OPTICAL ENGINEERING

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Abstract

A novel optical ultrasound sensor has been developed for backward-mode photoacoustic imaging. The sensor is based on a Fabry Perot polymer film interferometer, the mirrors of which are transparent to 1064nm, but highly reflective at 850nm. When illuminated by a CW interrogating laser source at the latter wavelength, the system acts as a resonant Fabry Perot (FP) sensing cavity, the reflected intensity output of which is dependent upon acoustically-induced changes in the optical thickness of the polymer film. By optically addressing different regions of the sensor, a notional ultrasound array of arbitrary aperture and dimensionality can be synthesised. The system was demonstrated in backward mode by transmitting 1064nm excitation laser pulses through the sensor into an Intralipid scattering solution (mu(a) =0.03mm(-1),mu(s)'=1mm(-1)) containing various absorbing structures and detecting the resulting photoacoustic signals over a line. A ID depth profile of a 1.3mm thick absorbing polymer sheet (mu(a)=0.8mm(-1)) immersed to a depth of 12mm in the Intralipid solution was obtained by performing an 11mm linescan. In another experiment, a 3-layer structure consisting of 0.076mm thick line absorbers was immersed in Intralipid and a 21) image reconstructed from the detected photoacoustic signals using an inverse k-space reconstruction algorithm. Lateral resolution was 0.4mm and the vertical resolution 0.1mm. The ability of this system to map wideband photoacoustic signals with high sensitivity in backward mode may provide a useful tool for high resolution imaging of superficial tissue structures such as the skin microvasculature.

Type:Proceedings paper
Title:Transparent Fabry Perot polymer film ultrasound array for backward-mode photoacoustic imaging
Event:Conference on Photons Plus Ultrasound
Location:San Jose, CA
Dates:2004-01-25 - 2004-01-26
ISBN:0-8194-5228-9
Keywords:OPTICAL-PROPERTIES, BLOOD, TOMOGRAPHY, TRANSDUCER, TRANSIENTS
UCL classification:UCL > School of BEAMS > Faculty of Engineering Science > Medical Physics and Bioengineering

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